Verifier and processor

gen pbs
proto changes
2026-01-09 21:38:05 -05:00 · 2022-02-13 21:20:37 -08:00 · 2022-02-10 21:18:12 -08:00 · 2022-02-10 20:01:25 -08:00 · 2022-02-10 23:51:20 -03:00 · 2022-02-10 23:15:01 +00:00
3058 changed files with 255294 additions and 147465 deletions
--- a/.bazelrc
+++ b/.bazelrc
@@ -21,34 +21,24 @@ run --host_force_python=PY2
 build --sandbox_default_allow_network=false

 # Stamp binaries with git information
-build --workspace_status_command=./scripts/workspace_status.sh
+build --workspace_status_command=./hack/workspace_status.sh
 build --stamp

-# Use mainnet protobufs at runtime
-run --define ssz=mainnet
-test --define ssz=mainnet
-build --define ssz=mainnet
-
 # Prevent PATH changes from rebuilding when switching from IDE to command line.
 build --incompatible_strict_action_env
 test --incompatible_strict_action_env
 run --incompatible_strict_action_env

-# Disable kafka by default, it takes a long time to build...
-build --define kafka_enabled=false
-test --define kafka_enabled=false
-run --define kafka_enabled=false
-
 build --define blst_disabled=false
 test --define blst_disabled=false
 run --define blst_disabled=false

-build:kafka_enabled --define kafka_enabled=true
-build:kafka_enabled --define gotags=kafka_enabled
-
 build:blst_disabled --define blst_disabled=true
 build:blst_disabled --define gotags=blst_disabled

+build:minimal --//proto:network=minimal
+build:minimal --@io_bazel_rules_go//go/config:tags=minimal
+
 # Release flags
 build:release --compilation_mode=opt
 build:release --config=llvm
@@ -72,20 +62,7 @@ build:llvm-asan --config=llvm
 build:llvm-asan --config=asan
 build:llvm-asan --linkopt -fuse-ld=ld.lld

-build:fuzz --define=gotags=libfuzzer
-build:fuzz --config=llvm-asan
-build:fuzz --copt=-fsanitize=fuzzer-no-link
-build:fuzz --linkopt=-fsanitize=fuzzer
-build:fuzz --copt=-fno-omit-frame-pointer
-build:fuzz --define=FUZZING_ENGINE=libfuzzer
-build:fuzz --copt=-DFUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION
-build:fuzz --linkopt -Wl,--no-as-needed
-build:fuzz --define=gc_goopts=-d=libfuzzer,checkptr
-build:fuzz --run_under=//tools:fuzz_wrapper
-build:fuzz --compilation_mode=opt
-build:fuzz --define=blst_disabled=true
-
-test:fuzz --local_test_jobs="HOST_CPUS*.5"
+build:fuzz --@io_bazel_rules_go//go/config:tags=fuzz

 # Build binary with cgo symbolizer for debugging / profiling.
 build:cgo_symbolizer --config=llvm
--- a/.bazelversion
+++ b/.bazelversion
@@ -1 +1 @@
-3.7.0
+4.2.2
--- a/.buildkite-bazelrc
+++ b/.buildkite-bazelrc
@@ -10,7 +10,7 @@

 # Prysm specific remote-cache properties.
 #build:remote-cache --disk_cache=
-build:remote-cache --remote_download_minimal
+build:remote-cache --remote_download_toplevel
 build:remote-cache --remote_cache=grpc://bazel-remote-cache:9092
 build:remote-cache --experimental_remote_downloader=grpc://bazel-remote-cache:9092
 build:remote-cache --remote_local_fallback
@@ -22,7 +22,7 @@ build:remote-cache --incompatible_strict_action_env=true
 # Import workspace options.
 import %workspace%/.bazelrc

-startup --host_jvm_args=-Xmx1000m --host_jvm_args=-Xms1000m
+startup --host_jvm_args=-Xmx2g --host_jvm_args=-Xms2g
 query --repository_cache=/tmp/repositorycache
 query --experimental_repository_cache_hardlinks
 build --repository_cache=/tmp/repositorycache
@@ -41,5 +41,6 @@ build --flaky_test_attempts=5
 # Disabled race detection due to unstable test results under constrained environment build kite
 # build --features=race

-# Disable flaky test detection for fuzzing.
-test:fuzz --flaky_test_attempts=1
+# Better caching
+build:nostamp --nostamp
+build:nostamp --workspace_status_command=./hack/workspace_status_ci.sh
--- a/.github/CODEOWNERS
+++ b/.github/CODEOWNERS
@@ -6,3 +6,11 @@

 # Anyone on prylabs team can approve dependency updates.
 deps.bzl @prysmaticlabs/core-team
+
+# Radek and Nishant are responsible for changes that can affect the native state feature.
+# See https://www.notion.so/prysmaticlabs/Native-Beacon-State-Redesign-6cc9744b4ec1439bb34fa829b36a35c1
+/beacon-chain/state/fieldtrie/ @rkapka @nisdas
+/beacon-chain/state/v1/ @rkapka @nisdas
+/beacon-chain/state/v2/ @rkapka @nisdas
+/beacon-chain/state/v3/ @rkapka @nisdas
+/beacon-chain/state/state-native/ @rkapka @nisdas
--- a/.github/workflows/go.yml
+++ b/.github/workflows/go.yml
@@ -25,6 +25,22 @@ jobs:
        with:
          path: ./

+      - name: GoImports checker
+        id: goimports
+        uses: Jerome1337/goimports-action@v1.0.2
+        with:
+          goimports-path: ./
+
+      - name: Gosec security scanner
+        uses: securego/gosec@master
+        with:
+          args: '-exclude=G307 -exclude-dir=crypto/bls/herumi ./...'
+
+      - name: Golangci-lint
+        uses: golangci/golangci-lint-action@v2
+        with:
+          args: --print-issued-lines --sort-results --no-config --timeout=10m --disable-all -E deadcode  -E errcheck -E gosimple --skip-files=validator/web/site_data.go --skip-dirs=proto
+
  build:
    name: Build
    runs-on: ubuntu-latest
--- a/.gitignore
+++ b/.gitignore
@@ -30,9 +30,5 @@ password.txt
 # Dist files
 dist

-# libfuzzer
-oom-*
-crash-*
-
 # deepsource cli
 bin
--- a/.well-known/security.txt
+++ b/.well-known/security.txt
@@ -5,21 +5,22 @@ Contact: mailto:security@prysmaticlabs.com
 Encryption: openpgp4fpr:0AE0051D647BA3C1A917AF4072E33E4DF1A5036E
 Encryption: openpgp4fpr:CD08DE68C60B82D3EE2A3F7D95452A701810FEDB
 Encryption: openpgp4fpr:317D6E91058F8F3C2303BA7756313E44581297A6
+Encryption: openpgp4fpr:79C59A585E3FD3AFFA00F5C22940A6479DA7C9EC
 Preferred-Languages: en
 Canonical: https://github.com/prysmaticlabs/prysm/tree/master/.well-known/security.txt
 -----BEGIN PGP SIGNATURE-----

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+FpFV0TTsxNLDx+AcR1eQ1nSayO7ImUDIfOQNDDnSZZy42Bc+F+QIGKB3aH/8bpG
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+OP5dZQtX6KPc9ewqqZgn622uHSezoBidgeTkdZsJ6tw2eIu0lsY=
+=V7L0
 -----END PGP SIGNATURE-----
--- a/BUILD.bazel
+++ b/BUILD.bazel
@@ -14,6 +14,7 @@ exports_files([

 # gazelle:prefix github.com/prysmaticlabs/prysm
 # gazelle:map_kind go_library go_library @prysm//tools/go:def.bzl
+# gazelle:map_kind go_test go_test @prysm//tools/go:def.bzl
 # gazelle:map_kind go_repository go_repository @prysm//tools/go:def.bzl
 gazelle(
    name = "gazelle",
@@ -23,7 +24,16 @@ gazelle(
 # Protobuf compiler (non-gRPC)
 alias(
    name = "proto_compiler",
-    actual = "@io_bazel_rules_go//proto:gogofast_proto",
+    actual = "@io_bazel_rules_go//proto:go_proto",
+    visibility = [
+        "//proto:__subpackages__",
+    ],
+)
+
+# Cast protobuf compiler (non-gRPC)
+alias(
+    name = "cast_proto_compiler",
+    actual = "@com_github_prysmaticlabs_protoc_gen_go_cast//:go_cast",
    visibility = [
        "//proto:__subpackages__",
    ],
@@ -32,21 +42,21 @@ alias(
 # Protobuf compiler (gRPC)
 alias(
    name = "grpc_proto_compiler",
-    actual = "@io_bazel_rules_go//proto:gogofast_grpc",
+    actual = "@io_bazel_rules_go//proto:go_grpc",
    visibility = ["//visibility:public"],
 )

-# Protobuf gRPC compiler without gogoproto. Required for gRPC gateway.
+# Cast protobuf compiler (gRPC)
 alias(
-    name = "grpc_nogogo_proto_compiler",
-    actual = "@io_bazel_rules_go//proto:go_grpc",
+    name = "cast_grpc_proto_compiler",
+    actual = "@com_github_prysmaticlabs_protoc_gen_go_cast//:go_cast_grpc",
    visibility = ["//visibility:public"],
 )

 # Protobuf gRPC gateway compiler
 alias(
    name = "grpc_gateway_proto_compiler",
-    actual = "@com_github_grpc_ecosystem_grpc_gateway//protoc-gen-grpc-gateway:go_gen_grpc_gateway",
+    actual = "@com_github_grpc_ecosystem_grpc_gateway_v2//protoc-gen-grpc-gateway:go_gen_grpc_gateway",
    visibility = ["//visibility:public"],
 )

@@ -76,49 +86,51 @@ nogo(
    config = "nogo_config.json",
    visibility = ["//visibility:public"],
    deps = [
-        "@org_golang_x_tools//go/analysis/passes/unsafeptr:go_tool_library",
-        "@org_golang_x_tools//go/analysis/passes/unreachable:go_tool_library",
-        "@org_golang_x_tools//go/analysis/passes/unmarshal:go_tool_library",
-        "@org_golang_x_tools//go/analysis/passes/tests:go_tool_library",
-        "@org_golang_x_tools//go/analysis/passes/structtag:go_tool_library",
-        "@org_golang_x_tools//go/analysis/passes/stdmethods:go_tool_library",
-        "@org_golang_x_tools//go/analysis/passes/shift:go_tool_library",
-        # "@org_golang_x_tools//go/analysis/passes/shadow:go_tool_library",
-        "@org_golang_x_tools//go/analysis/passes/printf:go_tool_library",
-        "@org_golang_x_tools//go/analysis/passes/pkgfact:go_tool_library",
-        "@org_golang_x_tools//go/analysis/passes/nilness:go_tool_library",
-        "@org_golang_x_tools//go/analysis/passes/nilfunc:go_tool_library",
-        "@org_golang_x_tools//go/analysis/passes/loopclosure:go_tool_library",
-        "@org_golang_x_tools//go/analysis/passes/httpresponse:go_tool_library",
-        "@org_golang_x_tools//go/analysis/passes/findcall:go_tool_library",
-        "@org_golang_x_tools//go/analysis/passes/deepequalerrors:go_tool_library",
-        "@org_golang_x_tools//go/analysis/passes/ctrlflow:go_tool_library",
-        "@org_golang_x_tools//go/analysis/passes/copylock:go_tool_library",
-        #  "@org_golang_x_tools//go/analysis/passes/cgocall:go_tool_library",
-        "@org_golang_x_tools//go/analysis/passes/buildtag:go_tool_library",
-        "@org_golang_x_tools//go/analysis/passes/buildssa:go_tool_library",
-        "@org_golang_x_tools//go/analysis/passes/bools:go_tool_library",
-        "@org_golang_x_tools//go/analysis/passes/atomicalign:go_tool_library",
-        "@org_golang_x_tools//go/analysis/passes/atomic:go_tool_library",
-        "@org_golang_x_tools//go/analysis/passes/assign:go_tool_library",
-        "@org_golang_x_tools//go/analysis/passes/inspect:go_tool_library",
-        "@org_golang_x_tools//go/analysis/passes/asmdecl:go_tool_library",
-        "//tools/analyzers/maligned:go_tool_library",
-        "//tools/analyzers/cryptorand:go_tool_library",
-        "//tools/analyzers/errcheck:go_tool_library",
-        "//tools/analyzers/featureconfig:go_tool_library",
-        "//tools/analyzers/comparesame:go_tool_library",
-        "//tools/analyzers/shadowpredecl:go_tool_library",
-        "//tools/analyzers/nop:go_tool_library",
-        "//tools/analyzers/slicedirect:go_tool_library",
-        "//tools/analyzers/ineffassign:go_tool_library",
-        "//tools/analyzers/properpermissions:go_tool_library",
+        "@org_golang_x_tools//go/analysis/passes/unsafeptr:go_default_library",
+        "@org_golang_x_tools//go/analysis/passes/unreachable:go_default_library",
+        "@org_golang_x_tools//go/analysis/passes/unmarshal:go_default_library",
+        "@org_golang_x_tools//go/analysis/passes/tests:go_default_library",
+        "@org_golang_x_tools//go/analysis/passes/structtag:go_default_library",
+        "@org_golang_x_tools//go/analysis/passes/stdmethods:go_default_library",
+        "@org_golang_x_tools//go/analysis/passes/shift:go_default_library",
+        # "@org_golang_x_tools//go/analysis/passes/shadow:go_default_library",
+        "@org_golang_x_tools//go/analysis/passes/printf:go_default_library",
+        "@org_golang_x_tools//go/analysis/passes/pkgfact:go_default_library",
+        "@org_golang_x_tools//go/analysis/passes/nilness:go_default_library",
+        "@org_golang_x_tools//go/analysis/passes/nilfunc:go_default_library",
+        "@org_golang_x_tools//go/analysis/passes/loopclosure:go_default_library",
+        "@org_golang_x_tools//go/analysis/passes/httpresponse:go_default_library",
+        "@org_golang_x_tools//go/analysis/passes/findcall:go_default_library",
+        "@org_golang_x_tools//go/analysis/passes/deepequalerrors:go_default_library",
+        "@org_golang_x_tools//go/analysis/passes/ctrlflow:go_default_library",
+        "@org_golang_x_tools//go/analysis/passes/copylock:go_default_library",
+        #  "@org_golang_x_tools//go/analysis/passes/cgocall:go_default_library",
+        "@org_golang_x_tools//go/analysis/passes/buildtag:go_default_library",
+        "@org_golang_x_tools//go/analysis/passes/buildssa:go_default_library",
+        "@org_golang_x_tools//go/analysis/passes/bools:go_default_library",
+        "@org_golang_x_tools//go/analysis/passes/atomicalign:go_default_library",
+        "@org_golang_x_tools//go/analysis/passes/atomic:go_default_library",
+        "@org_golang_x_tools//go/analysis/passes/assign:go_default_library",
+        "@org_golang_x_tools//go/analysis/passes/inspect:go_default_library",
+        "@org_golang_x_tools//go/analysis/passes/asmdecl:go_default_library",
+        "//tools/analyzers/maligned:go_default_library",
+        "//tools/analyzers/cryptorand:go_default_library",
+        "//tools/analyzers/errcheck:go_default_library",
+        "//tools/analyzers/featureconfig:go_default_library",
+        "//tools/analyzers/comparesame:go_default_library",
+        "//tools/analyzers/shadowpredecl:go_default_library",
+        "//tools/analyzers/nop:go_default_library",
+        "//tools/analyzers/slicedirect:go_default_library",
+        "//tools/analyzers/interfacechecker:go_default_library",
+        "//tools/analyzers/ineffassign:go_default_library",
+        "//tools/analyzers/properpermissions:go_default_library",
+        "//tools/analyzers/recursivelock:go_default_library",
    ] + select({
        # nogo checks that fail with coverage enabled.
        ":coverage_enabled": [],
        "//conditions:default": [
-            "@org_golang_x_tools//go/analysis/passes/lostcancel:go_tool_library",
-            "@org_golang_x_tools//go/analysis/passes/composite:go_tool_library",
+            "@org_golang_x_tools//go/analysis/passes/lostcancel:go_default_library",
+            "@org_golang_x_tools//go/analysis/passes/composite:go_default_library",
        ],
    }),
 )
@@ -133,17 +145,8 @@ common_files = {
    "//:README.md": "README.md",
 }

-toolchain(
-    name = "built_cmake_toolchain",
-    toolchain = "@rules_foreign_cc//tools/build_defs/native_tools:built_cmake",
-    toolchain_type = "@rules_foreign_cc//tools/build_defs:cmake_toolchain",
-)
-
-string_setting(
-    name = "gotags",
-    build_setting_default = "",
-    values = [
-        "",
-        "libfuzzer",
-    ],
+sh_binary(
+    name = "prysm_sh",
+    srcs = ["prysm.sh"],
+    visibility = ["//visibility:public"],
 )
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -175,7 +175,7 @@ We consider two types of contributions to our repo and categorize them as follow

 ### Part-Time Contributors

-Anyone can become a part-time contributor and help out on implementing eth2. The responsibilities of a part-time contributor include:
+Anyone can become a part-time contributor and help out on implementing Ethereum consensus. The responsibilities of a part-time contributor include:

 -   Engaging in Gitter conversations, asking the questions on how to begin contributing to the project
 -   Opening up github issues to express interest in code to implement
@@ -190,7 +190,7 @@ Anyone can become a part-time contributor and help out on implementing eth2. The

 Core contributors are remote contractors of Prysmatic Labs, LLC. and are considered critical team members of our organization. Core devs have all of the responsibilities of part-time contributors plus the majority of the following:

-   Stay up to date on the latest beacon chain sepcification
+-   Stay up to date on the latest beacon chain specification
 -   Monitor github issues and PR’s to make sure owner, labels, descriptions are correct
 -   Formulate independent ideas, suggest new work to do, point out improvements to existing approaches
 -   Participate in code review, ensure code quality is excellent, and have ensure high code coverage
--- a/DEPENDENCIES.md
+++ b/DEPENDENCIES.md
@@ -33,8 +33,8 @@ generates SSZ marshal related code based on defined data structures. These gener
 also be updated and checked in as frequently.

 ```bash
-./scripts/update-go-pbs.sh
-./scripts/update-go-ssz.sh
+./hack/update-go-pbs.sh
+./hack/update-go-ssz.sh
 ```

 *Recommendation: Use go build only for local development and use bazel build for production.*
--- a/INTEROP.md
+++ b/INTEROP.md
@@ -1,6 +1,6 @@
 # Prysm Client Interoperability Guide

-This README details how to setup Prysm for interop testing for usage with other Ethereum 2.0 clients.
+This README details how to setup Prysm for interop testing for usage with other Ethereum consensus clients.

 ## Installation & Setup

--- a/README.md
+++ b/README.md
@@ -1,11 +1,11 @@
-# Prysm: An Ethereum 2.0 Implementation Written in Go
+# Prysm: An Ethereum Consensus Implementation Written in Go

 [![Build status](https://badge.buildkite.com/b555891daf3614bae4284dcf365b2340cefc0089839526f096.svg?branch=master)](https://buildkite.com/prysmatic-labs/prysm)
 [![Go Report Card](https://goreportcard.com/badge/github.com/prysmaticlabs/prysm)](https://goreportcard.com/report/github.com/prysmaticlabs/prysm)
-[![ETH2.0_Spec_Version 1.0.0](https://img.shields.io/badge/ETH2.0%20Spec%20Version-v1.0.0-blue.svg)](https://github.com/ethereum/eth2.0-specs/tree/v1.0.0)
+[![Consensus_Spec_Version 1.1.8](https://img.shields.io/badge/Consensus%20Spec%20Version-v1.1.8-blue.svg)](https://github.com/ethereum/consensus-specs/tree/v1.1.8)
 [![Discord](https://user-images.githubusercontent.com/7288322/34471967-1df7808a-efbb-11e7-9088-ed0b04151291.png)](https://discord.gg/CTYGPUJ)

-This is the core repository for Prysm, a [Golang](https://golang.org/) implementation of the [Ethereum 2.0](https://ethereum.org/en/eth2/) specification, developed by [Prysmatic Labs](https://prysmaticlabs.com). See the [Changelog](https://github.com/prysmaticlabs/prysm/releases) for details of the latest releases and upcoming breaking changes.
+This is the core repository for Prysm, a [Golang](https://golang.org/) implementation of the [Ethereum Consensus](https://ethereum.org/en/eth2/) specification, developed by [Prysmatic Labs](https://prysmaticlabs.com). See the [Changelog](https://github.com/prysmaticlabs/prysm/releases) for details of the latest releases and upcoming breaking changes.

 ### Getting Started

--- a/SECURITY.md
+++ b/SECURITY.md
@@ -0,0 +1,11 @@
+# Security Policy
+
+## Supported Versions
+
+[Releases](https://github.com/prysmaticlabs/prysm/releases/) contains all available releases. We recommend using the [most recently released version](https://github.com/prysmaticlabs/prysm/releases/latest).
+
+## Reporting a Vulnerability
+
+Please see our signed [security.txt](https://github.com/prysmaticlabs/prysm/blob/develop/.well-known/security.txt) for preferred encryption and reporting destination.
+
+**Please do not file a public ticket** mentioning the vulnerability, as doing so could increase the likelihood of the vulnerability being used before a fix has been created, released and installed on the network.
--- a/TERMS_OF_SERVICE.md
+++ b/TERMS_OF_SERVICE.md
@@ -5,7 +5,7 @@ Effective as of Oct 14, 2020
 By downloading, accessing or using the Prysm implementation (“Prysm”), you (referenced herein as “you” or the “user”) certify that you have read and agreed to the terms and conditions below (the “Terms”) which form a binding contract between you and Prysmatic Labs (referenced herein as “we” or “us”). If you do not agree to the Terms, do not download or use Prysm.

 ### About Prysm
-Prysm is a client implementation for Ethereum 2.0 Phase 0 protocol for a proof-of-stake blockchain. To participate in the network, a user must send ETH from the Eth1.0 chain into a validator deposit contract, which will queue in the user as a validator in the system. Validators participate in proposing and voting on blocks in the protocol, and the network applies rewards/penalties based on their behavior. A detailed set of installation and usage instructions as well as breakdowns of each individual component are available in the official documentation portal, however, we do not warrant the accuracy, completeness or usefulness of this documentation. Any reliance you place on such information is strictly at your own risk.
+Prysm is a client implementation for Ethereum consensus protocol for a proof-of-stake blockchain. To participate in the network, a user must send ETH from the Eth1.0 chain into a validator deposit contract, which will queue in the user as a validator in the system. Validators participate in proposing and voting on blocks in the protocol, and the network applies rewards/penalties based on their behavior. A detailed set of installation and usage instructions as well as breakdowns of each individual component are available in the official documentation portal, however, we do not warrant the accuracy, completeness or usefulness of this documentation. Any reliance you place on such information is strictly at your own risk.

 ### Licensing Terms
 Prysm is a fully open-source software program licensed pursuant to the GNU General Public License v3.0.
@@ -13,7 +13,7 @@ Prysm is a fully open-source software program licensed pursuant to the GNU Gener
 The Prysmatic Labs name, the term “Prysm” and all related names, logos, product and service names, designs and slogans are trademarks of Prysmatic Labs or its affiliates and/or licensors. You must not use such marks without our prior written permission.

 ### Risks of Operating Prysm
-The use of Prysm and acting as a validator on the Ethereum 2.0 network can lead to loss of money. Ethereum is still an experimental system and ETH remains a risky investment. You alone are responsible for your actions on Prysm including the security of your ETH and meeting any applicable minimum system requirements.
+The use of Prysm and acting as a validator on the Ethereum network can lead to loss of money. Ethereum is still an experimental system and ETH remains a risky investment. You alone are responsible for your actions on Prysm including the security of your ETH and meeting any applicable minimum system requirements.

 Use of Prysm and the ability to receive rewards or penalties may be affected at any time by mistakes made by the user or other users, software problems such as bugs, errors, incorrectly constructed transactions, unsafe cryptographic libraries or malware affecting the network, technical failures in the hardware of a user, security problems experienced by a user and/or actions or inactions of third parties and/or events experienced by third parties, among other risks. We cannot and do not guarantee that any user of Prysm will make money, that the Prysm network will operate in accordance with the documentation or that transactions will be effective or secure.

--- a/274
+++ b/274
@@ -60,10 +60,10 @@ bazel_skylib_workspace()

 http_archive(
    name = "bazel_gazelle",
-    sha256 = "62ca106be173579c0a167deb23358fdfe71ffa1e4cfdddf5582af26520f1c66f",
+    sha256 = "de69a09dc70417580aabf20a28619bb3ef60d038470c7cf8442fafcf627c21cb",
    urls = [
-        "https://mirror.bazel.build/github.com/bazelbuild/bazel-gazelle/releases/download/v0.23.0/bazel-gazelle-v0.23.0.tar.gz",
-        "https://github.com/bazelbuild/bazel-gazelle/releases/download/v0.23.0/bazel-gazelle-v0.23.0.tar.gz",
+        "https://mirror.bazel.build/github.com/bazelbuild/bazel-gazelle/releases/download/v0.24.0/bazel-gazelle-v0.24.0.tar.gz",
+        "https://github.com/bazelbuild/bazel-gazelle/releases/download/v0.24.0/bazel-gazelle-v0.24.0.tar.gz",
    ],
 )

@@ -76,23 +76,22 @@ http_archive(

 http_archive(
    name = "io_bazel_rules_docker",
-    sha256 = "59d5b42ac315e7eadffa944e86e90c2990110a1c8075f1cd145f487e999d22b3",
-    strip_prefix = "rules_docker-0.17.0",
-    urls = ["https://github.com/bazelbuild/rules_docker/releases/download/v0.17.0/rules_docker-v0.17.0.tar.gz"],
+    sha256 = "1f4e59843b61981a96835dc4ac377ad4da9f8c334ebe5e0bb3f58f80c09735f4",
+    strip_prefix = "rules_docker-0.19.0",
+    urls = ["https://github.com/bazelbuild/rules_docker/releases/download/v0.19.0/rules_docker-v0.19.0.tar.gz"],
 )

 http_archive(
    name = "io_bazel_rules_go",
    patch_args = ["-p1"],
    patches = [
-        # Required until https://github.com/bazelbuild/rules_go/pull/2450 merges otherwise nilness
-        # nogo check fails for certain third_party dependencies.
-        "//third_party:io_bazel_rules_go.patch",
+        # Expose internals of go_test for custom build transitions.
+        "//third_party:io_bazel_rules_go_test.patch",
    ],
-    sha256 = "7c10271940c6bce577d51a075ae77728964db285dac0a46614a7934dc34303e6",
+    sha256 = "2b1641428dff9018f9e85c0384f03ec6c10660d935b750e3fa1492a281a53b0f",
    urls = [
-        "https://mirror.bazel.build/github.com/bazelbuild/rules_go/releases/download/v0.26.0/rules_go-v0.26.0.tar.gz",
-        "https://github.com/bazelbuild/rules_go/releases/download/v0.26.0/rules_go-v0.26.0.tar.gz",
+        "https://mirror.bazel.build/github.com/bazelbuild/rules_go/releases/download/v0.29.0/rules_go-v0.29.0.zip",
+        "https://github.com/bazelbuild/rules_go/releases/download/v0.29.0/rules_go-v0.29.0.zip",
    ],
 )

@@ -137,6 +136,34 @@ load(
    "container_pull",
 )

+container_pull(
+    name = "cc_image_base",
+    digest = "sha256:2c4bb6b7236db0a55ec54ba8845e4031f5db2be957ac61867872bf42e56c4deb",
+    registry = "gcr.io",
+    repository = "distroless/cc",
+)
+
+container_pull(
+    name = "cc_debug_image_base",
+    digest = "sha256:3680c61e81f68fc00bfb5e1ec65e8e678aaafa7c5f056bc2681c29527ebbb30c",
+    registry = "gcr.io",
+    repository = "distroless/cc",
+)
+
+container_pull(
+    name = "go_image_base",
+    digest = "sha256:ba7a315f86771332e76fa9c3d423ecfdbb8265879c6f1c264d6fff7d4fa460a4",
+    registry = "gcr.io",
+    repository = "distroless/base",
+)
+
+container_pull(
+    name = "go_debug_image_base",
+    digest = "sha256:efd8711717d9e9b5d0dbb20ea10876dab0609c923bc05321b912f9239090ca80",
+    registry = "gcr.io",
+    repository = "distroless/base",
+)
+
 container_pull(
    name = "alpine_cc_linux_amd64",
    digest = "sha256:752aa0c9a88461ffc50c5267bb7497ef03a303e38b2c8f7f2ded9bebe5f1f00e",
@@ -160,36 +187,6 @@ go_register_toolchains(
    nogo = "@//:nogo",
 )

-load("@bazel_gazelle//:deps.bzl", "gazelle_dependencies")
-
-gazelle_dependencies()
-
-load("@io_bazel_rules_go//extras:embed_data_deps.bzl", "go_embed_data_dependencies")
-
-go_embed_data_dependencies()
-
-load("@com_github_atlassian_bazel_tools//gometalinter:deps.bzl", "gometalinter_dependencies")
-
-gometalinter_dependencies()
-
-load(
-    "@io_bazel_rules_docker//go:image.bzl",
-    _go_image_repos = "repositories",
-)
-
-# Golang images
-# This is using gcr.io/distroless/base
-_go_image_repos()
-
-# CC images
-# This is using gcr.io/distroless/base
-load(
-    "@io_bazel_rules_docker//cc:image.bzl",
-    _cc_image_repos = "repositories",
-)
-
-_cc_image_repos()
-
 http_archive(
    name = "prysm_testnet_site",
    build_file_content = """
@@ -222,11 +219,15 @@ filegroup(
 )
    """,
    sha256 = "91434d5fd5e1c6eb7b0174fed2afe25e09bddf00e1e4c431db931b2cee4e7773",
-    url = "https://github.com/eth2-clients/slashing-protection-interchange-tests/archive/b8413ca42dc92308019d0d4db52c87e9e125c4e9.tar.gz",
+    url = "https://github.com/eth-clients/slashing-protection-interchange-tests/archive/b8413ca42dc92308019d0d4db52c87e9e125c4e9.tar.gz",
 )

+consensus_spec_version = "v1.1.9"
+
+bls_test_version = "v0.1.1"
+
 http_archive(
-    name = "eth2_spec_tests_general",
+    name = "consensus_spec_tests_general",
    build_file_content = """
 filegroup(
    name = "test_data",
@@ -237,12 +238,12 @@ filegroup(
    visibility = ["//visibility:public"],
 )
    """,
-    sha256 = "deacc076365c727d653ac064894ecf0d1b0a675d86704dc8de271259f6a7314b",
-    url = "https://github.com/ethereum/eth2.0-spec-tests/releases/download/v1.1.0-alpha.3/general.tar.gz",
+    sha256 = "207d9c326ba4fa1f34bab7b6169201c32f2611755db030909a3405873445e0ba",
+    url = "https://github.com/ethereum/consensus-spec-tests/releases/download/%s/general.tar.gz" % consensus_spec_version,
 )

 http_archive(
-    name = "eth2_spec_tests_minimal",
+    name = "consensus_spec_tests_minimal",
    build_file_content = """
 filegroup(
    name = "test_data",
@@ -253,12 +254,12 @@ filegroup(
    visibility = ["//visibility:public"],
 )
    """,
-    sha256 = "6e9886af3d2f024e563249d70388129e28e3e92f742f289238ed9b7ec7a7f930",
-    url = "https://github.com/ethereum/eth2.0-spec-tests/releases/download/v1.1.0-alpha.3/minimal.tar.gz",
+    sha256 = "a3995b39f412db236b2f1db909f288218da53cb53b9923b71dda9d144d68f40a",
+    url = "https://github.com/ethereum/consensus-spec-tests/releases/download/%s/minimal.tar.gz" % consensus_spec_version,
 )

 http_archive(
-    name = "eth2_spec_tests_mainnet",
+    name = "consensus_spec_tests_mainnet",
    build_file_content = """
 filegroup(
    name = "test_data",
@@ -269,95 +270,76 @@ filegroup(
    visibility = ["//visibility:public"],
 )
    """,
-    sha256 = "a7b3d0ffc02a567250f424d69b2474fdc9477cd56eada60af7474560b46a8527",
-    url = "https://github.com/ethereum/eth2.0-spec-tests/releases/download/v1.1.0-alpha.3/mainnet.tar.gz",
+    sha256 = "76cea7a4c8e32d458ad456b54bfbb30bc772481a91954a4cd97e229aa3023b1d",
+    url = "https://github.com/ethereum/consensus-spec-tests/releases/download/%s/mainnet.tar.gz" % consensus_spec_version,
+)
+
+http_archive(
+    name = "consensus_spec",
+    build_file_content = """
+filegroup(
+    name = "spec_data",
+    srcs = glob([
+        "**/*.yaml",
+    ]),
+    visibility = ["//visibility:public"],
+)
+    """,
+    sha256 = "0fc429684775f943250dce1f9c485ac25e26c6395d7f585c8d1317becec2ace7",
+    strip_prefix = "consensus-specs-" + consensus_spec_version[1:],
+    url = "https://github.com/ethereum/consensus-specs/archive/refs/tags/%s.tar.gz" % consensus_spec_version,
+)
+
+http_archive(
+    name = "bls_spec_tests",
+    build_file_content = """
+filegroup(
+    name = "test_data",
+    srcs = glob([
+        "**/*.yaml",
+    ]),
+    visibility = ["//visibility:public"],
+)
+    """,
+    sha256 = "93c7d006e7c5b882cbd11dc9ec6c5d0e07f4a8c6b27a32f964eb17cf2db9763a",
+    url = "https://github.com/ethereum/bls12-381-tests/releases/download/%s/bls_tests_yaml.tar.gz" % bls_test_version,
+)
+
+http_archive(
+    name = "eth2_networks",
+    build_file_content = """
+filegroup(
+    name = "configs",
+    srcs = glob([
+        "shared/**/config.yaml",
+    ]),
+    visibility = ["//visibility:public"],
+)
+    """,
+    sha256 = "4e8a18b21d056c4032605621b1a6632198eabab57cb90c61e273f344c287f1b2",
+    strip_prefix = "eth2-networks-791a5369c5981e829698b17fbcdcdacbdaba97c8",
+    url = "https://github.com/eth-clients/eth2-networks/archive/791a5369c5981e829698b17fbcdcdacbdaba97c8.tar.gz",
 )

 http_archive(
    name = "com_github_bazelbuild_buildtools",
-    sha256 = "b5d7dbc6832f11b6468328a376de05959a1a9e4e9f5622499d3bab509c26b46a",
-    strip_prefix = "buildtools-bf564b4925ab5876a3f64d8b90fab7f769013d42",
-    url = "https://github.com/bazelbuild/buildtools/archive/bf564b4925ab5876a3f64d8b90fab7f769013d42.zip",
+    sha256 = "7a182df18df1debabd9e36ae07c8edfa1378b8424a04561b674d933b965372b3",
+    strip_prefix = "buildtools-f2aed9ee205d62d45c55cfabbfd26342f8526862",
+    url = "https://github.com/bazelbuild/buildtools/archive/f2aed9ee205d62d45c55cfabbfd26342f8526862.zip",
 )

-load("@com_github_bazelbuild_buildtools//buildifier:deps.bzl", "buildifier_dependencies")
-
-buildifier_dependencies()
-
 git_repository(
    name = "com_google_protobuf",
-    commit = "fde7cf7358ec7cd69e8db9be4f1fa6a5c431386a",  # v3.13.0
+    commit = "436bd7880e458532901c58f4d9d1ea23fa7edd52",
    remote = "https://github.com/protocolbuffers/protobuf",
-    shallow_since = "1597443653 -0700",
+    shallow_since = "1617835118 -0700",
 )

-load("@com_google_protobuf//:protobuf_deps.bzl", "protobuf_deps")
-
-protobuf_deps()
-
 # Group the sources of the library so that CMake rule have access to it
 all_content = """filegroup(name = "all", srcs = glob(["**"]), visibility = ["//visibility:public"])"""

-http_archive(
-    name = "rules_foreign_cc",
-    sha256 = "b85ce66a3410f7370d1a9a61dfe3a29c7532b7637caeb2877d8d0dfd41d77abb",
-    strip_prefix = "rules_foreign_cc-3515b20a2417c4dd51c8a4a8cac1f6ecf3c6d934",
-    url = "https://github.com/bazelbuild/rules_foreign_cc/archive/3515b20a2417c4dd51c8a4a8cac1f6ecf3c6d934.zip",
-)
-
-load("@rules_foreign_cc//:workspace_definitions.bzl", "rules_foreign_cc_dependencies")
-
-rules_foreign_cc_dependencies([
-    "@prysm//:built_cmake_toolchain",
-])
-
-http_archive(
-    name = "librdkafka",
-    build_file_content = all_content,
-    sha256 = "3b99a36c082a67ef6295eabd4fb3e32ab0bff7c6b0d397d6352697335f4e57eb",
-    strip_prefix = "librdkafka-1.4.2",
-    urls = ["https://github.com/edenhill/librdkafka/archive/v1.4.2.tar.gz"],
-)
-
-http_archive(
-    name = "sigp_beacon_fuzz_corpora",
-    build_file = "//third_party:beacon-fuzz/corpora.BUILD",
-    sha256 = "42993d0901a316afda45b4ba6d53c7c21f30c551dcec290a4ca131c24453d1ef",
-    strip_prefix = "beacon-fuzz-corpora-bac24ad78d45cc3664c0172241feac969c1ac29b",
-    urls = [
-        "https://github.com/sigp/beacon-fuzz-corpora/archive/bac24ad78d45cc3664c0172241feac969c1ac29b.tar.gz",
-    ],
-)
-
 # External dependencies

-http_archive(
-    name = "sszgen",  # Hack because we don't want to build this binary with libfuzzer, but need it to build.
-    build_file_content = """
-load("@io_bazel_rules_go//go:def.bzl", "go_library", "go_binary")
-
-go_library(
-    name = "go_default_library",
-    srcs = [
-        "sszgen/main.go",
-        "sszgen/marshal.go",
-        "sszgen/size.go",
-        "sszgen/unmarshal.go",
-    ],
-    importpath = "github.com/ferranbt/fastssz/sszgen",
-    visibility = ["//visibility:private"],
-)
-
-go_binary(
-    name = "sszgen",
-    embed = [":go_default_library"],
-    visibility = ["//visibility:public"],
-)
-    """,
-    strip_prefix = "fastssz-06015a5d84f9e4eefe2c21377ca678fa8f1a1b09",
-    urls = ["https://github.com/ferranbt/fastssz/archive/06015a5d84f9e4eefe2c21377ca678fa8f1a1b09.tar.gz"],
-)
-
 http_archive(
    name = "prysm_web_ui",
    build_file_content = """
@@ -367,9 +349,9 @@ filegroup(
    visibility = ["//visibility:public"],
 )
 """,
-    sha256 = "edb80f3a695d84f6000f0e05abf7a4bbf207c03abb91219780ec97e7d6ad21c8",
+    sha256 = "f196fe4367c2d2d01d36565c0dc6eecfa4f03adba1fc03a61d62953fce606e1f",
    urls = [
-        "https://github.com/prysmaticlabs/prysm-web-ui/releases/download/v1.0.0-beta.3/prysm-web-ui.tar.gz",
+        "https://github.com/prysmaticlabs/prysm-web-ui/releases/download/v1.0.2/prysm-web-ui.tar.gz",
    ],
 )

@@ -382,8 +364,46 @@ load("@prysm//third_party/herumi:herumi.bzl", "bls_dependencies")

 bls_dependencies()

-load("@com_github_ethereum_go_ethereum//:deps.bzl", "geth_dependencies")
+load("@prysm//testing/endtoend:deps.bzl", "e2e_deps")

-geth_dependencies()
+e2e_deps()
+
+load(
+    "@io_bazel_rules_docker//go:image.bzl",
+    _go_image_repos = "repositories",
+)
+
+# Golang images
+# This is using gcr.io/distroless/base
+_go_image_repos()
+
+# CC images
+# This is using gcr.io/distroless/base
+load(
+    "@io_bazel_rules_docker//cc:image.bzl",
+    _cc_image_repos = "repositories",
+)
+
+_cc_image_repos()
+
+load("@io_bazel_rules_go//extras:embed_data_deps.bzl", "go_embed_data_dependencies")
+
+go_embed_data_dependencies()
+
+load("@com_github_atlassian_bazel_tools//gometalinter:deps.bzl", "gometalinter_dependencies")
+
+gometalinter_dependencies()
+
+load("@bazel_gazelle//:deps.bzl", "gazelle_dependencies")
+
+gazelle_dependencies()
+
+load("@com_github_bazelbuild_buildtools//buildifier:deps.bzl", "buildifier_dependencies")
+
+buildifier_dependencies()
+
+load("@com_google_protobuf//:protobuf_deps.bzl", "protobuf_deps")
+
+protobuf_deps()

 # Do NOT add new go dependencies here! Refer to DEPENDENCIES.md!
--- a/api/gateway/BUILD.bazel
+++ b/api/gateway/BUILD.bazel
@@ -0,0 +1,42 @@
+load("@prysm//tools/go:def.bzl", "go_library", "go_test")
+
+go_library(
+    name = "go_default_library",
+    srcs = [
+        "gateway.go",
+        "log.go",
+        "options.go",
+    ],
+    importpath = "github.com/prysmaticlabs/prysm/api/gateway",
+    visibility = [
+        "//beacon-chain:__subpackages__",
+        "//validator:__subpackages__",
+    ],
+    deps = [
+        "//api/gateway/apimiddleware:go_default_library",
+        "//runtime:go_default_library",
+        "@com_github_gorilla_mux//:go_default_library",
+        "@com_github_grpc_ecosystem_grpc_gateway_v2//runtime:go_default_library",
+        "@com_github_pkg_errors//:go_default_library",
+        "@com_github_rs_cors//:go_default_library",
+        "@com_github_sirupsen_logrus//:go_default_library",
+        "@org_golang_google_grpc//:go_default_library",
+        "@org_golang_google_grpc//connectivity:go_default_library",
+        "@org_golang_google_grpc//credentials:go_default_library",
+    ],
+)
+
+go_test(
+    name = "go_default_test",
+    srcs = ["gateway_test.go"],
+    embed = [":go_default_library"],
+    deps = [
+        "//api/gateway/apimiddleware:go_default_library",
+        "//cmd/beacon-chain/flags:go_default_library",
+        "//testing/assert:go_default_library",
+        "//testing/require:go_default_library",
+        "@com_github_gorilla_mux//:go_default_library",
+        "@com_github_sirupsen_logrus//hooks/test:go_default_library",
+        "@com_github_urfave_cli_v2//:go_default_library",
+    ],
+)
--- a/api/gateway/apimiddleware/BUILD.bazel
+++ b/api/gateway/apimiddleware/BUILD.bazel
@@ -0,0 +1,40 @@
+load("@prysm//tools/go:def.bzl", "go_library", "go_test")
+
+go_library(
+    name = "go_default_library",
+    srcs = [
+        "api_middleware.go",
+        "log.go",
+        "param_handling.go",
+        "process_field.go",
+        "process_request.go",
+        "structs.go",
+    ],
+    importpath = "github.com/prysmaticlabs/prysm/api/gateway/apimiddleware",
+    visibility = ["//visibility:public"],
+    deps = [
+        "//api/grpc:go_default_library",
+        "//encoding/bytesutil:go_default_library",
+        "@com_github_ethereum_go_ethereum//common/hexutil:go_default_library",
+        "@com_github_gorilla_mux//:go_default_library",
+        "@com_github_pkg_errors//:go_default_library",
+        "@com_github_sirupsen_logrus//:go_default_library",
+        "@com_github_wealdtech_go_bytesutil//:go_default_library",
+    ],
+)
+
+go_test(
+    name = "go_default_test",
+    srcs = [
+        "param_handling_test.go",
+        "process_request_test.go",
+    ],
+    embed = [":go_default_library"],
+    deps = [
+        "//api/grpc:go_default_library",
+        "//testing/assert:go_default_library",
+        "//testing/require:go_default_library",
+        "@com_github_gorilla_mux//:go_default_library",
+        "@com_github_sirupsen_logrus//hooks/test:go_default_library",
+    ],
+)
--- a/api/gateway/apimiddleware/api_middleware.go
+++ b/api/gateway/apimiddleware/api_middleware.go
@@ -0,0 +1,263 @@
+package apimiddleware
+
+import (
+	"net/http"
+	"reflect"
+
+	"github.com/gorilla/mux"
+)
+
+// ApiProxyMiddleware is a proxy between an Ethereum consensus API HTTP client and grpc-gateway.
+// The purpose of the proxy is to handle HTTP requests and gRPC responses in such a way that:
+//   - Ethereum consensus API requests can be handled by grpc-gateway correctly
+//   - gRPC responses can be returned as spec-compliant Ethereum consensus API responses
+type ApiProxyMiddleware struct {
+	GatewayAddress  string
+	EndpointCreator EndpointFactory
+	router          *mux.Router
+}
+
+// EndpointFactory is responsible for creating new instances of Endpoint values.
+type EndpointFactory interface {
+	Create(path string) (*Endpoint, error)
+	Paths() []string
+	IsNil() bool
+}
+
+// Endpoint is a representation of an API HTTP endpoint that should be proxied by the middleware.
+type Endpoint struct {
+	Path               string          // The path of the HTTP endpoint.
+	GetResponse        interface{}     // The struct corresponding to the JSON structure used in a GET response.
+	PostRequest        interface{}     // The struct corresponding to the JSON structure used in a POST request.
+	PostResponse       interface{}     // The struct corresponding to the JSON structure used in a POST response.
+	DeleteRequest      interface{}     // The struct corresponding to the JSON structure used in a DELETE request.
+	DeleteResponse     interface{}     // The struct corresponding to the JSON structure used in a DELETE response.
+	RequestURLLiterals []string        // Names of URL parameters that should not be base64-encoded.
+	RequestQueryParams []QueryParam    // Query parameters of the request.
+	Err                ErrorJson       // The struct corresponding to the error that should be returned in case of a request failure.
+	Hooks              HookCollection  // A collection of functions that can be invoked at various stages of the request/response cycle.
+	CustomHandlers     []CustomHandler // Functions that will be executed instead of the default request/response behaviour.
+}
+
+// RunDefault expresses whether the default processing logic should be carried out after running a pre hook.
+type RunDefault bool
+
+// DefaultEndpoint returns an Endpoint with default configuration, e.g. DefaultErrorJson for error handling.
+func DefaultEndpoint() Endpoint {
+	return Endpoint{
+		Err: &DefaultErrorJson{},
+	}
+}
+
+// QueryParam represents a single query parameter's metadata.
+type QueryParam struct {
+	Name string
+	Hex  bool
+	Enum bool
+}
+
+// CustomHandler is a function that can be invoked at the very beginning of the request,
+// essentially replacing the whole default request/response logic with custom logic for a specific endpoint.
+type CustomHandler = func(m *ApiProxyMiddleware, endpoint Endpoint, w http.ResponseWriter, req *http.Request) (handled bool)
+
+// HookCollection contains hooks that can be used to amend the default request/response cycle with custom logic for a specific endpoint.
+type HookCollection struct {
+	OnPreDeserializeRequestBodyIntoContainer      func(endpoint *Endpoint, w http.ResponseWriter, req *http.Request) (RunDefault, ErrorJson)
+	OnPostDeserializeRequestBodyIntoContainer     func(endpoint *Endpoint, w http.ResponseWriter, req *http.Request) ErrorJson
+	OnPreDeserializeGrpcResponseBodyIntoContainer func([]byte, interface{}) (RunDefault, ErrorJson)
+	OnPreSerializeMiddlewareResponseIntoJson      func(interface{}) (RunDefault, []byte, ErrorJson)
+}
+
+// fieldProcessor applies the processing function f to a value when the tag is present on the field.
+type fieldProcessor struct {
+	tag string
+	f   func(value reflect.Value) error
+}
+
+// Run starts the proxy, registering all proxy endpoints.
+func (m *ApiProxyMiddleware) Run(gatewayRouter *mux.Router) {
+	for _, path := range m.EndpointCreator.Paths() {
+		gatewayRouter.HandleFunc(path, m.WithMiddleware(path))
+	}
+	m.router = gatewayRouter
+}
+
+// ServeHTTP for the proxy middleware.
+func (m *ApiProxyMiddleware) ServeHTTP(w http.ResponseWriter, req *http.Request) {
+	m.router.ServeHTTP(w, req)
+}
+
+// WithMiddleware wraps the given endpoint handler with the middleware logic.
+func (m *ApiProxyMiddleware) WithMiddleware(path string) http.HandlerFunc {
+	return func(w http.ResponseWriter, req *http.Request) {
+		endpoint, err := m.EndpointCreator.Create(path)
+		if err != nil {
+			log.WithError(err).Errorf("Could not create endpoint for path: %s", path)
+			return
+		}
+
+		for _, handler := range endpoint.CustomHandlers {
+			if handler(m, *endpoint, w, req) {
+				return
+			}
+		}
+
+		if req.Method == "POST" {
+			if errJson := handlePostRequestForEndpoint(endpoint, w, req); errJson != nil {
+				WriteError(w, errJson, nil)
+				return
+			}
+		}
+
+		if req.Method == "DELETE" {
+			if errJson := handleDeleteRequestForEndpoint(endpoint, req); errJson != nil {
+				WriteError(w, errJson, nil)
+				return
+			}
+		}
+
+		if errJson := m.PrepareRequestForProxying(*endpoint, req); errJson != nil {
+			WriteError(w, errJson, nil)
+			return
+		}
+		grpcResp, errJson := ProxyRequest(req)
+		if errJson != nil {
+			WriteError(w, errJson, nil)
+			return
+		}
+		grpcRespBody, errJson := ReadGrpcResponseBody(grpcResp.Body)
+		if errJson != nil {
+			WriteError(w, errJson, nil)
+			return
+		}
+
+		var respJson []byte
+		if !GrpcResponseIsEmpty(grpcRespBody) {
+			respHasError, errJson := HandleGrpcResponseError(endpoint.Err, grpcResp, grpcRespBody, w)
+			if errJson != nil {
+				WriteError(w, errJson, nil)
+				return
+			}
+			if respHasError {
+				return
+			}
+
+			var resp interface{}
+			if req.Method == "GET" {
+				resp = endpoint.GetResponse
+			} else if req.Method == "DELETE" {
+				resp = endpoint.DeleteResponse
+			} else {
+				resp = endpoint.PostResponse
+			}
+			if errJson := deserializeGrpcResponseBodyIntoContainerWrapped(endpoint, grpcRespBody, resp); errJson != nil {
+				WriteError(w, errJson, nil)
+				return
+			}
+			if errJson := ProcessMiddlewareResponseFields(resp); errJson != nil {
+				WriteError(w, errJson, nil)
+				return
+			}
+
+			respJson, errJson = serializeMiddlewareResponseIntoJsonWrapped(endpoint, respJson, resp)
+			if errJson != nil {
+				WriteError(w, errJson, nil)
+				return
+			}
+		}
+
+		if errJson := WriteMiddlewareResponseHeadersAndBody(grpcResp, respJson, w); errJson != nil {
+			WriteError(w, errJson, nil)
+			return
+		}
+		if errJson := Cleanup(grpcResp.Body); errJson != nil {
+			WriteError(w, errJson, nil)
+			return
+		}
+	}
+}
+
+func handlePostRequestForEndpoint(endpoint *Endpoint, w http.ResponseWriter, req *http.Request) ErrorJson {
+	if errJson := deserializeRequestBodyIntoContainerWrapped(endpoint, req, w); errJson != nil {
+		return errJson
+	}
+	if errJson := ProcessRequestContainerFields(endpoint.PostRequest); errJson != nil {
+		return errJson
+	}
+	return SetRequestBodyToRequestContainer(endpoint.PostRequest, req)
+}
+
+func handleDeleteRequestForEndpoint(endpoint *Endpoint, req *http.Request) ErrorJson {
+	if errJson := DeserializeRequestBodyIntoContainer(req.Body, endpoint.DeleteRequest); errJson != nil {
+		return errJson
+	}
+	if errJson := ProcessRequestContainerFields(endpoint.DeleteRequest); errJson != nil {
+		return errJson
+	}
+	return SetRequestBodyToRequestContainer(endpoint.DeleteRequest, req)
+}
+
+func deserializeRequestBodyIntoContainerWrapped(endpoint *Endpoint, req *http.Request, w http.ResponseWriter) ErrorJson {
+	runDefault := true
+	if endpoint.Hooks.OnPreDeserializeRequestBodyIntoContainer != nil {
+		run, errJson := endpoint.Hooks.OnPreDeserializeRequestBodyIntoContainer(endpoint, w, req)
+		if errJson != nil {
+			return errJson
+		}
+		if !run {
+			runDefault = false
+		}
+	}
+	if runDefault {
+		if errJson := DeserializeRequestBodyIntoContainer(req.Body, endpoint.PostRequest); errJson != nil {
+			return errJson
+		}
+	}
+	if endpoint.Hooks.OnPostDeserializeRequestBodyIntoContainer != nil {
+		if errJson := endpoint.Hooks.OnPostDeserializeRequestBodyIntoContainer(endpoint, w, req); errJson != nil {
+			return errJson
+		}
+	}
+	return nil
+}
+
+func deserializeGrpcResponseBodyIntoContainerWrapped(endpoint *Endpoint, grpcResponseBody []byte, resp interface{}) ErrorJson {
+	runDefault := true
+	if endpoint.Hooks.OnPreDeserializeGrpcResponseBodyIntoContainer != nil {
+		run, errJson := endpoint.Hooks.OnPreDeserializeGrpcResponseBodyIntoContainer(grpcResponseBody, resp)
+		if errJson != nil {
+			return errJson
+		}
+		if !run {
+			runDefault = false
+		}
+	}
+	if runDefault {
+		if errJson := DeserializeGrpcResponseBodyIntoContainer(grpcResponseBody, resp); errJson != nil {
+			return errJson
+		}
+	}
+	return nil
+}
+
+func serializeMiddlewareResponseIntoJsonWrapped(endpoint *Endpoint, respJson []byte, resp interface{}) ([]byte, ErrorJson) {
+	runDefault := true
+	var errJson ErrorJson
+	if endpoint.Hooks.OnPreSerializeMiddlewareResponseIntoJson != nil {
+		var run RunDefault
+		run, respJson, errJson = endpoint.Hooks.OnPreSerializeMiddlewareResponseIntoJson(resp)
+		if errJson != nil {
+			return nil, errJson
+		}
+		if !run {
+			runDefault = false
+		}
+	}
+	if runDefault {
+		respJson, errJson = SerializeMiddlewareResponseIntoJson(resp)
+		if errJson != nil {
+			return nil, errJson
+		}
+	}
+	return respJson, nil
+}
--- a/api/gateway/apimiddleware/log.go
+++ b/api/gateway/apimiddleware/log.go
@@ -0,0 +1,5 @@
+package apimiddleware
+
+import "github.com/sirupsen/logrus"
+
+var log = logrus.WithField("prefix", "apimiddleware")
--- a/api/gateway/apimiddleware/param_handling.go
+++ b/api/gateway/apimiddleware/param_handling.go
@@ -0,0 +1,103 @@
+package apimiddleware
+
+import (
+	"encoding/base64"
+	"net/http"
+	"net/url"
+	"strings"
+
+	"github.com/gorilla/mux"
+	butil "github.com/prysmaticlabs/prysm/encoding/bytesutil"
+	"github.com/wealdtech/go-bytesutil"
+)
+
+// HandleURLParameters processes URL parameters, allowing parameterized URLs to be safely and correctly proxied to grpc-gateway.
+func HandleURLParameters(url string, req *http.Request, literals []string) ErrorJson {
+	segments := strings.Split(url, "/")
+
+segmentsLoop:
+	for i, s := range segments {
+		// We only care about segments which are parameterized.
+		if isRequestParam(s) {
+			// Don't do anything with parameters which should be forwarded literally to gRPC.
+			for _, l := range literals {
+				if s == "{"+l+"}" {
+					continue segmentsLoop
+				}
+			}
+
+			routeVar := mux.Vars(req)[s[1:len(s)-1]]
+			bRouteVar := []byte(routeVar)
+			if butil.IsHex(bRouteVar) {
+				var err error
+				bRouteVar, err = bytesutil.FromHexString(string(bRouteVar))
+				if err != nil {
+					return InternalServerErrorWithMessage(err, "could not process URL parameter")
+				}
+			}
+			// Converting hex to base64 may result in a value which malforms the URL.
+			// We use URLEncoding to safely escape such values.
+			base64RouteVar := base64.URLEncoding.EncodeToString(bRouteVar)
+
+			// Merge segments back into the full URL.
+			splitPath := strings.Split(req.URL.Path, "/")
+			splitPath[i] = base64RouteVar
+			req.URL.Path = strings.Join(splitPath, "/")
+		}
+	}
+	return nil
+}
+
+// HandleQueryParameters processes query parameters, allowing them to be safely and correctly proxied to grpc-gateway.
+func HandleQueryParameters(req *http.Request, params []QueryParam) ErrorJson {
+	queryParams := req.URL.Query()
+
+	normalizeQueryValues(queryParams)
+
+	for key, vals := range queryParams {
+		for _, p := range params {
+			if key == p.Name {
+				if p.Hex {
+					queryParams.Del(key)
+					for _, v := range vals {
+						b := []byte(v)
+						if butil.IsHex(b) {
+							var err error
+							b, err = bytesutil.FromHexString(v)
+							if err != nil {
+								return InternalServerErrorWithMessage(err, "could not process query parameter")
+							}
+						}
+						queryParams.Add(key, base64.URLEncoding.EncodeToString(b))
+					}
+				}
+				if p.Enum {
+					queryParams.Del(key)
+					for _, v := range vals {
+						// gRPC expects uppercase enum values.
+						queryParams.Add(key, strings.ToUpper(v))
+					}
+				}
+			}
+		}
+	}
+	req.URL.RawQuery = queryParams.Encode()
+	return nil
+}
+
+// isRequestParam verifies whether the passed string is a request parameter.
+// Request parameters are enclosed in { and }.
+func isRequestParam(s string) bool {
+	return len(s) > 2 && s[0] == '{' && s[len(s)-1] == '}'
+}
+
+func normalizeQueryValues(queryParams url.Values) {
+	// Replace comma-separated values with individual values.
+	for key, vals := range queryParams {
+		splitVals := make([]string, 0)
+		for _, v := range vals {
+			splitVals = append(splitVals, strings.Split(v, ",")...)
+		}
+		queryParams[key] = splitVals
+	}
+}
--- a/api/gateway/apimiddleware/param_handling_test.go
+++ b/api/gateway/apimiddleware/param_handling_test.go
@@ -0,0 +1,124 @@
+package apimiddleware
+
+import (
+	"bytes"
+	"net/http/httptest"
+	"testing"
+
+	"github.com/gorilla/mux"
+	"github.com/prysmaticlabs/prysm/testing/assert"
+	"github.com/prysmaticlabs/prysm/testing/require"
+)
+
+func TestHandleURLParameters(t *testing.T) {
+	var body bytes.Buffer
+
+	t.Run("no_params", func(t *testing.T) {
+		request := httptest.NewRequest("GET", "http://foo.example/bar", &body)
+
+		errJson := HandleURLParameters("/not_param", request, []string{})
+		require.Equal(t, true, errJson == nil)
+		assert.Equal(t, "/bar", request.URL.Path)
+	})
+
+	t.Run("with_params", func(t *testing.T) {
+		muxVars := make(map[string]string)
+		muxVars["bar_param"] = "bar"
+		muxVars["quux_param"] = "quux"
+		request := httptest.NewRequest("GET", "http://foo.example/bar/baz/quux", &body)
+		request = mux.SetURLVars(request, muxVars)
+
+		errJson := HandleURLParameters("/{bar_param}/not_param/{quux_param}", request, []string{})
+		require.Equal(t, true, errJson == nil)
+		assert.Equal(t, "/YmFy/baz/cXV1eA==", request.URL.Path)
+	})
+
+	t.Run("with_literal", func(t *testing.T) {
+		muxVars := make(map[string]string)
+		muxVars["bar_param"] = "bar"
+		request := httptest.NewRequest("GET", "http://foo.example/bar/baz", &body)
+		request = mux.SetURLVars(request, muxVars)
+
+		errJson := HandleURLParameters("/{bar_param}/not_param/", request, []string{"bar_param"})
+		require.Equal(t, true, errJson == nil)
+		assert.Equal(t, "/bar/baz", request.URL.Path)
+	})
+
+	t.Run("with_hex", func(t *testing.T) {
+		muxVars := make(map[string]string)
+		muxVars["hex_param"] = "0x626172"
+		request := httptest.NewRequest("GET", "http://foo.example/0x626172/baz", &body)
+		request = mux.SetURLVars(request, muxVars)
+
+		errJson := HandleURLParameters("/{hex_param}/not_param/", request, []string{})
+		require.Equal(t, true, errJson == nil)
+		assert.Equal(t, "/YmFy/baz", request.URL.Path)
+	})
+}
+
+func TestHandleQueryParameters(t *testing.T) {
+	var body bytes.Buffer
+
+	t.Run("regular_params", func(t *testing.T) {
+		request := httptest.NewRequest("GET", "http://foo.example?bar=bar&baz=baz", &body)
+
+		errJson := HandleQueryParameters(request, []QueryParam{{Name: "bar"}, {Name: "baz"}})
+		require.Equal(t, true, errJson == nil)
+		query := request.URL.Query()
+		v, ok := query["bar"]
+		require.Equal(t, true, ok, "query param not found")
+		require.Equal(t, 1, len(v), "wrong number of query param values")
+		assert.Equal(t, "bar", v[0])
+		v, ok = query["baz"]
+		require.Equal(t, true, ok, "query param not found")
+		require.Equal(t, 1, len(v), "wrong number of query param values")
+		assert.Equal(t, "baz", v[0])
+	})
+
+	t.Run("hex_and_enum_params", func(t *testing.T) {
+		request := httptest.NewRequest("GET", "http://foo.example?hex=0x626172&baz=baz", &body)
+
+		errJson := HandleQueryParameters(request, []QueryParam{{Name: "hex", Hex: true}, {Name: "baz", Enum: true}})
+		require.Equal(t, true, errJson == nil)
+		query := request.URL.Query()
+		v, ok := query["hex"]
+		require.Equal(t, true, ok, "query param not found")
+		require.Equal(t, 1, len(v), "wrong number of query param values")
+		assert.Equal(t, "YmFy", v[0])
+		v, ok = query["baz"]
+		require.Equal(t, true, ok, "query param not found")
+		require.Equal(t, 1, len(v), "wrong number of query param values")
+		assert.Equal(t, "BAZ", v[0])
+	})
+}
+
+func TestIsRequestParam(t *testing.T) {
+	tests := []struct {
+		s string
+		b bool
+	}{
+		{"", false},
+		{"{", false},
+		{"}", false},
+		{"{}", false},
+		{"{x}", true},
+		{"{very_long_parameter_name_with_underscores}", true},
+	}
+	for _, tt := range tests {
+		b := isRequestParam(tt.s)
+		assert.Equal(t, tt.b, b)
+	}
+}
+
+func TestNormalizeQueryValues(t *testing.T) {
+	input := make(map[string][]string)
+	input["key"] = []string{"value1", "value2,value3,value4", "value5"}
+
+	normalizeQueryValues(input)
+	require.Equal(t, 5, len(input["key"]))
+	assert.Equal(t, "value1", input["key"][0])
+	assert.Equal(t, "value2", input["key"][1])
+	assert.Equal(t, "value3", input["key"][2])
+	assert.Equal(t, "value4", input["key"][3])
+	assert.Equal(t, "value5", input["key"][4])
+}
--- a/api/gateway/apimiddleware/process_field.go
+++ b/api/gateway/apimiddleware/process_field.go
@@ -0,0 +1,108 @@
+package apimiddleware
+
+import (
+	"encoding/base64"
+	"fmt"
+	"reflect"
+	"strconv"
+	"strings"
+	"time"
+
+	"github.com/ethereum/go-ethereum/common/hexutil"
+	"github.com/pkg/errors"
+	"github.com/wealdtech/go-bytesutil"
+)
+
+// processField calls each processor function on any field that has the matching tag set.
+// It is a recursive function.
+func processField(s interface{}, processors []fieldProcessor) error {
+	kind := reflect.TypeOf(s).Kind()
+	if kind != reflect.Ptr && kind != reflect.Slice && kind != reflect.Array {
+		return fmt.Errorf("processing fields of kind '%v' is unsupported", kind)
+	}
+
+	t := reflect.TypeOf(s).Elem()
+	v := reflect.Indirect(reflect.ValueOf(s))
+
+	for i := 0; i < t.NumField(); i++ {
+		switch v.Field(i).Kind() {
+		case reflect.Slice:
+			sliceElem := t.Field(i).Type.Elem()
+			kind := sliceElem.Kind()
+			// Recursively process slices to struct pointers.
+			if kind == reflect.Ptr && sliceElem.Elem().Kind() == reflect.Struct {
+				for j := 0; j < v.Field(i).Len(); j++ {
+					if err := processField(v.Field(i).Index(j).Interface(), processors); err != nil {
+						return errors.Wrapf(err, "could not process field '%s'", t.Field(i).Name)
+					}
+				}
+			}
+			// Process each string in string slices.
+			if kind == reflect.String {
+				for _, proc := range processors {
+					_, hasTag := t.Field(i).Tag.Lookup(proc.tag)
+					if hasTag {
+						for j := 0; j < v.Field(i).Len(); j++ {
+							if err := proc.f(v.Field(i).Index(j)); err != nil {
+								return errors.Wrapf(err, "could not process field '%s'", t.Field(i).Name)
+							}
+						}
+					}
+				}
+
+			}
+		// Recursively process struct pointers.
+		case reflect.Ptr:
+			if v.Field(i).Elem().Kind() == reflect.Struct {
+				if err := processField(v.Field(i).Interface(), processors); err != nil {
+					return errors.Wrapf(err, "could not process field '%s'", t.Field(i).Name)
+				}
+			}
+		default:
+			field := t.Field(i)
+			for _, proc := range processors {
+				if _, hasTag := field.Tag.Lookup(proc.tag); hasTag {
+					if err := proc.f(v.Field(i)); err != nil {
+						return errors.Wrapf(err, "could not process field '%s'", t.Field(i).Name)
+					}
+				}
+			}
+		}
+	}
+	return nil
+}
+
+func hexToBase64Processor(v reflect.Value) error {
+	b, err := bytesutil.FromHexString(v.String())
+	if err != nil {
+		return err
+	}
+	v.SetString(base64.StdEncoding.EncodeToString(b))
+	return nil
+}
+
+func base64ToHexProcessor(v reflect.Value) error {
+	if v.String() == "" {
+		return nil
+	}
+	b, err := base64.StdEncoding.DecodeString(v.String())
+	if err != nil {
+		return err
+	}
+	v.SetString(hexutil.Encode(b))
+	return nil
+}
+
+func enumToLowercaseProcessor(v reflect.Value) error {
+	v.SetString(strings.ToLower(v.String()))
+	return nil
+}
+
+func timeToUnixProcessor(v reflect.Value) error {
+	t, err := time.Parse(time.RFC3339, v.String())
+	if err != nil {
+		return err
+	}
+	v.SetString(strconv.FormatUint(uint64(t.Unix()), 10))
+	return nil
+}
--- a/api/gateway/apimiddleware/process_request.go
+++ b/api/gateway/apimiddleware/process_request.go
@@ -0,0 +1,255 @@
+package apimiddleware
+
+import (
+	"bytes"
+	"encoding/json"
+	"io"
+	"io/ioutil"
+	"net/http"
+	"strconv"
+	"strings"
+	"time"
+
+	"github.com/pkg/errors"
+	"github.com/prysmaticlabs/prysm/api/grpc"
+)
+
+// DeserializeRequestBodyIntoContainer deserializes the request's body into an endpoint-specific struct.
+func DeserializeRequestBodyIntoContainer(body io.Reader, requestContainer interface{}) ErrorJson {
+	decoder := json.NewDecoder(body)
+	decoder.DisallowUnknownFields()
+	if err := decoder.Decode(&requestContainer); err != nil {
+		if strings.Contains(err.Error(), "json: unknown field") {
+			e := errors.Wrap(err, "could not decode request body")
+			return &DefaultErrorJson{
+				Message: e.Error(),
+				Code:    http.StatusBadRequest,
+			}
+		}
+		return InternalServerErrorWithMessage(err, "could not decode request body")
+	}
+	return nil
+}
+
+// ProcessRequestContainerFields processes fields of an endpoint-specific container according to field tags.
+func ProcessRequestContainerFields(requestContainer interface{}) ErrorJson {
+	if err := processField(requestContainer, []fieldProcessor{
+		{
+			tag: "hex",
+			f:   hexToBase64Processor,
+		},
+	}); err != nil {
+		return InternalServerErrorWithMessage(err, "could not process request data")
+	}
+	return nil
+}
+
+// SetRequestBodyToRequestContainer makes the endpoint-specific container the new body of the request.
+func SetRequestBodyToRequestContainer(requestContainer interface{}, req *http.Request) ErrorJson {
+	// Serialize the struct, which now includes a base64-encoded value, into JSON.
+	j, err := json.Marshal(requestContainer)
+	if err != nil {
+		return InternalServerErrorWithMessage(err, "could not marshal request")
+	}
+	// Set the body to the new JSON.
+	req.Body = ioutil.NopCloser(bytes.NewReader(j))
+	req.Header.Set("Content-Length", strconv.Itoa(len(j)))
+	req.ContentLength = int64(len(j))
+	return nil
+}
+
+// PrepareRequestForProxying applies additional logic to the request so that it can be correctly proxied to grpc-gateway.
+func (m *ApiProxyMiddleware) PrepareRequestForProxying(endpoint Endpoint, req *http.Request) ErrorJson {
+	req.URL.Scheme = "http"
+	req.URL.Host = m.GatewayAddress
+	req.RequestURI = ""
+	if errJson := HandleURLParameters(endpoint.Path, req, endpoint.RequestURLLiterals); errJson != nil {
+		return errJson
+	}
+	if errJson := HandleQueryParameters(req, endpoint.RequestQueryParams); errJson != nil {
+		return errJson
+	}
+	// We have to add the prefix after handling parameters because adding the prefix changes URL segment indexing.
+	req.URL.Path = "/internal" + req.URL.Path
+	return nil
+}
+
+// ProxyRequest proxies the request to grpc-gateway.
+func ProxyRequest(req *http.Request) (*http.Response, ErrorJson) {
+	// We do not use http.DefaultClient because it does not have any timeout.
+	netClient := &http.Client{Timeout: time.Minute * 2}
+	grpcResp, err := netClient.Do(req)
+	if err != nil {
+		return nil, InternalServerErrorWithMessage(err, "could not proxy request")
+	}
+	if grpcResp == nil {
+		return nil, &DefaultErrorJson{Message: "nil response from gRPC-gateway", Code: http.StatusInternalServerError}
+	}
+	return grpcResp, nil
+}
+
+// ReadGrpcResponseBody reads the body from the grpc-gateway's response.
+func ReadGrpcResponseBody(r io.Reader) ([]byte, ErrorJson) {
+	body, err := ioutil.ReadAll(r)
+	if err != nil {
+		return nil, InternalServerErrorWithMessage(err, "could not read response body")
+	}
+	return body, nil
+}
+
+// HandleGrpcResponseError acts on an error that resulted from a grpc-gateway's response.
+func HandleGrpcResponseError(errJson ErrorJson, resp *http.Response, respBody []byte, w http.ResponseWriter) (bool, ErrorJson) {
+	responseHasError := false
+	if err := json.Unmarshal(respBody, errJson); err != nil {
+		return false, InternalServerErrorWithMessage(err, "could not unmarshal error")
+	}
+	if errJson.Msg() != "" {
+		responseHasError = true
+		// Something went wrong, but the request completed, meaning we can write headers and the error message.
+		for h, vs := range resp.Header {
+			for _, v := range vs {
+				w.Header().Set(h, v)
+			}
+		}
+		// Set code to HTTP code because unmarshalled body contained gRPC code.
+		errJson.SetCode(resp.StatusCode)
+		WriteError(w, errJson, resp.Header)
+	}
+	return responseHasError, nil
+}
+
+// GrpcResponseIsEmpty determines whether the grpc-gateway's response body contains no data.
+func GrpcResponseIsEmpty(grpcResponseBody []byte) bool {
+	return len(grpcResponseBody) == 0 || string(grpcResponseBody) == "{}"
+}
+
+// DeserializeGrpcResponseBodyIntoContainer deserializes the grpc-gateway's response body into an endpoint-specific struct.
+func DeserializeGrpcResponseBodyIntoContainer(body []byte, responseContainer interface{}) ErrorJson {
+	if err := json.Unmarshal(body, &responseContainer); err != nil {
+		return InternalServerErrorWithMessage(err, "could not unmarshal response")
+	}
+	return nil
+}
+
+// ProcessMiddlewareResponseFields processes fields of an endpoint-specific container according to field tags.
+func ProcessMiddlewareResponseFields(responseContainer interface{}) ErrorJson {
+	if err := processField(responseContainer, []fieldProcessor{
+		{
+			tag: "hex",
+			f:   base64ToHexProcessor,
+		},
+		{
+			tag: "enum",
+			f:   enumToLowercaseProcessor,
+		},
+		{
+			tag: "time",
+			f:   timeToUnixProcessor,
+		},
+	}); err != nil {
+		return InternalServerErrorWithMessage(err, "could not process response data")
+	}
+	return nil
+}
+
+// SerializeMiddlewareResponseIntoJson serializes the endpoint-specific response struct into a JSON representation.
+func SerializeMiddlewareResponseIntoJson(responseContainer interface{}) (jsonResponse []byte, errJson ErrorJson) {
+	j, err := json.Marshal(responseContainer)
+	if err != nil {
+		return nil, InternalServerErrorWithMessage(err, "could not marshal response")
+	}
+	return j, nil
+}
+
+// WriteMiddlewareResponseHeadersAndBody populates headers and the body of the final response.
+func WriteMiddlewareResponseHeadersAndBody(grpcResp *http.Response, responseJson []byte, w http.ResponseWriter) ErrorJson {
+	var statusCodeHeader string
+	for h, vs := range grpcResp.Header {
+		// We don't want to expose any gRPC metadata in the HTTP response, so we skip forwarding metadata headers.
+		if strings.HasPrefix(h, "Grpc-Metadata") {
+			if h == "Grpc-Metadata-"+grpc.HttpCodeMetadataKey {
+				statusCodeHeader = vs[0]
+			}
+		} else {
+			for _, v := range vs {
+				w.Header().Set(h, v)
+			}
+		}
+	}
+	if !GrpcResponseIsEmpty(responseJson) {
+		w.Header().Set("Content-Length", strconv.Itoa(len(responseJson)))
+		if statusCodeHeader != "" {
+			code, err := strconv.Atoi(statusCodeHeader)
+			if err != nil {
+				return InternalServerErrorWithMessage(err, "could not parse status code")
+			}
+			w.WriteHeader(code)
+		} else {
+			w.WriteHeader(grpcResp.StatusCode)
+		}
+		if _, err := io.Copy(w, ioutil.NopCloser(bytes.NewReader(responseJson))); err != nil {
+			return InternalServerErrorWithMessage(err, "could not write response message")
+		}
+	} else {
+		w.Header().Set("Content-Length", "0")
+		w.WriteHeader(grpcResp.StatusCode)
+	}
+	return nil
+}
+
+// WriteError writes the error by manipulating headers and the body of the final response.
+func WriteError(w http.ResponseWriter, errJson ErrorJson, responseHeader http.Header) {
+	// Include custom error in the error JSON.
+	hasCustomError := false
+	if responseHeader != nil {
+		customError, ok := responseHeader["Grpc-Metadata-"+grpc.CustomErrorMetadataKey]
+		if ok {
+			hasCustomError = true
+			// Assume header has only one value and read the 0 index.
+			if err := json.Unmarshal([]byte(customError[0]), errJson); err != nil {
+				log.WithError(err).Error("Could not unmarshal custom error message")
+				return
+			}
+		}
+	}
+
+	var j []byte
+	if hasCustomError {
+		var err error
+		j, err = json.Marshal(errJson)
+		if err != nil {
+			log.WithError(err).Error("Could not marshal error message")
+			return
+		}
+	} else {
+		var err error
+		// We marshal the response body into a DefaultErrorJson if the custom error is not present.
+		// This is because the ErrorJson argument is the endpoint's error definition, which may contain custom fields.
+		// In such a scenario marhaling the endpoint's error would populate the resulting JSON
+		// with these fields even if they are not present in the gRPC header.
+		d := &DefaultErrorJson{
+			Message: errJson.Msg(),
+			Code:    errJson.StatusCode(),
+		}
+		j, err = json.Marshal(d)
+		if err != nil {
+			log.WithError(err).Error("Could not marshal error message")
+			return
+		}
+	}
+
+	w.Header().Set("Content-Length", strconv.Itoa(len(j)))
+	w.Header().Set("Content-Type", "application/json")
+	w.WriteHeader(errJson.StatusCode())
+	if _, err := io.Copy(w, ioutil.NopCloser(bytes.NewReader(j))); err != nil {
+		log.WithError(err).Error("Could not write error message")
+	}
+}
+
+// Cleanup performs final cleanup on the initial response from grpc-gateway.
+func Cleanup(grpcResponseBody io.ReadCloser) ErrorJson {
+	if err := grpcResponseBody.Close(); err != nil {
+		return InternalServerErrorWithMessage(err, "could not close response body")
+	}
+	return nil
+}
--- a/api/gateway/apimiddleware/process_request_test.go
+++ b/api/gateway/apimiddleware/process_request_test.go
@@ -0,0 +1,409 @@
+package apimiddleware
+
+import (
+	"bytes"
+	"encoding/json"
+	"net/http"
+	"net/http/httptest"
+	"strings"
+	"testing"
+
+	"github.com/prysmaticlabs/prysm/api/grpc"
+	"github.com/prysmaticlabs/prysm/testing/assert"
+	"github.com/prysmaticlabs/prysm/testing/require"
+	"github.com/sirupsen/logrus/hooks/test"
+)
+
+type testRequestContainer struct {
+	TestString    string
+	TestHexString string `hex:"true"`
+}
+
+func defaultRequestContainer() *testRequestContainer {
+	return &testRequestContainer{
+		TestString:    "test string",
+		TestHexString: "0x666F6F", // hex encoding of "foo"
+	}
+}
+
+type testResponseContainer struct {
+	TestString string
+	TestHex    string `hex:"true"`
+	TestEnum   string `enum:"true"`
+	TestTime   string `time:"true"`
+}
+
+func defaultResponseContainer() *testResponseContainer {
+	return &testResponseContainer{
+		TestString: "test string",
+		TestHex:    "Zm9v", // base64 encoding of "foo"
+		TestEnum:   "Test Enum",
+		TestTime:   "2006-01-02T15:04:05Z",
+	}
+}
+
+type testErrorJson struct {
+	Message     string
+	Code        int
+	CustomField string
+}
+
+// StatusCode returns the error's underlying error code.
+func (e *testErrorJson) StatusCode() int {
+	return e.Code
+}
+
+// Msg returns the error's underlying message.
+func (e *testErrorJson) Msg() string {
+	return e.Message
+}
+
+// SetCode sets the error's underlying error code.
+func (e *testErrorJson) SetCode(code int) {
+	e.Code = code
+}
+
+// SetMsg sets the error's underlying message.
+func (e *testErrorJson) SetMsg(msg string) {
+	e.Message = msg
+}
+
+func TestDeserializeRequestBodyIntoContainer(t *testing.T) {
+	t.Run("ok", func(t *testing.T) {
+		var bodyJson bytes.Buffer
+		err := json.NewEncoder(&bodyJson).Encode(defaultRequestContainer())
+		require.NoError(t, err)
+
+		container := &testRequestContainer{}
+		errJson := DeserializeRequestBodyIntoContainer(&bodyJson, container)
+		require.Equal(t, true, errJson == nil)
+		assert.Equal(t, "test string", container.TestString)
+	})
+
+	t.Run("error", func(t *testing.T) {
+		var bodyJson bytes.Buffer
+		bodyJson.Write([]byte("foo"))
+		errJson := DeserializeRequestBodyIntoContainer(&bodyJson, &testRequestContainer{})
+		require.NotNil(t, errJson)
+		assert.Equal(t, true, strings.Contains(errJson.Msg(), "could not decode request body"))
+		assert.Equal(t, http.StatusInternalServerError, errJson.StatusCode())
+	})
+
+	t.Run("unknown field", func(t *testing.T) {
+		var bodyJson bytes.Buffer
+		bodyJson.Write([]byte("{\"foo\":\"foo\"}"))
+		errJson := DeserializeRequestBodyIntoContainer(&bodyJson, &testRequestContainer{})
+		require.NotNil(t, errJson)
+		assert.Equal(t, true, strings.Contains(errJson.Msg(), "could not decode request body"))
+		assert.Equal(t, http.StatusBadRequest, errJson.StatusCode())
+	})
+}
+
+func TestProcessRequestContainerFields(t *testing.T) {
+	t.Run("ok", func(t *testing.T) {
+		container := defaultRequestContainer()
+
+		errJson := ProcessRequestContainerFields(container)
+		require.Equal(t, true, errJson == nil)
+		assert.Equal(t, "Zm9v", container.TestHexString)
+	})
+
+	t.Run("error", func(t *testing.T) {
+		errJson := ProcessRequestContainerFields("foo")
+		require.NotNil(t, errJson)
+		assert.Equal(t, true, strings.Contains(errJson.Msg(), "could not process request data"))
+		assert.Equal(t, http.StatusInternalServerError, errJson.StatusCode())
+	})
+}
+
+func TestSetRequestBodyToRequestContainer(t *testing.T) {
+	var body bytes.Buffer
+	request := httptest.NewRequest("GET", "http://foo.example", &body)
+
+	errJson := SetRequestBodyToRequestContainer(defaultRequestContainer(), request)
+	require.Equal(t, true, errJson == nil)
+	container := &testRequestContainer{}
+	require.NoError(t, json.NewDecoder(request.Body).Decode(container))
+	assert.Equal(t, "test string", container.TestString)
+	contentLengthHeader, ok := request.Header["Content-Length"]
+	require.Equal(t, true, ok)
+	require.Equal(t, 1, len(contentLengthHeader), "wrong number of header values")
+	assert.Equal(t, "55", contentLengthHeader[0])
+	assert.Equal(t, int64(55), request.ContentLength)
+}
+
+func TestPrepareRequestForProxying(t *testing.T) {
+	middleware := &ApiProxyMiddleware{
+		GatewayAddress: "http://gateway.example",
+	}
+	// We will set some params to make the request more interesting.
+	endpoint := Endpoint{
+		Path:               "/{url_param}",
+		RequestURLLiterals: []string{"url_param"},
+		RequestQueryParams: []QueryParam{{Name: "query_param"}},
+	}
+	var body bytes.Buffer
+	request := httptest.NewRequest("GET", "http://foo.example?query_param=bar", &body)
+
+	errJson := middleware.PrepareRequestForProxying(endpoint, request)
+	require.Equal(t, true, errJson == nil)
+	assert.Equal(t, "http", request.URL.Scheme)
+	assert.Equal(t, middleware.GatewayAddress, request.URL.Host)
+	assert.Equal(t, "", request.RequestURI)
+}
+
+func TestReadGrpcResponseBody(t *testing.T) {
+	var b bytes.Buffer
+	b.Write([]byte("foo"))
+
+	body, jsonErr := ReadGrpcResponseBody(&b)
+	require.Equal(t, true, jsonErr == nil)
+	assert.Equal(t, "foo", string(body))
+}
+
+func TestHandleGrpcResponseError(t *testing.T) {
+	response := &http.Response{
+		StatusCode: 400,
+		Header: http.Header{
+			"Foo": []string{"foo"},
+			"Bar": []string{"bar"},
+		},
+	}
+	writer := httptest.NewRecorder()
+	errJson := &testErrorJson{
+		Message: "foo",
+		Code:    400,
+	}
+	b, err := json.Marshal(errJson)
+	require.NoError(t, err)
+
+	hasError, e := HandleGrpcResponseError(errJson, response, b, writer)
+	require.Equal(t, true, e == nil)
+	assert.Equal(t, true, hasError)
+	v, ok := writer.Header()["Foo"]
+	require.Equal(t, true, ok, "header not found")
+	require.Equal(t, 1, len(v), "wrong number of header values")
+	assert.Equal(t, "foo", v[0])
+	v, ok = writer.Header()["Bar"]
+	require.Equal(t, true, ok, "header not found")
+	require.Equal(t, 1, len(v), "wrong number of header values")
+	assert.Equal(t, "bar", v[0])
+	assert.Equal(t, 400, errJson.StatusCode())
+}
+
+func TestGrpcResponseIsEmpty(t *testing.T) {
+	t.Run("nil", func(t *testing.T) {
+		assert.Equal(t, true, GrpcResponseIsEmpty(nil))
+	})
+	t.Run("empty_slice", func(t *testing.T) {
+		assert.Equal(t, true, GrpcResponseIsEmpty(make([]byte, 0)))
+	})
+	t.Run("empty_brackets", func(t *testing.T) {
+		assert.Equal(t, true, GrpcResponseIsEmpty([]byte("{}")))
+	})
+	t.Run("non_empty", func(t *testing.T) {
+		assert.Equal(t, false, GrpcResponseIsEmpty([]byte("{\"foo\":\"bar\"})")))
+	})
+}
+
+func TestDeserializeGrpcResponseBodyIntoContainer(t *testing.T) {
+	t.Run("ok", func(t *testing.T) {
+		body, err := json.Marshal(defaultRequestContainer())
+		require.NoError(t, err)
+
+		container := &testRequestContainer{}
+		errJson := DeserializeGrpcResponseBodyIntoContainer(body, container)
+		require.Equal(t, true, errJson == nil)
+		assert.Equal(t, "test string", container.TestString)
+	})
+
+	t.Run("error", func(t *testing.T) {
+		var bodyJson bytes.Buffer
+		bodyJson.Write([]byte("foo"))
+		errJson := DeserializeGrpcResponseBodyIntoContainer(bodyJson.Bytes(), &testRequestContainer{})
+		require.NotNil(t, errJson)
+		assert.Equal(t, true, strings.Contains(errJson.Msg(), "could not unmarshal response"))
+		assert.Equal(t, http.StatusInternalServerError, errJson.StatusCode())
+	})
+}
+
+func TestProcessMiddlewareResponseFields(t *testing.T) {
+	t.Run("Ok", func(t *testing.T) {
+		container := defaultResponseContainer()
+
+		errJson := ProcessMiddlewareResponseFields(container)
+		require.Equal(t, true, errJson == nil)
+		assert.Equal(t, "0x666f6f", container.TestHex)
+		assert.Equal(t, "test enum", container.TestEnum)
+		assert.Equal(t, "1136214245", container.TestTime)
+	})
+
+	t.Run("error", func(t *testing.T) {
+		errJson := ProcessMiddlewareResponseFields("foo")
+		require.NotNil(t, errJson)
+		assert.Equal(t, true, strings.Contains(errJson.Msg(), "could not process response data"))
+		assert.Equal(t, http.StatusInternalServerError, errJson.StatusCode())
+	})
+}
+
+func TestSerializeMiddlewareResponseIntoJson(t *testing.T) {
+	container := defaultResponseContainer()
+	j, errJson := SerializeMiddlewareResponseIntoJson(container)
+	assert.Equal(t, true, errJson == nil)
+	cToDeserialize := &testResponseContainer{}
+	require.NoError(t, json.Unmarshal(j, cToDeserialize))
+	assert.Equal(t, "test string", cToDeserialize.TestString)
+}
+
+func TestWriteMiddlewareResponseHeadersAndBody(t *testing.T) {
+	t.Run("GET", func(t *testing.T) {
+		response := &http.Response{
+			Header: http.Header{
+				"Foo": []string{"foo"},
+				"Grpc-Metadata-" + grpc.HttpCodeMetadataKey: []string{"204"},
+			},
+		}
+		container := defaultResponseContainer()
+		responseJson, err := json.Marshal(container)
+		require.NoError(t, err)
+		writer := httptest.NewRecorder()
+		writer.Body = &bytes.Buffer{}
+
+		errJson := WriteMiddlewareResponseHeadersAndBody(response, responseJson, writer)
+		require.Equal(t, true, errJson == nil)
+		v, ok := writer.Header()["Foo"]
+		require.Equal(t, true, ok, "header not found")
+		require.Equal(t, 1, len(v), "wrong number of header values")
+		assert.Equal(t, "foo", v[0])
+		v, ok = writer.Header()["Content-Length"]
+		require.Equal(t, true, ok, "header not found")
+		require.Equal(t, 1, len(v), "wrong number of header values")
+		assert.Equal(t, "102", v[0])
+		assert.Equal(t, 204, writer.Code)
+		assert.DeepEqual(t, responseJson, writer.Body.Bytes())
+	})
+
+	t.Run("GET_no_grpc_status_code_header", func(t *testing.T) {
+		response := &http.Response{
+			Header:     http.Header{},
+			StatusCode: 204,
+		}
+		container := defaultResponseContainer()
+		responseJson, err := json.Marshal(container)
+		require.NoError(t, err)
+		writer := httptest.NewRecorder()
+
+		errJson := WriteMiddlewareResponseHeadersAndBody(response, responseJson, writer)
+		require.Equal(t, true, errJson == nil)
+		assert.Equal(t, 204, writer.Code)
+	})
+
+	t.Run("GET_invalid_status_code", func(t *testing.T) {
+		response := &http.Response{
+			Header: http.Header{},
+		}
+
+		// Set invalid status code.
+		response.Header["Grpc-Metadata-"+grpc.HttpCodeMetadataKey] = []string{"invalid"}
+
+		container := defaultResponseContainer()
+		responseJson, err := json.Marshal(container)
+		require.NoError(t, err)
+		writer := httptest.NewRecorder()
+
+		errJson := WriteMiddlewareResponseHeadersAndBody(response, responseJson, writer)
+		require.Equal(t, false, errJson == nil)
+		assert.Equal(t, true, strings.Contains(errJson.Msg(), "could not parse status code"))
+		assert.Equal(t, http.StatusInternalServerError, errJson.StatusCode())
+	})
+
+	t.Run("POST", func(t *testing.T) {
+		response := &http.Response{
+			Header:     http.Header{},
+			StatusCode: 204,
+		}
+		container := defaultResponseContainer()
+		responseJson, err := json.Marshal(container)
+		require.NoError(t, err)
+		writer := httptest.NewRecorder()
+
+		errJson := WriteMiddlewareResponseHeadersAndBody(response, responseJson, writer)
+		require.Equal(t, true, errJson == nil)
+		assert.Equal(t, 204, writer.Code)
+	})
+
+	t.Run("POST_with_response_body", func(t *testing.T) {
+		response := &http.Response{
+			Header:     http.Header{},
+			StatusCode: 204,
+		}
+		container := defaultResponseContainer()
+		responseJson, err := json.Marshal(container)
+		require.NoError(t, err)
+		writer := httptest.NewRecorder()
+		writer.Body = &bytes.Buffer{}
+
+		errJson := WriteMiddlewareResponseHeadersAndBody(response, responseJson, writer)
+		require.Equal(t, true, errJson == nil)
+		assert.Equal(t, 204, writer.Code)
+		assert.DeepEqual(t, responseJson, writer.Body.Bytes())
+	})
+
+	t.Run("POST_with_empty_json_body", func(t *testing.T) {
+		response := &http.Response{
+			Header:     http.Header{},
+			StatusCode: 204,
+		}
+		responseJson, err := json.Marshal(struct{}{})
+		require.NoError(t, err)
+		writer := httptest.NewRecorder()
+		writer.Body = &bytes.Buffer{}
+
+		errJson := WriteMiddlewareResponseHeadersAndBody(response, responseJson, writer)
+		require.Equal(t, true, errJson == nil)
+		assert.Equal(t, 204, writer.Code)
+		assert.DeepEqual(t, []byte(nil), writer.Body.Bytes())
+		assert.Equal(t, "0", writer.Header()["Content-Length"][0])
+	})
+}
+
+func TestWriteError(t *testing.T) {
+	t.Run("ok", func(t *testing.T) {
+		responseHeader := http.Header{
+			"Grpc-Metadata-" + grpc.CustomErrorMetadataKey: []string{"{\"CustomField\":\"bar\"}"},
+		}
+		errJson := &testErrorJson{
+			Message: "foo",
+			Code:    500,
+		}
+		writer := httptest.NewRecorder()
+		writer.Body = &bytes.Buffer{}
+
+		WriteError(writer, errJson, responseHeader)
+		v, ok := writer.Header()["Content-Length"]
+		require.Equal(t, true, ok, "header not found")
+		require.Equal(t, 1, len(v), "wrong number of header values")
+		assert.Equal(t, "48", v[0])
+		v, ok = writer.Header()["Content-Type"]
+		require.Equal(t, true, ok, "header not found")
+		require.Equal(t, 1, len(v), "wrong number of header values")
+		assert.Equal(t, "application/json", v[0])
+		assert.Equal(t, 500, writer.Code)
+		eDeserialize := &testErrorJson{}
+		require.NoError(t, json.Unmarshal(writer.Body.Bytes(), eDeserialize))
+		assert.Equal(t, "foo", eDeserialize.Message)
+		assert.Equal(t, 500, eDeserialize.Code)
+		assert.Equal(t, "bar", eDeserialize.CustomField)
+	})
+
+	t.Run("invalid_custom_error_header", func(t *testing.T) {
+		logHook := test.NewGlobal()
+
+		responseHeader := http.Header{
+			"Grpc-Metadata-" + grpc.CustomErrorMetadataKey: []string{"invalid"},
+		}
+
+		WriteError(httptest.NewRecorder(), &testErrorJson{}, responseHeader)
+		assert.LogsContain(t, logHook, "Could not unmarshal custom error message")
+	})
+}
--- a/api/gateway/apimiddleware/structs.go
+++ b/api/gateway/apimiddleware/structs.go
@@ -0,0 +1,62 @@
+package apimiddleware
+
+import (
+	"net/http"
+
+	"github.com/pkg/errors"
+)
+
+// ---------------
+// Error handling.
+// ---------------
+
+// ErrorJson describes common functionality of all JSON error representations.
+type ErrorJson interface {
+	StatusCode() int
+	SetCode(code int)
+	Msg() string
+	SetMsg(msg string)
+}
+
+// DefaultErrorJson is a JSON representation of a simple error value, containing only a message and an error code.
+type DefaultErrorJson struct {
+	Message string `json:"message"`
+	Code    int    `json:"code"`
+}
+
+// InternalServerErrorWithMessage returns a DefaultErrorJson with 500 code and a custom message.
+func InternalServerErrorWithMessage(err error, message string) *DefaultErrorJson {
+	e := errors.Wrapf(err, message)
+	return &DefaultErrorJson{
+		Message: e.Error(),
+		Code:    http.StatusInternalServerError,
+	}
+}
+
+// InternalServerError returns a DefaultErrorJson with 500 code.
+func InternalServerError(err error) *DefaultErrorJson {
+	return &DefaultErrorJson{
+		Message: err.Error(),
+		Code:    http.StatusInternalServerError,
+	}
+}
+
+// StatusCode returns the error's underlying error code.
+func (e *DefaultErrorJson) StatusCode() int {
+	return e.Code
+}
+
+// Msg returns the error's underlying message.
+func (e *DefaultErrorJson) Msg() string {
+	return e.Message
+}
+
+// SetCode sets the error's underlying error code.
+func (e *DefaultErrorJson) SetCode(code int) {
+	e.Code = code
+}
+
+// SetMsg sets the error's underlying message.
+func (e *DefaultErrorJson) SetMsg(msg string) {
+	e.Message = msg
+}
--- a/api/gateway/gateway.go
+++ b/api/gateway/gateway.go
@@ -0,0 +1,254 @@
+// Package gateway defines a grpc-gateway server that serves HTTP-JSON traffic and acts a proxy between HTTP and gRPC.
+package gateway
+
+import (
+	"context"
+	"fmt"
+	"net"
+	"net/http"
+	"path"
+	"strings"
+	"time"
+
+	"github.com/gorilla/mux"
+	gwruntime "github.com/grpc-ecosystem/grpc-gateway/v2/runtime"
+	"github.com/pkg/errors"
+	"github.com/prysmaticlabs/prysm/api/gateway/apimiddleware"
+	"github.com/prysmaticlabs/prysm/runtime"
+	"github.com/rs/cors"
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/connectivity"
+	"google.golang.org/grpc/credentials"
+)
+
+var _ runtime.Service = (*Gateway)(nil)
+
+// PbMux serves grpc-gateway requests for selected patterns using registered protobuf handlers.
+type PbMux struct {
+	Registrations []PbHandlerRegistration // Protobuf registrations to be registered in Mux.
+	Patterns      []string                // URL patterns that will be handled by Mux.
+	Mux           *gwruntime.ServeMux     // The router that will be used for grpc-gateway requests.
+}
+
+// PbHandlerRegistration is a function that registers a protobuf handler.
+type PbHandlerRegistration func(context.Context, *gwruntime.ServeMux, *grpc.ClientConn) error
+
+// MuxHandler is a function that implements the mux handler functionality.
+type MuxHandler func(
+	apiMiddlewareHandler *apimiddleware.ApiProxyMiddleware,
+	h http.HandlerFunc,
+	w http.ResponseWriter,
+	req *http.Request,
+)
+
+// Config parameters for setting up the gateway service.
+type config struct {
+	maxCallRecvMsgSize           uint64
+	remoteCert                   string
+	gatewayAddr                  string
+	remoteAddr                   string
+	allowedOrigins               []string
+	apiMiddlewareEndpointFactory apimiddleware.EndpointFactory
+	muxHandler                   MuxHandler
+	pbHandlers                   []*PbMux
+	router                       *mux.Router
+}
+
+// Gateway is the gRPC gateway to serve HTTP JSON traffic as a proxy and forward it to the gRPC server.
+type Gateway struct {
+	cfg          *config
+	conn         *grpc.ClientConn
+	server       *http.Server
+	cancel       context.CancelFunc
+	proxy        *apimiddleware.ApiProxyMiddleware
+	ctx          context.Context
+	startFailure error
+}
+
+// New returns a new instance of the Gateway.
+func New(ctx context.Context, opts ...Option) (*Gateway, error) {
+	g := &Gateway{
+		ctx: ctx,
+		cfg: &config{
+			router: mux.NewRouter(),
+		},
+	}
+	for _, opt := range opts {
+		if err := opt(g); err != nil {
+			return nil, err
+		}
+	}
+	return g, nil
+}
+
+// Start the gateway service.
+func (g *Gateway) Start() {
+	ctx, cancel := context.WithCancel(g.ctx)
+	g.cancel = cancel
+
+	conn, err := g.dial(ctx, "tcp", g.cfg.remoteAddr)
+	if err != nil {
+		log.WithError(err).Error("Failed to connect to gRPC server")
+		g.startFailure = err
+		return
+	}
+	g.conn = conn
+
+	for _, h := range g.cfg.pbHandlers {
+		for _, r := range h.Registrations {
+			if err := r(ctx, h.Mux, g.conn); err != nil {
+				log.WithError(err).Error("Failed to register handler")
+				g.startFailure = err
+				return
+			}
+		}
+		for _, p := range h.Patterns {
+			g.cfg.router.PathPrefix(p).Handler(h.Mux)
+		}
+	}
+
+	corsMux := g.corsMiddleware(g.cfg.router)
+
+	if g.cfg.apiMiddlewareEndpointFactory != nil && !g.cfg.apiMiddlewareEndpointFactory.IsNil() {
+		g.registerApiMiddleware()
+	}
+
+	if g.cfg.muxHandler != nil {
+		g.cfg.router.PathPrefix("/").HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			g.cfg.muxHandler(g.proxy, corsMux.ServeHTTP, w, r)
+		})
+	}
+
+	g.server = &http.Server{
+		Addr:    g.cfg.gatewayAddr,
+		Handler: corsMux,
+	}
+
+	go func() {
+		log.WithField("address", g.cfg.gatewayAddr).Info("Starting gRPC gateway")
+		if err := g.server.ListenAndServe(); err != http.ErrServerClosed {
+			log.WithError(err).Error("Failed to start gRPC gateway")
+			g.startFailure = err
+			return
+		}
+	}()
+}
+
+// Status of grpc gateway. Returns an error if this service is unhealthy.
+func (g *Gateway) Status() error {
+	if g.startFailure != nil {
+		return g.startFailure
+	}
+	if s := g.conn.GetState(); s != connectivity.Ready {
+		return fmt.Errorf("grpc server is %s", s)
+	}
+	return nil
+}
+
+// Stop the gateway with a graceful shutdown.
+func (g *Gateway) Stop() error {
+	if g.server != nil {
+		shutdownCtx, shutdownCancel := context.WithTimeout(g.ctx, 2*time.Second)
+		defer shutdownCancel()
+		if err := g.server.Shutdown(shutdownCtx); err != nil {
+			if errors.Is(err, context.DeadlineExceeded) {
+				log.Warn("Existing connections terminated")
+			} else {
+				log.WithError(err).Error("Failed to gracefully shut down server")
+			}
+		}
+	}
+	if g.cancel != nil {
+		g.cancel()
+	}
+	return nil
+}
+
+func (g *Gateway) corsMiddleware(h http.Handler) http.Handler {
+	c := cors.New(cors.Options{
+		AllowedOrigins:   g.cfg.allowedOrigins,
+		AllowedMethods:   []string{http.MethodPost, http.MethodGet, http.MethodDelete, http.MethodOptions},
+		AllowCredentials: true,
+		MaxAge:           600,
+		AllowedHeaders:   []string{"*"},
+	})
+	return c.Handler(h)
+}
+
+const swaggerDir = "proto/prysm/v1alpha1/"
+
+// SwaggerServer returns swagger specification files located under "/swagger/"
+func SwaggerServer() http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		if !strings.HasSuffix(r.URL.Path, ".swagger.json") {
+			log.Debugf("Not found: %s", r.URL.Path)
+			http.NotFound(w, r)
+			return
+		}
+
+		log.Debugf("Serving %s\n", r.URL.Path)
+		p := strings.TrimPrefix(r.URL.Path, "/swagger/")
+		p = path.Join(swaggerDir, p)
+		http.ServeFile(w, r, p)
+	}
+}
+
+// dial the gRPC server.
+func (g *Gateway) dial(ctx context.Context, network, addr string) (*grpc.ClientConn, error) {
+	switch network {
+	case "tcp":
+		return g.dialTCP(ctx, addr)
+	case "unix":
+		return g.dialUnix(ctx, addr)
+	default:
+		return nil, fmt.Errorf("unsupported network type %q", network)
+	}
+}
+
+// dialTCP creates a client connection via TCP.
+// "addr" must be a valid TCP address with a port number.
+func (g *Gateway) dialTCP(ctx context.Context, addr string) (*grpc.ClientConn, error) {
+	security := grpc.WithInsecure()
+	if len(g.cfg.remoteCert) > 0 {
+		creds, err := credentials.NewClientTLSFromFile(g.cfg.remoteCert, "")
+		if err != nil {
+			return nil, err
+		}
+		security = grpc.WithTransportCredentials(creds)
+	}
+	opts := []grpc.DialOption{
+		security,
+		grpc.WithDefaultCallOptions(grpc.MaxCallRecvMsgSize(int(g.cfg.maxCallRecvMsgSize))),
+	}
+
+	return grpc.DialContext(ctx, addr, opts...)
+}
+
+// dialUnix creates a client connection via a unix domain socket.
+// "addr" must be a valid path to the socket.
+func (g *Gateway) dialUnix(ctx context.Context, addr string) (*grpc.ClientConn, error) {
+	d := func(addr string, timeout time.Duration) (net.Conn, error) {
+		return net.DialTimeout("unix", addr, timeout)
+	}
+	f := func(ctx context.Context, addr string) (net.Conn, error) {
+		if deadline, ok := ctx.Deadline(); ok {
+			return d(addr, time.Until(deadline))
+		}
+		return d(addr, 0)
+	}
+	opts := []grpc.DialOption{
+		grpc.WithInsecure(),
+		grpc.WithContextDialer(f),
+		grpc.WithDefaultCallOptions(grpc.MaxCallRecvMsgSize(int(g.cfg.maxCallRecvMsgSize))),
+	}
+	return grpc.DialContext(ctx, addr, opts...)
+}
+
+func (g *Gateway) registerApiMiddleware() {
+	g.proxy = &apimiddleware.ApiProxyMiddleware{
+		GatewayAddress:  g.cfg.gatewayAddr,
+		EndpointCreator: g.cfg.apiMiddlewareEndpointFactory,
+	}
+	log.Info("Starting API middleware")
+	g.proxy.Run(g.cfg.router)
+}
--- a/api/gateway/gateway_test.go
+++ b/api/gateway/gateway_test.go
@@ -0,0 +1,128 @@
+package gateway
+
+import (
+	"context"
+	"flag"
+	"fmt"
+	"net/http"
+	"net/http/httptest"
+	"net/url"
+	"testing"
+
+	"github.com/gorilla/mux"
+	"github.com/prysmaticlabs/prysm/api/gateway/apimiddleware"
+	"github.com/prysmaticlabs/prysm/cmd/beacon-chain/flags"
+	"github.com/prysmaticlabs/prysm/testing/assert"
+	"github.com/prysmaticlabs/prysm/testing/require"
+	logTest "github.com/sirupsen/logrus/hooks/test"
+	"github.com/urfave/cli/v2"
+)
+
+type mockEndpointFactory struct {
+}
+
+func (*mockEndpointFactory) Paths() []string {
+	return []string{}
+}
+
+func (*mockEndpointFactory) Create(_ string) (*apimiddleware.Endpoint, error) {
+	return nil, nil
+}
+
+func (*mockEndpointFactory) IsNil() bool {
+	return false
+}
+
+func TestGateway_Customized(t *testing.T) {
+	r := mux.NewRouter()
+	cert := "cert"
+	origins := []string{"origin"}
+	size := uint64(100)
+	endpointFactory := &mockEndpointFactory{}
+
+	opts := []Option{
+		WithRouter(r),
+		WithRemoteCert(cert),
+		WithAllowedOrigins(origins),
+		WithMaxCallRecvMsgSize(size),
+		WithApiMiddleware(endpointFactory),
+		WithMuxHandler(func(
+			_ *apimiddleware.ApiProxyMiddleware,
+			_ http.HandlerFunc,
+			_ http.ResponseWriter,
+			_ *http.Request,
+		) {
+		}),
+	}
+
+	g, err := New(context.Background(), opts...)
+	require.NoError(t, err)
+
+	assert.Equal(t, r, g.cfg.router)
+	assert.Equal(t, cert, g.cfg.remoteCert)
+	require.Equal(t, 1, len(g.cfg.allowedOrigins))
+	assert.Equal(t, origins[0], g.cfg.allowedOrigins[0])
+	assert.Equal(t, size, g.cfg.maxCallRecvMsgSize)
+	assert.Equal(t, endpointFactory, g.cfg.apiMiddlewareEndpointFactory)
+}
+
+func TestGateway_StartStop(t *testing.T) {
+	hook := logTest.NewGlobal()
+
+	app := cli.App{}
+	set := flag.NewFlagSet("test", 0)
+	ctx := cli.NewContext(&app, set, nil)
+
+	gatewayPort := ctx.Int(flags.GRPCGatewayPort.Name)
+	gatewayHost := ctx.String(flags.GRPCGatewayHost.Name)
+	rpcHost := ctx.String(flags.RPCHost.Name)
+	selfAddress := fmt.Sprintf("%s:%d", rpcHost, ctx.Int(flags.RPCPort.Name))
+	gatewayAddress := fmt.Sprintf("%s:%d", gatewayHost, gatewayPort)
+
+	opts := []Option{
+		WithGatewayAddr(gatewayAddress),
+		WithRemoteAddr(selfAddress),
+		WithMuxHandler(func(
+			_ *apimiddleware.ApiProxyMiddleware,
+			_ http.HandlerFunc,
+			_ http.ResponseWriter,
+			_ *http.Request,
+		) {
+		}),
+	}
+
+	g, err := New(context.Background(), opts...)
+	require.NoError(t, err)
+
+	g.Start()
+	go func() {
+		require.LogsContain(t, hook, "Starting gRPC gateway")
+		require.LogsDoNotContain(t, hook, "Starting API middleware")
+	}()
+	err = g.Stop()
+	require.NoError(t, err)
+}
+
+func TestGateway_NilHandler_NotFoundHandlerRegistered(t *testing.T) {
+	app := cli.App{}
+	set := flag.NewFlagSet("test", 0)
+	ctx := cli.NewContext(&app, set, nil)
+
+	gatewayPort := ctx.Int(flags.GRPCGatewayPort.Name)
+	gatewayHost := ctx.String(flags.GRPCGatewayHost.Name)
+	rpcHost := ctx.String(flags.RPCHost.Name)
+	selfAddress := fmt.Sprintf("%s:%d", rpcHost, ctx.Int(flags.RPCPort.Name))
+	gatewayAddress := fmt.Sprintf("%s:%d", gatewayHost, gatewayPort)
+
+	opts := []Option{
+		WithGatewayAddr(gatewayAddress),
+		WithRemoteAddr(selfAddress),
+	}
+
+	g, err := New(context.Background(), opts...)
+	require.NoError(t, err)
+
+	writer := httptest.NewRecorder()
+	g.cfg.router.ServeHTTP(writer, &http.Request{Method: "GET", Host: "localhost", URL: &url.URL{Path: "/foo"}})
+	assert.Equal(t, http.StatusNotFound, writer.Code)
+}
--- a/shared/gateway/log.go
+++ b/shared/gateway/log.go
--- a/api/gateway/options.go
+++ b/api/gateway/options.go
@@ -0,0 +1,81 @@
+package gateway
+
+import (
+	"github.com/gorilla/mux"
+	"github.com/prysmaticlabs/prysm/api/gateway/apimiddleware"
+)
+
+type Option func(g *Gateway) error
+
+func (g *Gateway) SetRouter(r *mux.Router) *Gateway {
+	g.cfg.router = r
+	return g
+}
+
+func WithPbHandlers(handlers []*PbMux) Option {
+	return func(g *Gateway) error {
+		g.cfg.pbHandlers = handlers
+		return nil
+	}
+}
+
+func WithMuxHandler(m MuxHandler) Option {
+	return func(g *Gateway) error {
+		g.cfg.muxHandler = m
+		return nil
+	}
+}
+
+func WithGatewayAddr(addr string) Option {
+	return func(g *Gateway) error {
+		g.cfg.gatewayAddr = addr
+		return nil
+	}
+}
+
+func WithRemoteAddr(addr string) Option {
+	return func(g *Gateway) error {
+		g.cfg.remoteAddr = addr
+		return nil
+	}
+}
+
+// WithRouter allows adding a custom mux router to the gateway.
+func WithRouter(r *mux.Router) Option {
+	return func(g *Gateway) error {
+		g.cfg.router = r
+		return nil
+	}
+}
+
+// WithAllowedOrigins allows adding a set of allowed origins to the gateway.
+func WithAllowedOrigins(origins []string) Option {
+	return func(g *Gateway) error {
+		g.cfg.allowedOrigins = origins
+		return nil
+	}
+}
+
+// WithRemoteCert allows adding a custom certificate to the gateway,
+func WithRemoteCert(cert string) Option {
+	return func(g *Gateway) error {
+		g.cfg.remoteCert = cert
+		return nil
+	}
+}
+
+// WithMaxCallRecvMsgSize allows specifying the maximum allowed gRPC message size.
+func WithMaxCallRecvMsgSize(size uint64) Option {
+	return func(g *Gateway) error {
+		g.cfg.maxCallRecvMsgSize = size
+		return nil
+	}
+}
+
+// WithApiMiddleware allows adding an API middleware proxy to the gateway.
+func WithApiMiddleware(endpointFactory apimiddleware.EndpointFactory) Option {
+	return func(g *Gateway) error {
+		g.cfg.apiMiddlewareEndpointFactory = endpointFactory
+		return nil
+	}
+}
--- a/api/grpc/BUILD.bazel
+++ b/api/grpc/BUILD.bazel
@@ -0,0 +1,30 @@
+load("@prysm//tools/go:def.bzl", "go_library", "go_test")
+
+go_library(
+    name = "go_default_library",
+    srcs = [
+        "grpcutils.go",
+        "parameters.go",
+    ],
+    importpath = "github.com/prysmaticlabs/prysm/api/grpc",
+    visibility = ["//visibility:public"],
+    deps = [
+        "@com_github_sirupsen_logrus//:go_default_library",
+        "@org_golang_google_grpc//:go_default_library",
+        "@org_golang_google_grpc//metadata:go_default_library",
+    ],
+)
+
+go_test(
+    name = "go_default_test",
+    srcs = ["grpcutils_test.go"],
+    embed = [":go_default_library"],
+    deps = [
+        "//testing/assert:go_default_library",
+        "//testing/require:go_default_library",
+        "@com_github_grpc_ecosystem_grpc_gateway_v2//runtime:go_default_library",
+        "@com_github_sirupsen_logrus//hooks/test:go_default_library",
+        "@org_golang_google_grpc//:go_default_library",
+        "@org_golang_google_grpc//metadata:go_default_library",
+    ],
+)
--- a/shared/grpcutils/grpcutils.go
+++ b/shared/grpcutils/grpcutils.go
@@ -1,7 +1,9 @@
-package grpcutils
+package grpc

 import (
 	"context"
+	"encoding/json"
+	"fmt"
 	"strings"
 	"time"

@@ -79,3 +81,16 @@ func AppendHeaders(parent context.Context, headers []string) context.Context {
 	}
 	return parent
 }
+
+// AppendCustomErrorHeader sets a CustomErrorMetadataKey gRPC header on the passed in context,
+// using the passed in error data as the header's value. The data is serialized as JSON.
+func AppendCustomErrorHeader(ctx context.Context, errorData interface{}) error {
+	j, err := json.Marshal(errorData)
+	if err != nil {
+		return fmt.Errorf("could not marshal error data into JSON: %w", err)
+	}
+	if err := grpc.SetHeader(ctx, metadata.Pairs(CustomErrorMetadataKey, string(j))); err != nil {
+		return fmt.Errorf("could not set custom error header: %w", err)
+	}
+	return nil
+}
--- a/api/grpc/grpcutils_test.go
+++ b/api/grpc/grpcutils_test.go
@@ -0,0 +1,78 @@
+package grpc
+
+import (
+	"context"
+	"encoding/json"
+	"strings"
+	"testing"
+
+	"github.com/grpc-ecosystem/grpc-gateway/v2/runtime"
+	"github.com/prysmaticlabs/prysm/testing/assert"
+	"github.com/prysmaticlabs/prysm/testing/require"
+	logTest "github.com/sirupsen/logrus/hooks/test"
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/metadata"
+)
+
+type customErrorData struct {
+	Message string `json:"message"`
+}
+
+func TestAppendHeaders(t *testing.T) {
+	t.Run("one_header", func(t *testing.T) {
+		ctx := AppendHeaders(context.Background(), []string{"first=value1"})
+		md, ok := metadata.FromOutgoingContext(ctx)
+		require.Equal(t, true, ok, "Failed to read context metadata")
+		require.Equal(t, 1, md.Len(), "MetadataV0 contains wrong number of values")
+		assert.Equal(t, "value1", md.Get("first")[0])
+	})
+
+	t.Run("multiple_headers", func(t *testing.T) {
+		ctx := AppendHeaders(context.Background(), []string{"first=value1", "second=value2"})
+		md, ok := metadata.FromOutgoingContext(ctx)
+		require.Equal(t, true, ok, "Failed to read context metadata")
+		require.Equal(t, 2, md.Len(), "MetadataV0 contains wrong number of values")
+		assert.Equal(t, "value1", md.Get("first")[0])
+		assert.Equal(t, "value2", md.Get("second")[0])
+	})
+
+	t.Run("one_empty_header", func(t *testing.T) {
+		ctx := AppendHeaders(context.Background(), []string{"first=value1", ""})
+		md, ok := metadata.FromOutgoingContext(ctx)
+		require.Equal(t, true, ok, "Failed to read context metadata")
+		require.Equal(t, 1, md.Len(), "MetadataV0 contains wrong number of values")
+		assert.Equal(t, "value1", md.Get("first")[0])
+	})
+
+	t.Run("incorrect_header", func(t *testing.T) {
+		logHook := logTest.NewGlobal()
+		ctx := AppendHeaders(context.Background(), []string{"first=value1", "second"})
+		md, ok := metadata.FromOutgoingContext(ctx)
+		require.Equal(t, true, ok, "Failed to read context metadata")
+		require.Equal(t, 1, md.Len(), "MetadataV0 contains wrong number of values")
+		assert.Equal(t, "value1", md.Get("first")[0])
+		assert.LogsContain(t, logHook, "Skipping second")
+	})
+
+	t.Run("header_value_with_equal_sign", func(t *testing.T) {
+		ctx := AppendHeaders(context.Background(), []string{"first=value=1"})
+		md, ok := metadata.FromOutgoingContext(ctx)
+		require.Equal(t, true, ok, "Failed to read context metadata")
+		require.Equal(t, 1, md.Len(), "MetadataV0 contains wrong number of values")
+		assert.Equal(t, "value=1", md.Get("first")[0])
+	})
+}
+
+func TestAppendCustomErrorHeader(t *testing.T) {
+	stream := &runtime.ServerTransportStream{}
+	ctx := grpc.NewContextWithServerTransportStream(context.Background(), stream)
+	data := &customErrorData{Message: "foo"}
+	require.NoError(t, AppendCustomErrorHeader(ctx, data))
+	// The stream used in test setup sets the metadata key in lowercase.
+	value, ok := stream.Header()[strings.ToLower(CustomErrorMetadataKey)]
+	require.Equal(t, true, ok, "Failed to retrieve custom error metadata value")
+	expected, err := json.Marshal(data)
+	require.NoError(t, err)
+	assert.Equal(t, string(expected), value[0])
+
+}
--- a/api/grpc/parameters.go
+++ b/api/grpc/parameters.go
@@ -0,0 +1,8 @@
+package grpc
+
+// CustomErrorMetadataKey is the name of the metadata key storing additional error information.
+// Metadata value is expected to be a byte-encoded JSON object.
+const CustomErrorMetadataKey = "Custom-Error"
+
+// HttpCodeMetadataKey is the key to use when setting custom HTTP status codes in gRPC metadata.
+const HttpCodeMetadataKey = "X-Http-Code"
--- a/api/pagination/BUILD.bazel
+++ b/api/pagination/BUILD.bazel
@@ -0,0 +1,22 @@
+load("@prysm//tools/go:def.bzl", "go_library", "go_test")
+
+go_library(
+    name = "go_default_library",
+    srcs = ["pagination.go"],
+    importpath = "github.com/prysmaticlabs/prysm/api/pagination",
+    visibility = ["//visibility:public"],
+    deps = [
+        "//config/params:go_default_library",
+        "@com_github_pkg_errors//:go_default_library",
+    ],
+)
+
+go_test(
+    name = "go_default_test",
+    srcs = ["pagination_test.go"],
+    deps = [
+        ":go_default_library",
+        "//testing/assert:go_default_library",
+        "//testing/require:go_default_library",
+    ],
+)
--- a/shared/pagination/pagination.go
+++ b/shared/pagination/pagination.go
@@ -6,7 +6,7 @@ import (
 	"strconv"

 	"github.com/pkg/errors"
-	"github.com/prysmaticlabs/prysm/shared/params"
+	"github.com/prysmaticlabs/prysm/config/params"
 )

 // StartAndEndPage takes in the requested page token, wanted page size, total page size.
--- a/shared/pagination/pagination_test.go
+++ b/shared/pagination/pagination_test.go
@@ -3,9 +3,9 @@ package pagination_test
 import (
 	"testing"

-	"github.com/prysmaticlabs/prysm/shared/pagination"
-	"github.com/prysmaticlabs/prysm/shared/testutil/assert"
-	"github.com/prysmaticlabs/prysm/shared/testutil/require"
+	"github.com/prysmaticlabs/prysm/api/pagination"
+	"github.com/prysmaticlabs/prysm/testing/assert"
+	"github.com/prysmaticlabs/prysm/testing/require"
 )

 func TestStartAndEndPage(t *testing.T) {
--- a/async/BUILD.bazel
+++ b/async/BUILD.bazel
@@ -0,0 +1,33 @@
+load("@prysm//tools/go:def.bzl", "go_library", "go_test")
+
+go_library(
+    name = "go_default_library",
+    srcs = [
+        "debounce.go",
+        "every.go",
+        "multilock.go",
+        "scatter.go",
+    ],
+    importpath = "github.com/prysmaticlabs/prysm/async",
+    visibility = ["//visibility:public"],
+    deps = ["@com_github_sirupsen_logrus//:go_default_library"],
+)
+
+go_test(
+    name = "go_default_test",
+    srcs = [
+        "benchmark_test.go",
+        "debounce_test.go",
+        "every_test.go",
+        "multilock_test.go",
+        "scatter_test.go",
+    ],
+    embed = [":go_default_library"],
+    deps = [
+        "//testing/assert:go_default_library",
+        "//testing/require:go_default_library",
+        "//testing/util:go_default_library",
+        "@com_github_sirupsen_logrus//:go_default_library",
+        "@com_github_stretchr_testify//assert:go_default_library",
+    ],
+)
--- a/async/abool/BUILD.bazel
+++ b/async/abool/BUILD.bazel
@@ -0,0 +1,14 @@
+load("@prysm//tools/go:def.bzl", "go_library", "go_test")
+
+go_library(
+    name = "go_default_library",
+    srcs = ["abool.go"],
+    importpath = "github.com/prysmaticlabs/prysm/async/abool",
+    visibility = ["//visibility:public"],
+)
+
+go_test(
+    name = "go_default_test",
+    srcs = ["abool_test.go"],
+    embed = [":go_default_library"],
+)
--- a/shared/abool/abool.go
+++ b/shared/abool/abool.go
--- a/shared/abool/abool_test.go
+++ b/shared/abool/abool_test.go
--- a/async/benchmark_test.go
+++ b/async/benchmark_test.go
@@ -0,0 +1,63 @@
+package async_test
+
+import (
+	"crypto/rand"
+	"crypto/sha256"
+	"sync"
+	"testing"
+
+	"github.com/prysmaticlabs/prysm/async"
+	"github.com/prysmaticlabs/prysm/testing/require"
+	log "github.com/sirupsen/logrus"
+)
+
+var input [][]byte
+
+const (
+	benchmarkElements    = 65536
+	benchmarkElementSize = 32
+	benchmarkHashRuns    = 128
+)
+
+func init() {
+	input = make([][]byte, benchmarkElements)
+	for i := 0; i < benchmarkElements; i++ {
+		input[i] = make([]byte, benchmarkElementSize)
+		_, err := rand.Read(input[i])
+		if err != nil {
+			log.WithError(err).Debug("Cannot read from rand")
+		}
+	}
+}
+
+// hash repeatedly hashes the data passed to it
+func hash(input [][]byte) [][]byte {
+	output := make([][]byte, len(input))
+	for i := range input {
+		copy(output, input)
+		for j := 0; j < benchmarkHashRuns; j++ {
+			hash := sha256.Sum256(output[i])
+			output[i] = hash[:]
+		}
+	}
+	return output
+}
+
+func BenchmarkHash(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		hash(input)
+	}
+}
+
+func BenchmarkHashMP(b *testing.B) {
+	output := make([][]byte, len(input))
+	for i := 0; i < b.N; i++ {
+		workerResults, err := async.Scatter(len(input), func(offset int, entries int, _ *sync.RWMutex) (interface{}, error) {
+			return hash(input[offset : offset+entries]), nil
+		})
+		require.NoError(b, err)
+		for _, result := range workerResults {
+			copy(output[result.Offset:], result.Extent.([][]byte))
+		}
+	}
+}
--- a/shared/asyncutil/debounce.go
+++ b/shared/asyncutil/debounce.go
@@ -1,4 +1,4 @@
-package asyncutil
+package async

 import (
 	"context"
--- a/shared/asyncutil/debounce_test.go
+++ b/shared/asyncutil/debounce_test.go
@@ -1,4 +1,4 @@
-package asyncutil
+package async_test

 import (
 	"context"
@@ -6,9 +6,10 @@ import (
 	"testing"
 	"time"

-	"github.com/prysmaticlabs/prysm/shared/testutil"
-	"github.com/prysmaticlabs/prysm/shared/testutil/assert"
-	"github.com/prysmaticlabs/prysm/shared/testutil/require"
+	"github.com/prysmaticlabs/prysm/async"
+	"github.com/prysmaticlabs/prysm/testing/assert"
+	"github.com/prysmaticlabs/prysm/testing/require"
+	"github.com/prysmaticlabs/prysm/testing/util"
 )

 func TestDebounce_NoEvents(t *testing.T) {
@@ -24,12 +25,12 @@ func TestDebounce_NoEvents(t *testing.T) {
 		})
 	}()
 	go func() {
-		Debounce(ctx, interval, eventsChan, func(event interface{}) {
+		async.Debounce(ctx, interval, eventsChan, func(event interface{}) {
 			timesHandled++
 		})
 		wg.Done()
 	}()
-	if testutil.WaitTimeout(wg, interval*2) {
+	if util.WaitTimeout(wg, interval*2) {
 		t.Fatalf("Test should have exited by now, timed out")
 	}
 	assert.Equal(t, 0, timesHandled, "Wrong number of handled calls")
@@ -60,12 +61,12 @@ func TestDebounce_CtxClosing(t *testing.T) {
 		})
 	}()
 	go func() {
-		Debounce(ctx, interval, eventsChan, func(event interface{}) {
+		async.Debounce(ctx, interval, eventsChan, func(event interface{}) {
 			timesHandled++
 		})
 		wg.Done()
 	}()
-	if testutil.WaitTimeout(wg, interval*2) {
+	if util.WaitTimeout(wg, interval*2) {
 		t.Fatalf("Test should have exited by now, timed out")
 	}
 	assert.Equal(t, 0, timesHandled, "Wrong number of handled calls")
@@ -76,7 +77,7 @@ func TestDebounce_SingleHandlerInvocation(t *testing.T) {
 	ctx, cancel := context.WithCancel(context.Background())
 	interval := time.Second
 	timesHandled := 0
-	go Debounce(ctx, interval, eventsChan, func(event interface{}) {
+	go async.Debounce(ctx, interval, eventsChan, func(event interface{}) {
 		timesHandled++
 	})
 	for i := 0; i < 100; i++ {
@@ -94,7 +95,7 @@ func TestDebounce_MultipleHandlerInvocation(t *testing.T) {
 	ctx, cancel := context.WithCancel(context.Background())
 	interval := time.Second
 	timesHandled := 0
-	go Debounce(ctx, interval, eventsChan, func(event interface{}) {
+	go async.Debounce(ctx, interval, eventsChan, func(event interface{}) {
 		timesHandled++
 	})
 	for i := 0; i < 100; i++ {
--- a/async/event/BUILD.bazel
+++ b/async/event/BUILD.bazel
@@ -0,0 +1,29 @@
+load("@prysm//tools/go:def.bzl", "go_library", "go_test")
+
+go_library(
+    name = "go_default_library",
+    srcs = [
+        "feed.go",
+        "subscription.go",
+    ],
+    importpath = "github.com/prysmaticlabs/prysm/async/event",
+    visibility = ["//visibility:public"],
+    deps = ["//time/mclock:go_default_library"],
+)
+
+go_test(
+    name = "go_default_test",
+    size = "small",
+    srcs = [
+        "example_feed_test.go",
+        "example_scope_test.go",
+        "example_subscription_test.go",
+        "feed_test.go",
+        "subscription_test.go",
+    ],
+    embed = [":go_default_library"],
+    deps = [
+        "//testing/assert:go_default_library",
+        "//testing/require:go_default_library",
+    ],
+)
--- a/shared/event/example_feed_test.go
+++ b/shared/event/example_feed_test.go
@@ -19,7 +19,7 @@ package event_test
 import (
 	"fmt"

-	"github.com/prysmaticlabs/prysm/shared/event"
+	"github.com/prysmaticlabs/prysm/async/event"
 )

 func ExampleFeed_acknowledgedEvents() {
--- a/shared/event/example_scope_test.go
+++ b/shared/event/example_scope_test.go
@@ -20,7 +20,7 @@ import (
 	"fmt"
 	"sync"

-	"github.com/prysmaticlabs/prysm/shared/event"
+	"github.com/prysmaticlabs/prysm/async/event"
 )

 // This example demonstrates how SubscriptionScope can be used to control the lifetime of
--- a/shared/event/example_subscription_test.go
+++ b/shared/event/example_subscription_test.go
@@ -19,7 +19,7 @@ package event_test
 import (
 	"fmt"

-	"github.com/prysmaticlabs/prysm/shared/event"
+	"github.com/prysmaticlabs/prysm/async/event"
 )

 func ExampleNewSubscription() {
--- a/shared/event/feed.go
+++ b/shared/event/feed.go
@@ -98,6 +98,11 @@ func (f *Feed) typecheck(typ reflect.Type) bool {
 		f.etype = typ
 		return true
 	}
+	// In the event the feed's type is an actual interface, we
+	// perform an interface conformance check here.
+	if f.etype.Kind() == reflect.Interface && typ.Implements(f.etype) {
+		return true
+	}
 	return f.etype == typ
 }

--- a/async/event/feed_test.go
+++ b/async/event/feed_test.go
@@ -0,0 +1,507 @@
+// Copyright 2016 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+package event
+
+import (
+	"fmt"
+	"reflect"
+	"sync"
+	"testing"
+	"time"
+
+	"github.com/prysmaticlabs/prysm/testing/assert"
+)
+
+func TestFeedPanics(t *testing.T) {
+	{
+		var f Feed
+		f.Send(2)
+		want := feedTypeError{op: "Send", got: reflect.TypeOf(uint64(0)), want: reflect.TypeOf(0)}
+		assert.NoError(t, checkPanic(want, func() { f.Send(uint64(2)) }))
+	}
+	{
+		var f Feed
+		ch := make(chan int)
+		f.Subscribe(ch)
+		want := feedTypeError{op: "Send", got: reflect.TypeOf(uint64(0)), want: reflect.TypeOf(0)}
+		assert.NoError(t, checkPanic(want, func() { f.Send(uint64(2)) }))
+	}
+	{
+		var f Feed
+		f.Send(2)
+		want := feedTypeError{op: "Subscribe", got: reflect.TypeOf(make(chan uint64)), want: reflect.TypeOf(make(chan<- int))}
+		assert.NoError(t, checkPanic(want, func() { f.Subscribe(make(chan uint64)) }))
+	}
+	{
+		var f Feed
+		assert.NoError(t, checkPanic(errBadChannel, func() { f.Subscribe(make(<-chan int)) }))
+	}
+	{
+		var f Feed
+		assert.NoError(t, checkPanic(errBadChannel, func() { f.Subscribe(0) }))
+	}
+}
+
+func checkPanic(want error, fn func()) (err error) {
+	defer func() {
+		panicResult := recover()
+		if panicResult == nil {
+			err = fmt.Errorf("didn't panic")
+		} else if !reflect.DeepEqual(panicResult, want) {
+			err = fmt.Errorf("panicked with wrong error: got %q, want %q", panicResult, want)
+		}
+	}()
+	fn()
+	return nil
+}
+
+func TestFeed(t *testing.T) {
+	var feed Feed
+	var done, subscribed sync.WaitGroup
+	subscriber := func(i int) {
+		defer done.Done()
+
+		subchan := make(chan int)
+		sub := feed.Subscribe(subchan)
+		timeout := time.NewTimer(2 * time.Second)
+		subscribed.Done()
+
+		select {
+		case v := <-subchan:
+			if v != 1 {
+				t.Errorf("%d: received value %d, want 1", i, v)
+			}
+		case <-timeout.C:
+			t.Errorf("%d: receive timeout", i)
+		}
+
+		sub.Unsubscribe()
+		select {
+		case _, ok := <-sub.Err():
+			if ok {
+				t.Errorf("%d: error channel not closed after unsubscribe", i)
+			}
+		case <-timeout.C:
+			t.Errorf("%d: unsubscribe timeout", i)
+		}
+	}
+
+	const n = 1000
+	done.Add(n)
+	subscribed.Add(n)
+	for i := 0; i < n; i++ {
+		go subscriber(i)
+	}
+	subscribed.Wait()
+	if nsent := feed.Send(1); nsent != n {
+		t.Errorf("first send delivered %d times, want %d", nsent, n)
+	}
+	if nsent := feed.Send(2); nsent != 0 {
+		t.Errorf("second send delivered %d times, want 0", nsent)
+	}
+	done.Wait()
+}
+
+func TestFeedSubscribeSameChannel(t *testing.T) {
+	var (
+		feed Feed
+		done sync.WaitGroup
+		ch   = make(chan int)
+		sub1 = feed.Subscribe(ch)
+		sub2 = feed.Subscribe(ch)
+		_    = feed.Subscribe(ch)
+	)
+	expectSends := func(value, n int) {
+		if nsent := feed.Send(value); nsent != n {
+			t.Errorf("send delivered %d times, want %d", nsent, n)
+		}
+		done.Done()
+	}
+	expectRecv := func(wantValue, n int) {
+		for i := 0; i < n; i++ {
+			if v := <-ch; v != wantValue {
+				t.Errorf("received %d, want %d", v, wantValue)
+			}
+		}
+	}
+
+	done.Add(1)
+	go expectSends(1, 3)
+	expectRecv(1, 3)
+	done.Wait()
+
+	sub1.Unsubscribe()
+
+	done.Add(1)
+	go expectSends(2, 2)
+	expectRecv(2, 2)
+	done.Wait()
+
+	sub2.Unsubscribe()
+
+	done.Add(1)
+	go expectSends(3, 1)
+	expectRecv(3, 1)
+	done.Wait()
+}
+
+func TestFeedSubscribeBlockedPost(_ *testing.T) {
+	var (
+		feed   Feed
+		nsends = 2000
+		ch1    = make(chan int)
+		ch2    = make(chan int)
+		wg     sync.WaitGroup
+	)
+	defer wg.Wait()
+
+	feed.Subscribe(ch1)
+	wg.Add(nsends)
+	for i := 0; i < nsends; i++ {
+		go func() {
+			feed.Send(99)
+			wg.Done()
+		}()
+	}
+
+	sub2 := feed.Subscribe(ch2)
+	defer sub2.Unsubscribe()
+
+	// We're done when ch1 has received N times.
+	// The number of receives on ch2 depends on scheduling.
+	for i := 0; i < nsends; {
+		select {
+		case <-ch1:
+			i++
+		case <-ch2:
+		}
+	}
+}
+
+func TestFeedUnsubscribeBlockedPost(_ *testing.T) {
+	var (
+		feed   Feed
+		nsends = 200
+		chans  = make([]chan int, 2000)
+		subs   = make([]Subscription, len(chans))
+		bchan  = make(chan int)
+		bsub   = feed.Subscribe(bchan)
+		wg     sync.WaitGroup
+	)
+	for i := range chans {
+		chans[i] = make(chan int, nsends)
+	}
+
+	// Queue up some Sends. None of these can make progress while bchan isn't read.
+	wg.Add(nsends)
+	for i := 0; i < nsends; i++ {
+		go func() {
+			feed.Send(99)
+			wg.Done()
+		}()
+	}
+	// Subscribe the other channels.
+	for i, ch := range chans {
+		subs[i] = feed.Subscribe(ch)
+	}
+	// Unsubscribe them again.
+	for _, sub := range subs {
+		sub.Unsubscribe()
+	}
+	// Unblock the Sends.
+	bsub.Unsubscribe()
+	wg.Wait()
+}
+
+// Checks that unsubscribing a channel during Send works even if that
+// channel has already been sent on.
+func TestFeedUnsubscribeSentChan(_ *testing.T) {
+	var (
+		feed Feed
+		ch1  = make(chan int)
+		ch2  = make(chan int)
+		sub1 = feed.Subscribe(ch1)
+		sub2 = feed.Subscribe(ch2)
+		wg   sync.WaitGroup
+	)
+	defer sub2.Unsubscribe()
+
+	wg.Add(1)
+	go func() {
+		feed.Send(0)
+		wg.Done()
+	}()
+
+	// Wait for the value on ch1.
+	<-ch1
+	// Unsubscribe ch1, removing it from the send cases.
+	sub1.Unsubscribe()
+
+	// Receive ch2, finishing Send.
+	<-ch2
+	wg.Wait()
+
+	// Send again. This should send to ch2 only, so the wait group will unblock
+	// as soon as a value is received on ch2.
+	wg.Add(1)
+	go func() {
+		feed.Send(0)
+		wg.Done()
+	}()
+	<-ch2
+	wg.Wait()
+}
+
+func TestFeedUnsubscribeFromInbox(t *testing.T) {
+	var (
+		feed Feed
+		ch1  = make(chan int)
+		ch2  = make(chan int)
+		sub1 = feed.Subscribe(ch1)
+		sub2 = feed.Subscribe(ch1)
+		sub3 = feed.Subscribe(ch2)
+	)
+	assert.Equal(t, 3, len(feed.inbox))
+	assert.Equal(t, 1, len(feed.sendCases), "sendCases is non-empty after unsubscribe")
+
+	sub1.Unsubscribe()
+	sub2.Unsubscribe()
+	sub3.Unsubscribe()
+	assert.Equal(t, 0, len(feed.inbox), "Inbox is non-empty after unsubscribe")
+	assert.Equal(t, 1, len(feed.sendCases), "sendCases is non-empty after unsubscribe")
+}
+
+func BenchmarkFeedSend1000(b *testing.B) {
+	var (
+		done  sync.WaitGroup
+		feed  Feed
+		nsubs = 1000
+	)
+	subscriber := func(ch <-chan int) {
+		for i := 0; i < b.N; i++ {
+			<-ch
+		}
+		done.Done()
+	}
+	done.Add(nsubs)
+	for i := 0; i < nsubs; i++ {
+		ch := make(chan int, 200)
+		feed.Subscribe(ch)
+		go subscriber(ch)
+	}
+
+	// The actual benchmark.
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		if feed.Send(i) != nsubs {
+			panic("wrong number of sends")
+		}
+	}
+
+	b.StopTimer()
+	done.Wait()
+}
+
+func TestFeed_Send(t *testing.T) {
+	tests := []struct {
+		name        string
+		evFeed      *Feed
+		testSetup   func(fd *Feed, t *testing.T, o interface{})
+		obj         interface{}
+		expectPanic bool
+	}{
+		{
+			name:   "normal struct",
+			evFeed: new(Feed),
+			testSetup: func(fd *Feed, t *testing.T, o interface{}) {
+				testChan := make(chan testFeedWithPointer, 1)
+				fd.Subscribe(testChan)
+			},
+			obj: testFeedWithPointer{
+				a: new(uint64),
+				b: new(string),
+			},
+			expectPanic: false,
+		},
+		{
+			name:   "un-implemented interface",
+			evFeed: new(Feed),
+			testSetup: func(fd *Feed, t *testing.T, o interface{}) {
+				testChan := make(chan testFeedIface, 1)
+				fd.Subscribe(testChan)
+			},
+			obj: testFeedWithPointer{
+				a: new(uint64),
+				b: new(string),
+			},
+			expectPanic: true,
+		},
+		{
+			name:   "semi-implemented interface",
+			evFeed: new(Feed),
+			testSetup: func(fd *Feed, t *testing.T, o interface{}) {
+				testChan := make(chan testFeedIface, 1)
+				fd.Subscribe(testChan)
+			},
+			obj: testFeed2{
+				a: 0,
+				b: "",
+				c: []byte{'A'},
+			},
+			expectPanic: true,
+		},
+		{
+			name:   "fully-implemented interface",
+			evFeed: new(Feed),
+			testSetup: func(fd *Feed, t *testing.T, o interface{}) {
+				testChan := make(chan testFeedIface)
+				// Make it unbuffered to allow message to
+				// pass through
+				go func() {
+					a := <-testChan
+					if !reflect.DeepEqual(a, o) {
+						t.Errorf("Got = %v, want = %v", a, o)
+					}
+				}()
+				fd.Subscribe(testChan)
+			},
+			obj: testFeed{
+				a: 0,
+				b: "",
+			},
+			expectPanic: false,
+		},
+		{
+			name:   "fully-implemented interface with additional methods",
+			evFeed: new(Feed),
+			testSetup: func(fd *Feed, t *testing.T, o interface{}) {
+				testChan := make(chan testFeedIface)
+				// Make it unbuffered to allow message to
+				// pass through
+				go func() {
+					a := <-testChan
+					if !reflect.DeepEqual(a, o) {
+						t.Errorf("Got = %v, want = %v", a, o)
+					}
+				}()
+				fd.Subscribe(testChan)
+			},
+			obj: testFeed3{
+				a: 0,
+				b: "",
+				c: []byte{'A'},
+				d: []byte{'B'},
+			},
+			expectPanic: false,
+		},
+		{
+			name:   "concrete types implementing the same interface",
+			evFeed: new(Feed),
+			testSetup: func(fd *Feed, t *testing.T, o interface{}) {
+				testChan := make(chan testFeed, 1)
+				// Make it unbuffered to allow message to
+				// pass through
+				go func() {
+					a := <-testChan
+					if !reflect.DeepEqual(a, o) {
+						t.Errorf("Got = %v, want = %v", a, o)
+					}
+				}()
+				fd.Subscribe(testChan)
+			},
+			obj: testFeed3{
+				a: 0,
+				b: "",
+				c: []byte{'A'},
+				d: []byte{'B'},
+			},
+			expectPanic: true,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			defer func() {
+				if r := recover(); r != nil {
+					if !tt.expectPanic {
+						t.Errorf("panic triggered when unexpected: %v", r)
+					}
+				} else {
+					if tt.expectPanic {
+						t.Error("panic not triggered when expected")
+					}
+				}
+			}()
+			tt.testSetup(tt.evFeed, t, tt.obj)
+			if gotNsent := tt.evFeed.Send(tt.obj); gotNsent != 1 {
+				t.Errorf("Send() = %v, want %v", gotNsent, 1)
+			}
+		})
+	}
+}
+
+// The following objects below are a collection of different
+// struct types to test with.
+type testFeed struct {
+	a uint64
+	b string
+}
+
+func (testFeed) method1() {
+
+}
+
+func (testFeed) method2() {
+
+}
+
+type testFeedWithPointer struct {
+	a *uint64
+	b *string
+}
+
+type testFeed2 struct {
+	a uint64
+	b string
+	c []byte
+}
+
+func (testFeed2) method1() {
+
+}
+
+type testFeed3 struct {
+	a    uint64
+	b    string
+	c, d []byte
+}
+
+func (testFeed3) method1() {
+
+}
+
+func (testFeed3) method2() {
+
+}
+
+func (testFeed3) method3() {
+
+}
+
+type testFeedIface interface {
+	method1()
+	method2()
+}
--- a/shared/event/subscription.go
+++ b/shared/event/subscription.go
@@ -21,7 +21,7 @@ import (
 	"sync"
 	"time"

-	"github.com/prysmaticlabs/prysm/shared/mclockutil"
+	"github.com/prysmaticlabs/prysm/time/mclock"
 )

 // waitQuotient is divided against the max backoff time, in order to have N requests based on the full
@@ -120,7 +120,7 @@ type resubscribeSub struct {
 	err                  chan error
 	unsub                chan struct{}
 	unsubOnce            sync.Once
-	lastTry              mclockutil.AbsTime
+	lastTry              mclock.AbsTime
 	waitTime, backoffMax time.Duration
 }

@@ -151,11 +151,11 @@ func (s *resubscribeSub) loop() {
 }

 func (s *resubscribeSub) subscribe() Subscription {
-	subscribed := make(chan error)
+	subscribed := make(chan error, 1)
 	var sub Subscription
 retry:
 	for {
-		s.lastTry = mclockutil.Now()
+		s.lastTry = mclock.Now()
 		ctx, cancel := context.WithCancel(context.TODO())
 		go func() {
 			rsub, err := s.fn(ctx)
@@ -194,7 +194,7 @@ func (s *resubscribeSub) waitForError(sub Subscription) bool {
 }

 func (s *resubscribeSub) backoffWait() bool {
-	if time.Duration(mclockutil.Now()-s.lastTry) > s.backoffMax {
+	if time.Duration(mclock.Now()-s.lastTry) > s.backoffMax {
 		s.waitTime = s.backoffMax / waitQuotient
 	} else {
 		s.waitTime *= 2
--- a/shared/event/subscription_test.go
+++ b/shared/event/subscription_test.go
@@ -19,10 +19,11 @@ package event
 import (
 	"context"
 	"errors"
+	"runtime"
 	"testing"
 	"time"

-	"github.com/prysmaticlabs/prysm/shared/testutil/require"
+	"github.com/prysmaticlabs/prysm/testing/require"
 )

 var errInts = errors.New("error in subscribeInts")
@@ -108,3 +109,18 @@ func TestResubscribeAbort(t *testing.T) {
 	sub.Unsubscribe()
 	require.NoError(t, <-done)
 }
+
+func TestResubscribeNonBlocking(t *testing.T) {
+	done := make(chan struct{})
+	sub := Resubscribe(0, func(ctx context.Context) (Subscription, error) {
+		<-done
+		return nil, nil
+	})
+
+	resub, ok := sub.(*resubscribeSub)
+	require.Equal(t, true, ok)
+	currNum := runtime.NumGoroutine()
+	resub.unsub <- struct{}{}
+	done <- struct{}{}
+	require.Equal(t, currNum-1, runtime.NumGoroutine())
+}
--- a/shared/runutil/every.go
+++ b/shared/runutil/every.go
@@ -1,5 +1,5 @@
-// Package runutil includes helpers for scheduling runnable, periodic functions.
-package runutil
+// Package async includes helpers for scheduling runnable, periodic functions and contains useful helpers for converting multi-processor computation.
+package async

 import (
 	"context"
--- a/shared/runutil/every_test.go
+++ b/shared/runutil/every_test.go
@@ -1,18 +1,18 @@
-package runutil_test
+package async_test

 import (
 	"context"
 	"testing"
 	"time"

-	"github.com/prysmaticlabs/prysm/shared/runutil"
+	"github.com/prysmaticlabs/prysm/async"
 )

 func TestEveryRuns(t *testing.T) {
 	ctx, cancel := context.WithCancel(context.Background())

 	i := 0
-	runutil.RunEvery(ctx, 100*time.Millisecond, func() {
+	async.RunEvery(ctx, 100*time.Millisecond, func() {
 		i++
 	})

--- a/shared/mputil/multilock.go
+++ b/shared/mputil/multilock.go
@@ -10,7 +10,7 @@ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 See the License for the specific language governing permissions and
 limitations under the License.
 */
-package mputil
+package async

 import (
 	"runtime"
--- a/shared/mputil/multilock_test.go
+++ b/shared/mputil/multilock_test.go
@@ -10,7 +10,7 @@ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 See the License for the specific language governing permissions and
 limitations under the License.
 */
-package mputil
+package async

 import (
 	"sync"
@@ -50,7 +50,7 @@ func TestGetChan(t *testing.T) {
 	assert.Equal(ch1, ch3)
 }

-func TestLockUnlock(t *testing.T) {
+func TestLockUnlock(_ *testing.T) {
 	var wg sync.WaitGroup

 	wg.Add(5)
--- a/shared/mputil/scatter.go
+++ b/shared/mputil/scatter.go
@@ -1,6 +1,4 @@
-// Package mputil contains useful helpers for converting
-// multi-processor computation.
-package mputil
+package async

 import (
 	"errors"
--- a/shared/mputil/scatter_test.go
+++ b/shared/mputil/scatter_test.go
@@ -1,13 +1,13 @@
-package mputil_test
+package async_test

 import (
 	"errors"
 	"sync"
 	"testing"

-	"github.com/prysmaticlabs/prysm/shared/mputil"
-	"github.com/prysmaticlabs/prysm/shared/testutil/assert"
-	"github.com/prysmaticlabs/prysm/shared/testutil/require"
+	"github.com/prysmaticlabs/prysm/async"
+	"github.com/prysmaticlabs/prysm/testing/assert"
+	"github.com/prysmaticlabs/prysm/testing/require"
 )

 func TestDouble(t *testing.T) {
@@ -46,7 +46,7 @@ func TestDouble(t *testing.T) {
 				inValues[i] = i
 			}
 			outValues := make([]int, test.inValues)
-			workerResults, err := mputil.Scatter(len(inValues), func(offset int, entries int, _ *sync.RWMutex) (interface{}, error) {
+			workerResults, err := async.Scatter(len(inValues), func(offset int, entries int, _ *sync.RWMutex) (interface{}, error) {
 				extent := make([]int, entries)
 				for i := 0; i < entries; i++ {
 					extent[i] = inValues[offset+i] * 2
@@ -72,7 +72,7 @@ func TestDouble(t *testing.T) {
 func TestMutex(t *testing.T) {
 	totalRuns := 1048576
 	val := 0
-	_, err := mputil.Scatter(totalRuns, func(offset int, entries int, mu *sync.RWMutex) (interface{}, error) {
+	_, err := async.Scatter(totalRuns, func(offset int, entries int, mu *sync.RWMutex) (interface{}, error) {
 		for i := 0; i < entries; i++ {
 			mu.Lock()
 			val++
@@ -90,7 +90,7 @@ func TestMutex(t *testing.T) {
 func TestError(t *testing.T) {
 	totalRuns := 1024
 	val := 0
-	_, err := mputil.Scatter(totalRuns, func(offset int, entries int, mu *sync.RWMutex) (interface{}, error) {
+	_, err := async.Scatter(totalRuns, func(offset int, entries int, mu *sync.RWMutex) (interface{}, error) {
 		for i := 0; i < entries; i++ {
 			mu.Lock()
 			val++
--- a/beacon-chain/README.md
+++ b/beacon-chain/README.md
@@ -1,9 +1,9 @@
 # Prysmatic Labs Beacon Chain Implementation

-This is the main project folder for the beacon chain implementation of eth2 written in Go by [Prysmatic Labs](https://prysmaticlabs.com).
+This is the main project folder for the beacon chain implementation of Ethereum written in Go by [Prysmatic Labs](https://prysmaticlabs.com).

 You can also read our main [README](https://github.com/prysmaticlabs/prysm/blob/master/README.md) and join our active chat room on Discord.

 [![Discord](https://user-images.githubusercontent.com/7288322/34471967-1df7808a-efbb-11e7-9088-ed0b04151291.png)](https://discord.gg/CTYGPUJ)

-Also, read the official beacon chain [specification](https://github.com/ethereum/eth2.0-specs/blob/master/specs/phase0/beacon-chain.md), this design spec serves as a source of truth for the beacon chain implementation we follow at Prysmatic Labs.
+Also, read the official beacon chain [specification](https://github.com/ethereum/consensus-specs/blob/master/specs/phase0/beacon-chain.md), this design spec serves as a source of truth for the beacon chain implementation we follow at Prysmatic Labs.
--- a/beacon-chain/blockchain/BUILD.bazel
+++ b/beacon-chain/blockchain/BUILD.bazel
@@ -1,15 +1,20 @@
-load("@prysm//tools/go:def.bzl", "go_library")
-load("@io_bazel_rules_go//go:def.bzl", "go_test")
+load("@prysm//tools/go:def.bzl", "go_library", "go_test")

 go_library(
    name = "go_default_library",
    srcs = [
        "chain_info.go",
+        "error.go",
        "head.go",
+        "head_sync_committee_info.go",
        "info.go",
        "init_sync_process_block.go",
        "log.go",
        "metrics.go",
+        "new_slot.go",
+        "optimistic_sync.go",
+        "options.go",
+        "pow_block.go",
        "process_attestation.go",
        "process_attestation_helpers.go",
        "process_block.go",
@@ -17,21 +22,31 @@ go_library(
        "receive_attestation.go",
        "receive_block.go",
        "service.go",
+        "state_balance_cache.go",
        "weak_subjectivity_checks.go",
    ],
    importpath = "github.com/prysmaticlabs/prysm/beacon-chain/blockchain",
    visibility = [
        "//beacon-chain:__subpackages__",
-        "//fuzz:__pkg__",
+        "//cmd/beacon-chain:__subpackages__",
+        "//testing/slasher/simulator:__pkg__",
+        "//testing/spectest:__subpackages__",
    ],
    deps = [
+        "//async:go_default_library",
+        "//async/event:go_default_library",
+        "//beacon-chain/blockchain/store:go_default_library",
        "//beacon-chain/cache:go_default_library",
        "//beacon-chain/cache/depositcache:go_default_library",
+        "//beacon-chain/core/altair:go_default_library",
+        "//beacon-chain/core/blocks:go_default_library",
        "//beacon-chain/core/epoch/precompute:go_default_library",
        "//beacon-chain/core/feed:go_default_library",
        "//beacon-chain/core/feed/state:go_default_library",
        "//beacon-chain/core/helpers:go_default_library",
-        "//beacon-chain/core/state:go_default_library",
+        "//beacon-chain/core/signing:go_default_library",
+        "//beacon-chain/core/time:go_default_library",
+        "//beacon-chain/core/transition:go_default_library",
        "//beacon-chain/db:go_default_library",
        "//beacon-chain/db/filters:go_default_library",
        "//beacon-chain/forkchoice:go_default_library",
@@ -41,26 +56,28 @@ go_library(
        "//beacon-chain/operations/voluntaryexits:go_default_library",
        "//beacon-chain/p2p:go_default_library",
        "//beacon-chain/powchain:go_default_library",
-        "//beacon-chain/state/interface:go_default_library",
-        "//beacon-chain/state/stateV0:go_default_library",
+        "//beacon-chain/state:go_default_library",
        "//beacon-chain/state/stategen:go_default_library",
        "//cmd/beacon-chain/flags:go_default_library",
-        "//proto/beacon/p2p/v1:go_default_library",
-        "//shared/attestationutil:go_default_library",
-        "//shared/bls:go_default_library",
-        "//shared/bytesutil:go_default_library",
-        "//shared/featureconfig:go_default_library",
-        "//shared/mputil:go_default_library",
-        "//shared/params:go_default_library",
-        "//shared/slotutil:go_default_library",
-        "//shared/timeutils:go_default_library",
-        "//shared/traceutil:go_default_library",
+        "//config/features:go_default_library",
+        "//config/fieldparams:go_default_library",
+        "//config/params:go_default_library",
+        "//crypto/bls:go_default_library",
+        "//encoding/bytesutil:go_default_library",
+        "//monitoring/tracing:go_default_library",
+        "//proto/eth/v1:go_default_library",
+        "//proto/prysm/v1alpha1:go_default_library",
+        "//proto/prysm/v1alpha1/attestation:go_default_library",
+        "//proto/prysm/v1alpha1/block:go_default_library",
+        "//runtime/version:go_default_library",
+        "//time:go_default_library",
+        "//time/slots:go_default_library",
        "@com_github_emicklei_dot//:go_default_library",
+        "@com_github_holiman_uint256//:go_default_library",
        "@com_github_pkg_errors//:go_default_library",
        "@com_github_prometheus_client_golang//prometheus:go_default_library",
        "@com_github_prometheus_client_golang//prometheus/promauto:go_default_library",
        "@com_github_prysmaticlabs_eth2_types//:go_default_library",
-        "@com_github_prysmaticlabs_ethereumapis//eth/v1alpha1:go_default_library",
        "@com_github_sirupsen_logrus//:go_default_library",
        "@io_opencensus_go//trace:go_default_library",
    ],
@@ -81,10 +98,15 @@ go_test(
        "blockchain_test.go",
        "chain_info_test.go",
        "checktags_test.go",
+        "head_sync_committee_info_test.go",
        "head_test.go",
        "info_test.go",
        "init_test.go",
+        "log_test.go",
        "metrics_test.go",
+        "mock_test.go",
+        "optimistic_sync_test.go",
+        "pow_block_test.go",
        "process_attestation_test.go",
        "process_block_test.go",
        "receive_attestation_test.go",
@@ -95,32 +117,33 @@ go_test(
    embed = [":go_default_library"],
    gotags = ["develop"],
    deps = [
+        "//async/event:go_default_library",
        "//beacon-chain/blockchain/testing:go_default_library",
        "//beacon-chain/cache/depositcache:go_default_library",
        "//beacon-chain/core/blocks:go_default_library",
        "//beacon-chain/core/helpers:go_default_library",
-        "//beacon-chain/core/state:go_default_library",
+        "//beacon-chain/core/transition:go_default_library",
        "//beacon-chain/db:go_default_library",
        "//beacon-chain/db/testing:go_default_library",
        "//beacon-chain/p2p:go_default_library",
        "//beacon-chain/powchain:go_default_library",
        "//beacon-chain/state/stateutil:go_default_library",
-        "//proto/beacon/db:go_default_library",
-        "//proto/beacon/p2p/v1:go_default_library",
-        "//shared/bytesutil:go_default_library",
-        "//shared/event:go_default_library",
-        "//shared/params:go_default_library",
-        "//shared/testutil:go_default_library",
-        "//shared/testutil/assert:go_default_library",
-        "//shared/testutil/require:go_default_library",
+        "//beacon-chain/state/v1:go_default_library",
+        "//config/fieldparams:go_default_library",
+        "//config/params:go_default_library",
+        "//encoding/bytesutil:go_default_library",
+        "//proto/prysm/v1alpha1:go_default_library",
+        "//proto/prysm/v1alpha1/wrapper:go_default_library",
+        "//testing/assert:go_default_library",
+        "//testing/require:go_default_library",
+        "//testing/util:go_default_library",
        "@com_github_ethereum_go_ethereum//:go_default_library",
        "@com_github_ethereum_go_ethereum//common:go_default_library",
        "@com_github_ethereum_go_ethereum//core/types:go_default_library",
-        "@com_github_gogo_protobuf//proto:go_default_library",
-        "@com_github_prysmaticlabs_ethereumapis//eth/v1alpha1:go_default_library",
        "@com_github_sirupsen_logrus//:go_default_library",
        "@com_github_sirupsen_logrus//hooks/test:go_default_library",
        "@in_gopkg_d4l3k_messagediff_v1//:go_default_library",
+        "@org_golang_google_protobuf//proto:go_default_library",
        "@org_golang_x_net//context:go_default_library",
    ],
 )
@@ -131,6 +154,7 @@ go_test(
        "chain_info_norace_test.go",
        "checktags_test.go",
        "init_test.go",
+        "mock_test.go",
        "receive_block_test.go",
        "service_norace_test.go",
    ],
@@ -146,29 +170,29 @@ go_test(
    race = "on",
    tags = ["race_on"],
    deps = [
+        "//async/event:go_default_library",
        "//beacon-chain/blockchain/testing:go_default_library",
        "//beacon-chain/cache/depositcache:go_default_library",
        "//beacon-chain/core/blocks:go_default_library",
        "//beacon-chain/core/helpers:go_default_library",
-        "//beacon-chain/core/state:go_default_library",
+        "//beacon-chain/core/transition:go_default_library",
        "//beacon-chain/db:go_default_library",
        "//beacon-chain/db/testing:go_default_library",
        "//beacon-chain/p2p:go_default_library",
        "//beacon-chain/powchain:go_default_library",
-        "//proto/beacon/p2p/v1:go_default_library",
-        "//shared/bytesutil:go_default_library",
-        "//shared/event:go_default_library",
-        "//shared/params:go_default_library",
-        "//shared/testutil:go_default_library",
-        "//shared/testutil/assert:go_default_library",
-        "//shared/testutil/require:go_default_library",
+        "//config/params:go_default_library",
+        "//encoding/bytesutil:go_default_library",
+        "//proto/prysm/v1alpha1:go_default_library",
+        "//proto/prysm/v1alpha1/wrapper:go_default_library",
+        "//testing/assert:go_default_library",
+        "//testing/require:go_default_library",
+        "//testing/util:go_default_library",
        "@com_github_ethereum_go_ethereum//:go_default_library",
        "@com_github_ethereum_go_ethereum//common:go_default_library",
        "@com_github_ethereum_go_ethereum//core/types:go_default_library",
-        "@com_github_gogo_protobuf//proto:go_default_library",
-        "@com_github_prysmaticlabs_ethereumapis//eth/v1alpha1:go_default_library",
        "@com_github_sirupsen_logrus//:go_default_library",
        "@com_github_sirupsen_logrus//hooks/test:go_default_library",
+        "@org_golang_google_protobuf//proto:go_default_library",
        "@org_golang_x_net//context:go_default_library",
    ],
 )
--- a/beacon-chain/blockchain/chain_info.go
+++ b/beacon-chain/blockchain/chain_info.go
@@ -5,14 +5,14 @@ import (
 	"time"

 	types "github.com/prysmaticlabs/eth2-types"
-	ethpb "github.com/prysmaticlabs/ethereumapis/eth/v1alpha1"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/helpers"
 	"github.com/prysmaticlabs/prysm/beacon-chain/forkchoice/protoarray"
-	iface "github.com/prysmaticlabs/prysm/beacon-chain/state/interface"
-	"github.com/prysmaticlabs/prysm/beacon-chain/state/stateV0"
-	pb "github.com/prysmaticlabs/prysm/proto/beacon/p2p/v1"
-	"github.com/prysmaticlabs/prysm/shared/bytesutil"
-	"github.com/prysmaticlabs/prysm/shared/params"
+	"github.com/prysmaticlabs/prysm/beacon-chain/state"
+	fieldparams "github.com/prysmaticlabs/prysm/config/fieldparams"
+	"github.com/prysmaticlabs/prysm/config/params"
+	"github.com/prysmaticlabs/prysm/encoding/bytesutil"
+	ethpb "github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1"
+	"github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1/block"
 	"go.opencensus.io/trace"
 )

@@ -23,15 +23,18 @@ type ChainInfoFetcher interface {
 	FinalizationFetcher
 	GenesisFetcher
 	CanonicalFetcher
+	ForkFetcher
+	TimeFetcher
+	HeadDomainFetcher
 }

-// TimeFetcher retrieves the Eth2 data that's related to time.
+// TimeFetcher retrieves the Ethereum consensus data that's related to time.
 type TimeFetcher interface {
 	GenesisTime() time.Time
 	CurrentSlot() types.Slot
 }

-// GenesisFetcher retrieves the eth2 data related to its genesis.
+// GenesisFetcher retrieves the Ethereum consensus data related to its genesis.
 type GenesisFetcher interface {
 	GenesisValidatorRoot() [32]byte
 }
@@ -41,19 +44,25 @@ type GenesisFetcher interface {
 type HeadFetcher interface {
 	HeadSlot() types.Slot
 	HeadRoot(ctx context.Context) ([]byte, error)
-	HeadBlock(ctx context.Context) (*ethpb.SignedBeaconBlock, error)
-	HeadState(ctx context.Context) (iface.BeaconState, error)
+	HeadBlock(ctx context.Context) (block.SignedBeaconBlock, error)
+	HeadState(ctx context.Context) (state.BeaconState, error)
 	HeadValidatorsIndices(ctx context.Context, epoch types.Epoch) ([]types.ValidatorIndex, error)
 	HeadSeed(ctx context.Context, epoch types.Epoch) ([32]byte, error)
 	HeadGenesisValidatorRoot() [32]byte
 	HeadETH1Data() *ethpb.Eth1Data
+	HeadPublicKeyToValidatorIndex(pubKey [fieldparams.BLSPubkeyLength]byte) (types.ValidatorIndex, bool)
+	HeadValidatorIndexToPublicKey(ctx context.Context, index types.ValidatorIndex) ([fieldparams.BLSPubkeyLength]byte, error)
 	ProtoArrayStore() *protoarray.Store
 	ChainHeads() ([][32]byte, []types.Slot)
+	IsOptimistic(ctx context.Context) (bool, error)
+	IsOptimisticForRoot(ctx context.Context, root [32]byte, slot types.Slot) (bool, error)
+	HeadSyncCommitteeFetcher
+	HeadDomainFetcher
 }

 // ForkFetcher retrieves the current fork information of the Ethereum beacon chain.
 type ForkFetcher interface {
-	CurrentFork() *pb.Fork
+	CurrentFork() *ethpb.Fork
 }

 // CanonicalFetcher retrieves the current chain's canonical information.
@@ -70,31 +79,45 @@ type FinalizationFetcher interface {
 	PreviousJustifiedCheckpt() *ethpb.Checkpoint
 }

-// FinalizedCheckpt returns the latest finalized checkpoint from head state.
+// FinalizedCheckpt returns the latest finalized checkpoint from chain store.
 func (s *Service) FinalizedCheckpt() *ethpb.Checkpoint {
-	if s.finalizedCheckpt == nil {
+	cp := s.store.FinalizedCheckpt()
+	if cp == nil {
 		return &ethpb.Checkpoint{Root: params.BeaconConfig().ZeroHash[:]}
 	}

-	return stateV0.CopyCheckpoint(s.finalizedCheckpt)
+	return ethpb.CopyCheckpoint(cp)
 }

-// CurrentJustifiedCheckpt returns the current justified checkpoint from head state.
+// CurrentJustifiedCheckpt returns the current justified checkpoint from chain store.
 func (s *Service) CurrentJustifiedCheckpt() *ethpb.Checkpoint {
-	if s.justifiedCheckpt == nil {
+	cp := s.store.JustifiedCheckpt()
+	if cp == nil {
 		return &ethpb.Checkpoint{Root: params.BeaconConfig().ZeroHash[:]}
 	}

-	return stateV0.CopyCheckpoint(s.justifiedCheckpt)
+	return ethpb.CopyCheckpoint(cp)
 }

-// PreviousJustifiedCheckpt returns the previous justified checkpoint from head state.
+// PreviousJustifiedCheckpt returns the previous justified checkpoint from chain store.
 func (s *Service) PreviousJustifiedCheckpt() *ethpb.Checkpoint {
-	if s.prevJustifiedCheckpt == nil {
+	cp := s.store.PrevJustifiedCheckpt()
+	if cp == nil {
 		return &ethpb.Checkpoint{Root: params.BeaconConfig().ZeroHash[:]}
 	}

-	return stateV0.CopyCheckpoint(s.prevJustifiedCheckpt)
+	return ethpb.CopyCheckpoint(cp)
+}
+
+// BestJustifiedCheckpt returns the best justified checkpoint from store.
+func (s *Service) BestJustifiedCheckpt() *ethpb.Checkpoint {
+	cp := s.store.BestJustifiedCheckpt()
+	// If there is no best justified checkpoint, return the checkpoint with root as zeros to be used for genesis cases.
+	if cp == nil {
+		return &ethpb.Checkpoint{Root: params.BeaconConfig().ZeroHash[:]}
+	}
+
+	return ethpb.CopyCheckpoint(cp)
 }

 // HeadSlot returns the slot of the head of the chain.
@@ -123,11 +146,11 @@ func (s *Service) HeadRoot(ctx context.Context) ([]byte, error) {
 	if err != nil {
 		return nil, err
 	}
-	if b == nil {
+	if b == nil || b.IsNil() {
 		return params.BeaconConfig().ZeroHash[:], nil
 	}

-	r, err := b.Block.HashTreeRoot()
+	r, err := b.Block().HashTreeRoot()
 	if err != nil {
 		return nil, err
 	}
@@ -138,7 +161,7 @@ func (s *Service) HeadRoot(ctx context.Context) ([]byte, error) {
 // HeadBlock returns the head block of the chain.
 // If the head is nil from service struct,
 // it will attempt to get the head block from DB.
-func (s *Service) HeadBlock(ctx context.Context) (*ethpb.SignedBeaconBlock, error) {
+func (s *Service) HeadBlock(ctx context.Context) (block.SignedBeaconBlock, error) {
 	s.headLock.RLock()
 	defer s.headLock.RUnlock()

@@ -152,7 +175,7 @@ func (s *Service) HeadBlock(ctx context.Context) (*ethpb.SignedBeaconBlock, erro
 // HeadState returns the head state of the chain.
 // If the head is nil from service struct,
 // it will attempt to get the head state from DB.
-func (s *Service) HeadState(ctx context.Context) (iface.BeaconState, error) {
+func (s *Service) HeadState(ctx context.Context) (state.BeaconState, error) {
 	ctx, span := trace.StartSpan(ctx, "blockChain.HeadState")
 	defer span.End()
 	s.headLock.RLock()
@@ -176,7 +199,7 @@ func (s *Service) HeadValidatorsIndices(ctx context.Context, epoch types.Epoch)
 	if !s.hasHeadState() {
 		return []types.ValidatorIndex{}, nil
 	}
-	return helpers.ActiveValidatorIndices(s.headState(ctx), epoch)
+	return helpers.ActiveValidatorIndices(ctx, s.headState(ctx), epoch)
 }

 // HeadSeed returns the seed from the head view of a given epoch.
@@ -237,12 +260,12 @@ func (s *Service) GenesisValidatorRoot() [32]byte {
 }

 // CurrentFork retrieves the latest fork information of the beacon chain.
-func (s *Service) CurrentFork() *pb.Fork {
+func (s *Service) CurrentFork() *ethpb.Fork {
 	s.headLock.RLock()
 	defer s.headLock.RUnlock()

 	if !s.hasHeadState() {
-		return &pb.Fork{
+		return &ethpb.Fork{
 			PreviousVersion: params.BeaconConfig().GenesisForkVersion,
 			CurrentVersion:  params.BeaconConfig().GenesisForkVersion,
 		}
@@ -282,3 +305,45 @@ func (s *Service) ChainHeads() ([][32]byte, []types.Slot) {

 	return headsRoots, headsSlots
 }
+
+// HeadPublicKeyToValidatorIndex returns the validator index of the `pubkey` in current head state.
+func (s *Service) HeadPublicKeyToValidatorIndex(pubKey [fieldparams.BLSPubkeyLength]byte) (types.ValidatorIndex, bool) {
+	s.headLock.RLock()
+	defer s.headLock.RUnlock()
+	if !s.hasHeadState() {
+		return 0, false
+	}
+	return s.headValidatorIndexAtPubkey(pubKey)
+}
+
+// HeadValidatorIndexToPublicKey returns the pubkey of the validator `index`  in current head state.
+func (s *Service) HeadValidatorIndexToPublicKey(_ context.Context, index types.ValidatorIndex) ([fieldparams.BLSPubkeyLength]byte, error) {
+	s.headLock.RLock()
+	defer s.headLock.RUnlock()
+	if !s.hasHeadState() {
+		return [fieldparams.BLSPubkeyLength]byte{}, nil
+	}
+	v, err := s.headValidatorAtIndex(index)
+	if err != nil {
+		return [fieldparams.BLSPubkeyLength]byte{}, err
+	}
+	return v.PublicKey(), nil
+}
+
+// IsOptimistic returns true if the current head is optimistic.
+func (s *Service) IsOptimistic(ctx context.Context) (bool, error) {
+	s.headLock.RLock()
+	defer s.headLock.RUnlock()
+	return s.cfg.ForkChoiceStore.Optimistic(ctx, s.head.root, s.head.slot)
+}
+
+// IsOptimisticForRoot takes the root and slot as aguments instead of the current head
+// and returns true if it is optimistic.
+func (s *Service) IsOptimisticForRoot(ctx context.Context, root [32]byte, slot types.Slot) (bool, error) {
+	return s.cfg.ForkChoiceStore.Optimistic(ctx, root, slot)
+}
+
+// SetGenesisTime sets the genesis time of beacon chain.
+func (s *Service) SetGenesisTime(t time.Time) {
+	s.genesisTime = t
+}
--- a/beacon-chain/blockchain/chain_info_norace_test.go
+++ b/beacon-chain/blockchain/chain_info_norace_test.go
@@ -4,16 +4,17 @@ import (
 	"context"
 	"testing"

-	ethpb "github.com/prysmaticlabs/ethereumapis/eth/v1alpha1"
 	testDB "github.com/prysmaticlabs/prysm/beacon-chain/db/testing"
 	"github.com/prysmaticlabs/prysm/beacon-chain/state/stategen"
-	"github.com/prysmaticlabs/prysm/shared/testutil/require"
+	ethpb "github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1"
+	"github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1/wrapper"
+	"github.com/prysmaticlabs/prysm/testing/require"
 )

 func TestHeadSlot_DataRace(t *testing.T) {
 	beaconDB := testDB.SetupDB(t)
 	s := &Service{
-		cfg: &Config{BeaconDB: beaconDB},
+		cfg: &config{BeaconDB: beaconDB},
 	}
 	go func() {
 		require.NoError(t, s.saveHead(context.Background(), [32]byte{}))
@@ -24,7 +25,7 @@ func TestHeadSlot_DataRace(t *testing.T) {
 func TestHeadRoot_DataRace(t *testing.T) {
 	beaconDB := testDB.SetupDB(t)
 	s := &Service{
-		cfg:  &Config{BeaconDB: beaconDB, StateGen: stategen.New(beaconDB)},
+		cfg:  &config{BeaconDB: beaconDB, StateGen: stategen.New(beaconDB)},
 		head: &head{root: [32]byte{'A'}},
 	}
 	go func() {
@@ -37,8 +38,8 @@ func TestHeadRoot_DataRace(t *testing.T) {
 func TestHeadBlock_DataRace(t *testing.T) {
 	beaconDB := testDB.SetupDB(t)
 	s := &Service{
-		cfg:  &Config{BeaconDB: beaconDB, StateGen: stategen.New(beaconDB)},
-		head: &head{block: &ethpb.SignedBeaconBlock{}},
+		cfg:  &config{BeaconDB: beaconDB, StateGen: stategen.New(beaconDB)},
+		head: &head{block: wrapper.WrappedPhase0SignedBeaconBlock(&ethpb.SignedBeaconBlock{})},
 	}
 	go func() {
 		require.NoError(t, s.saveHead(context.Background(), [32]byte{}))
@@ -50,7 +51,7 @@ func TestHeadBlock_DataRace(t *testing.T) {
 func TestHeadState_DataRace(t *testing.T) {
 	beaconDB := testDB.SetupDB(t)
 	s := &Service{
-		cfg: &Config{BeaconDB: beaconDB, StateGen: stategen.New(beaconDB)},
+		cfg: &config{BeaconDB: beaconDB, StateGen: stategen.New(beaconDB)},
 	}
 	go func() {
 		require.NoError(t, s.saveHead(context.Background(), [32]byte{}))
--- a/beacon-chain/blockchain/chain_info_test.go
+++ b/beacon-chain/blockchain/chain_info_test.go
@@ -5,19 +5,20 @@ import (
 	"testing"
 	"time"

-	"github.com/gogo/protobuf/proto"
 	types "github.com/prysmaticlabs/eth2-types"
-	ethpb "github.com/prysmaticlabs/ethereumapis/eth/v1alpha1"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/helpers"
 	testDB "github.com/prysmaticlabs/prysm/beacon-chain/db/testing"
 	"github.com/prysmaticlabs/prysm/beacon-chain/forkchoice/protoarray"
-	"github.com/prysmaticlabs/prysm/beacon-chain/state/stateV0"
-	pb "github.com/prysmaticlabs/prysm/proto/beacon/p2p/v1"
-	"github.com/prysmaticlabs/prysm/shared/bytesutil"
-	"github.com/prysmaticlabs/prysm/shared/params"
-	"github.com/prysmaticlabs/prysm/shared/testutil"
-	"github.com/prysmaticlabs/prysm/shared/testutil/assert"
-	"github.com/prysmaticlabs/prysm/shared/testutil/require"
+	v1 "github.com/prysmaticlabs/prysm/beacon-chain/state/v1"
+	fieldparams "github.com/prysmaticlabs/prysm/config/fieldparams"
+	"github.com/prysmaticlabs/prysm/config/params"
+	"github.com/prysmaticlabs/prysm/encoding/bytesutil"
+	ethpb "github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1"
+	"github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1/wrapper"
+	"github.com/prysmaticlabs/prysm/testing/assert"
+	"github.com/prysmaticlabs/prysm/testing/require"
+	"github.com/prysmaticlabs/prysm/testing/util"
+	"google.golang.org/protobuf/proto"
 )

 // Ensure Service implements chain info interface.
@@ -44,7 +45,7 @@ func TestFinalizedCheckpt_CanRetrieve(t *testing.T) {

 	cp := &ethpb.Checkpoint{Epoch: 5, Root: bytesutil.PadTo([]byte("foo"), 32)}
 	c := setupBeaconChain(t, beaconDB)
-	c.finalizedCheckpt = cp
+	c.store.SetFinalizedCheckpt(cp)

 	assert.Equal(t, cp.Epoch, c.FinalizedCheckpt().Epoch, "Unexpected finalized epoch")
 }
@@ -55,9 +56,9 @@ func TestFinalizedCheckpt_GenesisRootOk(t *testing.T) {
 	genesisRoot := [32]byte{'A'}
 	cp := &ethpb.Checkpoint{Root: genesisRoot[:]}
 	c := setupBeaconChain(t, beaconDB)
-	c.finalizedCheckpt = cp
-	c.genesisRoot = genesisRoot
-	assert.DeepEqual(t, c.genesisRoot[:], c.FinalizedCheckpt().Root)
+	c.store.SetFinalizedCheckpt(cp)
+	c.originBlockRoot = genesisRoot
+	assert.DeepEqual(t, c.originBlockRoot[:], c.FinalizedCheckpt().Root)
 }

 func TestCurrentJustifiedCheckpt_CanRetrieve(t *testing.T) {
@@ -66,7 +67,7 @@ func TestCurrentJustifiedCheckpt_CanRetrieve(t *testing.T) {
 	c := setupBeaconChain(t, beaconDB)
 	assert.Equal(t, params.BeaconConfig().ZeroHash, bytesutil.ToBytes32(c.CurrentJustifiedCheckpt().Root), "Unexpected justified epoch")
 	cp := &ethpb.Checkpoint{Epoch: 6, Root: bytesutil.PadTo([]byte("foo"), 32)}
-	c.justifiedCheckpt = cp
+	c.store.SetJustifiedCheckpt(cp)
 	assert.Equal(t, cp.Epoch, c.CurrentJustifiedCheckpt().Epoch, "Unexpected justified epoch")
 }

@@ -76,9 +77,9 @@ func TestJustifiedCheckpt_GenesisRootOk(t *testing.T) {
 	c := setupBeaconChain(t, beaconDB)
 	genesisRoot := [32]byte{'B'}
 	cp := &ethpb.Checkpoint{Root: genesisRoot[:]}
-	c.justifiedCheckpt = cp
-	c.genesisRoot = genesisRoot
-	assert.DeepEqual(t, c.genesisRoot[:], c.CurrentJustifiedCheckpt().Root)
+	c.store.SetJustifiedCheckpt(cp)
+	c.originBlockRoot = genesisRoot
+	assert.DeepEqual(t, c.originBlockRoot[:], c.CurrentJustifiedCheckpt().Root)
 }

 func TestPreviousJustifiedCheckpt_CanRetrieve(t *testing.T) {
@@ -87,7 +88,7 @@ func TestPreviousJustifiedCheckpt_CanRetrieve(t *testing.T) {
 	cp := &ethpb.Checkpoint{Epoch: 7, Root: bytesutil.PadTo([]byte("foo"), 32)}
 	c := setupBeaconChain(t, beaconDB)
 	assert.Equal(t, params.BeaconConfig().ZeroHash, bytesutil.ToBytes32(c.CurrentJustifiedCheckpt().Root), "Unexpected justified epoch")
-	c.prevJustifiedCheckpt = cp
+	c.store.SetPrevJustifiedCheckpt(cp)
 	assert.Equal(t, cp.Epoch, c.PreviousJustifiedCheckpt().Epoch, "Unexpected previous justified epoch")
 }

@@ -97,14 +98,14 @@ func TestPrevJustifiedCheckpt_GenesisRootOk(t *testing.T) {
 	genesisRoot := [32]byte{'C'}
 	cp := &ethpb.Checkpoint{Root: genesisRoot[:]}
 	c := setupBeaconChain(t, beaconDB)
-	c.prevJustifiedCheckpt = cp
-	c.genesisRoot = genesisRoot
-	assert.DeepEqual(t, c.genesisRoot[:], c.PreviousJustifiedCheckpt().Root)
+	c.store.SetPrevJustifiedCheckpt(cp)
+	c.originBlockRoot = genesisRoot
+	assert.DeepEqual(t, c.originBlockRoot[:], c.PreviousJustifiedCheckpt().Root)
 }

 func TestHeadSlot_CanRetrieve(t *testing.T) {
 	c := &Service{}
-	s, err := stateV0.InitializeFromProto(&pb.BeaconState{})
+	s, err := v1.InitializeFromProto(&ethpb.BeaconState{})
 	require.NoError(t, err)
 	c.head = &head{slot: 100, state: s}
 	assert.Equal(t, types.Slot(100), c.HeadSlot())
@@ -120,13 +121,13 @@ func TestHeadRoot_CanRetrieve(t *testing.T) {

 func TestHeadRoot_UseDB(t *testing.T) {
 	beaconDB := testDB.SetupDB(t)
-	c := &Service{cfg: &Config{BeaconDB: beaconDB}}
+	c := &Service{cfg: &config{BeaconDB: beaconDB}}
 	c.head = &head{root: params.BeaconConfig().ZeroHash}
-	b := testutil.NewBeaconBlock()
+	b := util.NewBeaconBlock()
 	br, err := b.Block.HashTreeRoot()
 	require.NoError(t, err)
-	require.NoError(t, beaconDB.SaveBlock(context.Background(), b))
-	require.NoError(t, beaconDB.SaveStateSummary(context.Background(), &pb.StateSummary{Root: br[:]}))
+	require.NoError(t, beaconDB.SaveBlock(context.Background(), wrapper.WrappedPhase0SignedBeaconBlock(b)))
+	require.NoError(t, beaconDB.SaveStateSummary(context.Background(), &ethpb.StateSummary{Root: br[:]}))
 	require.NoError(t, beaconDB.SaveHeadBlockRoot(context.Background(), br))
 	r, err := c.HeadRoot(context.Background())
 	require.NoError(t, err)
@@ -134,20 +135,20 @@ func TestHeadRoot_UseDB(t *testing.T) {
 }

 func TestHeadBlock_CanRetrieve(t *testing.T) {
-	b := testutil.NewBeaconBlock()
+	b := util.NewBeaconBlock()
 	b.Block.Slot = 1
-	s, err := stateV0.InitializeFromProto(&pb.BeaconState{})
+	s, err := v1.InitializeFromProto(&ethpb.BeaconState{})
 	require.NoError(t, err)
 	c := &Service{}
-	c.head = &head{block: b, state: s}
+	c.head = &head{block: wrapper.WrappedPhase0SignedBeaconBlock(b), state: s}

 	recevied, err := c.HeadBlock(context.Background())
 	require.NoError(t, err)
-	assert.DeepEqual(t, b, recevied, "Incorrect head block received")
+	assert.DeepEqual(t, b, recevied.Proto(), "Incorrect head block received")
 }

 func TestHeadState_CanRetrieve(t *testing.T) {
-	s, err := stateV0.InitializeFromProto(&pb.BeaconState{Slot: 2, GenesisValidatorsRoot: params.BeaconConfig().ZeroHash[:]})
+	s, err := v1.InitializeFromProto(&ethpb.BeaconState{Slot: 2, GenesisValidatorsRoot: params.BeaconConfig().ZeroHash[:]})
 	require.NoError(t, err)
 	c := &Service{}
 	c.head = &head{state: s}
@@ -163,8 +164,8 @@ func TestGenesisTime_CanRetrieve(t *testing.T) {
 }

 func TestCurrentFork_CanRetrieve(t *testing.T) {
-	f := &pb.Fork{Epoch: 999}
-	s, err := stateV0.InitializeFromProto(&pb.BeaconState{Fork: f})
+	f := &ethpb.Fork{Epoch: 999}
+	s, err := v1.InitializeFromProto(&ethpb.BeaconState{Fork: f})
 	require.NoError(t, err)
 	c := &Service{}
 	c.head = &head{state: s}
@@ -174,7 +175,7 @@ func TestCurrentFork_CanRetrieve(t *testing.T) {
 }

 func TestCurrentFork_NilHeadSTate(t *testing.T) {
-	f := &pb.Fork{
+	f := &ethpb.Fork{
 		PreviousVersion: params.BeaconConfig().GenesisForkVersion,
 		CurrentVersion:  params.BeaconConfig().GenesisForkVersion,
 	}
@@ -189,7 +190,7 @@ func TestGenesisValidatorRoot_CanRetrieve(t *testing.T) {
 	c := &Service{}
 	assert.Equal(t, [32]byte{}, c.GenesisValidatorRoot(), "Did not get correct genesis validator root")

-	s, err := stateV0.InitializeFromProto(&pb.BeaconState{GenesisValidatorsRoot: []byte{'a'}})
+	s, err := v1.InitializeFromProto(&ethpb.BeaconState{GenesisValidatorsRoot: []byte{'a'}})
 	require.NoError(t, err)
 	c.head = &head{state: s}
 	assert.Equal(t, [32]byte{'a'}, c.GenesisValidatorRoot(), "Did not get correct genesis validator root")
@@ -203,7 +204,7 @@ func TestHeadETH1Data_Nil(t *testing.T) {

 func TestHeadETH1Data_CanRetrieve(t *testing.T) {
 	d := &ethpb.Eth1Data{DepositCount: 999}
-	s, err := stateV0.InitializeFromProto(&pb.BeaconState{Eth1Data: d})
+	s, err := v1.InitializeFromProto(&ethpb.BeaconState{Eth1Data: d})
 	require.NoError(t, err)
 	c := &Service{}
 	c.head = &head{state: s}
@@ -217,11 +218,11 @@ func TestIsCanonical_Ok(t *testing.T) {
 	beaconDB := testDB.SetupDB(t)
 	c := setupBeaconChain(t, beaconDB)

-	blk := testutil.NewBeaconBlock()
+	blk := util.NewBeaconBlock()
 	blk.Block.Slot = 0
 	root, err := blk.Block.HashTreeRoot()
 	require.NoError(t, err)
-	require.NoError(t, beaconDB.SaveBlock(ctx, blk))
+	require.NoError(t, beaconDB.SaveBlock(ctx, wrapper.WrappedPhase0SignedBeaconBlock(blk)))
 	require.NoError(t, beaconDB.SaveGenesisBlockRoot(ctx, root))
 	can, err := c.IsCanonical(ctx, root)
 	require.NoError(t, err)
@@ -233,7 +234,7 @@ func TestIsCanonical_Ok(t *testing.T) {
 }

 func TestService_HeadValidatorsIndices(t *testing.T) {
-	s, _ := testutil.DeterministicGenesisState(t, 10)
+	s, _ := util.DeterministicGenesisState(t, 10)
 	c := &Service{}

 	c.head = &head{}
@@ -248,7 +249,7 @@ func TestService_HeadValidatorsIndices(t *testing.T) {
 }

 func TestService_HeadSeed(t *testing.T) {
-	s, _ := testutil.DeterministicGenesisState(t, 1)
+	s, _ := util.DeterministicGenesisState(t, 1)
 	c := &Service{}
 	seed, err := helpers.Seed(s, 0, params.BeaconConfig().DomainBeaconAttester)
 	require.NoError(t, err)
@@ -265,7 +266,7 @@ func TestService_HeadSeed(t *testing.T) {
 }

 func TestService_HeadGenesisValidatorRoot(t *testing.T) {
-	s, _ := testutil.DeterministicGenesisState(t, 1)
+	s, _ := util.DeterministicGenesisState(t, 1)
 	c := &Service{}

 	c.head = &head{}
@@ -278,14 +279,14 @@ func TestService_HeadGenesisValidatorRoot(t *testing.T) {
 }

 func TestService_ProtoArrayStore(t *testing.T) {
-	c := &Service{cfg: &Config{ForkChoiceStore: protoarray.New(0, 0, [32]byte{})}}
+	c := &Service{cfg: &config{ForkChoiceStore: protoarray.New(0, 0, [32]byte{})}}
 	p := c.ProtoArrayStore()
 	require.Equal(t, 0, int(p.FinalizedEpoch()))
 }

 func TestService_ChainHeads(t *testing.T) {
 	ctx := context.Background()
-	c := &Service{cfg: &Config{ForkChoiceStore: protoarray.New(0, 0, [32]byte{})}}
+	c := &Service{cfg: &config{ForkChoiceStore: protoarray.New(0, 0, [32]byte{})}}
 	require.NoError(t, c.cfg.ForkChoiceStore.ProcessBlock(ctx, 100, [32]byte{'a'}, [32]byte{}, [32]byte{}, 0, 0))
 	require.NoError(t, c.cfg.ForkChoiceStore.ProcessBlock(ctx, 101, [32]byte{'b'}, [32]byte{'a'}, [32]byte{}, 0, 0))
 	require.NoError(t, c.cfg.ForkChoiceStore.ProcessBlock(ctx, 102, [32]byte{'c'}, [32]byte{'b'}, [32]byte{}, 0, 0))
@@ -296,3 +297,83 @@ func TestService_ChainHeads(t *testing.T) {
 	require.DeepEqual(t, [][32]byte{{'c'}, {'d'}, {'e'}}, roots)
 	require.DeepEqual(t, []types.Slot{102, 103, 104}, slots)
 }
+
+func TestService_HeadPublicKeyToValidatorIndex(t *testing.T) {
+	s, _ := util.DeterministicGenesisState(t, 10)
+	c := &Service{}
+	c.head = &head{state: s}
+
+	_, e := c.HeadPublicKeyToValidatorIndex([fieldparams.BLSPubkeyLength]byte{})
+	require.Equal(t, false, e)
+
+	v, err := s.ValidatorAtIndex(0)
+	require.NoError(t, err)
+
+	i, e := c.HeadPublicKeyToValidatorIndex(bytesutil.ToBytes48(v.PublicKey))
+	require.Equal(t, true, e)
+	require.Equal(t, types.ValidatorIndex(0), i)
+}
+
+func TestService_HeadPublicKeyToValidatorIndexNil(t *testing.T) {
+	c := &Service{}
+	c.head = nil
+
+	idx, e := c.HeadPublicKeyToValidatorIndex([fieldparams.BLSPubkeyLength]byte{})
+	require.Equal(t, false, e)
+	require.Equal(t, types.ValidatorIndex(0), idx)
+
+	c.head = &head{state: nil}
+	i, e := c.HeadPublicKeyToValidatorIndex([fieldparams.BLSPubkeyLength]byte{})
+	require.Equal(t, false, e)
+	require.Equal(t, types.ValidatorIndex(0), i)
+}
+
+func TestService_HeadValidatorIndexToPublicKey(t *testing.T) {
+	s, _ := util.DeterministicGenesisState(t, 10)
+	c := &Service{}
+	c.head = &head{state: s}
+
+	p, err := c.HeadValidatorIndexToPublicKey(context.Background(), 0)
+	require.NoError(t, err)
+
+	v, err := s.ValidatorAtIndex(0)
+	require.NoError(t, err)
+
+	require.Equal(t, bytesutil.ToBytes48(v.PublicKey), p)
+}
+
+func TestService_HeadValidatorIndexToPublicKeyNil(t *testing.T) {
+	c := &Service{}
+	c.head = nil
+
+	p, err := c.HeadValidatorIndexToPublicKey(context.Background(), 0)
+	require.NoError(t, err)
+	require.Equal(t, [fieldparams.BLSPubkeyLength]byte{}, p)
+
+	c.head = &head{state: nil}
+	p, err = c.HeadValidatorIndexToPublicKey(context.Background(), 0)
+	require.NoError(t, err)
+	require.Equal(t, [fieldparams.BLSPubkeyLength]byte{}, p)
+}
+
+func TestService_IsOptimistic(t *testing.T) {
+	ctx := context.Background()
+	c := &Service{cfg: &config{ForkChoiceStore: protoarray.New(0, 0, [32]byte{})}, head: &head{slot: 101, root: [32]byte{'b'}}}
+	require.NoError(t, c.cfg.ForkChoiceStore.ProcessBlock(ctx, 100, [32]byte{'a'}, [32]byte{}, [32]byte{}, 0, 0))
+	require.NoError(t, c.cfg.ForkChoiceStore.ProcessBlock(ctx, 101, [32]byte{'b'}, [32]byte{'a'}, [32]byte{}, 0, 0))
+
+	opt, err := c.IsOptimistic(ctx)
+	require.NoError(t, err)
+	require.Equal(t, true, opt)
+}
+
+func TestService_IsOptimisticForRoot(t *testing.T) {
+	ctx := context.Background()
+	c := &Service{cfg: &config{ForkChoiceStore: protoarray.New(0, 0, [32]byte{})}, head: &head{slot: 101, root: [32]byte{'b'}}}
+	require.NoError(t, c.cfg.ForkChoiceStore.ProcessBlock(ctx, 100, [32]byte{'a'}, [32]byte{}, [32]byte{}, 0, 0))
+	require.NoError(t, c.cfg.ForkChoiceStore.ProcessBlock(ctx, 101, [32]byte{'b'}, [32]byte{'a'}, [32]byte{}, 0, 0))
+
+	opt, err := c.IsOptimisticForRoot(ctx, [32]byte{'a'}, 100)
+	require.NoError(t, err)
+	require.Equal(t, true, opt)
+}
--- a/beacon-chain/blockchain/error.go
+++ b/beacon-chain/blockchain/error.go
@@ -0,0 +1,12 @@
+package blockchain
+
+import "github.com/pkg/errors"
+
+var (
+	// errNilJustifiedInStore is returned when a nil justified checkpt is returned from store.
+	errNilJustifiedInStore = errors.New("nil justified checkpoint returned from store")
+	// errNilBestJustifiedInStore is returned when a nil justified checkpt is returned from store.
+	errNilBestJustifiedInStore = errors.New("nil best justified checkpoint returned from store")
+	// errNilFinalizedInStore is returned when a nil finalized checkpt is returned from store.
+	errNilFinalizedInStore = errors.New("nil finalized checkpoint returned from store")
+)
--- a/beacon-chain/blockchain/head.go
+++ b/beacon-chain/blockchain/head.go
@@ -7,25 +7,43 @@ import (

 	"github.com/pkg/errors"
 	types "github.com/prysmaticlabs/eth2-types"
-	ethpb "github.com/prysmaticlabs/ethereumapis/eth/v1alpha1"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/feed"
 	statefeed "github.com/prysmaticlabs/prysm/beacon-chain/core/feed/state"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/helpers"
 	"github.com/prysmaticlabs/prysm/beacon-chain/forkchoice/protoarray"
-	iface "github.com/prysmaticlabs/prysm/beacon-chain/state/interface"
-	"github.com/prysmaticlabs/prysm/beacon-chain/state/stateV0"
-	"github.com/prysmaticlabs/prysm/shared/bytesutil"
-	"github.com/prysmaticlabs/prysm/shared/params"
+	"github.com/prysmaticlabs/prysm/beacon-chain/state"
+	"github.com/prysmaticlabs/prysm/config/features"
+	fieldparams "github.com/prysmaticlabs/prysm/config/fieldparams"
+	"github.com/prysmaticlabs/prysm/config/params"
+	"github.com/prysmaticlabs/prysm/encoding/bytesutil"
+	ethpbv1 "github.com/prysmaticlabs/prysm/proto/eth/v1"
+	"github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1/block"
+	"github.com/prysmaticlabs/prysm/time/slots"
 	"github.com/sirupsen/logrus"
 	"go.opencensus.io/trace"
 )

+// UpdateHeadWithBalances updates the beacon state head after getting justified balanced from cache.
+func (s *Service) UpdateHeadWithBalances(ctx context.Context) error {
+	cp := s.store.JustifiedCheckpt()
+	if cp == nil {
+		return errors.New("no justified checkpoint")
+	}
+	balances, err := s.justifiedBalances.get(ctx, bytesutil.ToBytes32(cp.Root))
+	if err != nil {
+		msg := fmt.Sprintf("could not read balances for state w/ justified checkpoint %#x", cp.Root)
+		return errors.Wrap(err, msg)
+	}
+
+	return s.updateHead(ctx, balances)
+}
+
 // This defines the current chain service's view of head.
 type head struct {
-	slot  types.Slot               // current head slot.
-	root  [32]byte                 // current head root.
-	block *ethpb.SignedBeaconBlock // current head block.
-	state iface.BeaconState        // current head state.
+	slot  types.Slot              // current head slot.
+	root  [32]byte                // current head root.
+	block block.SignedBeaconBlock // current head block.
+	state state.BeaconState       // current head state.
 }

 // Determined the head from the fork choice service and saves its new data
@@ -34,24 +52,20 @@ func (s *Service) updateHead(ctx context.Context, balances []uint64) error {
 	ctx, span := trace.StartSpan(ctx, "blockChain.updateHead")
 	defer span.End()

-	// To get the proper head update, a node first checks its best justified
-	// can become justified. This is designed to prevent bounce attack and
-	// ensure head gets its best justified info.
-	if s.bestJustifiedCheckpt.Epoch > s.justifiedCheckpt.Epoch {
-		s.justifiedCheckpt = s.bestJustifiedCheckpt
-		if err := s.cacheJustifiedStateBalances(ctx, bytesutil.ToBytes32(s.justifiedCheckpt.Root)); err != nil {
-			return err
-		}
-	}
-
 	// Get head from the fork choice service.
-	f := s.finalizedCheckpt
-	j := s.justifiedCheckpt
-	// To get head before the first justified epoch, the fork choice will start with genesis root
+	f := s.store.FinalizedCheckpt()
+	if f == nil {
+		return errNilFinalizedInStore
+	}
+	j := s.store.JustifiedCheckpt()
+	if j == nil {
+		return errNilJustifiedInStore
+	}
+	// To get head before the first justified epoch, the fork choice will start with origin root
 	// instead of zero hashes.
 	headStartRoot := bytesutil.ToBytes32(j.Root)
 	if headStartRoot == params.BeaconConfig().ZeroHash {
-		headStartRoot = s.genesisRoot
+		headStartRoot = s.originBlockRoot
 	}

 	// In order to process head, fork choice store requires justified info.
@@ -64,7 +78,7 @@ func (s *Service) updateHead(ctx context.Context, balances []uint64) error {
 			return err
 		}
 		s.cfg.ForkChoiceStore = protoarray.New(j.Epoch, f.Epoch, bytesutil.ToBytes32(f.Root))
-		if err := s.insertBlockToForkChoiceStore(ctx, jb.Block, headStartRoot, f, j); err != nil {
+		if err := s.insertBlockToForkChoiceStore(ctx, jb.Block(), headStartRoot, f, j); err != nil {
 			return err
 		}
 	}
@@ -104,8 +118,8 @@ func (s *Service) saveHead(ctx context.Context, headRoot [32]byte) error {
 	if err != nil {
 		return err
 	}
-	if newHeadBlock == nil || newHeadBlock.Block == nil {
-		return errors.New("cannot save nil head block")
+	if err := helpers.BeaconBlockIsNil(newHeadBlock); err != nil {
+		return err
 	}

 	// Get the new head state from cached state or DB.
@@ -113,25 +127,39 @@ func (s *Service) saveHead(ctx context.Context, headRoot [32]byte) error {
 	if err != nil {
 		return errors.Wrap(err, "could not retrieve head state in DB")
 	}
-	if newHeadState == nil {
+	if newHeadState == nil || newHeadState.IsNil() {
 		return errors.New("cannot save nil head state")
 	}

 	// A chain re-org occurred, so we fire an event notifying the rest of the services.
 	headSlot := s.HeadSlot()
-	if bytesutil.ToBytes32(newHeadBlock.Block.ParentRoot) != bytesutil.ToBytes32(r) {
+	newHeadSlot := newHeadBlock.Block().Slot()
+	oldHeadRoot := s.headRoot()
+	oldStateRoot := s.headBlock().Block().StateRoot()
+	newStateRoot := newHeadBlock.Block().StateRoot()
+	if bytesutil.ToBytes32(newHeadBlock.Block().ParentRoot()) != bytesutil.ToBytes32(r) {
 		log.WithFields(logrus.Fields{
-			"newSlot": fmt.Sprintf("%d", newHeadBlock.Block.Slot),
+			"newSlot": fmt.Sprintf("%d", newHeadSlot),
 			"oldSlot": fmt.Sprintf("%d", headSlot),
 		}).Debug("Chain reorg occurred")
+		absoluteSlotDifference := slots.AbsoluteValueSlotDifference(newHeadSlot, headSlot)
 		s.cfg.StateNotifier.StateFeed().Send(&feed.Event{
 			Type: statefeed.Reorg,
-			Data: &statefeed.ReorgData{
-				NewSlot: newHeadBlock.Block.Slot,
-				OldSlot: headSlot,
+			Data: &ethpbv1.EventChainReorg{
+				Slot:         newHeadSlot,
+				Depth:        absoluteSlotDifference,
+				OldHeadBlock: oldHeadRoot[:],
+				NewHeadBlock: headRoot[:],
+				OldHeadState: oldStateRoot,
+				NewHeadState: newStateRoot,
+				Epoch:        slots.ToEpoch(newHeadSlot),
 			},
 		})

+		if err := s.saveOrphanedAtts(ctx, bytesutil.ToBytes32(r)); err != nil {
+			return err
+		}
+
 		reorgCount.Inc()
 	}

@@ -143,14 +171,22 @@ func (s *Service) saveHead(ctx context.Context, headRoot [32]byte) error {
 		return errors.Wrap(err, "could not save head root in DB")
 	}

+	// Forward an event capturing a new chain head over a common event feed
+	// done in a goroutine to avoid blocking the critical runtime main routine.
+	go func() {
+		if err := s.notifyNewHeadEvent(newHeadSlot, newHeadState, newStateRoot, headRoot[:]); err != nil {
+			log.WithError(err).Error("Could not notify event feed of new chain head")
+		}
+	}()
+
 	return nil
 }

 // This gets called to update canonical root mapping. It does not save head block
 // root in DB. With the inception of initial-sync-cache-state flag, it uses finalized
 // check point as anchors to resume sync therefore head is no longer needed to be saved on per slot basis.
-func (s *Service) saveHeadNoDB(ctx context.Context, b *ethpb.SignedBeaconBlock, r [32]byte, hs iface.BeaconState) error {
-	if err := helpers.VerifyNilBeaconBlock(b); err != nil {
+func (s *Service) saveHeadNoDB(ctx context.Context, b block.SignedBeaconBlock, r [32]byte, hs state.BeaconState) error {
+	if err := helpers.BeaconBlockIsNil(b); err != nil {
 		return err
 	}
 	cachedHeadRoot, err := s.HeadRoot(ctx)
@@ -161,20 +197,20 @@ func (s *Service) saveHeadNoDB(ctx context.Context, b *ethpb.SignedBeaconBlock,
 		return nil
 	}

-	s.setHeadInitialSync(r, stateV0.CopySignedBeaconBlock(b), hs)
+	s.setHeadInitialSync(r, b.Copy(), hs)
 	return nil
 }

 // This sets head view object which is used to track the head slot, root, block and state.
-func (s *Service) setHead(root [32]byte, block *ethpb.SignedBeaconBlock, state iface.BeaconState) {
+func (s *Service) setHead(root [32]byte, block block.SignedBeaconBlock, state state.BeaconState) {
 	s.headLock.Lock()
 	defer s.headLock.Unlock()

 	// This does a full copy of the block and state.
 	s.head = &head{
-		slot:  block.Block.Slot,
+		slot:  block.Block().Slot(),
 		root:  root,
-		block: stateV0.CopySignedBeaconBlock(block),
+		block: block.Copy(),
 		state: state.Copy(),
 	}
 }
@@ -182,15 +218,15 @@ func (s *Service) setHead(root [32]byte, block *ethpb.SignedBeaconBlock, state i
 // This sets head view object which is used to track the head slot, root, block and state. The method
 // assumes that state being passed into the method will not be modified by any other alternate
 // caller which holds the state's reference.
-func (s *Service) setHeadInitialSync(root [32]byte, block *ethpb.SignedBeaconBlock, state iface.BeaconState) {
+func (s *Service) setHeadInitialSync(root [32]byte, block block.SignedBeaconBlock, state state.BeaconState) {
 	s.headLock.Lock()
 	defer s.headLock.Unlock()

 	// This does a full copy of the block only.
 	s.head = &head{
-		slot:  block.Block.Slot,
+		slot:  block.Block().Slot(),
 		root:  root,
-		block: stateV0.CopySignedBeaconBlock(block),
+		block: block.Copy(),
 		state: state,
 	}
 }
@@ -215,15 +251,15 @@ func (s *Service) headRoot() [32]byte {
 // This returns the head block.
 // It does a full copy on head block for immutability.
 // This is a lock free version.
-func (s *Service) headBlock() *ethpb.SignedBeaconBlock {
-	return stateV0.CopySignedBeaconBlock(s.head.block)
+func (s *Service) headBlock() block.SignedBeaconBlock {
+	return s.head.block.Copy()
 }

 // This returns the head state.
 // It does a full copy on head state for immutability.
 // This is a lock free version.
-func (s *Service) headState(ctx context.Context) iface.BeaconState {
-	ctx, span := trace.StartSpan(ctx, "blockChain.headState")
+func (s *Service) headState(ctx context.Context) state.BeaconState {
+	_, span := trace.StartSpan(ctx, "blockChain.headState")
 	defer span.End()

 	return s.head.state.Copy()
@@ -235,59 +271,109 @@ func (s *Service) headGenesisValidatorRoot() [32]byte {
 	return bytesutil.ToBytes32(s.head.state.GenesisValidatorRoot())
 }

+// This returns the validator referenced by the provided index in
+// the head state.
+// This is a lock free version.
+func (s *Service) headValidatorAtIndex(index types.ValidatorIndex) (state.ReadOnlyValidator, error) {
+	return s.head.state.ValidatorAtIndexReadOnly(index)
+}
+
+// This returns the validator index referenced by the provided pubkey in
+// the head state.
+// This is a lock free version.
+func (s *Service) headValidatorIndexAtPubkey(pubKey [fieldparams.BLSPubkeyLength]byte) (types.ValidatorIndex, bool) {
+	return s.head.state.ValidatorIndexByPubkey(pubKey)
+}
+
 // Returns true if head state exists.
 // This is the lock free version.
 func (s *Service) hasHeadState() bool {
 	return s.head != nil && s.head.state != nil
 }

-// This caches justified state balances to be used for fork choice.
-func (s *Service) cacheJustifiedStateBalances(ctx context.Context, justifiedRoot [32]byte) error {
-	if err := s.cfg.BeaconDB.SaveBlocks(ctx, s.getInitSyncBlocks()); err != nil {
-		return err
+// Notifies a common event feed of a new chain head event. Called right after a new
+// chain head is determined, set, and saved to disk.
+func (s *Service) notifyNewHeadEvent(
+	newHeadSlot types.Slot,
+	newHeadState state.BeaconState,
+	newHeadStateRoot,
+	newHeadRoot []byte,
+) error {
+	previousDutyDependentRoot := s.originBlockRoot[:]
+	currentDutyDependentRoot := s.originBlockRoot[:]
+
+	var previousDutyEpoch types.Epoch
+	currentDutyEpoch := slots.ToEpoch(newHeadSlot)
+	if currentDutyEpoch > 0 {
+		previousDutyEpoch = currentDutyEpoch.Sub(1)
 	}
-
-	s.clearInitSyncBlocks()
-
-	var justifiedState iface.BeaconState
-	var err error
-	if justifiedRoot == s.genesisRoot {
-		justifiedState, err = s.cfg.BeaconDB.GenesisState(ctx)
+	currentDutySlot, err := slots.EpochStart(currentDutyEpoch)
+	if err != nil {
+		return errors.Wrap(err, "could not get duty slot")
+	}
+	previousDutySlot, err := slots.EpochStart(previousDutyEpoch)
+	if err != nil {
+		return errors.Wrap(err, "could not get duty slot")
+	}
+	if currentDutySlot > 0 {
+		currentDutyDependentRoot, err = helpers.BlockRootAtSlot(newHeadState, currentDutySlot-1)
 		if err != nil {
-			return err
+			return errors.Wrap(err, "could not get duty dependent root")
 		}
-	} else {
-		justifiedState, err = s.cfg.StateGen.StateByRoot(ctx, justifiedRoot)
+	}
+	if previousDutySlot > 0 {
+		previousDutyDependentRoot, err = helpers.BlockRootAtSlot(newHeadState, previousDutySlot-1)
 		if err != nil {
-			return err
+			return errors.Wrap(err, "could not get duty dependent root")
 		}
 	}
-	if justifiedState == nil {
-		return errors.New("justified state can't be nil")
-	}
-
-	epoch := helpers.CurrentEpoch(justifiedState)
-
-	justifiedBalances := make([]uint64, justifiedState.NumValidators())
-	if err := justifiedState.ReadFromEveryValidator(func(idx int, val iface.ReadOnlyValidator) error {
-		if helpers.IsActiveValidatorUsingTrie(val, epoch) {
-			justifiedBalances[idx] = val.EffectiveBalance()
-		} else {
-			justifiedBalances[idx] = 0
-		}
-		return nil
-	}); err != nil {
-		return err
-	}
-
-	s.justifiedBalancesLock.Lock()
-	defer s.justifiedBalancesLock.Unlock()
-	s.justifiedBalances = justifiedBalances
+	s.cfg.StateNotifier.StateFeed().Send(&feed.Event{
+		Type: statefeed.NewHead,
+		Data: &ethpbv1.EventHead{
+			Slot:                      newHeadSlot,
+			Block:                     newHeadRoot,
+			State:                     newHeadStateRoot,
+			EpochTransition:           slots.IsEpochStart(newHeadSlot),
+			PreviousDutyDependentRoot: previousDutyDependentRoot,
+			CurrentDutyDependentRoot:  currentDutyDependentRoot,
+		},
+	})
 	return nil
 }

-func (s *Service) getJustifiedBalances() []uint64 {
-	s.justifiedBalancesLock.RLock()
-	defer s.justifiedBalancesLock.RUnlock()
-	return s.justifiedBalances
+// This saves the attestations inside the beacon block with respect to root `orphanedRoot` back into the
+// attestation pool. It also filters out the attestations that is one epoch older as a
+// defense so invalid attestations don't flow into the attestation pool.
+func (s *Service) saveOrphanedAtts(ctx context.Context, orphanedRoot [32]byte) error {
+	if !features.Get().CorrectlyInsertOrphanedAtts {
+		return nil
+	}
+
+	orphanedBlk, err := s.cfg.BeaconDB.Block(ctx, orphanedRoot)
+	if err != nil {
+		return err
+	}
+
+	if orphanedBlk == nil || orphanedBlk.IsNil() {
+		return errors.New("orphaned block can't be nil")
+	}
+
+	for _, a := range orphanedBlk.Block().Body().Attestations() {
+		// Is the attestation one epoch older.
+		if a.Data.Slot+params.BeaconConfig().SlotsPerEpoch < s.CurrentSlot() {
+			continue
+		}
+		if helpers.IsAggregated(a) {
+			if err := s.cfg.AttPool.SaveAggregatedAttestation(a); err != nil {
+				return err
+			}
+		} else {
+			if err := s.cfg.AttPool.SaveUnaggregatedAttestation(a); err != nil {
+				return err
+			}
+		}
+		saveOrphanedAttCount.Inc()
+	}
+
+	return nil
 }
--- a/beacon-chain/blockchain/head_sync_committee_info.go
+++ b/beacon-chain/blockchain/head_sync_committee_info.go
@@ -0,0 +1,172 @@
+package blockchain
+
+import (
+	"context"
+	"fmt"
+
+	"github.com/pkg/errors"
+	types "github.com/prysmaticlabs/eth2-types"
+	"github.com/prysmaticlabs/prysm/async"
+	"github.com/prysmaticlabs/prysm/beacon-chain/cache"
+	"github.com/prysmaticlabs/prysm/beacon-chain/core/altair"
+	"github.com/prysmaticlabs/prysm/beacon-chain/core/helpers"
+	"github.com/prysmaticlabs/prysm/beacon-chain/core/signing"
+	"github.com/prysmaticlabs/prysm/beacon-chain/core/transition"
+	"github.com/prysmaticlabs/prysm/beacon-chain/state"
+	"github.com/prysmaticlabs/prysm/config/params"
+	ethpb "github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1"
+	"github.com/prysmaticlabs/prysm/time/slots"
+)
+
+// Initialize the state cache for sync committees.
+var syncCommitteeHeadStateCache = cache.NewSyncCommitteeHeadState()
+
+// HeadSyncCommitteeFetcher is the interface that wraps the head sync committee related functions.
+// The head sync committee functions return callers sync committee indices and public keys with respect to current head state.
+type HeadSyncCommitteeFetcher interface {
+	HeadSyncCommitteeIndices(ctx context.Context, index types.ValidatorIndex, slot types.Slot) ([]types.CommitteeIndex, error)
+	HeadSyncCommitteePubKeys(ctx context.Context, slot types.Slot, committeeIndex types.CommitteeIndex) ([][]byte, error)
+}
+
+// HeadDomainFetcher is the interface that wraps the head sync domain related functions.
+// The head sync committee domain functions return callers domain data with respect to slot and head state.
+type HeadDomainFetcher interface {
+	HeadSyncCommitteeDomain(ctx context.Context, slot types.Slot) ([]byte, error)
+	HeadSyncSelectionProofDomain(ctx context.Context, slot types.Slot) ([]byte, error)
+	HeadSyncContributionProofDomain(ctx context.Context, slot types.Slot) ([]byte, error)
+}
+
+// HeadSyncCommitteeDomain returns the head sync committee domain using current head state advanced up to `slot`.
+func (s *Service) HeadSyncCommitteeDomain(ctx context.Context, slot types.Slot) ([]byte, error) {
+	return s.domainWithHeadState(ctx, slot, params.BeaconConfig().DomainSyncCommittee)
+}
+
+// HeadSyncSelectionProofDomain returns the head sync committee domain using current head state advanced up to `slot`.
+func (s *Service) HeadSyncSelectionProofDomain(ctx context.Context, slot types.Slot) ([]byte, error) {
+	return s.domainWithHeadState(ctx, slot, params.BeaconConfig().DomainSyncCommitteeSelectionProof)
+}
+
+// HeadSyncContributionProofDomain returns the head sync committee domain using current head state advanced up to `slot`.
+func (s *Service) HeadSyncContributionProofDomain(ctx context.Context, slot types.Slot) ([]byte, error) {
+	return s.domainWithHeadState(ctx, slot, params.BeaconConfig().DomainContributionAndProof)
+}
+
+// HeadSyncCommitteeIndices returns the sync committee index position using the head state. Input `slot` is taken in consideration
+// where validator's duty for `slot - 1` is used for block inclusion in `slot`. That means when a validator is at epoch boundary
+// across EPOCHS_PER_SYNC_COMMITTEE_PERIOD then the valiator will be considered using next period sync committee.
+//
+// Spec definition:
+// Being assigned to a sync committee for a given slot means that the validator produces and broadcasts signatures for slot - 1 for inclusion in slot.
+// This means that when assigned to an epoch sync committee signatures must be produced and broadcast for slots on range
+// [compute_start_slot_at_epoch(epoch) - 1, compute_start_slot_at_epoch(epoch) + SLOTS_PER_EPOCH - 1)
+// rather than for the range
+// [compute_start_slot_at_epoch(epoch), compute_start_slot_at_epoch(epoch) + SLOTS_PER_EPOCH)
+func (s *Service) HeadSyncCommitteeIndices(ctx context.Context, index types.ValidatorIndex, slot types.Slot) ([]types.CommitteeIndex, error) {
+	nextSlotEpoch := slots.ToEpoch(slot + 1)
+	currentEpoch := slots.ToEpoch(slot)
+
+	switch {
+	case slots.SyncCommitteePeriod(nextSlotEpoch) == slots.SyncCommitteePeriod(currentEpoch):
+		return s.headCurrentSyncCommitteeIndices(ctx, index, slot)
+	// At sync committee period boundary, validator should sample the next epoch sync committee.
+	case slots.SyncCommitteePeriod(nextSlotEpoch) == slots.SyncCommitteePeriod(currentEpoch)+1:
+		return s.headNextSyncCommitteeIndices(ctx, index, slot)
+	default:
+		// Impossible condition.
+		return nil, errors.New("could get calculate sync subcommittee based on the period")
+	}
+}
+
+// headCurrentSyncCommitteeIndices returns the input validator `index`'s position indices in the current sync committee with respect to `slot`.
+// Head state advanced up to `slot` is used for calculation.
+func (s *Service) headCurrentSyncCommitteeIndices(ctx context.Context, index types.ValidatorIndex, slot types.Slot) ([]types.CommitteeIndex, error) {
+	headState, err := s.getSyncCommitteeHeadState(ctx, slot)
+	if err != nil {
+		return nil, err
+	}
+	return helpers.CurrentPeriodSyncSubcommitteeIndices(headState, index)
+}
+
+// headNextSyncCommitteeIndices returns the input validator `index`'s position indices in the next sync committee with respect to `slot`.
+// Head state advanced up to `slot` is used for calculation.
+func (s *Service) headNextSyncCommitteeIndices(ctx context.Context, index types.ValidatorIndex, slot types.Slot) ([]types.CommitteeIndex, error) {
+	headState, err := s.getSyncCommitteeHeadState(ctx, slot)
+	if err != nil {
+		return nil, err
+	}
+	return helpers.NextPeriodSyncSubcommitteeIndices(headState, index)
+}
+
+// HeadSyncCommitteePubKeys returns the head sync committee public keys with respect to `slot` and subcommittee index `committeeIndex`.
+// Head state advanced up to `slot` is used for calculation.
+func (s *Service) HeadSyncCommitteePubKeys(ctx context.Context, slot types.Slot, committeeIndex types.CommitteeIndex) ([][]byte, error) {
+	headState, err := s.getSyncCommitteeHeadState(ctx, slot)
+	if err != nil {
+		return nil, err
+	}
+
+	nextSlotEpoch := slots.ToEpoch(headState.Slot() + 1)
+	currEpoch := slots.ToEpoch(headState.Slot())
+
+	var syncCommittee *ethpb.SyncCommittee
+	if currEpoch == nextSlotEpoch || slots.SyncCommitteePeriod(currEpoch) == slots.SyncCommitteePeriod(nextSlotEpoch) {
+		syncCommittee, err = headState.CurrentSyncCommittee()
+		if err != nil {
+			return nil, err
+		}
+	} else {
+		syncCommittee, err = headState.NextSyncCommittee()
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	return altair.SyncSubCommitteePubkeys(syncCommittee, committeeIndex)
+}
+
+// returns calculated domain using input `domain` and `slot`.
+func (s *Service) domainWithHeadState(ctx context.Context, slot types.Slot, domain [4]byte) ([]byte, error) {
+	headState, err := s.getSyncCommitteeHeadState(ctx, slot)
+	if err != nil {
+		return nil, err
+	}
+	return signing.Domain(headState.Fork(), slots.ToEpoch(headState.Slot()), domain, headState.GenesisValidatorRoot())
+}
+
+// returns the head state that is advanced up to `slot`. It utilizes the cache `syncCommitteeHeadState` by retrieving using `slot` as key.
+// For the cache miss, it processes head state up to slot and fill the cache with `slot` as key.
+func (s *Service) getSyncCommitteeHeadState(ctx context.Context, slot types.Slot) (state.BeaconState, error) {
+	var headState state.BeaconState
+	var err error
+	mLock := async.NewMultilock(fmt.Sprintf("%s-%d", "syncHeadState", slot))
+	mLock.Lock()
+	defer mLock.Unlock()
+
+	// If there's already a head state exists with the request slot, we don't need to process slots.
+	cachedState, err := syncCommitteeHeadStateCache.Get(slot)
+	switch {
+	case err == nil:
+		syncHeadStateHit.Inc()
+		headState = cachedState
+		return headState, nil
+	case errors.Is(err, cache.ErrNotFound):
+		headState, err = s.HeadState(ctx)
+		if err != nil {
+			return nil, err
+		}
+		if headState == nil || headState.IsNil() {
+			return nil, errors.New("nil state")
+		}
+		headState, err = transition.ProcessSlotsIfPossible(ctx, headState, slot)
+		if err != nil {
+			return nil, err
+		}
+		syncHeadStateMiss.Inc()
+		err = syncCommitteeHeadStateCache.Put(slot, headState)
+		return headState, err
+	default:
+		// In the event, we encounter another error
+		// we return it.
+		return nil, err
+	}
+}
--- a/beacon-chain/blockchain/head_sync_committee_info_test.go
+++ b/beacon-chain/blockchain/head_sync_committee_info_test.go
@@ -0,0 +1,176 @@
+package blockchain
+
+import (
+	"context"
+	"testing"
+
+	types "github.com/prysmaticlabs/eth2-types"
+	"github.com/prysmaticlabs/prysm/beacon-chain/cache"
+	"github.com/prysmaticlabs/prysm/beacon-chain/core/signing"
+	dbtest "github.com/prysmaticlabs/prysm/beacon-chain/db/testing"
+	"github.com/prysmaticlabs/prysm/beacon-chain/state/stategen"
+	"github.com/prysmaticlabs/prysm/config/params"
+	"github.com/prysmaticlabs/prysm/testing/require"
+	"github.com/prysmaticlabs/prysm/testing/util"
+	"github.com/prysmaticlabs/prysm/time/slots"
+)
+
+func TestService_headSyncCommitteeFetcher_Errors(t *testing.T) {
+	beaconDB := dbtest.SetupDB(t)
+	c := &Service{
+		cfg: &config{
+			StateGen: stategen.New(beaconDB),
+		},
+	}
+	c.head = &head{}
+	_, err := c.headCurrentSyncCommitteeIndices(context.Background(), types.ValidatorIndex(0), types.Slot(0))
+	require.ErrorContains(t, "nil state", err)
+
+	_, err = c.headNextSyncCommitteeIndices(context.Background(), types.ValidatorIndex(0), types.Slot(0))
+	require.ErrorContains(t, "nil state", err)
+
+	_, err = c.HeadSyncCommitteePubKeys(context.Background(), types.Slot(0), types.CommitteeIndex(0))
+	require.ErrorContains(t, "nil state", err)
+}
+
+func TestService_HeadDomainFetcher_Errors(t *testing.T) {
+	beaconDB := dbtest.SetupDB(t)
+	c := &Service{
+		cfg: &config{
+			StateGen: stategen.New(beaconDB),
+		},
+	}
+	c.head = &head{}
+	_, err := c.HeadSyncCommitteeDomain(context.Background(), types.Slot(0))
+	require.ErrorContains(t, "nil state", err)
+
+	_, err = c.HeadSyncSelectionProofDomain(context.Background(), types.Slot(0))
+	require.ErrorContains(t, "nil state", err)
+
+	_, err = c.HeadSyncSelectionProofDomain(context.Background(), types.Slot(0))
+	require.ErrorContains(t, "nil state", err)
+}
+
+func TestService_HeadSyncCommitteeIndices(t *testing.T) {
+	s, _ := util.DeterministicGenesisStateAltair(t, params.BeaconConfig().TargetCommitteeSize)
+	c := &Service{}
+	c.head = &head{state: s}
+
+	// Current period
+	slot := 2*uint64(params.BeaconConfig().EpochsPerSyncCommitteePeriod)*uint64(params.BeaconConfig().SlotsPerEpoch) + 1
+	a, err := c.HeadSyncCommitteeIndices(context.Background(), 0, types.Slot(slot))
+	require.NoError(t, err)
+
+	// Current period where slot-2 across EPOCHS_PER_SYNC_COMMITTEE_PERIOD
+	slot = 3*uint64(params.BeaconConfig().EpochsPerSyncCommitteePeriod)*uint64(params.BeaconConfig().SlotsPerEpoch) - 2
+	b, err := c.HeadSyncCommitteeIndices(context.Background(), 0, types.Slot(slot))
+	require.NoError(t, err)
+	require.DeepEqual(t, a, b)
+
+	// Next period where slot-1 across EPOCHS_PER_SYNC_COMMITTEE_PERIOD
+	slot = 3*uint64(params.BeaconConfig().EpochsPerSyncCommitteePeriod)*uint64(params.BeaconConfig().SlotsPerEpoch) - 1
+	b, err = c.HeadSyncCommitteeIndices(context.Background(), 0, types.Slot(slot))
+	require.NoError(t, err)
+	require.DeepNotEqual(t, a, b)
+}
+
+func TestService_headCurrentSyncCommitteeIndices(t *testing.T) {
+	s, _ := util.DeterministicGenesisStateAltair(t, params.BeaconConfig().TargetCommitteeSize)
+	c := &Service{}
+	c.head = &head{state: s}
+
+	// Process slot up to `EpochsPerSyncCommitteePeriod` so it can `ProcessSyncCommitteeUpdates`.
+	slot := uint64(params.BeaconConfig().EpochsPerSyncCommitteePeriod)*uint64(params.BeaconConfig().SlotsPerEpoch) + 1
+	indices, err := c.headCurrentSyncCommitteeIndices(context.Background(), 0, types.Slot(slot))
+	require.NoError(t, err)
+
+	// NextSyncCommittee becomes CurrentSyncCommittee so it should be empty by default.
+	require.Equal(t, 0, len(indices))
+}
+
+func TestService_headNextSyncCommitteeIndices(t *testing.T) {
+	s, _ := util.DeterministicGenesisStateAltair(t, params.BeaconConfig().TargetCommitteeSize)
+	c := &Service{}
+	c.head = &head{state: s}
+
+	// Process slot up to `EpochsPerSyncCommitteePeriod` so it can `ProcessSyncCommitteeUpdates`.
+	slot := uint64(params.BeaconConfig().EpochsPerSyncCommitteePeriod)*uint64(params.BeaconConfig().SlotsPerEpoch) + 1
+	indices, err := c.headNextSyncCommitteeIndices(context.Background(), 0, types.Slot(slot))
+	require.NoError(t, err)
+
+	// NextSyncCommittee should be be empty after `ProcessSyncCommitteeUpdates`. Validator should get indices.
+	require.NotEqual(t, 0, len(indices))
+}
+
+func TestService_HeadSyncCommitteePubKeys(t *testing.T) {
+	s, _ := util.DeterministicGenesisStateAltair(t, params.BeaconConfig().TargetCommitteeSize)
+	c := &Service{}
+	c.head = &head{state: s}
+
+	// Process slot up to 2 * `EpochsPerSyncCommitteePeriod` so it can run `ProcessSyncCommitteeUpdates` twice.
+	slot := uint64(2*params.BeaconConfig().EpochsPerSyncCommitteePeriod)*uint64(params.BeaconConfig().SlotsPerEpoch) + 1
+	pubkeys, err := c.HeadSyncCommitteePubKeys(context.Background(), types.Slot(slot), 0)
+	require.NoError(t, err)
+
+	// Any subcommittee should match the subcommittee size.
+	subCommitteeSize := params.BeaconConfig().SyncCommitteeSize / params.BeaconConfig().SyncCommitteeSubnetCount
+	require.Equal(t, int(subCommitteeSize), len(pubkeys))
+}
+
+func TestService_HeadSyncCommitteeDomain(t *testing.T) {
+	s, _ := util.DeterministicGenesisStateAltair(t, params.BeaconConfig().TargetCommitteeSize)
+	c := &Service{}
+	c.head = &head{state: s}
+
+	wanted, err := signing.Domain(s.Fork(), slots.ToEpoch(s.Slot()), params.BeaconConfig().DomainSyncCommittee, s.GenesisValidatorRoot())
+	require.NoError(t, err)
+
+	d, err := c.HeadSyncCommitteeDomain(context.Background(), 0)
+	require.NoError(t, err)
+
+	require.DeepEqual(t, wanted, d)
+}
+
+func TestService_HeadSyncContributionProofDomain(t *testing.T) {
+	s, _ := util.DeterministicGenesisStateAltair(t, params.BeaconConfig().TargetCommitteeSize)
+	c := &Service{}
+	c.head = &head{state: s}
+
+	wanted, err := signing.Domain(s.Fork(), slots.ToEpoch(s.Slot()), params.BeaconConfig().DomainContributionAndProof, s.GenesisValidatorRoot())
+	require.NoError(t, err)
+
+	d, err := c.HeadSyncContributionProofDomain(context.Background(), 0)
+	require.NoError(t, err)
+
+	require.DeepEqual(t, wanted, d)
+}
+
+func TestService_HeadSyncSelectionProofDomain(t *testing.T) {
+	s, _ := util.DeterministicGenesisStateAltair(t, params.BeaconConfig().TargetCommitteeSize)
+	c := &Service{}
+	c.head = &head{state: s}
+
+	wanted, err := signing.Domain(s.Fork(), slots.ToEpoch(s.Slot()), params.BeaconConfig().DomainSyncCommitteeSelectionProof, s.GenesisValidatorRoot())
+	require.NoError(t, err)
+
+	d, err := c.HeadSyncSelectionProofDomain(context.Background(), 0)
+	require.NoError(t, err)
+
+	require.DeepEqual(t, wanted, d)
+}
+
+func TestSyncCommitteeHeadStateCache_RoundTrip(t *testing.T) {
+	c := syncCommitteeHeadStateCache
+	t.Cleanup(func() {
+		syncCommitteeHeadStateCache = cache.NewSyncCommitteeHeadState()
+	})
+	beaconState, _ := util.DeterministicGenesisStateAltair(t, 100)
+	require.NoError(t, beaconState.SetSlot(100))
+	cachedState, err := c.Get(101)
+	require.ErrorContains(t, cache.ErrNotFound.Error(), err)
+	require.Equal(t, nil, cachedState)
+	require.NoError(t, c.Put(101, beaconState))
+	cachedState, err = c.Get(101)
+	require.NoError(t, err)
+	require.DeepEqual(t, beaconState, cachedState)
+}
--- a/beacon-chain/blockchain/head_test.go
+++ b/beacon-chain/blockchain/head_test.go
@@ -4,14 +4,20 @@ import (
 	"bytes"
 	"context"
 	"testing"
+	"time"

 	types "github.com/prysmaticlabs/eth2-types"
-	ethpb "github.com/prysmaticlabs/ethereumapis/eth/v1alpha1"
+	mock "github.com/prysmaticlabs/prysm/beacon-chain/blockchain/testing"
 	testDB "github.com/prysmaticlabs/prysm/beacon-chain/db/testing"
-	pb "github.com/prysmaticlabs/prysm/proto/beacon/p2p/v1"
-	"github.com/prysmaticlabs/prysm/shared/testutil"
-	"github.com/prysmaticlabs/prysm/shared/testutil/assert"
-	"github.com/prysmaticlabs/prysm/shared/testutil/require"
+	"github.com/prysmaticlabs/prysm/config/features"
+	"github.com/prysmaticlabs/prysm/config/params"
+	ethpbv1 "github.com/prysmaticlabs/prysm/proto/eth/v1"
+	ethpb "github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1"
+	"github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1/wrapper"
+	"github.com/prysmaticlabs/prysm/testing/assert"
+	"github.com/prysmaticlabs/prysm/testing/require"
+	"github.com/prysmaticlabs/prysm/testing/util"
+	"github.com/prysmaticlabs/prysm/time/slots"
 	logTest "github.com/sirupsen/logrus/hooks/test"
 )

@@ -32,20 +38,30 @@ func TestSaveHead_Different(t *testing.T) {
 	beaconDB := testDB.SetupDB(t)
 	service := setupBeaconChain(t, beaconDB)

-	oldRoot := [32]byte{'A'}
-	service.head = &head{slot: 0, root: oldRoot}
+	util.NewBeaconBlock()
+	oldBlock := wrapper.WrappedPhase0SignedBeaconBlock(
+		util.NewBeaconBlock(),
+	)
+	require.NoError(t, service.cfg.BeaconDB.SaveBlock(context.Background(), oldBlock))
+	oldRoot, err := oldBlock.Block().HashTreeRoot()
+	require.NoError(t, err)
+	service.head = &head{
+		slot:  0,
+		root:  oldRoot,
+		block: oldBlock,
+	}

-	newHeadSignedBlock := testutil.NewBeaconBlock()
+	newHeadSignedBlock := util.NewBeaconBlock()
 	newHeadSignedBlock.Block.Slot = 1
 	newHeadBlock := newHeadSignedBlock.Block

-	require.NoError(t, service.cfg.BeaconDB.SaveBlock(context.Background(), newHeadSignedBlock))
+	require.NoError(t, service.cfg.BeaconDB.SaveBlock(context.Background(), wrapper.WrappedPhase0SignedBeaconBlock(newHeadSignedBlock)))
 	newRoot, err := newHeadBlock.HashTreeRoot()
 	require.NoError(t, err)
-	headState, err := testutil.NewBeaconState()
+	headState, err := util.NewBeaconState()
 	require.NoError(t, err)
 	require.NoError(t, headState.SetSlot(1))
-	require.NoError(t, service.cfg.BeaconDB.SaveStateSummary(context.Background(), &pb.StateSummary{Slot: 1, Root: newRoot[:]}))
+	require.NoError(t, service.cfg.BeaconDB.SaveStateSummary(context.Background(), &ethpb.StateSummary{Slot: 1, Root: newRoot[:]}))
 	require.NoError(t, service.cfg.BeaconDB.SaveState(context.Background(), headState, newRoot))
 	require.NoError(t, service.saveHead(context.Background(), newRoot))

@@ -54,7 +70,7 @@ func TestSaveHead_Different(t *testing.T) {
 	cachedRoot, err := service.HeadRoot(context.Background())
 	require.NoError(t, err)
 	assert.DeepEqual(t, cachedRoot, newRoot[:], "Head did not change")
-	assert.DeepEqual(t, newHeadSignedBlock, service.headBlock(), "Head did not change")
+	assert.DeepEqual(t, newHeadSignedBlock, service.headBlock().Proto(), "Head did not change")
 	assert.DeepSSZEqual(t, headState.CloneInnerState(), service.headState(ctx).CloneInnerState(), "Head did not change")
 }

@@ -64,22 +80,31 @@ func TestSaveHead_Different_Reorg(t *testing.T) {
 	beaconDB := testDB.SetupDB(t)
 	service := setupBeaconChain(t, beaconDB)

-	oldRoot := [32]byte{'A'}
-	service.head = &head{slot: 0, root: oldRoot}
+	oldBlock := wrapper.WrappedPhase0SignedBeaconBlock(
+		util.NewBeaconBlock(),
+	)
+	require.NoError(t, service.cfg.BeaconDB.SaveBlock(context.Background(), oldBlock))
+	oldRoot, err := oldBlock.Block().HashTreeRoot()
+	require.NoError(t, err)
+	service.head = &head{
+		slot:  0,
+		root:  oldRoot,
+		block: oldBlock,
+	}

 	reorgChainParent := [32]byte{'B'}
-	newHeadSignedBlock := testutil.NewBeaconBlock()
+	newHeadSignedBlock := util.NewBeaconBlock()
 	newHeadSignedBlock.Block.Slot = 1
 	newHeadSignedBlock.Block.ParentRoot = reorgChainParent[:]
 	newHeadBlock := newHeadSignedBlock.Block

-	require.NoError(t, service.cfg.BeaconDB.SaveBlock(context.Background(), newHeadSignedBlock))
+	require.NoError(t, service.cfg.BeaconDB.SaveBlock(context.Background(), wrapper.WrappedPhase0SignedBeaconBlock(newHeadSignedBlock)))
 	newRoot, err := newHeadBlock.HashTreeRoot()
 	require.NoError(t, err)
-	headState, err := testutil.NewBeaconState()
+	headState, err := util.NewBeaconState()
 	require.NoError(t, err)
 	require.NoError(t, headState.SetSlot(1))
-	require.NoError(t, service.cfg.BeaconDB.SaveStateSummary(context.Background(), &pb.StateSummary{Slot: 1, Root: newRoot[:]}))
+	require.NoError(t, service.cfg.BeaconDB.SaveStateSummary(context.Background(), &ethpb.StateSummary{Slot: 1, Root: newRoot[:]}))
 	require.NoError(t, service.cfg.BeaconDB.SaveState(context.Background(), headState, newRoot))
 	require.NoError(t, service.saveHead(context.Background(), newRoot))

@@ -90,7 +115,7 @@ func TestSaveHead_Different_Reorg(t *testing.T) {
 	if !bytes.Equal(cachedRoot, newRoot[:]) {
 		t.Error("Head did not change")
 	}
-	assert.DeepEqual(t, newHeadSignedBlock, service.headBlock(), "Head did not change")
+	assert.DeepEqual(t, newHeadSignedBlock, service.headBlock().Proto(), "Head did not change")
 	assert.DeepSSZEqual(t, headState.CloneInnerState(), service.headState(ctx).CloneInnerState(), "Head did not change")
 	require.LogsContain(t, hook, "Chain reorg occurred")
 }
@@ -98,27 +123,147 @@ func TestSaveHead_Different_Reorg(t *testing.T) {
 func TestCacheJustifiedStateBalances_CanCache(t *testing.T) {
 	beaconDB := testDB.SetupDB(t)
 	service := setupBeaconChain(t, beaconDB)
+	ctx := context.Background()

-	state, _ := testutil.DeterministicGenesisState(t, 100)
+	state, _ := util.DeterministicGenesisState(t, 100)
 	r := [32]byte{'a'}
-	require.NoError(t, service.cfg.BeaconDB.SaveStateSummary(context.Background(), &pb.StateSummary{Root: r[:]}))
+	require.NoError(t, service.cfg.BeaconDB.SaveStateSummary(context.Background(), &ethpb.StateSummary{Root: r[:]}))
 	require.NoError(t, service.cfg.BeaconDB.SaveState(context.Background(), state, r))
-	require.NoError(t, service.cacheJustifiedStateBalances(context.Background(), r))
-	require.DeepEqual(t, service.getJustifiedBalances(), state.Balances(), "Incorrect justified balances")
+	balances, err := service.justifiedBalances.get(ctx, r)
+	require.NoError(t, err)
+	require.DeepEqual(t, balances, state.Balances(), "Incorrect justified balances")
 }

 func TestUpdateHead_MissingJustifiedRoot(t *testing.T) {
 	beaconDB := testDB.SetupDB(t)
 	service := setupBeaconChain(t, beaconDB)

-	b := testutil.NewBeaconBlock()
-	require.NoError(t, service.cfg.BeaconDB.SaveBlock(context.Background(), b))
+	b := util.NewBeaconBlock()
+	require.NoError(t, service.cfg.BeaconDB.SaveBlock(context.Background(), wrapper.WrappedPhase0SignedBeaconBlock(b)))
 	r, err := b.Block.HashTreeRoot()
 	require.NoError(t, err)

-	service.justifiedCheckpt = &ethpb.Checkpoint{Root: r[:]}
-	service.finalizedCheckpt = &ethpb.Checkpoint{}
-	service.bestJustifiedCheckpt = &ethpb.Checkpoint{}
+	service.store.SetJustifiedCheckpt(&ethpb.Checkpoint{Root: r[:]})
+	service.store.SetFinalizedCheckpt(&ethpb.Checkpoint{})
+	service.store.SetBestJustifiedCheckpt(&ethpb.Checkpoint{})

 	require.NoError(t, service.updateHead(context.Background(), []uint64{}))
 }
+
+func Test_notifyNewHeadEvent(t *testing.T) {
+	t.Run("genesis_state_root", func(t *testing.T) {
+		bState, _ := util.DeterministicGenesisState(t, 10)
+		notifier := &mock.MockStateNotifier{RecordEvents: true}
+		srv := &Service{
+			cfg: &config{
+				StateNotifier: notifier,
+			},
+			originBlockRoot: [32]byte{1},
+		}
+		newHeadStateRoot := [32]byte{2}
+		newHeadRoot := [32]byte{3}
+		err := srv.notifyNewHeadEvent(1, bState, newHeadStateRoot[:], newHeadRoot[:])
+		require.NoError(t, err)
+		events := notifier.ReceivedEvents()
+		require.Equal(t, 1, len(events))
+
+		eventHead, ok := events[0].Data.(*ethpbv1.EventHead)
+		require.Equal(t, true, ok)
+		wanted := &ethpbv1.EventHead{
+			Slot:                      1,
+			Block:                     newHeadRoot[:],
+			State:                     newHeadStateRoot[:],
+			EpochTransition:           false,
+			PreviousDutyDependentRoot: srv.originBlockRoot[:],
+			CurrentDutyDependentRoot:  srv.originBlockRoot[:],
+		}
+		require.DeepSSZEqual(t, wanted, eventHead)
+	})
+	t.Run("non_genesis_values", func(t *testing.T) {
+		bState, _ := util.DeterministicGenesisState(t, 10)
+		notifier := &mock.MockStateNotifier{RecordEvents: true}
+		genesisRoot := [32]byte{1}
+		srv := &Service{
+			cfg: &config{
+				StateNotifier: notifier,
+			},
+			originBlockRoot: genesisRoot,
+		}
+		epoch1Start, err := slots.EpochStart(1)
+		require.NoError(t, err)
+		epoch2Start, err := slots.EpochStart(1)
+		require.NoError(t, err)
+		require.NoError(t, bState.SetSlot(epoch1Start))
+
+		newHeadStateRoot := [32]byte{2}
+		newHeadRoot := [32]byte{3}
+		err = srv.notifyNewHeadEvent(epoch2Start, bState, newHeadStateRoot[:], newHeadRoot[:])
+		require.NoError(t, err)
+		events := notifier.ReceivedEvents()
+		require.Equal(t, 1, len(events))
+
+		eventHead, ok := events[0].Data.(*ethpbv1.EventHead)
+		require.Equal(t, true, ok)
+		wanted := &ethpbv1.EventHead{
+			Slot:                      epoch2Start,
+			Block:                     newHeadRoot[:],
+			State:                     newHeadStateRoot[:],
+			EpochTransition:           true,
+			PreviousDutyDependentRoot: genesisRoot[:],
+			CurrentDutyDependentRoot:  make([]byte, 32),
+		}
+		require.DeepSSZEqual(t, wanted, eventHead)
+	})
+}
+
+func TestSaveOrphanedAtts(t *testing.T) {
+	resetCfg := features.InitWithReset(&features.Flags{
+		CorrectlyInsertOrphanedAtts: true,
+	})
+	defer resetCfg()
+
+	genesis, keys := util.DeterministicGenesisState(t, 64)
+	b, err := util.GenerateFullBlock(genesis, keys, util.DefaultBlockGenConfig(), 1)
+	assert.NoError(t, err)
+	r, err := b.Block.HashTreeRoot()
+	require.NoError(t, err)
+
+	ctx := context.Background()
+	beaconDB := testDB.SetupDB(t)
+	service := setupBeaconChain(t, beaconDB)
+	service.genesisTime = time.Now()
+
+	require.NoError(t, service.cfg.BeaconDB.SaveBlock(ctx, wrapper.WrappedPhase0SignedBeaconBlock(b)))
+	require.NoError(t, service.saveOrphanedAtts(ctx, r))
+
+	require.Equal(t, len(b.Block.Body.Attestations), service.cfg.AttPool.AggregatedAttestationCount())
+	savedAtts := service.cfg.AttPool.AggregatedAttestations()
+	atts := b.Block.Body.Attestations
+	require.DeepSSZEqual(t, atts, savedAtts)
+}
+
+func TestSaveOrphanedAtts_CanFilter(t *testing.T) {
+	resetCfg := features.InitWithReset(&features.Flags{
+		CorrectlyInsertOrphanedAtts: true,
+	})
+	defer resetCfg()
+
+	genesis, keys := util.DeterministicGenesisState(t, 64)
+	b, err := util.GenerateFullBlock(genesis, keys, util.DefaultBlockGenConfig(), 1)
+	assert.NoError(t, err)
+	r, err := b.Block.HashTreeRoot()
+	require.NoError(t, err)
+
+	ctx := context.Background()
+	beaconDB := testDB.SetupDB(t)
+	service := setupBeaconChain(t, beaconDB)
+	service.genesisTime = time.Now().Add(time.Duration(-1*int64(params.BeaconConfig().SlotsPerEpoch+1)*int64(params.BeaconConfig().SecondsPerSlot)) * time.Second)
+
+	require.NoError(t, service.cfg.BeaconDB.SaveBlock(ctx, wrapper.WrappedPhase0SignedBeaconBlock(b)))
+	require.NoError(t, service.saveOrphanedAtts(ctx, r))
+
+	require.Equal(t, 0, service.cfg.AttPool.AggregatedAttestationCount())
+	savedAtts := service.cfg.AttPool.AggregatedAttestations()
+	atts := b.Block.Body.Attestations
+	require.DeepNotSSZEqual(t, atts, savedAtts)
+}
--- a/beacon-chain/blockchain/info.go
+++ b/beacon-chain/blockchain/info.go
@@ -6,7 +6,7 @@ import (
 	"net/http"

 	"github.com/emicklei/dot"
-	"github.com/prysmaticlabs/prysm/shared/params"
+	"github.com/prysmaticlabs/prysm/config/params"
 )

 const template = `<html>
@@ -39,7 +39,7 @@ func (s *Service) TreeHandler(w http.ResponseWriter, r *http.Request) {
 		log.WithError(err).Error("Could not get head state")
 		return
 	}
-	if headState == nil {
+	if headState == nil || headState.IsNil() {
 		if _, err := w.Write([]byte("Unavailable during initial syncing")); err != nil {
 			log.WithError(err).Error("Failed to render p2p info page")
 		}
--- a/beacon-chain/blockchain/info_test.go
+++ b/beacon-chain/blockchain/info_test.go
@@ -9,10 +9,11 @@ import (
 	testDB "github.com/prysmaticlabs/prysm/beacon-chain/db/testing"
 	"github.com/prysmaticlabs/prysm/beacon-chain/forkchoice/protoarray"
 	"github.com/prysmaticlabs/prysm/beacon-chain/state/stategen"
-	"github.com/prysmaticlabs/prysm/shared/params"
-	"github.com/prysmaticlabs/prysm/shared/testutil"
-	"github.com/prysmaticlabs/prysm/shared/testutil/assert"
-	"github.com/prysmaticlabs/prysm/shared/testutil/require"
+	"github.com/prysmaticlabs/prysm/config/params"
+	"github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1/wrapper"
+	"github.com/prysmaticlabs/prysm/testing/assert"
+	"github.com/prysmaticlabs/prysm/testing/require"
+	"github.com/prysmaticlabs/prysm/testing/util"
 )

 func TestService_TreeHandler(t *testing.T) {
@@ -21,23 +22,24 @@ func TestService_TreeHandler(t *testing.T) {

 	ctx := context.Background()
 	beaconDB := testDB.SetupDB(t)
-	headState, err := testutil.NewBeaconState()
+	headState, err := util.NewBeaconState()
 	require.NoError(t, err)
 	require.NoError(t, headState.SetBalances([]uint64{params.BeaconConfig().GweiPerEth}))
-	cfg := &Config{
-		BeaconDB: beaconDB,
-		ForkChoiceStore: protoarray.New(
-			0, // justifiedEpoch
-			0, // finalizedEpoch
-			[32]byte{'a'},
-		),
-		StateGen: stategen.New(beaconDB),
+	fcs := protoarray.New(
+		0, // justifiedEpoch
+		0, // finalizedEpoch
+		[32]byte{'a'},
+	)
+	opts := []Option{
+		WithDatabase(beaconDB),
+		WithStateGen(stategen.New(beaconDB)),
+		WithForkChoiceStore(fcs),
 	}
-	s, err := NewService(ctx, cfg)
+	s, err := NewService(ctx, opts...)
 	require.NoError(t, err)
 	require.NoError(t, s.cfg.ForkChoiceStore.ProcessBlock(ctx, 0, [32]byte{'a'}, [32]byte{'g'}, [32]byte{'c'}, 0, 0))
 	require.NoError(t, s.cfg.ForkChoiceStore.ProcessBlock(ctx, 1, [32]byte{'b'}, [32]byte{'a'}, [32]byte{'c'}, 0, 0))
-	s.setHead([32]byte{'a'}, testutil.NewBeaconBlock(), headState)
+	s.setHead([32]byte{'a'}, wrapper.WrappedPhase0SignedBeaconBlock(util.NewBeaconBlock()), headState)

 	rr := httptest.NewRecorder()
 	handler := http.HandlerFunc(s.TreeHandler)
--- a/beacon-chain/blockchain/init_sync_process_block.go
+++ b/beacon-chain/blockchain/init_sync_process_block.go
@@ -1,11 +1,11 @@
 package blockchain

 import (
-	ethpb "github.com/prysmaticlabs/ethereumapis/eth/v1alpha1"
+	"github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1/block"
 )

 // This saves a beacon block to the initial sync blocks cache.
-func (s *Service) saveInitSyncBlock(r [32]byte, b *ethpb.SignedBeaconBlock) {
+func (s *Service) saveInitSyncBlock(r [32]byte, b block.SignedBeaconBlock) {
 	s.initSyncBlocksLock.Lock()
 	defer s.initSyncBlocksLock.Unlock()
 	s.initSyncBlocks[r] = b
@@ -22,7 +22,7 @@ func (s *Service) hasInitSyncBlock(r [32]byte) bool {

 // This retrieves a beacon block from the initial sync blocks cache using the root of
 // the block.
-func (s *Service) getInitSyncBlock(r [32]byte) *ethpb.SignedBeaconBlock {
+func (s *Service) getInitSyncBlock(r [32]byte) block.SignedBeaconBlock {
 	s.initSyncBlocksLock.RLock()
 	defer s.initSyncBlocksLock.RUnlock()
 	b := s.initSyncBlocks[r]
@@ -31,11 +31,11 @@ func (s *Service) getInitSyncBlock(r [32]byte) *ethpb.SignedBeaconBlock {

 // This retrieves all the beacon blocks from the initial sync blocks cache, the returned
 // blocks are unordered.
-func (s *Service) getInitSyncBlocks() []*ethpb.SignedBeaconBlock {
+func (s *Service) getInitSyncBlocks() []block.SignedBeaconBlock {
 	s.initSyncBlocksLock.RLock()
 	defer s.initSyncBlocksLock.RUnlock()

-	blks := make([]*ethpb.SignedBeaconBlock, 0, len(s.initSyncBlocks))
+	blks := make([]block.SignedBeaconBlock, 0, len(s.initSyncBlocks))
 	for _, b := range s.initSyncBlocks {
 		blks = append(blks, b)
 	}
@@ -46,5 +46,5 @@ func (s *Service) getInitSyncBlocks() []*ethpb.SignedBeaconBlock {
 func (s *Service) clearInitSyncBlocks() {
 	s.initSyncBlocksLock.Lock()
 	defer s.initSyncBlocksLock.Unlock()
-	s.initSyncBlocks = make(map[[32]byte]*ethpb.SignedBeaconBlock)
+	s.initSyncBlocks = make(map[[32]byte]block.SignedBeaconBlock)
 }
--- a/beacon-chain/blockchain/init_test.go
+++ b/beacon-chain/blockchain/init_test.go
@@ -1,7 +1,7 @@
 package blockchain

 import (
-	"github.com/prysmaticlabs/prysm/shared/params"
+	"github.com/prysmaticlabs/prysm/config/params"
 )

 func init() {
--- a/beacon-chain/blockchain/log.go
+++ b/beacon-chain/blockchain/log.go
@@ -5,53 +5,63 @@ import (
 	"fmt"
 	"time"

-	ethpb "github.com/prysmaticlabs/ethereumapis/eth/v1alpha1"
-	"github.com/prysmaticlabs/prysm/beacon-chain/core/helpers"
-	"github.com/prysmaticlabs/prysm/shared/params"
-	"github.com/prysmaticlabs/prysm/shared/timeutils"
+	"github.com/prysmaticlabs/prysm/config/params"
+	ethpb "github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1"
+	"github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1/block"
+	"github.com/prysmaticlabs/prysm/runtime/version"
+	prysmTime "github.com/prysmaticlabs/prysm/time"
+	"github.com/prysmaticlabs/prysm/time/slots"
 	"github.com/sirupsen/logrus"
 )

 var log = logrus.WithField("prefix", "blockchain")

 // logs state transition related data every slot.
-func logStateTransitionData(b *ethpb.BeaconBlock) {
-	log := log.WithField("slot", b.Slot)
-	if len(b.Body.Attestations) > 0 {
-		log = log.WithField("attestations", len(b.Body.Attestations))
+func logStateTransitionData(b block.BeaconBlock) {
+	log := log.WithField("slot", b.Slot())
+	if len(b.Body().Attestations()) > 0 {
+		log = log.WithField("attestations", len(b.Body().Attestations()))
 	}
-	if len(b.Body.Deposits) > 0 {
-		log = log.WithField("deposits", len(b.Body.Deposits))
+	if len(b.Body().Deposits()) > 0 {
+		log = log.WithField("deposits", len(b.Body().Deposits()))
 	}
-	if len(b.Body.AttesterSlashings) > 0 {
-		log = log.WithField("attesterSlashings", len(b.Body.AttesterSlashings))
+	if len(b.Body().AttesterSlashings()) > 0 {
+		log = log.WithField("attesterSlashings", len(b.Body().AttesterSlashings()))
 	}
-	if len(b.Body.ProposerSlashings) > 0 {
-		log = log.WithField("proposerSlashings", len(b.Body.ProposerSlashings))
+	if len(b.Body().ProposerSlashings()) > 0 {
+		log = log.WithField("proposerSlashings", len(b.Body().ProposerSlashings()))
 	}
-	if len(b.Body.VoluntaryExits) > 0 {
-		log = log.WithField("voluntaryExits", len(b.Body.VoluntaryExits))
+	if len(b.Body().VoluntaryExits()) > 0 {
+		log = log.WithField("voluntaryExits", len(b.Body().VoluntaryExits()))
+	}
+	if b.Version() == version.Altair {
+		agg, err := b.Body().SyncAggregate()
+		if err == nil {
+			log = log.WithField("syncBitsCount", agg.SyncCommitteeBits.Count())
+		}
 	}
 	log.Info("Finished applying state transition")
 }

-func logBlockSyncStatus(block *ethpb.BeaconBlock, blockRoot [32]byte, finalized *ethpb.Checkpoint, receivedTime time.Time, genesisTime uint64) error {
-	startTime, err := helpers.SlotToTime(genesisTime, block.Slot)
+func logBlockSyncStatus(block block.BeaconBlock, blockRoot [32]byte, finalized *ethpb.Checkpoint, receivedTime time.Time, genesisTime uint64) error {
+	startTime, err := slots.ToTime(genesisTime, block.Slot())
 	if err != nil {
 		return err
 	}
 	log.WithFields(logrus.Fields{
-		"slot":           block.Slot,
-		"slotInEpoch":    block.Slot % params.BeaconConfig().SlotsPerEpoch,
+		"slot":           block.Slot(),
+		"slotInEpoch":    block.Slot() % params.BeaconConfig().SlotsPerEpoch,
 		"block":          fmt.Sprintf("0x%s...", hex.EncodeToString(blockRoot[:])[:8]),
-		"epoch":          helpers.SlotToEpoch(block.Slot),
+		"epoch":          slots.ToEpoch(block.Slot()),
 		"finalizedEpoch": finalized.Epoch,
 		"finalizedRoot":  fmt.Sprintf("0x%s...", hex.EncodeToString(finalized.Root)[:8]),
+		"parentRoot":     fmt.Sprintf("0x%s...", hex.EncodeToString(block.ParentRoot())[:8]),
+		"version":        version.String(block.Version()),
 	}).Info("Synced new block")
 	log.WithFields(logrus.Fields{
 		"slot":                      block.Slot,
-		"sinceSlotStartTime":        timeutils.Now().Sub(startTime),
-		"chainServiceProcessedTime": timeutils.Now().Sub(receivedTime),
+		"sinceSlotStartTime":        prysmTime.Now().Sub(startTime),
+		"chainServiceProcessedTime": prysmTime.Now().Sub(receivedTime),
 	}).Debug("Sync new block times")
 	return nil
 }
--- a/beacon-chain/blockchain/log_test.go
+++ b/beacon-chain/blockchain/log_test.go
@@ -3,53 +3,56 @@ package blockchain
 import (
 	"testing"

-	ethpb "github.com/prysmaticlabs/ethereumapis/eth/v1alpha1"
-	"github.com/prysmaticlabs/prysm/shared/testutil/require"
+	ethpb "github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1"
+	"github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1/block"
+	"github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1/wrapper"
+	"github.com/prysmaticlabs/prysm/testing/require"
 	logTest "github.com/sirupsen/logrus/hooks/test"
 )

 func Test_logStateTransitionData(t *testing.T) {
 	tests := []struct {
 		name string
-		b    *ethpb.BeaconBlock
+		b    block.BeaconBlock
 		want string
 	}{
 		{name: "empty block body",
-			b:    &ethpb.BeaconBlock{Body: &ethpb.BeaconBlockBody{}},
+			b:    wrapper.WrappedPhase0BeaconBlock(&ethpb.BeaconBlock{Body: &ethpb.BeaconBlockBody{}}),
 			want: "\"Finished applying state transition\" prefix=blockchain slot=0",
 		},
 		{name: "has attestation",
-			b:    &ethpb.BeaconBlock{Body: &ethpb.BeaconBlockBody{Attestations: []*ethpb.Attestation{{}}}},
+			b:    wrapper.WrappedPhase0BeaconBlock(&ethpb.BeaconBlock{Body: &ethpb.BeaconBlockBody{Attestations: []*ethpb.Attestation{{}}}}),
 			want: "\"Finished applying state transition\" attestations=1 prefix=blockchain slot=0",
 		},
 		{name: "has deposit",
-			b: &ethpb.BeaconBlock{Body: &ethpb.BeaconBlockBody{
-				Attestations: []*ethpb.Attestation{{}},
-				Deposits:     []*ethpb.Deposit{{}}}},
+			b: wrapper.WrappedPhase0BeaconBlock(
+				&ethpb.BeaconBlock{Body: &ethpb.BeaconBlockBody{
+					Attestations: []*ethpb.Attestation{{}},
+					Deposits:     []*ethpb.Deposit{{}}}}),
 			want: "\"Finished applying state transition\" attestations=1 deposits=1 prefix=blockchain slot=0",
 		},
 		{name: "has attester slashing",
-			b: &ethpb.BeaconBlock{Body: &ethpb.BeaconBlockBody{
-				AttesterSlashings: []*ethpb.AttesterSlashing{{}}}},
+			b: wrapper.WrappedPhase0BeaconBlock(&ethpb.BeaconBlock{Body: &ethpb.BeaconBlockBody{
+				AttesterSlashings: []*ethpb.AttesterSlashing{{}}}}),
 			want: "\"Finished applying state transition\" attesterSlashings=1 prefix=blockchain slot=0",
 		},
 		{name: "has proposer slashing",
-			b: &ethpb.BeaconBlock{Body: &ethpb.BeaconBlockBody{
-				ProposerSlashings: []*ethpb.ProposerSlashing{{}}}},
+			b: wrapper.WrappedPhase0BeaconBlock(&ethpb.BeaconBlock{Body: &ethpb.BeaconBlockBody{
+				ProposerSlashings: []*ethpb.ProposerSlashing{{}}}}),
 			want: "\"Finished applying state transition\" prefix=blockchain proposerSlashings=1 slot=0",
 		},
 		{name: "has exit",
-			b: &ethpb.BeaconBlock{Body: &ethpb.BeaconBlockBody{
-				VoluntaryExits: []*ethpb.SignedVoluntaryExit{{}}}},
+			b: wrapper.WrappedPhase0BeaconBlock(&ethpb.BeaconBlock{Body: &ethpb.BeaconBlockBody{
+				VoluntaryExits: []*ethpb.SignedVoluntaryExit{{}}}}),
 			want: "\"Finished applying state transition\" prefix=blockchain slot=0 voluntaryExits=1",
 		},
 		{name: "has everything",
-			b: &ethpb.BeaconBlock{Body: &ethpb.BeaconBlockBody{
+			b: wrapper.WrappedPhase0BeaconBlock(&ethpb.BeaconBlock{Body: &ethpb.BeaconBlockBody{
 				Attestations:      []*ethpb.Attestation{{}},
 				Deposits:          []*ethpb.Deposit{{}},
 				AttesterSlashings: []*ethpb.AttesterSlashing{{}},
 				ProposerSlashings: []*ethpb.ProposerSlashing{{}},
-				VoluntaryExits:    []*ethpb.SignedVoluntaryExit{{}}}},
+				VoluntaryExits:    []*ethpb.SignedVoluntaryExit{{}}}}),
 			want: "\"Finished applying state transition\" attestations=1 attesterSlashings=1 deposits=1 prefix=blockchain proposerSlashings=1 slot=0 voluntaryExits=1",
 		},
 	}
--- a/beacon-chain/blockchain/metrics.go
+++ b/beacon-chain/blockchain/metrics.go
@@ -3,14 +3,18 @@ package blockchain
 import (
 	"context"

+	"github.com/pkg/errors"
 	"github.com/prometheus/client_golang/prometheus"
 	"github.com/prometheus/client_golang/prometheus/promauto"
 	types "github.com/prysmaticlabs/eth2-types"
-	ethpb "github.com/prysmaticlabs/ethereumapis/eth/v1alpha1"
+	"github.com/prysmaticlabs/prysm/beacon-chain/core/altair"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/epoch/precompute"
-	iface "github.com/prysmaticlabs/prysm/beacon-chain/state/interface"
-	"github.com/prysmaticlabs/prysm/shared/bytesutil"
-	"github.com/prysmaticlabs/prysm/shared/params"
+	"github.com/prysmaticlabs/prysm/beacon-chain/state"
+	"github.com/prysmaticlabs/prysm/config/params"
+	"github.com/prysmaticlabs/prysm/encoding/bytesutil"
+	ethpb "github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1"
+	"github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1/block"
+	"github.com/prysmaticlabs/prysm/runtime/version"
 )

 var (
@@ -59,6 +63,10 @@ var (
 		Name: "beacon_previous_justified_root",
 		Help: "Previous justified root of the processed state",
 	})
+	activeValidatorCount = promauto.NewGauge(prometheus.GaugeOpts{
+		Name: "beacon_current_active_validators",
+		Help: "Current total active validators",
+	})
 	validatorsCount = promauto.NewGaugeVec(prometheus.GaugeOpts{
 		Name: "validator_count",
 		Help: "The total number of validators",
@@ -75,6 +83,10 @@ var (
 		Name: "current_eth1_data_deposit_count",
 		Help: "The current eth1 deposit count in the last processed state eth1data field.",
 	})
+	processedDepositsCount = promauto.NewGauge(prometheus.GaugeOpts{
+		Name: "beacon_processed_deposits_total",
+		Help: "Total number of deposits processed",
+	})
 	stateTrieReferences = promauto.NewGaugeVec(prometheus.GaugeOpts{
 		Name: "field_references",
 		Help: "The number of states a particular field is shared with.",
@@ -96,9 +108,13 @@ var (
 		Help: "The total amount of ether, in gwei, that has been used in voting attestation head of previous epoch",
 	})
 	reorgCount = promauto.NewCounter(prometheus.CounterOpts{
-		Name: "beacon_reorg_total",
+		Name: "beacon_reorgs_total",
 		Help: "Count the number of times beacon chain has a reorg",
 	})
+	saveOrphanedAttCount = promauto.NewCounter(prometheus.CounterOpts{
+		Name: "saved_orphaned_att_total",
+		Help: "Count the number of times an orphaned attestation is saved",
+	})
 	attestationInclusionDelay = promauto.NewHistogram(
 		prometheus.HistogramOpts{
 			Name:    "attestation_inclusion_delay_slots",
@@ -106,6 +122,22 @@ var (
 			Buckets: []float64{1, 2, 3, 4, 6, 32, 64},
 		},
 	)
+	syncHeadStateMiss = promauto.NewCounter(prometheus.CounterOpts{
+		Name: "sync_head_state_miss",
+		Help: "The number of sync head state requests that are not present in the cache.",
+	})
+	syncHeadStateHit = promauto.NewCounter(prometheus.CounterOpts{
+		Name: "sync_head_state_hit",
+		Help: "The number of sync head state requests that are present in the cache.",
+	})
+	stateBalanceCacheHit = promauto.NewCounter(prometheus.CounterOpts{
+		Name: "state_balance_cache_hit",
+		Help: "Count the number of state balance cache hits.",
+	})
+	stateBalanceCacheMiss = promauto.NewCounter(prometheus.CounterOpts{
+		Name: "state_balance_cache_miss",
+		Help: "Count the number of state balance cache hits.",
+	})
 )

 // reportSlotMetrics reports slot related metrics.
@@ -120,7 +152,7 @@ func reportSlotMetrics(stateSlot, headSlot, clockSlot types.Slot, finalizedCheck
 }

 // reportEpochMetrics reports epoch related metrics.
-func reportEpochMetrics(ctx context.Context, postState, headState iface.BeaconState) error {
+func reportEpochMetrics(ctx context.Context, postState, headState state.BeaconState) error {
 	currentEpoch := types.Epoch(postState.Slot() / params.BeaconConfig().SlotsPerEpoch)

 	// Validator instances
@@ -178,6 +210,7 @@ func reportEpochMetrics(ctx context.Context, postState, headState iface.BeaconSt
 	activeBalance += exitingBalance + slashingBalance
 	activeEffectiveBalance += exitingEffectiveBalance + slashingEffectiveBalance

+	activeValidatorCount.Set(float64(activeInstances))
 	validatorsCount.WithLabelValues("Pending").Set(float64(pendingInstances))
 	validatorsCount.WithLabelValues("Active").Set(float64(activeInstances))
 	validatorsCount.WithLabelValues("Exiting").Set(float64(exitingInstances))
@@ -204,15 +237,33 @@ func reportEpochMetrics(ctx context.Context, postState, headState iface.BeaconSt
 	beaconFinalizedEpoch.Set(float64(postState.FinalizedCheckpointEpoch()))
 	beaconFinalizedRoot.Set(float64(bytesutil.ToLowInt64(postState.FinalizedCheckpoint().Root)))
 	currentEth1DataDepositCount.Set(float64(postState.Eth1Data().DepositCount))
+	processedDepositsCount.Set(float64(postState.Eth1DepositIndex() + 1))

-	// Validator participation should be viewed on the canonical chain.
-	v, b, err := precompute.New(ctx, headState)
-	if err != nil {
-		return err
-	}
-	_, b, err = precompute.ProcessAttestations(ctx, headState, v, b)
-	if err != nil {
-		return err
+	var b *precompute.Balance
+	var v []*precompute.Validator
+	var err error
+	switch headState.Version() {
+	case version.Phase0:
+		// Validator participation should be viewed on the canonical chain.
+		v, b, err = precompute.New(ctx, headState)
+		if err != nil {
+			return err
+		}
+		_, b, err = precompute.ProcessAttestations(ctx, headState, v, b)
+		if err != nil {
+			return err
+		}
+	case version.Altair, version.Bellatrix:
+		v, b, err = altair.InitializePrecomputeValidators(ctx, headState)
+		if err != nil {
+			return err
+		}
+		_, b, err = altair.ProcessEpochParticipation(ctx, headState, b, v)
+		if err != nil {
+			return err
+		}
+	default:
+		return errors.Errorf("invalid state type provided: %T", headState.InnerStateUnsafe())
 	}
 	prevEpochActiveBalances.Set(float64(b.ActivePrevEpoch))
 	prevEpochSourceBalances.Set(float64(b.PrevEpochAttested))
@@ -227,8 +278,8 @@ func reportEpochMetrics(ctx context.Context, postState, headState iface.BeaconSt
 	return nil
 }

-func reportAttestationInclusion(blk *ethpb.BeaconBlock) {
-	for _, att := range blk.Body.Attestations {
-		attestationInclusionDelay.Observe(float64(blk.Slot - att.Data.Slot))
+func reportAttestationInclusion(blk block.BeaconBlock) {
+	for _, att := range blk.Body().Attestations() {
+		attestationInclusionDelay.Observe(float64(blk.Slot() - att.Data.Slot))
 	}
 }
--- a/beacon-chain/blockchain/metrics_test.go
+++ b/beacon-chain/blockchain/metrics_test.go
@@ -4,16 +4,15 @@ import (
 	"context"
 	"testing"

-	eth "github.com/prysmaticlabs/ethereumapis/eth/v1alpha1"
-	pb "github.com/prysmaticlabs/prysm/proto/beacon/p2p/v1"
-	"github.com/prysmaticlabs/prysm/shared/testutil"
-	"github.com/prysmaticlabs/prysm/shared/testutil/require"
+	eth "github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1"
+	"github.com/prysmaticlabs/prysm/testing/require"
+	"github.com/prysmaticlabs/prysm/testing/util"
 )

 func TestReportEpochMetrics_BadHeadState(t *testing.T) {
-	s, err := testutil.NewBeaconState()
+	s, err := util.NewBeaconState()
 	require.NoError(t, err)
-	h, err := testutil.NewBeaconState()
+	h, err := util.NewBeaconState()
 	require.NoError(t, err)
 	require.NoError(t, h.SetValidators(nil))
 	err = reportEpochMetrics(context.Background(), s, h)
@@ -21,22 +20,22 @@ func TestReportEpochMetrics_BadHeadState(t *testing.T) {
 }

 func TestReportEpochMetrics_BadAttestation(t *testing.T) {
-	s, err := testutil.NewBeaconState()
+	s, err := util.NewBeaconState()
 	require.NoError(t, err)
-	h, err := testutil.NewBeaconState()
+	h, err := util.NewBeaconState()
 	require.NoError(t, err)
-	require.NoError(t, h.AppendCurrentEpochAttestations(&pb.PendingAttestation{InclusionDelay: 0}))
+	require.NoError(t, h.AppendCurrentEpochAttestations(&eth.PendingAttestation{InclusionDelay: 0}))
 	err = reportEpochMetrics(context.Background(), s, h)
 	require.ErrorContains(t, "attestation with inclusion delay of 0", err)
 }

 func TestReportEpochMetrics_SlashedValidatorOutOfBound(t *testing.T) {
-	h, _ := testutil.DeterministicGenesisState(t, 1)
+	h, _ := util.DeterministicGenesisState(t, 1)
 	v, err := h.ValidatorAtIndex(0)
 	require.NoError(t, err)
 	v.Slashed = true
 	require.NoError(t, h.UpdateValidatorAtIndex(0, v))
-	require.NoError(t, h.AppendCurrentEpochAttestations(&pb.PendingAttestation{InclusionDelay: 1, Data: testutil.HydrateAttestationData(&eth.AttestationData{})}))
+	require.NoError(t, h.AppendCurrentEpochAttestations(&eth.PendingAttestation{InclusionDelay: 1, Data: util.HydrateAttestationData(&eth.AttestationData{})}))
 	err = reportEpochMetrics(context.Background(), h, h)
 	require.ErrorContains(t, "slot 0 out of bounds", err)
 }
--- a/beacon-chain/blockchain/mock_test.go
+++ b/beacon-chain/blockchain/mock_test.go
@@ -0,0 +1,50 @@
+package blockchain
+
+import (
+	"context"
+	"errors"
+	"testing"
+
+	testDB "github.com/prysmaticlabs/prysm/beacon-chain/db/testing"
+	"github.com/prysmaticlabs/prysm/beacon-chain/forkchoice/protoarray"
+	"github.com/prysmaticlabs/prysm/beacon-chain/state"
+	"github.com/prysmaticlabs/prysm/beacon-chain/state/stategen"
+)
+
+func testServiceOptsWithDB(t *testing.T) []Option {
+	beaconDB := testDB.SetupDB(t)
+	fcs := protoarray.New(0, 0, [32]byte{'a'})
+	return []Option{
+		WithDatabase(beaconDB),
+		WithStateGen(stategen.New(beaconDB)),
+		WithForkChoiceStore(fcs),
+	}
+}
+
+// warning: only use these opts when you are certain there are no db calls
+// in your code path. this is a lightweight way to satisfy the stategen/beacondb
+// initialization requirements w/o the overhead of db init.
+func testServiceOptsNoDB() []Option {
+	return []Option{
+		withStateBalanceCache(satisfactoryStateBalanceCache()),
+	}
+}
+
+type mockStateByRooter struct {
+	state state.BeaconState
+	err   error
+}
+
+var _ stateByRooter = &mockStateByRooter{}
+
+func (m mockStateByRooter) StateByRoot(_ context.Context, _ [32]byte) (state.BeaconState, error) {
+	return m.state, m.err
+}
+
+// returns an instance of the state balance cache that can be used
+// to satisfy the requirement for one in NewService, but which will
+// always return an error if used.
+func satisfactoryStateBalanceCache() *stateBalanceCache {
+	err := errors.New("satisfactoryStateBalanceCache doesn't perform real caching")
+	return &stateBalanceCache{stateGen: mockStateByRooter{err: err}}
+}
--- a/beacon-chain/blockchain/new_slot.go
+++ b/beacon-chain/blockchain/new_slot.go
@@ -0,0 +1,72 @@
+package blockchain
+
+import (
+	"bytes"
+	"context"
+
+	"github.com/pkg/errors"
+	types "github.com/prysmaticlabs/eth2-types"
+	"github.com/prysmaticlabs/prysm/time/slots"
+)
+
+// NewSlot mimics the implementation of `on_tick` in fork choice consensus spec.
+// It resets the proposer boost root in fork choice, and it updates store's justified checkpoint
+// if a better checkpoint on the store's finalized checkpoint chain.
+// This should only be called at the start of every slot interval.
+//
+// Spec pseudocode definition:
+//    # Reset store.proposer_boost_root if this is a new slot
+//    if current_slot > previous_slot:
+//        store.proposer_boost_root = Root()
+//
+//    # Not a new epoch, return
+//    if not (current_slot > previous_slot and compute_slots_since_epoch_start(current_slot) == 0):
+//        return
+//
+//    # Update store.justified_checkpoint if a better checkpoint on the store.finalized_checkpoint chain
+//    if store.best_justified_checkpoint.epoch > store.justified_checkpoint.epoch:
+//        finalized_slot = compute_start_slot_at_epoch(store.finalized_checkpoint.epoch)
+//        ancestor_at_finalized_slot = get_ancestor(store, store.best_justified_checkpoint.root, finalized_slot)
+//        if ancestor_at_finalized_slot == store.finalized_checkpoint.root:
+//            store.justified_checkpoint = store.best_justified_checkpoint
+func (s *Service) NewSlot(ctx context.Context, slot types.Slot) error {
+
+	// Reset proposer boost root in fork choice.
+	if err := s.cfg.ForkChoiceStore.ResetBoostedProposerRoot(ctx); err != nil {
+		return errors.Wrap(err, "could not reset boosted proposer root in fork choice")
+	}
+
+	// Return if it's not a new epoch.
+	if !slots.IsEpochStart(slot) {
+		return nil
+	}
+
+	// Update store.justified_checkpoint if a better checkpoint on the store.finalized_checkpoint chain
+	bj := s.store.BestJustifiedCheckpt()
+	if bj == nil {
+		return errNilBestJustifiedInStore
+	}
+	j := s.store.JustifiedCheckpt()
+	if j == nil {
+		return errNilJustifiedInStore
+	}
+	f := s.store.FinalizedCheckpt()
+	if f == nil {
+		return errNilFinalizedInStore
+	}
+	if bj.Epoch > j.Epoch {
+		finalizedSlot, err := slots.EpochStart(f.Epoch)
+		if err != nil {
+			return err
+		}
+		r, err := s.ancestor(ctx, bj.Root, finalizedSlot)
+		if err != nil {
+			return err
+		}
+		if bytes.Equal(r, f.Root) {
+			s.store.SetJustifiedCheckpt(bj)
+		}
+	}
+	return nil
+
+}
--- a/beacon-chain/blockchain/new_slot_test.go
+++ b/beacon-chain/blockchain/new_slot_test.go
@@ -0,0 +1,100 @@
+package blockchain
+
+import (
+	"context"
+	"testing"
+
+	types "github.com/prysmaticlabs/eth2-types"
+	"github.com/prysmaticlabs/prysm/beacon-chain/blockchain/store"
+	testDB "github.com/prysmaticlabs/prysm/beacon-chain/db/testing"
+	"github.com/prysmaticlabs/prysm/beacon-chain/forkchoice/protoarray"
+	"github.com/prysmaticlabs/prysm/beacon-chain/state/stategen"
+	"github.com/prysmaticlabs/prysm/config/params"
+	"github.com/prysmaticlabs/prysm/encoding/bytesutil"
+	ethpb "github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1"
+	"github.com/prysmaticlabs/prysm/testing/require"
+)
+
+func TestService_newSlot(t *testing.T) {
+	beaconDB := testDB.SetupDB(t)
+	fcs := protoarray.New(0, 0, [32]byte{})
+	opts := []Option{
+		WithDatabase(beaconDB),
+		WithStateGen(stategen.New(beaconDB)),
+		WithForkChoiceStore(fcs),
+	}
+	ctx := context.Background()
+
+	require.NoError(t, fcs.ProcessBlock(ctx, 0, [32]byte{}, [32]byte{}, [32]byte{}, 0, 0))        // genesis
+	require.NoError(t, fcs.ProcessBlock(ctx, 32, [32]byte{'a'}, [32]byte{}, [32]byte{}, 0, 0))    // finalized
+	require.NoError(t, fcs.ProcessBlock(ctx, 64, [32]byte{'b'}, [32]byte{'a'}, [32]byte{}, 0, 0)) // justified
+	require.NoError(t, fcs.ProcessBlock(ctx, 96, [32]byte{'c'}, [32]byte{'a'}, [32]byte{}, 0, 0)) // best justified
+	require.NoError(t, fcs.ProcessBlock(ctx, 97, [32]byte{'d'}, [32]byte{}, [32]byte{}, 0, 0))    // bad
+
+	type args struct {
+		slot          types.Slot
+		finalized     *ethpb.Checkpoint
+		justified     *ethpb.Checkpoint
+		bestJustified *ethpb.Checkpoint
+		shouldEqual   bool
+	}
+	tests := []struct {
+		name string
+		args args
+	}{
+		{
+			name: "Not epoch boundary. No change",
+			args: args{
+				slot:          params.BeaconConfig().SlotsPerEpoch + 1,
+				finalized:     &ethpb.Checkpoint{Epoch: 1, Root: bytesutil.PadTo([]byte{'a'}, 32)},
+				justified:     &ethpb.Checkpoint{Epoch: 2, Root: bytesutil.PadTo([]byte{'b'}, 32)},
+				bestJustified: &ethpb.Checkpoint{Epoch: 3, Root: bytesutil.PadTo([]byte{'c'}, 32)},
+				shouldEqual:   false,
+			},
+		},
+		{
+			name: "Justified higher than best justified. No change",
+			args: args{
+				slot:          params.BeaconConfig().SlotsPerEpoch,
+				finalized:     &ethpb.Checkpoint{Epoch: 1, Root: bytesutil.PadTo([]byte{'a'}, 32)},
+				justified:     &ethpb.Checkpoint{Epoch: 3, Root: bytesutil.PadTo([]byte{'b'}, 32)},
+				bestJustified: &ethpb.Checkpoint{Epoch: 2, Root: bytesutil.PadTo([]byte{'c'}, 32)},
+				shouldEqual:   false,
+			},
+		},
+		{
+			name: "Best justified not on the same chain as finalized. No change",
+			args: args{
+				slot:          params.BeaconConfig().SlotsPerEpoch,
+				finalized:     &ethpb.Checkpoint{Epoch: 1, Root: bytesutil.PadTo([]byte{'a'}, 32)},
+				justified:     &ethpb.Checkpoint{Epoch: 2, Root: bytesutil.PadTo([]byte{'b'}, 32)},
+				bestJustified: &ethpb.Checkpoint{Epoch: 3, Root: bytesutil.PadTo([]byte{'d'}, 32)},
+				shouldEqual:   false,
+			},
+		},
+		{
+			name: "Best justified on the same chain as finalized. Yes change",
+			args: args{
+				slot:          params.BeaconConfig().SlotsPerEpoch,
+				finalized:     &ethpb.Checkpoint{Epoch: 1, Root: bytesutil.PadTo([]byte{'a'}, 32)},
+				justified:     &ethpb.Checkpoint{Epoch: 2, Root: bytesutil.PadTo([]byte{'b'}, 32)},
+				bestJustified: &ethpb.Checkpoint{Epoch: 3, Root: bytesutil.PadTo([]byte{'c'}, 32)},
+				shouldEqual:   true,
+			},
+		},
+	}
+	for _, test := range tests {
+		service, err := NewService(ctx, opts...)
+		require.NoError(t, err)
+		store := store.New(test.args.justified, test.args.finalized)
+		store.SetBestJustifiedCheckpt(test.args.bestJustified)
+		service.store = store
+
+		require.NoError(t, service.NewSlot(ctx, test.args.slot))
+		if test.args.shouldEqual {
+			require.DeepSSZEqual(t, service.store.BestJustifiedCheckpt(), service.store.JustifiedCheckpt())
+		} else {
+			require.DeepNotSSZEqual(t, service.store.BestJustifiedCheckpt(), service.store.JustifiedCheckpt())
+		}
+	}
+}
--- a/beacon-chain/blockchain/optimistic_sync.go
+++ b/beacon-chain/blockchain/optimistic_sync.go
@@ -0,0 +1,53 @@
+package blockchain
+
+import (
+	"context"
+
+	"github.com/pkg/errors"
+	types "github.com/prysmaticlabs/eth2-types"
+	"github.com/prysmaticlabs/prysm/beacon-chain/core/blocks"
+	"github.com/prysmaticlabs/prysm/config/params"
+	"github.com/prysmaticlabs/prysm/encoding/bytesutil"
+	"github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1/block"
+)
+
+// optimisticCandidateBlock returns true if this block can be optimistically synced.
+//
+// Spec pseudocode definition:
+// def is_optimistic_candidate_block(opt_store: OptimisticStore, current_slot: Slot, block: BeaconBlock) -> bool:
+//     justified_root = opt_store.block_states[opt_store.head_block_root].current_justified_checkpoint.root
+//     justified_is_execution_block = is_execution_block(opt_store.blocks[justified_root])
+//     block_is_deep = block.slot + SAFE_SLOTS_TO_IMPORT_OPTIMISTICALLY <= current_slot
+//     return justified_is_execution_block or block_is_deep
+func (s *Service) optimisticCandidateBlock(ctx context.Context, blk block.BeaconBlock) (bool, error) {
+	if blk.Slot()+params.BeaconConfig().SafeSlotsToImportOptimistically <= s.CurrentSlot() {
+		return true, nil
+	}
+	j := s.store.JustifiedCheckpt()
+	if j == nil {
+		return false, errNilJustifiedInStore
+	}
+	jBlock, err := s.cfg.BeaconDB.Block(ctx, bytesutil.ToBytes32(j.Root))
+	if err != nil {
+		return false, err
+	}
+	return blocks.ExecutionBlock(jBlock.Block().Body())
+}
+
+// loadSyncedTips loads a previously saved synced Tips from DB
+// if no synced tips are saved, then it creates one from the given
+// root and slot number.
+func (s *Service) loadSyncedTips(root [32]byte, slot types.Slot) error {
+	// Initialize synced tips
+	tips, err := s.cfg.BeaconDB.ValidatedTips(s.ctx)
+	if err != nil {
+		return errors.Wrap(err, "could not get synced tips")
+	}
+	if len(tips) == 0 {
+		tips[root] = slot
+	}
+	if err := s.cfg.ForkChoiceStore.SetSyncedTips(tips); err != nil {
+		return errors.Wrap(err, "could not set synced tips")
+	}
+	return nil
+}
--- a/beacon-chain/blockchain/optimistic_sync_test.go
+++ b/beacon-chain/blockchain/optimistic_sync_test.go
@@ -0,0 +1,141 @@
+package blockchain
+
+import (
+	"context"
+	"testing"
+	"time"
+
+	testDB "github.com/prysmaticlabs/prysm/beacon-chain/db/testing"
+	"github.com/prysmaticlabs/prysm/beacon-chain/forkchoice/protoarray"
+	"github.com/prysmaticlabs/prysm/beacon-chain/state/stategen"
+	fieldparams "github.com/prysmaticlabs/prysm/config/fieldparams"
+	"github.com/prysmaticlabs/prysm/config/params"
+	"github.com/prysmaticlabs/prysm/encoding/bytesutil"
+	ethpb "github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1"
+	"github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1/block"
+	"github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1/wrapper"
+	"github.com/prysmaticlabs/prysm/testing/require"
+	"github.com/prysmaticlabs/prysm/testing/util"
+	"github.com/prysmaticlabs/prysm/time/slots"
+)
+
+func Test_IsOptimisticCandidateBlock(t *testing.T) {
+	params.SetupTestConfigCleanup(t)
+	params.OverrideBeaconConfig(params.MainnetConfig())
+
+	ctx := context.Background()
+	beaconDB := testDB.SetupDB(t)
+	fcs := protoarray.New(0, 0, [32]byte{'a'})
+	opts := []Option{
+		WithDatabase(beaconDB),
+		WithStateGen(stategen.New(beaconDB)),
+		WithForkChoiceStore(fcs),
+	}
+
+	service, err := NewService(ctx, opts...)
+	require.NoError(t, err)
+
+	params.BeaconConfig().SafeSlotsToImportOptimistically = 128
+	service.genesisTime = time.Now().Add(-time.Second * 12 * 2 * 128)
+
+	tests := []struct {
+		name      string
+		blk       block.BeaconBlock
+		justified block.SignedBeaconBlock
+		want      bool
+	}{
+		{
+			name: "deep block",
+			blk: func(tt *testing.T) block.BeaconBlock {
+				blk := util.NewBeaconBlockBellatrix()
+				blk.Block.Slot = 1
+				wr, err := wrapper.WrappedBellatrixBeaconBlock(blk.Block)
+				require.NoError(tt, err)
+				return wr
+			}(t),
+			justified: func(tt *testing.T) block.SignedBeaconBlock {
+				blk := util.NewBeaconBlockBellatrix()
+				blk.Block.Slot = 32
+				wr, err := wrapper.WrappedBellatrixSignedBeaconBlock(blk)
+				require.NoError(tt, err)
+				return wr
+			}(t),
+			want: true,
+		},
+		{
+			name: "shallow block, Altair justified chkpt",
+			blk: func(tt *testing.T) block.BeaconBlock {
+				blk := util.NewBeaconBlockAltair()
+				blk.Block.Slot = 200
+				wr, err := wrapper.WrappedAltairBeaconBlock(blk.Block)
+				require.NoError(tt, err)
+				return wr
+			}(t),
+			justified: func(tt *testing.T) block.SignedBeaconBlock {
+				blk := util.NewBeaconBlockAltair()
+				blk.Block.Slot = 32
+				wr, err := wrapper.WrappedAltairSignedBeaconBlock(blk)
+				require.NoError(tt, err)
+				return wr
+			}(t),
+			want: false,
+		},
+		{
+			name: "shallow block, Bellatrix justified chkpt without execution",
+			blk: func(tt *testing.T) block.BeaconBlock {
+				blk := util.NewBeaconBlockBellatrix()
+				blk.Block.Slot = 200
+				wr, err := wrapper.WrappedBellatrixBeaconBlock(blk.Block)
+				require.NoError(tt, err)
+				return wr
+			}(t),
+			justified: func(tt *testing.T) block.SignedBeaconBlock {
+				blk := util.NewBeaconBlockBellatrix()
+				blk.Block.Slot = 32
+				wr, err := wrapper.WrappedBellatrixSignedBeaconBlock(blk)
+				require.NoError(tt, err)
+				return wr
+			}(t),
+			want: false,
+		},
+		{
+			name: "shallow block, execution enabled justified chkpt",
+			blk: func(tt *testing.T) block.BeaconBlock {
+				blk := util.NewBeaconBlockBellatrix()
+				blk.Block.Slot = 200
+				wr, err := wrapper.WrappedBellatrixBeaconBlock(blk.Block)
+				require.NoError(tt, err)
+				return wr
+			}(t),
+			justified: func(tt *testing.T) block.SignedBeaconBlock {
+				blk := util.NewBeaconBlockBellatrix()
+				blk.Block.Slot = 32
+				blk.Block.Body.ExecutionPayload.ParentHash = bytesutil.PadTo([]byte{'a'}, fieldparams.RootLength)
+				blk.Block.Body.ExecutionPayload.FeeRecipient = bytesutil.PadTo([]byte{'a'}, fieldparams.FeeRecipientLength)
+				blk.Block.Body.ExecutionPayload.StateRoot = bytesutil.PadTo([]byte{'a'}, fieldparams.RootLength)
+				blk.Block.Body.ExecutionPayload.ReceiptsRoot = bytesutil.PadTo([]byte{'a'}, fieldparams.RootLength)
+				blk.Block.Body.ExecutionPayload.LogsBloom = bytesutil.PadTo([]byte{'a'}, fieldparams.LogsBloomLength)
+				blk.Block.Body.ExecutionPayload.Random = bytesutil.PadTo([]byte{'a'}, fieldparams.RootLength)
+				blk.Block.Body.ExecutionPayload.BaseFeePerGas = bytesutil.PadTo([]byte{'a'}, fieldparams.RootLength)
+				blk.Block.Body.ExecutionPayload.BlockHash = bytesutil.PadTo([]byte{'a'}, fieldparams.RootLength)
+				wr, err := wrapper.WrappedBellatrixSignedBeaconBlock(blk)
+				require.NoError(tt, err)
+				return wr
+			}(t),
+			want: true,
+		},
+	}
+	for _, tt := range tests {
+		jroot, err := tt.justified.Block().HashTreeRoot()
+		require.NoError(t, err)
+		require.NoError(t, service.cfg.BeaconDB.SaveBlock(ctx, tt.justified))
+		service.store.SetJustifiedCheckpt(
+			&ethpb.Checkpoint{
+				Root:  jroot[:],
+				Epoch: slots.ToEpoch(tt.justified.Block().Slot()),
+			})
+		candidate, err := service.optimisticCandidateBlock(ctx, tt.blk)
+		require.NoError(t, err)
+		require.Equal(t, tt.want, candidate, tt.name)
+	}
+}
--- a/beacon-chain/blockchain/options.go
+++ b/beacon-chain/blockchain/options.go
@@ -0,0 +1,146 @@
+package blockchain
+
+import (
+	"github.com/prysmaticlabs/prysm/async/event"
+	"github.com/prysmaticlabs/prysm/beacon-chain/cache/depositcache"
+	statefeed "github.com/prysmaticlabs/prysm/beacon-chain/core/feed/state"
+	"github.com/prysmaticlabs/prysm/beacon-chain/db"
+	"github.com/prysmaticlabs/prysm/beacon-chain/forkchoice"
+	"github.com/prysmaticlabs/prysm/beacon-chain/operations/attestations"
+	"github.com/prysmaticlabs/prysm/beacon-chain/operations/slashings"
+	"github.com/prysmaticlabs/prysm/beacon-chain/operations/voluntaryexits"
+	"github.com/prysmaticlabs/prysm/beacon-chain/p2p"
+	"github.com/prysmaticlabs/prysm/beacon-chain/powchain"
+	"github.com/prysmaticlabs/prysm/beacon-chain/state"
+	"github.com/prysmaticlabs/prysm/beacon-chain/state/stategen"
+	ethpb "github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1"
+)
+
+type Option func(s *Service) error
+
+// WithMaxGoroutines to control resource use of the blockchain service.
+func WithMaxGoroutines(x int) Option {
+	return func(s *Service) error {
+		s.cfg.MaxRoutines = x
+		return nil
+	}
+}
+
+// WithWeakSubjectivityCheckpoint for checkpoint sync.
+func WithWeakSubjectivityCheckpoint(c *ethpb.Checkpoint) Option {
+	return func(s *Service) error {
+		s.cfg.WeakSubjectivityCheckpt = c
+		return nil
+	}
+}
+
+// WithDatabase for head access.
+func WithDatabase(beaconDB db.HeadAccessDatabase) Option {
+	return func(s *Service) error {
+		s.cfg.BeaconDB = beaconDB
+		return nil
+	}
+}
+
+// WithChainStartFetcher to retrieve information about genesis.
+func WithChainStartFetcher(f powchain.ChainStartFetcher) Option {
+	return func(s *Service) error {
+		s.cfg.ChainStartFetcher = f
+		return nil
+	}
+}
+
+// WithDepositCache for deposit lifecycle after chain inclusion.
+func WithDepositCache(c *depositcache.DepositCache) Option {
+	return func(s *Service) error {
+		s.cfg.DepositCache = c
+		return nil
+	}
+}
+
+// WithAttestationPool for attestation lifecycle after chain inclusion.
+func WithAttestationPool(p attestations.Pool) Option {
+	return func(s *Service) error {
+		s.cfg.AttPool = p
+		return nil
+	}
+}
+
+// WithExitPool for exits lifecycle after chain inclusion.
+func WithExitPool(p voluntaryexits.PoolManager) Option {
+	return func(s *Service) error {
+		s.cfg.ExitPool = p
+		return nil
+	}
+}
+
+// WithSlashingPool for slashings lifecycle after chain inclusion.
+func WithSlashingPool(p slashings.PoolManager) Option {
+	return func(s *Service) error {
+		s.cfg.SlashingPool = p
+		return nil
+	}
+}
+
+// WithP2PBroadcaster to broadcast messages after appropriate processing.
+func WithP2PBroadcaster(p p2p.Broadcaster) Option {
+	return func(s *Service) error {
+		s.cfg.P2p = p
+		return nil
+	}
+}
+
+// WithStateNotifier to notify an event feed of state processing.
+func WithStateNotifier(n statefeed.Notifier) Option {
+	return func(s *Service) error {
+		s.cfg.StateNotifier = n
+		return nil
+	}
+}
+
+// WithForkChoiceStore to update an optimized fork-choice representation.
+func WithForkChoiceStore(f forkchoice.ForkChoicer) Option {
+	return func(s *Service) error {
+		s.cfg.ForkChoiceStore = f
+		return nil
+	}
+}
+
+// WithAttestationService for dealing with attestation lifecycles.
+func WithAttestationService(srv *attestations.Service) Option {
+	return func(s *Service) error {
+		s.cfg.AttService = srv
+		return nil
+	}
+}
+
+// WithStateGen for managing state regeneration and replay.
+func WithStateGen(g *stategen.State) Option {
+	return func(s *Service) error {
+		s.cfg.StateGen = g
+		return nil
+	}
+}
+
+// WithSlasherAttestationsFeed to forward attestations into slasher if enabled.
+func WithSlasherAttestationsFeed(f *event.Feed) Option {
+	return func(s *Service) error {
+		s.cfg.SlasherAttestationsFeed = f
+		return nil
+	}
+}
+
+func withStateBalanceCache(c *stateBalanceCache) Option {
+	return func(s *Service) error {
+		s.justifiedBalances = c
+		return nil
+	}
+}
+
+// WithFinalizedStateAtStartUp to store finalized state at start up.
+func WithFinalizedStateAtStartUp(st state.BeaconState) Option {
+	return func(s *Service) error {
+		s.cfg.FinalizedStateAtStartUp = st
+		return nil
+	}
+}
--- a/beacon-chain/blockchain/pow_block.go
+++ b/beacon-chain/blockchain/pow_block.go
@@ -0,0 +1,29 @@
+package blockchain
+
+import (
+	"math/big"
+
+	"github.com/holiman/uint256"
+	"github.com/pkg/errors"
+	"github.com/prysmaticlabs/prysm/config/params"
+)
+
+// validates terminal pow block by comparing own total difficulty with parent's total difficulty.
+//
+// def is_valid_terminal_pow_block(block: PowBlock, parent: PowBlock) -> bool:
+//    is_total_difficulty_reached = block.total_difficulty >= TERMINAL_TOTAL_DIFFICULTY
+//    is_parent_total_difficulty_valid = parent.total_difficulty < TERMINAL_TOTAL_DIFFICULTY
+//    return is_total_difficulty_reached and is_parent_total_difficulty_valid
+func validTerminalPowBlock(currentDifficulty *uint256.Int, parentDifficulty *uint256.Int) (bool, error) {
+	b, ok := new(big.Int).SetString(params.BeaconConfig().TerminalTotalDifficulty, 10)
+	if !ok {
+		return false, errors.New("failed to parse terminal total difficulty")
+	}
+	ttd, of := uint256.FromBig(b)
+	if of {
+		return false, errors.New("overflow terminal total difficulty")
+	}
+	totalDifficultyReached := currentDifficulty.Cmp(ttd) >= 0
+	parentTotalDifficultyValid := ttd.Cmp(parentDifficulty) > 0
+	return totalDifficultyReached && parentTotalDifficultyValid, nil
+}
--- a/beacon-chain/blockchain/pow_block_test.go
+++ b/beacon-chain/blockchain/pow_block_test.go
@@ -0,0 +1,93 @@
+package blockchain
+
+import (
+	"fmt"
+	"math/big"
+	"testing"
+
+	"github.com/holiman/uint256"
+	"github.com/prysmaticlabs/prysm/config/params"
+	"github.com/prysmaticlabs/prysm/testing/require"
+)
+
+func Test_validTerminalPowBlock(t *testing.T) {
+	tests := []struct {
+		name              string
+		currentDifficulty *uint256.Int
+		parentDifficulty  *uint256.Int
+		ttd               uint64
+		want              bool
+	}{
+		{
+			name:              "current > ttd, parent > ttd",
+			currentDifficulty: uint256.NewInt(2),
+			parentDifficulty:  uint256.NewInt(2),
+			ttd:               1,
+			want:              false,
+		},
+		{
+			name:              "current < ttd, parent < ttd",
+			currentDifficulty: uint256.NewInt(2),
+			parentDifficulty:  uint256.NewInt(2),
+			ttd:               3,
+			want:              false,
+		},
+		{
+			name:              "current == ttd, parent == ttd",
+			currentDifficulty: uint256.NewInt(2),
+			parentDifficulty:  uint256.NewInt(2),
+			ttd:               2,
+			want:              false,
+		},
+		{
+			name:              "current > ttd, parent == ttd",
+			currentDifficulty: uint256.NewInt(2),
+			parentDifficulty:  uint256.NewInt(1),
+			ttd:               1,
+			want:              false,
+		},
+		{
+			name:              "current == ttd, parent < ttd",
+			currentDifficulty: uint256.NewInt(2),
+			parentDifficulty:  uint256.NewInt(1),
+			ttd:               2,
+			want:              true,
+		},
+		{
+			name:              "current > ttd, parent < ttd",
+			currentDifficulty: uint256.NewInt(3),
+			parentDifficulty:  uint256.NewInt(1),
+			ttd:               2,
+			want:              true,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			cfg := params.BeaconConfig()
+			cfg.TerminalTotalDifficulty = fmt.Sprint(tt.ttd)
+			params.OverrideBeaconConfig(cfg)
+			got, err := validTerminalPowBlock(tt.currentDifficulty, tt.parentDifficulty)
+			require.NoError(t, err)
+			if got != tt.want {
+				t.Errorf("validTerminalPowBlock() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}
+
+func Test_validTerminalPowBlockSpecConfig(t *testing.T) {
+	cfg := params.BeaconConfig()
+	cfg.TerminalTotalDifficulty = "115792089237316195423570985008687907853269984665640564039457584007913129638912"
+	params.OverrideBeaconConfig(cfg)
+
+	i, _ := new(big.Int).SetString("115792089237316195423570985008687907853269984665640564039457584007913129638912", 10)
+	current, of := uint256.FromBig(i)
+	require.Equal(t, of, false)
+	i, _ = new(big.Int).SetString("115792089237316195423570985008687907853269984665640564039457584007913129638911", 10)
+	parent, of := uint256.FromBig(i)
+	require.Equal(t, of, false)
+
+	got, err := validTerminalPowBlock(current, parent)
+	require.NoError(t, err)
+	require.Equal(t, true, got)
+}
--- a/beacon-chain/blockchain/process_attestation.go
+++ b/beacon-chain/blockchain/process_attestation.go
@@ -2,19 +2,19 @@ package blockchain

 import (
 	"context"
+	"time"

 	"github.com/pkg/errors"
-	ethpb "github.com/prysmaticlabs/ethereumapis/eth/v1alpha1"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/helpers"
-	"github.com/prysmaticlabs/prysm/beacon-chain/state/stateV0"
-	"github.com/prysmaticlabs/prysm/shared/attestationutil"
-	"github.com/prysmaticlabs/prysm/shared/bytesutil"
-	"github.com/prysmaticlabs/prysm/shared/params"
-	"github.com/prysmaticlabs/prysm/shared/timeutils"
+	"github.com/prysmaticlabs/prysm/config/params"
+	"github.com/prysmaticlabs/prysm/encoding/bytesutil"
+	ethpb "github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1"
+	"github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1/attestation"
+	"github.com/prysmaticlabs/prysm/time/slots"
 	"go.opencensus.io/trace"
 )

-// onAttestation is called whenever an attestation is received, verifies the attestation is valid and saves
+// OnAttestation is called whenever an attestation is received, verifies the attestation is valid and saves
 // it to the DB. As a stateless function, this does not hold nor delay attestation based on the spec descriptions.
 // The delay is handled by the caller in `processAttestations`.
 //
@@ -36,7 +36,7 @@ import (
 //
 //    # Update latest messages for attesting indices
 //    update_latest_messages(store, indexed_attestation.attesting_indices, attestation)
-func (s *Service) onAttestation(ctx context.Context, a *ethpb.Attestation) error {
+func (s *Service) OnAttestation(ctx context.Context, a *ethpb.Attestation) error {
 	ctx, span := trace.StartSpan(ctx, "blockChain.onAttestation")
 	defer span.End()

@@ -46,7 +46,7 @@ func (s *Service) onAttestation(ctx context.Context, a *ethpb.Attestation) error
 	if err := helpers.ValidateSlotTargetEpoch(a.Data); err != nil {
 		return err
 	}
-	tgt := stateV0.CopyCheckpoint(a.Data.Target)
+	tgt := ethpb.CopyCheckpoint(a.Data.Target)

 	// Note that target root check is ignored here because it was performed in sync's validation pipeline:
 	// validate_aggregate_proof.go and validate_beacon_attestation.go
@@ -59,10 +59,10 @@ func (s *Service) onAttestation(ctx context.Context, a *ethpb.Attestation) error
 		return err
 	}

-	genesisTime := baseState.GenesisTime()
+	genesisTime := uint64(s.genesisTime.Unix())

 	// Verify attestation target is from current epoch or previous epoch.
-	if err := s.verifyAttTargetEpoch(ctx, genesisTime, uint64(timeutils.Now().Unix()), tgt); err != nil {
+	if err := verifyAttTargetEpoch(ctx, genesisTime, uint64(time.Now().Unix()), tgt); err != nil {
 		return err
 	}

@@ -75,20 +75,20 @@ func (s *Service) onAttestation(ctx context.Context, a *ethpb.Attestation) error
 	// validate_aggregate_proof.go and validate_beacon_attestation.go

 	// Verify attestations can only affect the fork choice of subsequent slots.
-	if err := helpers.VerifySlotTime(genesisTime, a.Data.Slot+1, params.BeaconNetworkConfig().MaximumGossipClockDisparity); err != nil {
+	if err := slots.VerifyTime(genesisTime, a.Data.Slot+1, params.BeaconNetworkConfig().MaximumGossipClockDisparity); err != nil {
 		return err
 	}

 	// Use the target state to verify attesting indices are valid.
-	committee, err := helpers.BeaconCommitteeFromState(baseState, a.Data.Slot, a.Data.CommitteeIndex)
+	committee, err := helpers.BeaconCommitteeFromState(ctx, baseState, a.Data.Slot, a.Data.CommitteeIndex)
 	if err != nil {
 		return err
 	}
-	indexedAtt, err := attestationutil.ConvertToIndexed(ctx, a, committee)
+	indexedAtt, err := attestation.ConvertToIndexed(ctx, a, committee)
 	if err != nil {
 		return err
 	}
-	if err := attestationutil.IsValidAttestationIndices(ctx, indexedAtt); err != nil {
+	if err := attestation.IsValidAttestationIndices(ctx, indexedAtt); err != nil {
 		return err
 	}

--- a/beacon-chain/blockchain/process_attestation_helpers.go
+++ b/beacon-chain/blockchain/process_attestation_helpers.go
@@ -7,29 +7,29 @@ import (

 	"github.com/pkg/errors"
 	types "github.com/prysmaticlabs/eth2-types"
-	ethpb "github.com/prysmaticlabs/ethereumapis/eth/v1alpha1"
+	"github.com/prysmaticlabs/prysm/async"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/helpers"
-	"github.com/prysmaticlabs/prysm/beacon-chain/core/state"
-	iface "github.com/prysmaticlabs/prysm/beacon-chain/state/interface"
-	"github.com/prysmaticlabs/prysm/shared/bytesutil"
-	"github.com/prysmaticlabs/prysm/shared/featureconfig"
-	"github.com/prysmaticlabs/prysm/shared/mputil"
-	"github.com/prysmaticlabs/prysm/shared/params"
+	"github.com/prysmaticlabs/prysm/beacon-chain/core/transition"
+	"github.com/prysmaticlabs/prysm/beacon-chain/state"
+	"github.com/prysmaticlabs/prysm/config/params"
+	"github.com/prysmaticlabs/prysm/encoding/bytesutil"
+	ethpb "github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1"
+	"github.com/prysmaticlabs/prysm/time/slots"
 )

 // getAttPreState retrieves the att pre state by either from the cache or the DB.
-func (s *Service) getAttPreState(ctx context.Context, c *ethpb.Checkpoint) (iface.BeaconState, error) {
+func (s *Service) getAttPreState(ctx context.Context, c *ethpb.Checkpoint) (state.BeaconState, error) {
 	// Use a multilock to allow scoped holding of a mutex by a checkpoint root + epoch
 	// allowing us to behave smarter in terms of how this function is used concurrently.
 	epochKey := strconv.FormatUint(uint64(c.Epoch), 10 /* base 10 */)
-	lock := mputil.NewMultilock(string(c.Root) + epochKey)
+	lock := async.NewMultilock(string(c.Root) + epochKey)
 	lock.Lock()
 	defer lock.Unlock()
 	cachedState, err := s.checkpointStateCache.StateByCheckpoint(c)
 	if err != nil {
 		return nil, errors.Wrap(err, "could not get cached checkpoint state")
 	}
-	if cachedState != nil {
+	if cachedState != nil && !cachedState.IsNil() {
 		return cachedState, nil
 	}

@@ -38,47 +38,30 @@ func (s *Service) getAttPreState(ctx context.Context, c *ethpb.Checkpoint) (ifac
 		return nil, errors.Wrapf(err, "could not get pre state for epoch %d", c.Epoch)
 	}

-	epochStartSlot, err := helpers.StartSlot(c.Epoch)
+	epochStartSlot, err := slots.EpochStart(c.Epoch)
 	if err != nil {
 		return nil, err
 	}
-	if epochStartSlot > baseState.Slot() {
-		if featureconfig.Get().EnableNextSlotStateCache {
-			baseState, err = state.ProcessSlotsUsingNextSlotCache(ctx, baseState, c.Root, epochStartSlot)
-			if err != nil {
-				return nil, errors.Wrapf(err, "could not process slots up to epoch %d", c.Epoch)
-			}
-		} else {
-			baseState, err = state.ProcessSlots(ctx, baseState, epochStartSlot)
-			if err != nil {
-				return nil, errors.Wrapf(err, "could not process slots up to epoch %d", c.Epoch)
-			}
-		}
-		if err := s.checkpointStateCache.AddCheckpointState(c, baseState); err != nil {
-			return nil, errors.Wrap(err, "could not saved checkpoint state to cache")
-		}
-		return baseState, nil
+	baseState, err = transition.ProcessSlotsIfPossible(ctx, baseState, epochStartSlot)
+	if err != nil {
+		return nil, errors.Wrapf(err, "could not process slots up to epoch %d", c.Epoch)
 	}

-	// To avoid sharing the same state across checkpoint state cache and hot state cache,
-	// we don't add the state to check point cache.
-	has, err := s.cfg.StateGen.HasStateInCache(ctx, bytesutil.ToBytes32(c.Root))
-	if err != nil {
-		return nil, err
-	}
-	if !has {
-		if err := s.checkpointStateCache.AddCheckpointState(c, baseState); err != nil {
-			return nil, errors.Wrap(err, "could not saved checkpoint state to cache")
-		}
+	// Sharing the same state across caches is perfectly fine here, the fetching
+	// of attestation prestate is by far the most accessed state fetching pattern in
+	// the beacon node. An extra state instance cached isn't an issue in the bigger
+	// picture.
+	if err := s.checkpointStateCache.AddCheckpointState(c, baseState); err != nil {
+		return nil, errors.Wrap(err, "could not save checkpoint state to cache")
 	}
 	return baseState, nil

 }

 // verifyAttTargetEpoch validates attestation is from the current or previous epoch.
-func (s *Service) verifyAttTargetEpoch(_ context.Context, genesisTime, nowTime uint64, c *ethpb.Checkpoint) error {
+func verifyAttTargetEpoch(_ context.Context, genesisTime, nowTime uint64, c *ethpb.Checkpoint) error {
 	currentSlot := types.Slot((nowTime - genesisTime) / params.BeaconConfig().SecondsPerSlot)
-	currentEpoch := helpers.SlotToEpoch(currentSlot)
+	currentEpoch := slots.ToEpoch(currentSlot)
 	var prevEpoch types.Epoch
 	// Prevents previous epoch under flow
 	if currentEpoch > 1 {
@@ -99,14 +82,14 @@ func (s *Service) verifyBeaconBlock(ctx context.Context, data *ethpb.Attestation
 	}
 	// If the block does not exist in db, check again if block exists in initial sync block cache.
 	// This could happen as the node first syncs to head.
-	if b == nil && s.hasInitSyncBlock(r) {
+	if (b == nil || b.IsNil()) && s.hasInitSyncBlock(r) {
 		b = s.getInitSyncBlock(r)
 	}
-	if err := helpers.VerifyNilBeaconBlock(b); err != nil {
+	if err := helpers.BeaconBlockIsNil(b); err != nil {
 		return err
 	}
-	if b.Block.Slot > data.Slot {
-		return fmt.Errorf("could not process attestation for future block, block.Slot=%d > attestation.Data.Slot=%d", b.Block.Slot, data.Slot)
+	if b.Block().Slot() > data.Slot {
+		return fmt.Errorf("could not process attestation for future block, block.Slot=%d > attestation.Data.Slot=%d", b.Block().Slot(), data.Slot)
 	}
 	return nil
 }
--- a/beacon-chain/blockchain/process_attestation_test.go
+++ b/beacon-chain/blockchain/process_attestation_test.go
@@ -3,64 +3,65 @@ package blockchain
 import (
 	"context"
 	"testing"
+	"time"

 	types "github.com/prysmaticlabs/eth2-types"
-	ethpb "github.com/prysmaticlabs/ethereumapis/eth/v1alpha1"
-	"github.com/prysmaticlabs/prysm/beacon-chain/core/helpers"
-	"github.com/prysmaticlabs/prysm/beacon-chain/core/state"
+	"github.com/prysmaticlabs/prysm/beacon-chain/core/transition"
 	testDB "github.com/prysmaticlabs/prysm/beacon-chain/db/testing"
 	"github.com/prysmaticlabs/prysm/beacon-chain/forkchoice/protoarray"
 	"github.com/prysmaticlabs/prysm/beacon-chain/state/stategen"
-	pb "github.com/prysmaticlabs/prysm/proto/beacon/p2p/v1"
-	"github.com/prysmaticlabs/prysm/shared/bytesutil"
-	"github.com/prysmaticlabs/prysm/shared/params"
-	"github.com/prysmaticlabs/prysm/shared/testutil"
-	"github.com/prysmaticlabs/prysm/shared/testutil/assert"
-	"github.com/prysmaticlabs/prysm/shared/testutil/require"
-	"github.com/prysmaticlabs/prysm/shared/timeutils"
+	fieldparams "github.com/prysmaticlabs/prysm/config/fieldparams"
+	"github.com/prysmaticlabs/prysm/config/params"
+	"github.com/prysmaticlabs/prysm/encoding/bytesutil"
+	ethpb "github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1"
+	"github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1/wrapper"
+	"github.com/prysmaticlabs/prysm/testing/assert"
+	"github.com/prysmaticlabs/prysm/testing/require"
+	"github.com/prysmaticlabs/prysm/testing/util"
+	"github.com/prysmaticlabs/prysm/time/slots"
 )

 func TestStore_OnAttestation_ErrorConditions(t *testing.T) {
 	ctx := context.Background()
 	beaconDB := testDB.SetupDB(t)

-	cfg := &Config{
-		BeaconDB:        beaconDB,
-		ForkChoiceStore: protoarray.New(0, 0, [32]byte{}),
-		StateGen:        stategen.New(beaconDB),
+	opts := []Option{
+		WithDatabase(beaconDB),
+		WithForkChoiceStore(protoarray.New(0, 0, [32]byte{})),
+		WithStateGen(stategen.New(beaconDB)),
 	}
-	service, err := NewService(ctx, cfg)
+	service, err := NewService(ctx, opts...)
 	require.NoError(t, err)

 	_, err = blockTree1(t, beaconDB, []byte{'g'})
 	require.NoError(t, err)

-	BlkWithOutState := testutil.NewBeaconBlock()
+	BlkWithOutState := util.NewBeaconBlock()
 	BlkWithOutState.Block.Slot = 0
-	require.NoError(t, beaconDB.SaveBlock(ctx, BlkWithOutState))
+	require.NoError(t, beaconDB.SaveBlock(ctx, wrapper.WrappedPhase0SignedBeaconBlock(BlkWithOutState)))
 	BlkWithOutStateRoot, err := BlkWithOutState.Block.HashTreeRoot()
 	require.NoError(t, err)

-	BlkWithStateBadAtt := testutil.NewBeaconBlock()
+	BlkWithStateBadAtt := util.NewBeaconBlock()
 	BlkWithStateBadAtt.Block.Slot = 1
-	require.NoError(t, beaconDB.SaveBlock(ctx, BlkWithStateBadAtt))
+	require.NoError(t, beaconDB.SaveBlock(ctx, wrapper.WrappedPhase0SignedBeaconBlock(BlkWithStateBadAtt)))
 	BlkWithStateBadAttRoot, err := BlkWithStateBadAtt.Block.HashTreeRoot()
 	require.NoError(t, err)

-	s, err := testutil.NewBeaconState()
+	s, err := util.NewBeaconState()
 	require.NoError(t, err)
 	require.NoError(t, s.SetSlot(100*params.BeaconConfig().SlotsPerEpoch))
 	require.NoError(t, service.cfg.BeaconDB.SaveState(ctx, s, BlkWithStateBadAttRoot))

-	BlkWithValidState := testutil.NewBeaconBlock()
+	BlkWithValidState := util.NewBeaconBlock()
 	BlkWithValidState.Block.Slot = 2
-	require.NoError(t, beaconDB.SaveBlock(ctx, BlkWithValidState))
+	require.NoError(t, beaconDB.SaveBlock(ctx, wrapper.WrappedPhase0SignedBeaconBlock(BlkWithValidState)))

 	BlkWithValidStateRoot, err := BlkWithValidState.Block.HashTreeRoot()
 	require.NoError(t, err)
-	s, err = testutil.NewBeaconState()
+	s, err = util.NewBeaconState()
 	require.NoError(t, err)
-	err = s.SetFork(&pb.Fork{
+	err = s.SetFork(&ethpb.Fork{
 		Epoch:           0,
 		CurrentVersion:  params.BeaconConfig().GenesisForkVersion,
 		PreviousVersion: params.BeaconConfig().GenesisForkVersion,
@@ -75,17 +76,17 @@ func TestStore_OnAttestation_ErrorConditions(t *testing.T) {
 	}{
 		{
 			name:      "attestation's data slot not aligned with target vote",
-			a:         testutil.HydrateAttestation(&ethpb.Attestation{Data: &ethpb.AttestationData{Slot: params.BeaconConfig().SlotsPerEpoch, Target: &ethpb.Checkpoint{Root: make([]byte, 32)}}}),
+			a:         util.HydrateAttestation(&ethpb.Attestation{Data: &ethpb.AttestationData{Slot: params.BeaconConfig().SlotsPerEpoch, Target: &ethpb.Checkpoint{Root: make([]byte, 32)}}}),
 			wantedErr: "slot 32 does not match target epoch 0",
 		},
 		{
 			name:      "no pre state for attestations's target block",
-			a:         testutil.HydrateAttestation(&ethpb.Attestation{Data: &ethpb.AttestationData{Target: &ethpb.Checkpoint{Root: BlkWithOutStateRoot[:]}}}),
+			a:         util.HydrateAttestation(&ethpb.Attestation{Data: &ethpb.AttestationData{Target: &ethpb.Checkpoint{Root: BlkWithOutStateRoot[:]}}}),
 			wantedErr: "could not get pre state for epoch 0",
 		},
 		{
 			name: "process attestation doesn't match current epoch",
-			a: testutil.HydrateAttestation(&ethpb.Attestation{Data: &ethpb.AttestationData{Slot: 100 * params.BeaconConfig().SlotsPerEpoch, Target: &ethpb.Checkpoint{Epoch: 100,
+			a: util.HydrateAttestation(&ethpb.Attestation{Data: &ethpb.AttestationData{Slot: 100 * params.BeaconConfig().SlotsPerEpoch, Target: &ethpb.Checkpoint{Epoch: 100,
 				Root: BlkWithStateBadAttRoot[:]}}}),
 			wantedErr: "target epoch 100 does not match current epoch",
 		},
@@ -103,9 +104,9 @@ func TestStore_OnAttestation_ErrorConditions(t *testing.T) {
 			name: "process nil field (a.Target) in attestation",
 			a: &ethpb.Attestation{
 				Data: &ethpb.AttestationData{
-					BeaconBlockRoot: make([]byte, 32),
+					BeaconBlockRoot: make([]byte, fieldparams.RootLength),
 					Target:          nil,
-					Source:          &ethpb.Checkpoint{Root: make([]byte, 32)},
+					Source:          &ethpb.Checkpoint{Root: make([]byte, fieldparams.RootLength)},
 				},
 				AggregationBits: make([]byte, 1),
 				Signature:       make([]byte, 96),
@@ -116,7 +117,7 @@ func TestStore_OnAttestation_ErrorConditions(t *testing.T) {

 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
-			err := service.onAttestation(ctx, tt.a)
+			err := service.OnAttestation(ctx, tt.a)
 			if tt.wantedErr != "" {
 				assert.ErrorContains(t, tt.wantedErr, err)
 			} else {
@@ -130,45 +131,46 @@ func TestStore_OnAttestation_Ok(t *testing.T) {
 	ctx := context.Background()
 	beaconDB := testDB.SetupDB(t)

-	cfg := &Config{
-		BeaconDB:        beaconDB,
-		ForkChoiceStore: protoarray.New(0, 0, [32]byte{}),
-		StateGen:        stategen.New(beaconDB),
+	fcs := protoarray.New(0, 0, [32]byte{'a'})
+	opts := []Option{
+		WithDatabase(beaconDB),
+		WithStateGen(stategen.New(beaconDB)),
+		WithForkChoiceStore(fcs),
 	}
-	service, err := NewService(ctx, cfg)
+	service, err := NewService(ctx, opts...)
 	require.NoError(t, err)
-	genesisState, pks := testutil.DeterministicGenesisState(t, 64)
-	require.NoError(t, genesisState.SetGenesisTime(uint64(timeutils.Now().Unix())-params.BeaconConfig().SecondsPerSlot))
+	genesisState, pks := util.DeterministicGenesisState(t, 64)
+	service.SetGenesisTime(time.Unix(time.Now().Unix()-int64(params.BeaconConfig().SecondsPerSlot), 0))
 	require.NoError(t, service.saveGenesisData(ctx, genesisState))
-	att, err := testutil.GenerateAttestations(genesisState, pks, 1, 0, false)
+	att, err := util.GenerateAttestations(genesisState, pks, 1, 0, false)
 	require.NoError(t, err)
 	tRoot := bytesutil.ToBytes32(att[0].Data.Target.Root)
 	copied := genesisState.Copy()
-	copied, err = state.ProcessSlots(ctx, copied, 1)
+	copied, err = transition.ProcessSlots(ctx, copied, 1)
 	require.NoError(t, err)
 	require.NoError(t, service.cfg.BeaconDB.SaveState(ctx, copied, tRoot))
 	require.NoError(t, service.cfg.ForkChoiceStore.ProcessBlock(ctx, 0, tRoot, tRoot, tRoot, 1, 1))
-	require.NoError(t, service.onAttestation(ctx, att[0]))
+	require.NoError(t, service.OnAttestation(ctx, att[0]))
 }

 func TestStore_SaveCheckpointState(t *testing.T) {
 	ctx := context.Background()
 	beaconDB := testDB.SetupDB(t)

-	cfg := &Config{
-		BeaconDB: beaconDB,
-		StateGen: stategen.New(beaconDB),
+	opts := []Option{
+		WithDatabase(beaconDB),
+		WithStateGen(stategen.New(beaconDB)),
 	}
-	service, err := NewService(ctx, cfg)
+	service, err := NewService(ctx, opts...)
 	require.NoError(t, err)

-	s, err := testutil.NewBeaconState()
+	s, err := util.NewBeaconState()
 	require.NoError(t, err)
-	err = s.SetFinalizedCheckpoint(&ethpb.Checkpoint{Root: bytesutil.PadTo([]byte{'A'}, 32)})
+	err = s.SetFinalizedCheckpoint(&ethpb.Checkpoint{Root: bytesutil.PadTo([]byte{'A'}, fieldparams.RootLength)})
 	require.NoError(t, err)
 	val := &ethpb.Validator{
 		PublicKey:             bytesutil.PadTo([]byte("foo"), 48),
-		WithdrawalCredentials: bytesutil.PadTo([]byte("bar"), 32),
+		WithdrawalCredentials: bytesutil.PadTo([]byte("bar"), fieldparams.RootLength),
 	}
 	err = s.SetValidators([]*ethpb.Validator{val})
 	require.NoError(t, err)
@@ -177,23 +179,23 @@ func TestStore_SaveCheckpointState(t *testing.T) {
 	r := [32]byte{'g'}
 	require.NoError(t, service.cfg.BeaconDB.SaveState(ctx, s, r))

-	service.justifiedCheckpt = &ethpb.Checkpoint{Root: r[:]}
-	service.bestJustifiedCheckpt = &ethpb.Checkpoint{Root: r[:]}
-	service.finalizedCheckpt = &ethpb.Checkpoint{Root: r[:]}
-	service.prevFinalizedCheckpt = &ethpb.Checkpoint{Root: r[:]}
+	service.store.SetJustifiedCheckpt(&ethpb.Checkpoint{Root: r[:]})
+	service.store.SetBestJustifiedCheckpt(&ethpb.Checkpoint{Root: r[:]})
+	service.store.SetFinalizedCheckpt(&ethpb.Checkpoint{Root: r[:]})
+	service.store.SetPrevFinalizedCheckpt(&ethpb.Checkpoint{Root: r[:]})

 	r = bytesutil.ToBytes32([]byte{'A'})
-	cp1 := &ethpb.Checkpoint{Epoch: 1, Root: bytesutil.PadTo([]byte{'A'}, 32)}
+	cp1 := &ethpb.Checkpoint{Epoch: 1, Root: bytesutil.PadTo([]byte{'A'}, fieldparams.RootLength)}
 	require.NoError(t, service.cfg.BeaconDB.SaveState(ctx, s, bytesutil.ToBytes32([]byte{'A'})))
-	require.NoError(t, service.cfg.BeaconDB.SaveStateSummary(ctx, &pb.StateSummary{Root: bytesutil.PadTo([]byte{'A'}, 32)}))
+	require.NoError(t, service.cfg.BeaconDB.SaveStateSummary(ctx, &ethpb.StateSummary{Root: bytesutil.PadTo([]byte{'A'}, fieldparams.RootLength)}))

 	s1, err := service.getAttPreState(ctx, cp1)
 	require.NoError(t, err)
 	assert.Equal(t, 1*params.BeaconConfig().SlotsPerEpoch, s1.Slot(), "Unexpected state slot")

-	cp2 := &ethpb.Checkpoint{Epoch: 2, Root: bytesutil.PadTo([]byte{'B'}, 32)}
+	cp2 := &ethpb.Checkpoint{Epoch: 2, Root: bytesutil.PadTo([]byte{'B'}, fieldparams.RootLength)}
 	require.NoError(t, service.cfg.BeaconDB.SaveState(ctx, s, bytesutil.ToBytes32([]byte{'B'})))
-	require.NoError(t, service.cfg.BeaconDB.SaveStateSummary(ctx, &pb.StateSummary{Root: bytesutil.PadTo([]byte{'B'}, 32)}))
+	require.NoError(t, service.cfg.BeaconDB.SaveStateSummary(ctx, &ethpb.StateSummary{Root: bytesutil.PadTo([]byte{'B'}, fieldparams.RootLength)}))
 	s2, err := service.getAttPreState(ctx, cp2)
 	require.NoError(t, err)
 	assert.Equal(t, 2*params.BeaconConfig().SlotsPerEpoch, s2.Slot(), "Unexpected state slot")
@@ -211,13 +213,13 @@ func TestStore_SaveCheckpointState(t *testing.T) {
 	assert.Equal(t, 2*params.BeaconConfig().SlotsPerEpoch, s2.Slot(), "Unexpected state slot")

 	require.NoError(t, s.SetSlot(params.BeaconConfig().SlotsPerEpoch+1))
-	service.justifiedCheckpt = &ethpb.Checkpoint{Root: r[:]}
-	service.bestJustifiedCheckpt = &ethpb.Checkpoint{Root: r[:]}
-	service.finalizedCheckpt = &ethpb.Checkpoint{Root: r[:]}
-	service.prevFinalizedCheckpt = &ethpb.Checkpoint{Root: r[:]}
-	cp3 := &ethpb.Checkpoint{Epoch: 1, Root: bytesutil.PadTo([]byte{'C'}, 32)}
+	service.store.SetJustifiedCheckpt(&ethpb.Checkpoint{Root: r[:]})
+	service.store.SetBestJustifiedCheckpt(&ethpb.Checkpoint{Root: r[:]})
+	service.store.SetFinalizedCheckpt(&ethpb.Checkpoint{Root: r[:]})
+	service.store.SetPrevFinalizedCheckpt(&ethpb.Checkpoint{Root: r[:]})
+	cp3 := &ethpb.Checkpoint{Epoch: 1, Root: bytesutil.PadTo([]byte{'C'}, fieldparams.RootLength)}
 	require.NoError(t, service.cfg.BeaconDB.SaveState(ctx, s, bytesutil.ToBytes32([]byte{'C'})))
-	require.NoError(t, service.cfg.BeaconDB.SaveStateSummary(ctx, &pb.StateSummary{Root: bytesutil.PadTo([]byte{'C'}, 32)}))
+	require.NoError(t, service.cfg.BeaconDB.SaveStateSummary(ctx, &ethpb.StateSummary{Root: bytesutil.PadTo([]byte{'C'}, fieldparams.RootLength)}))
 	s3, err := service.getAttPreState(ctx, cp3)
 	require.NoError(t, err)
 	assert.Equal(t, s.Slot(), s3.Slot(), "Unexpected state slot")
@@ -227,16 +229,16 @@ func TestStore_UpdateCheckpointState(t *testing.T) {
 	ctx := context.Background()
 	beaconDB := testDB.SetupDB(t)

-	cfg := &Config{
-		BeaconDB: beaconDB,
-		StateGen: stategen.New(beaconDB),
+	opts := []Option{
+		WithDatabase(beaconDB),
+		WithStateGen(stategen.New(beaconDB)),
 	}
-	service, err := NewService(ctx, cfg)
+	service, err := NewService(ctx, opts...)
 	require.NoError(t, err)

 	epoch := types.Epoch(1)
-	baseState, _ := testutil.DeterministicGenesisState(t, 1)
-	checkpoint := &ethpb.Checkpoint{Epoch: epoch, Root: bytesutil.PadTo([]byte("hi"), 32)}
+	baseState, _ := util.DeterministicGenesisState(t, 1)
+	checkpoint := &ethpb.Checkpoint{Epoch: epoch, Root: bytesutil.PadTo([]byte("hi"), fieldparams.RootLength)}
 	require.NoError(t, service.cfg.BeaconDB.SaveState(ctx, baseState, bytesutil.ToBytes32(checkpoint.Root)))
 	returned, err := service.getAttPreState(ctx, checkpoint)
 	require.NoError(t, err)
@@ -247,13 +249,13 @@ func TestStore_UpdateCheckpointState(t *testing.T) {
 	assert.Equal(t, returned.Slot(), cached.Slot(), "State should have been cached")

 	epoch = 2
-	newCheckpoint := &ethpb.Checkpoint{Epoch: epoch, Root: bytesutil.PadTo([]byte("bye"), 32)}
+	newCheckpoint := &ethpb.Checkpoint{Epoch: epoch, Root: bytesutil.PadTo([]byte("bye"), fieldparams.RootLength)}
 	require.NoError(t, service.cfg.BeaconDB.SaveState(ctx, baseState, bytesutil.ToBytes32(newCheckpoint.Root)))
 	returned, err = service.getAttPreState(ctx, newCheckpoint)
 	require.NoError(t, err)
-	s, err := helpers.StartSlot(newCheckpoint.Epoch)
+	s, err := slots.EpochStart(newCheckpoint.Epoch)
 	require.NoError(t, err)
-	baseState, err = state.ProcessSlots(ctx, baseState, s)
+	baseState, err = transition.ProcessSlots(ctx, baseState, s)
 	require.NoError(t, err)
 	assert.Equal(t, returned.Slot(), baseState.Slot(), "Incorrectly returned base state")

@@ -264,64 +266,46 @@ func TestStore_UpdateCheckpointState(t *testing.T) {

 func TestAttEpoch_MatchPrevEpoch(t *testing.T) {
 	ctx := context.Background()
-	beaconDB := testDB.SetupDB(t)
-
-	cfg := &Config{BeaconDB: beaconDB}
-	service, err := NewService(ctx, cfg)
-	require.NoError(t, err)

 	nowTime := uint64(params.BeaconConfig().SlotsPerEpoch) * params.BeaconConfig().SecondsPerSlot
-	require.NoError(t, service.verifyAttTargetEpoch(ctx, 0, nowTime, &ethpb.Checkpoint{Root: make([]byte, 32)}))
+	require.NoError(t, verifyAttTargetEpoch(ctx, 0, nowTime, &ethpb.Checkpoint{Root: make([]byte, fieldparams.RootLength)}))
 }

 func TestAttEpoch_MatchCurrentEpoch(t *testing.T) {
 	ctx := context.Background()
-	beaconDB := testDB.SetupDB(t)
-
-	cfg := &Config{BeaconDB: beaconDB}
-	service, err := NewService(ctx, cfg)
-	require.NoError(t, err)

 	nowTime := uint64(params.BeaconConfig().SlotsPerEpoch) * params.BeaconConfig().SecondsPerSlot
-	require.NoError(t, service.verifyAttTargetEpoch(ctx, 0, nowTime, &ethpb.Checkpoint{Epoch: 1}))
+	require.NoError(t, verifyAttTargetEpoch(ctx, 0, nowTime, &ethpb.Checkpoint{Epoch: 1}))
 }

 func TestAttEpoch_NotMatch(t *testing.T) {
 	ctx := context.Background()
-	beaconDB := testDB.SetupDB(t)
-
-	cfg := &Config{BeaconDB: beaconDB}
-	service, err := NewService(ctx, cfg)
-	require.NoError(t, err)

 	nowTime := 2 * uint64(params.BeaconConfig().SlotsPerEpoch) * params.BeaconConfig().SecondsPerSlot
-	err = service.verifyAttTargetEpoch(ctx, 0, nowTime, &ethpb.Checkpoint{Root: make([]byte, 32)})
+	err := verifyAttTargetEpoch(ctx, 0, nowTime, &ethpb.Checkpoint{Root: make([]byte, fieldparams.RootLength)})
 	assert.ErrorContains(t, "target epoch 0 does not match current epoch 2 or prev epoch 1", err)
 }

 func TestVerifyBeaconBlock_NoBlock(t *testing.T) {
 	ctx := context.Background()
-	beaconDB := testDB.SetupDB(t)
-
-	cfg := &Config{BeaconDB: beaconDB}
-	service, err := NewService(ctx, cfg)
+	opts := testServiceOptsWithDB(t)
+	service, err := NewService(ctx, opts...)
 	require.NoError(t, err)

-	d := testutil.HydrateAttestationData(&ethpb.AttestationData{})
+	d := util.HydrateAttestationData(&ethpb.AttestationData{})
 	assert.ErrorContains(t, "signed beacon block can't be nil", service.verifyBeaconBlock(ctx, d))
 }

 func TestVerifyBeaconBlock_futureBlock(t *testing.T) {
 	ctx := context.Background()
-	beaconDB := testDB.SetupDB(t)

-	cfg := &Config{BeaconDB: beaconDB}
-	service, err := NewService(ctx, cfg)
+	opts := testServiceOptsWithDB(t)
+	service, err := NewService(ctx, opts...)
 	require.NoError(t, err)

-	b := testutil.NewBeaconBlock()
+	b := util.NewBeaconBlock()
 	b.Block.Slot = 2
-	require.NoError(t, service.cfg.BeaconDB.SaveBlock(ctx, b))
+	require.NoError(t, service.cfg.BeaconDB.SaveBlock(ctx, wrapper.WrappedPhase0SignedBeaconBlock(b)))
 	r, err := b.Block.HashTreeRoot()
 	require.NoError(t, err)
 	d := &ethpb.AttestationData{Slot: 1, BeaconBlockRoot: r[:]}
@@ -331,15 +315,14 @@ func TestVerifyBeaconBlock_futureBlock(t *testing.T) {

 func TestVerifyBeaconBlock_OK(t *testing.T) {
 	ctx := context.Background()
-	beaconDB := testDB.SetupDB(t)

-	cfg := &Config{BeaconDB: beaconDB}
-	service, err := NewService(ctx, cfg)
+	opts := testServiceOptsWithDB(t)
+	service, err := NewService(ctx, opts...)
 	require.NoError(t, err)

-	b := testutil.NewBeaconBlock()
+	b := util.NewBeaconBlock()
 	b.Block.Slot = 2
-	require.NoError(t, service.cfg.BeaconDB.SaveBlock(ctx, b))
+	require.NoError(t, service.cfg.BeaconDB.SaveBlock(ctx, wrapper.WrappedPhase0SignedBeaconBlock(b)))
 	r, err := b.Block.HashTreeRoot()
 	require.NoError(t, err)
 	d := &ethpb.AttestationData{Slot: 2, BeaconBlockRoot: r[:]}
@@ -351,22 +334,26 @@ func TestVerifyFinalizedConsistency_InconsistentRoot(t *testing.T) {
 	ctx := context.Background()
 	beaconDB := testDB.SetupDB(t)

-	cfg := &Config{BeaconDB: beaconDB, ForkChoiceStore: protoarray.New(0, 0, [32]byte{})}
-	service, err := NewService(ctx, cfg)
+	fcs := protoarray.New(0, 0, [32]byte{'a'})
+	opts := []Option{
+		WithDatabase(beaconDB),
+		WithStateGen(stategen.New(beaconDB)),
+		WithForkChoiceStore(fcs),
+	}
+	service, err := NewService(ctx, opts...)
 	require.NoError(t, err)

-	b32 := testutil.NewBeaconBlock()
+	b32 := util.NewBeaconBlock()
 	b32.Block.Slot = 32
-	require.NoError(t, service.cfg.BeaconDB.SaveBlock(ctx, b32))
+	require.NoError(t, service.cfg.BeaconDB.SaveBlock(ctx, wrapper.WrappedPhase0SignedBeaconBlock(b32)))
 	r32, err := b32.Block.HashTreeRoot()
 	require.NoError(t, err)

-	service.finalizedCheckpt = &ethpb.Checkpoint{Epoch: 1}
-
-	b33 := testutil.NewBeaconBlock()
+	service.store.SetFinalizedCheckpt(&ethpb.Checkpoint{Epoch: 1})
+	b33 := util.NewBeaconBlock()
 	b33.Block.Slot = 33
 	b33.Block.ParentRoot = r32[:]
-	require.NoError(t, service.cfg.BeaconDB.SaveBlock(ctx, b33))
+	require.NoError(t, service.cfg.BeaconDB.SaveBlock(ctx, wrapper.WrappedPhase0SignedBeaconBlock(b33)))
 	r33, err := b33.Block.HashTreeRoot()
 	require.NoError(t, err)

@@ -376,24 +363,23 @@ func TestVerifyFinalizedConsistency_InconsistentRoot(t *testing.T) {

 func TestVerifyFinalizedConsistency_OK(t *testing.T) {
 	ctx := context.Background()
-	beaconDB := testDB.SetupDB(t)

-	cfg := &Config{BeaconDB: beaconDB, ForkChoiceStore: protoarray.New(0, 0, [32]byte{})}
-	service, err := NewService(ctx, cfg)
+	opts := testServiceOptsWithDB(t)
+	service, err := NewService(ctx, opts...)
 	require.NoError(t, err)

-	b32 := testutil.NewBeaconBlock()
+	b32 := util.NewBeaconBlock()
 	b32.Block.Slot = 32
-	require.NoError(t, service.cfg.BeaconDB.SaveBlock(ctx, b32))
+	require.NoError(t, service.cfg.BeaconDB.SaveBlock(ctx, wrapper.WrappedPhase0SignedBeaconBlock(b32)))
 	r32, err := b32.Block.HashTreeRoot()
 	require.NoError(t, err)

-	service.finalizedCheckpt = &ethpb.Checkpoint{Epoch: 1, Root: r32[:]}
+	service.store.SetFinalizedCheckpt(&ethpb.Checkpoint{Root: r32[:], Epoch: 1})

-	b33 := testutil.NewBeaconBlock()
+	b33 := util.NewBeaconBlock()
 	b33.Block.Slot = 33
 	b33.Block.ParentRoot = r32[:]
-	require.NoError(t, service.cfg.BeaconDB.SaveBlock(ctx, b33))
+	require.NoError(t, service.cfg.BeaconDB.SaveBlock(ctx, wrapper.WrappedPhase0SignedBeaconBlock(b33)))
 	r33, err := b33.Block.HashTreeRoot()
 	require.NoError(t, err)

@@ -403,20 +389,19 @@ func TestVerifyFinalizedConsistency_OK(t *testing.T) {

 func TestVerifyFinalizedConsistency_IsCanonical(t *testing.T) {
 	ctx := context.Background()
-	beaconDB := testDB.SetupDB(t)

-	cfg := &Config{BeaconDB: beaconDB, ForkChoiceStore: protoarray.New(0, 0, [32]byte{})}
-	service, err := NewService(ctx, cfg)
+	opts := testServiceOptsWithDB(t)
+	service, err := NewService(ctx, opts...)
 	require.NoError(t, err)

-	b32 := testutil.NewBeaconBlock()
+	b32 := util.NewBeaconBlock()
 	b32.Block.Slot = 32
 	r32, err := b32.Block.HashTreeRoot()
 	require.NoError(t, err)

-	service.finalizedCheckpt = &ethpb.Checkpoint{Epoch: 1, Root: r32[:]}
+	service.store.SetFinalizedCheckpt(&ethpb.Checkpoint{Root: r32[:], Epoch: 1})

-	b33 := testutil.NewBeaconBlock()
+	b33 := util.NewBeaconBlock()
 	b33.Block.Slot = 33
 	b33.Block.ParentRoot = r32[:]
 	r33, err := b33.Block.HashTreeRoot()
--- a/beacon-chain/blockchain/process_block.go
+++ b/beacon-chain/blockchain/process_block.go
@@ -6,18 +6,22 @@ import (
 	"time"

 	"github.com/pkg/errors"
-	ethpb "github.com/prysmaticlabs/ethereumapis/eth/v1alpha1"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/feed"
 	statefeed "github.com/prysmaticlabs/prysm/beacon-chain/core/feed/state"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/helpers"
-	"github.com/prysmaticlabs/prysm/beacon-chain/core/state"
-	iface "github.com/prysmaticlabs/prysm/beacon-chain/state/interface"
-	pb "github.com/prysmaticlabs/prysm/proto/beacon/p2p/v1"
-	"github.com/prysmaticlabs/prysm/shared/attestationutil"
-	"github.com/prysmaticlabs/prysm/shared/bls"
-	"github.com/prysmaticlabs/prysm/shared/bytesutil"
-	"github.com/prysmaticlabs/prysm/shared/featureconfig"
-	"github.com/prysmaticlabs/prysm/shared/params"
+	coreTime "github.com/prysmaticlabs/prysm/beacon-chain/core/time"
+	"github.com/prysmaticlabs/prysm/beacon-chain/core/transition"
+	"github.com/prysmaticlabs/prysm/beacon-chain/state"
+	"github.com/prysmaticlabs/prysm/config/features"
+	"github.com/prysmaticlabs/prysm/config/params"
+	"github.com/prysmaticlabs/prysm/crypto/bls"
+	"github.com/prysmaticlabs/prysm/encoding/bytesutil"
+	"github.com/prysmaticlabs/prysm/monitoring/tracing"
+	ethpbv1 "github.com/prysmaticlabs/prysm/proto/eth/v1"
+	ethpb "github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1"
+	"github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1/attestation"
+	"github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1/block"
+	"github.com/prysmaticlabs/prysm/time/slots"
 	"go.opencensus.io/trace"
 )

@@ -81,81 +85,132 @@ var initialSyncBlockCacheSize = uint64(2 * params.BeaconConfig().SlotsPerEpoch)
 //            ancestor_at_finalized_slot = get_ancestor(store, store.justified_checkpoint.root, finalized_slot)
 //            if ancestor_at_finalized_slot != store.finalized_checkpoint.root:
 //                store.justified_checkpoint = state.current_justified_checkpoint
-func (s *Service) onBlock(ctx context.Context, signed *ethpb.SignedBeaconBlock, blockRoot [32]byte) error {
+func (s *Service) onBlock(ctx context.Context, signed block.SignedBeaconBlock, blockRoot [32]byte) error {
 	ctx, span := trace.StartSpan(ctx, "blockChain.onBlock")
 	defer span.End()
-
-	if signed == nil || signed.Block == nil {
-		return errors.New("nil block")
+	if err := helpers.BeaconBlockIsNil(signed); err != nil {
+		return err
 	}
-	b := signed.Block
+	b := signed.Block()

 	preState, err := s.getBlockPreState(ctx, b)
 	if err != nil {
 		return err
 	}

-	set, postState, err := state.ExecuteStateTransitionNoVerifyAnySig(ctx, preState, signed)
+	postState, err := transition.ExecuteStateTransition(ctx, preState, signed)
 	if err != nil {
-		return errors.Wrap(err, "could not execute state transition")
+		return err
 	}
-	valid, err := set.Verify()
-	if err != nil {
-		return errors.Wrap(err, "could not batch verify signature")
-	}
-	if !valid {
-		return errors.New("signature in block failed to verify")
+
+	// We add a proposer score boost to fork choice for the block root if applicable, right after
+	// running a successful state transition for the block.
+	if err := s.cfg.ForkChoiceStore.BoostProposerRoot(
+		ctx, signed.Block().Slot(), blockRoot, s.genesisTime,
+	); err != nil {
+		return err
 	}

 	if err := s.savePostStateInfo(ctx, blockRoot, signed, postState, false /* reg sync */); err != nil {
 		return err
 	}

-	// Updating next slot state cache can happen in the background. It shouldn't block rest of the process.
-	if featureconfig.Get().EnableNextSlotStateCache {
+	// If slasher is configured, forward the attestations in the block via
+	// an event feed for processing.
+	if features.Get().EnableSlasher {
+		// Feed the indexed attestation to slasher if enabled. This action
+		// is done in the background to avoid adding more load to this critical code path.
 		go func() {
-			// Use a custom deadline here, since this method runs asynchronously.
-			// We ignore the parent method's context and instead create a new one
-			// with a custom deadline, therefore using the background context instead.
-			slotCtx, cancel := context.WithTimeout(context.Background(), slotDeadline)
-			defer cancel()
-			if err := state.UpdateNextSlotCache(slotCtx, blockRoot[:], postState); err != nil {
-				log.WithError(err).Debug("could not update next slot state cache")
+			// Using a different context to prevent timeouts as this operation can be expensive
+			// and we want to avoid affecting the critical code path.
+			ctx := context.TODO()
+			for _, att := range signed.Block().Body().Attestations() {
+				committee, err := helpers.BeaconCommitteeFromState(ctx, preState, att.Data.Slot, att.Data.CommitteeIndex)
+				if err != nil {
+					log.WithError(err).Error("Could not get attestation committee")
+					tracing.AnnotateError(span, err)
+					return
+				}
+				indexedAtt, err := attestation.ConvertToIndexed(ctx, att, committee)
+				if err != nil {
+					log.WithError(err).Error("Could not convert to indexed attestation")
+					tracing.AnnotateError(span, err)
+					return
+				}
+				s.cfg.SlasherAttestationsFeed.Send(indexedAtt)
 			}
 		}()
 	}

 	// Update justified check point.
-	if postState.CurrentJustifiedCheckpoint().Epoch > s.justifiedCheckpt.Epoch {
+	justified := s.store.JustifiedCheckpt()
+	if justified == nil {
+		return errNilJustifiedInStore
+	}
+	currJustifiedEpoch := justified.Epoch
+	if postState.CurrentJustifiedCheckpoint().Epoch > currJustifiedEpoch {
 		if err := s.updateJustified(ctx, postState); err != nil {
 			return err
 		}
 	}

-	newFinalized := postState.FinalizedCheckpointEpoch() > s.finalizedCheckpt.Epoch
-	if featureconfig.Get().UpdateHeadTimely {
-		if newFinalized {
-			if err := s.finalizedImpliesNewJustified(ctx, postState); err != nil {
-				return errors.Wrap(err, "could not save new justified")
-			}
-			s.prevFinalizedCheckpt = s.finalizedCheckpt
-			s.finalizedCheckpt = postState.FinalizedCheckpoint()
-		}
+	finalized := s.store.FinalizedCheckpt()
+	if finalized == nil {
+		return errNilFinalizedInStore
+	}
+	newFinalized := postState.FinalizedCheckpointEpoch() > finalized.Epoch
+	if newFinalized {
+		s.store.SetPrevFinalizedCheckpt(finalized)
+		s.store.SetFinalizedCheckpt(postState.FinalizedCheckpoint())
+		s.store.SetPrevJustifiedCheckpt(justified)
+		s.store.SetJustifiedCheckpt(postState.CurrentJustifiedCheckpoint())
+	}

-		if err := s.updateHead(ctx, s.getJustifiedBalances()); err != nil {
-			log.WithError(err).Warn("Could not update head")
-		}
+	balances, err := s.justifiedBalances.get(ctx, bytesutil.ToBytes32(justified.Root))
+	if err != nil {
+		msg := fmt.Sprintf("could not read balances for state w/ justified checkpoint %#x", justified.Root)
+		return errors.Wrap(err, msg)
+	}
+	if err := s.updateHead(ctx, balances); err != nil {
+		log.WithError(err).Warn("Could not update head")
+	}

-		// Send notification of the processed block to the state feed.
-		s.cfg.StateNotifier.StateFeed().Send(&feed.Event{
-			Type: statefeed.BlockProcessed,
-			Data: &statefeed.BlockProcessedData{
-				Slot:        signed.Block.Slot,
-				BlockRoot:   blockRoot,
-				SignedBlock: signed,
-				Verified:    true,
-			},
-		})
+	if err := s.saveSyncedTipsDB(ctx); err != nil {
+		return errors.Wrap(err, "could not save synced tips")
+	}
+
+	if err := s.pruneCanonicalAttsFromPool(ctx, blockRoot, signed); err != nil {
+		return err
+	}
+
+	// Send notification of the processed block to the state feed.
+	s.cfg.StateNotifier.StateFeed().Send(&feed.Event{
+		Type: statefeed.BlockProcessed,
+		Data: &statefeed.BlockProcessedData{
+			Slot:        signed.Block().Slot(),
+			BlockRoot:   blockRoot,
+			SignedBlock: signed,
+			Verified:    true,
+		},
+	})
+
+	// Updating next slot state cache can happen in the background. It shouldn't block rest of the process.
+	go func() {
+		// Use a custom deadline here, since this method runs asynchronously.
+		// We ignore the parent method's context and instead create a new one
+		// with a custom deadline, therefore using the background context instead.
+		slotCtx, cancel := context.WithTimeout(context.Background(), slotDeadline)
+		defer cancel()
+		if err := transition.UpdateNextSlotCache(slotCtx, blockRoot[:], postState); err != nil {
+			log.WithError(err).Debug("could not update next slot state cache")
+		}
+	}()
+
+	// Save justified check point to db.
+	if postState.CurrentJustifiedCheckpoint().Epoch > currJustifiedEpoch {
+		if err := s.cfg.BeaconDB.SaveJustifiedCheckpoint(ctx, postState.CurrentJustifiedCheckpoint()); err != nil {
+			return err
+		}
 	}

 	// Update finalized check point.
@@ -167,12 +222,17 @@ func (s *Service) onBlock(ctx context.Context, signed *ethpb.SignedBeaconBlock,
 		if err := s.cfg.ForkChoiceStore.Prune(ctx, fRoot); err != nil {
 			return errors.Wrap(err, "could not prune proto array fork choice nodes")
 		}
-		if !featureconfig.Get().UpdateHeadTimely {
-			if err := s.finalizedImpliesNewJustified(ctx, postState); err != nil {
-				return errors.Wrap(err, "could not save new justified")
-			}
-		}
 		go func() {
+			// Send an event regarding the new finalized checkpoint over a common event feed.
+			s.cfg.StateNotifier.StateFeed().Send(&feed.Event{
+				Type: statefeed.FinalizedCheckpoint,
+				Data: &ethpbv1.EventFinalizedCheckpoint{
+					Epoch: postState.FinalizedCheckpoint().Epoch,
+					Block: postState.FinalizedCheckpoint().Root,
+					State: signed.Block().StateRoot(),
+				},
+			})
+
 			// Use a custom deadline here, since this method runs asynchronously.
 			// We ignore the parent method's context and instead create a new one
 			// with a custom deadline, therefore using the background context instead.
@@ -182,6 +242,7 @@ func (s *Service) onBlock(ctx context.Context, signed *ethpb.SignedBeaconBlock,
 				log.WithError(err).Error("Could not insert finalized deposits.")
 			}
 		}()
+
 	}

 	defer reportAttestationInclusion(b)
@@ -189,7 +250,7 @@ func (s *Service) onBlock(ctx context.Context, signed *ethpb.SignedBeaconBlock,
 	return s.handleEpochBoundary(ctx, postState)
 }

-func (s *Service) onBlockBatch(ctx context.Context, blks []*ethpb.SignedBeaconBlock,
+func (s *Service) onBlockBatch(ctx context.Context, blks []block.SignedBeaconBlock,
 	blockRoots [][32]byte) ([]*ethpb.Checkpoint, []*ethpb.Checkpoint, error) {
 	ctx, span := trace.StartSpan(ctx, "blockChain.onBlockBatch")
 	defer span.End()
@@ -197,39 +258,39 @@ func (s *Service) onBlockBatch(ctx context.Context, blks []*ethpb.SignedBeaconBl
 	if len(blks) == 0 || len(blockRoots) == 0 {
 		return nil, nil, errors.New("no blocks provided")
 	}
-	if blks[0] == nil || blks[0].Block == nil {
-		return nil, nil, errors.New("nil block")
+	if err := helpers.BeaconBlockIsNil(blks[0]); err != nil {
+		return nil, nil, err
 	}
-	b := blks[0].Block
+	b := blks[0].Block()

 	// Retrieve incoming block's pre state.
 	if err := s.verifyBlkPreState(ctx, b); err != nil {
 		return nil, nil, err
 	}
-	preState, err := s.cfg.StateGen.StateByRootInitialSync(ctx, bytesutil.ToBytes32(b.ParentRoot))
+	preState, err := s.cfg.StateGen.StateByRootInitialSync(ctx, bytesutil.ToBytes32(b.ParentRoot()))
 	if err != nil {
 		return nil, nil, err
 	}
-	if preState == nil {
-		return nil, nil, fmt.Errorf("nil pre state for slot %d", b.Slot)
+	if preState == nil || preState.IsNil() {
+		return nil, nil, fmt.Errorf("nil pre state for slot %d", b.Slot())
 	}

 	jCheckpoints := make([]*ethpb.Checkpoint, len(blks))
 	fCheckpoints := make([]*ethpb.Checkpoint, len(blks))
-	sigSet := &bls.SignatureSet{
+	sigSet := &bls.SignatureBatch{
 		Signatures: [][]byte{},
 		PublicKeys: []bls.PublicKey{},
 		Messages:   [][32]byte{},
 	}
-	var set *bls.SignatureSet
-	boundaries := make(map[[32]byte]iface.BeaconState)
+	var set *bls.SignatureBatch
+	boundaries := make(map[[32]byte]state.BeaconState)
 	for i, b := range blks {
-		set, preState, err = state.ExecuteStateTransitionNoVerifyAnySig(ctx, preState, b)
+		set, preState, err = transition.ExecuteStateTransitionNoVerifyAnySig(ctx, preState, b)
 		if err != nil {
 			return nil, nil, err
 		}
 		// Save potential boundary states.
-		if helpers.IsEpochStart(preState.Slot()) {
+		if slots.IsEpochStart(preState.Slot()) {
 			boundaries[blockRoots[i]] = preState.Copy()
 			if err := s.handleEpochBoundary(ctx, preState); err != nil {
 				return nil, nil, errors.Wrap(err, "could not handle epoch boundary state")
@@ -265,16 +326,20 @@ func (s *Service) onBlockBatch(ctx context.Context, blks []*ethpb.SignedBeaconBl

 // handles a block after the block's batch has been verified, where we can save blocks
 // their state summaries and split them off to relative hot/cold storage.
-func (s *Service) handleBlockAfterBatchVerify(ctx context.Context, signed *ethpb.SignedBeaconBlock,
+func (s *Service) handleBlockAfterBatchVerify(ctx context.Context, signed block.SignedBeaconBlock,
 	blockRoot [32]byte, fCheckpoint, jCheckpoint *ethpb.Checkpoint) error {
-	b := signed.Block
+	b := signed.Block()

 	s.saveInitSyncBlock(blockRoot, signed)
 	if err := s.insertBlockToForkChoiceStore(ctx, b, blockRoot, fCheckpoint, jCheckpoint); err != nil {
 		return err
 	}
-	if err := s.cfg.BeaconDB.SaveStateSummary(ctx, &pb.StateSummary{
-		Slot: signed.Block.Slot,
+	if err := s.saveSyncedTipsDB(ctx); err != nil {
+		return errors.Wrap(err, "could not save synced tips")
+	}
+
+	if err := s.cfg.BeaconDB.SaveStateSummary(ctx, &ethpb.StateSummary{
+		Slot: signed.Block().Slot(),
 		Root: blockRoot[:],
 	}); err != nil {
 		return err
@@ -288,34 +353,47 @@ func (s *Service) handleBlockAfterBatchVerify(ctx context.Context, signed *ethpb
 		s.clearInitSyncBlocks()
 	}

-	if jCheckpoint.Epoch > s.justifiedCheckpt.Epoch {
+	justified := s.store.JustifiedCheckpt()
+	if justified == nil {
+		return errNilJustifiedInStore
+	}
+	if jCheckpoint.Epoch > justified.Epoch {
 		if err := s.updateJustifiedInitSync(ctx, jCheckpoint); err != nil {
 			return err
 		}
 	}

+	finalized := s.store.FinalizedCheckpt()
+	if finalized == nil {
+		return errNilFinalizedInStore
+	}
 	// Update finalized check point. Prune the block cache and helper caches on every new finalized epoch.
-	if fCheckpoint.Epoch > s.finalizedCheckpt.Epoch {
+	if fCheckpoint.Epoch > finalized.Epoch {
 		if err := s.updateFinalized(ctx, fCheckpoint); err != nil {
 			return err
 		}
+		s.store.SetPrevFinalizedCheckpt(finalized)
+		s.store.SetFinalizedCheckpt(fCheckpoint)
 	}
 	return nil
 }

 // Epoch boundary bookkeeping such as logging epoch summaries.
-func (s *Service) handleEpochBoundary(ctx context.Context, postState iface.BeaconState) error {
+func (s *Service) handleEpochBoundary(ctx context.Context, postState state.BeaconState) error {
+	ctx, span := trace.StartSpan(ctx, "blockChain.handleEpochBoundary")
+	defer span.End()
+
 	if postState.Slot()+1 == s.nextEpochBoundarySlot {
 		// Update caches for the next epoch at epoch boundary slot - 1.
-		if err := helpers.UpdateCommitteeCache(postState, helpers.NextEpoch(postState)); err != nil {
+		if err := helpers.UpdateCommitteeCache(postState, coreTime.NextEpoch(postState)); err != nil {
 			return err
 		}
 		copied := postState.Copy()
-		copied, err := state.ProcessSlots(ctx, copied, copied.Slot()+1)
+		copied, err := transition.ProcessSlots(ctx, copied, copied.Slot()+1)
 		if err != nil {
 			return err
 		}
-		if err := helpers.UpdateProposerIndicesInCache(copied); err != nil {
+		if err := helpers.UpdateProposerIndicesInCache(ctx, copied); err != nil {
 			return err
 		}
 	} else if postState.Slot() >= s.nextEpochBoundarySlot {
@@ -323,17 +401,17 @@ func (s *Service) handleEpochBoundary(ctx context.Context, postState iface.Beaco
 			return err
 		}
 		var err error
-		s.nextEpochBoundarySlot, err = helpers.StartSlot(helpers.NextEpoch(postState))
+		s.nextEpochBoundarySlot, err = slots.EpochStart(coreTime.NextEpoch(postState))
 		if err != nil {
 			return err
 		}

 		// Update caches at epoch boundary slot.
 		// The following updates have short cut to return nil cheaply if fulfilled during boundary slot - 1.
-		if err := helpers.UpdateCommitteeCache(postState, helpers.CurrentEpoch(postState)); err != nil {
+		if err := helpers.UpdateCommitteeCache(postState, coreTime.CurrentEpoch(postState)); err != nil {
 			return err
 		}
-		if err := helpers.UpdateProposerIndicesInCache(postState); err != nil {
+		if err := helpers.UpdateProposerIndicesInCache(ctx, postState); err != nil {
 			return err
 		}
 	}
@@ -343,20 +421,23 @@ func (s *Service) handleEpochBoundary(ctx context.Context, postState iface.Beaco

 // This feeds in the block and block's attestations to fork choice store. It's allows fork choice store
 // to gain information on the most current chain.
-func (s *Service) insertBlockAndAttestationsToForkChoiceStore(ctx context.Context, blk *ethpb.BeaconBlock, root [32]byte,
-	st iface.BeaconState) error {
+func (s *Service) insertBlockAndAttestationsToForkChoiceStore(ctx context.Context, blk block.BeaconBlock, root [32]byte,
+	st state.BeaconState) error {
+	ctx, span := trace.StartSpan(ctx, "blockChain.insertBlockAndAttestationsToForkChoiceStore")
+	defer span.End()
+
 	fCheckpoint := st.FinalizedCheckpoint()
 	jCheckpoint := st.CurrentJustifiedCheckpoint()
 	if err := s.insertBlockToForkChoiceStore(ctx, blk, root, fCheckpoint, jCheckpoint); err != nil {
 		return err
 	}
 	// Feed in block's attestations to fork choice store.
-	for _, a := range blk.Body.Attestations {
-		committee, err := helpers.BeaconCommitteeFromState(st, a.Data.Slot, a.Data.CommitteeIndex)
+	for _, a := range blk.Body().Attestations() {
+		committee, err := helpers.BeaconCommitteeFromState(ctx, st, a.Data.Slot, a.Data.CommitteeIndex)
 		if err != nil {
 			return err
 		}
-		indices, err := attestationutil.AttestingIndices(a.AggregationBits, committee)
+		indices, err := attestation.AttestingIndices(a.AggregationBits, committee)
 		if err != nil {
 			return err
 		}
@@ -365,14 +446,14 @@ func (s *Service) insertBlockAndAttestationsToForkChoiceStore(ctx context.Contex
 	return nil
 }

-func (s *Service) insertBlockToForkChoiceStore(ctx context.Context, blk *ethpb.BeaconBlock,
+func (s *Service) insertBlockToForkChoiceStore(ctx context.Context, blk block.BeaconBlock,
 	root [32]byte, fCheckpoint, jCheckpoint *ethpb.Checkpoint) error {
 	if err := s.fillInForkChoiceMissingBlocks(ctx, blk, fCheckpoint, jCheckpoint); err != nil {
 		return err
 	}
 	// Feed in block to fork choice store.
 	if err := s.cfg.ForkChoiceStore.ProcessBlock(ctx,
-		blk.Slot, root, bytesutil.ToBytes32(blk.ParentRoot), bytesutil.ToBytes32(blk.Body.Graffiti),
+		blk.Slot(), root, bytesutil.ToBytes32(blk.ParentRoot()), bytesutil.ToBytes32(blk.Body().Graffiti()),
 		jCheckpoint.Epoch,
 		fCheckpoint.Epoch); err != nil {
 		return errors.Wrap(err, "could not process block for proto array fork choice")
@@ -382,19 +463,58 @@ func (s *Service) insertBlockToForkChoiceStore(ctx context.Context, blk *ethpb.B

 // This saves post state info to DB or cache. This also saves post state info to fork choice store.
 // Post state info consists of processed block and state. Do not call this method unless the block and state are verified.
-func (s *Service) savePostStateInfo(ctx context.Context, r [32]byte, b *ethpb.SignedBeaconBlock, st iface.BeaconState, initSync bool) error {
+func (s *Service) savePostStateInfo(ctx context.Context, r [32]byte, b block.SignedBeaconBlock, st state.BeaconState, initSync bool) error {
 	ctx, span := trace.StartSpan(ctx, "blockChain.savePostStateInfo")
 	defer span.End()
 	if initSync {
 		s.saveInitSyncBlock(r, b)
 	} else if err := s.cfg.BeaconDB.SaveBlock(ctx, b); err != nil {
-		return errors.Wrapf(err, "could not save block from slot %d", b.Block.Slot)
+		return errors.Wrapf(err, "could not save block from slot %d", b.Block().Slot())
 	}
 	if err := s.cfg.StateGen.SaveState(ctx, r, st); err != nil {
 		return errors.Wrap(err, "could not save state")
 	}
-	if err := s.insertBlockAndAttestationsToForkChoiceStore(ctx, b.Block, r, st); err != nil {
-		return errors.Wrapf(err, "could not insert block %d to fork choice store", b.Block.Slot)
+	if err := s.insertBlockAndAttestationsToForkChoiceStore(ctx, b.Block(), r, st); err != nil {
+		return errors.Wrapf(err, "could not insert block %d to fork choice store", b.Block().Slot())
 	}
 	return nil
 }
+
+// This removes the attestations from the mem pool. It will only remove the attestations if input root `r` is canonical,
+// meaning the block `b` is part of the canonical chain.
+func (s *Service) pruneCanonicalAttsFromPool(ctx context.Context, r [32]byte, b block.SignedBeaconBlock) error {
+	if !features.Get().CorrectlyPruneCanonicalAtts {
+		return nil
+	}
+
+	canonical, err := s.IsCanonical(ctx, r)
+	if err != nil {
+		return err
+	}
+	if !canonical {
+		return nil
+	}
+
+	atts := b.Block().Body().Attestations()
+	for _, att := range atts {
+		if helpers.IsAggregated(att) {
+			if err := s.cfg.AttPool.DeleteAggregatedAttestation(att); err != nil {
+				return err
+			}
+		} else {
+			if err := s.cfg.AttPool.DeleteUnaggregatedAttestation(att); err != nil {
+				return err
+			}
+		}
+	}
+	return nil
+}
+
+// Saves synced and validated tips to DB.
+func (s *Service) saveSyncedTipsDB(ctx context.Context) error {
+	tips := s.cfg.ForkChoiceStore.SyncedTips()
+	if len(tips) == 0 {
+		return nil
+	}
+	return s.cfg.BeaconDB.UpdateValidatedTips(ctx, tips)
+}
--- a/beacon-chain/blockchain/process_block_helpers.go
+++ b/beacon-chain/blockchain/process_block_helpers.go
@@ -7,26 +7,26 @@ import (

 	"github.com/pkg/errors"
 	types "github.com/prysmaticlabs/eth2-types"
-	ethpb "github.com/prysmaticlabs/ethereumapis/eth/v1alpha1"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/helpers"
-	iface "github.com/prysmaticlabs/prysm/beacon-chain/state/interface"
-	"github.com/prysmaticlabs/prysm/shared/attestationutil"
-	"github.com/prysmaticlabs/prysm/shared/bytesutil"
-	"github.com/prysmaticlabs/prysm/shared/featureconfig"
-	"github.com/prysmaticlabs/prysm/shared/params"
-	"github.com/prysmaticlabs/prysm/shared/traceutil"
+	"github.com/prysmaticlabs/prysm/beacon-chain/state"
+	"github.com/prysmaticlabs/prysm/config/params"
+	"github.com/prysmaticlabs/prysm/encoding/bytesutil"
+	"github.com/prysmaticlabs/prysm/monitoring/tracing"
+	ethpb "github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1"
+	"github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1/block"
+	"github.com/prysmaticlabs/prysm/time/slots"
 	"go.opencensus.io/trace"
 )

 // CurrentSlot returns the current slot based on time.
 func (s *Service) CurrentSlot() types.Slot {
-	return helpers.CurrentSlot(uint64(s.genesisTime.Unix()))
+	return slots.CurrentSlot(uint64(s.genesisTime.Unix()))
 }

 // getBlockPreState returns the pre state of an incoming block. It uses the parent root of the block
 // to retrieve the state in DB. It verifies the pre state's validity and the incoming block
 // is in the correct time window.
-func (s *Service) getBlockPreState(ctx context.Context, b *ethpb.BeaconBlock) (iface.BeaconState, error) {
+func (s *Service) getBlockPreState(ctx context.Context, b block.BeaconBlock) (state.BeaconState, error) {
 	ctx, span := trace.StartSpan(ctx, "blockChain.getBlockPreState")
 	defer span.End()

@@ -35,16 +35,16 @@ func (s *Service) getBlockPreState(ctx context.Context, b *ethpb.BeaconBlock) (i
 		return nil, err
 	}

-	preState, err := s.cfg.StateGen.StateByRoot(ctx, bytesutil.ToBytes32(b.ParentRoot))
+	preState, err := s.cfg.StateGen.StateByRoot(ctx, bytesutil.ToBytes32(b.ParentRoot()))
 	if err != nil {
-		return nil, errors.Wrapf(err, "could not get pre state for slot %d", b.Slot)
+		return nil, errors.Wrapf(err, "could not get pre state for slot %d", b.Slot())
 	}
-	if preState == nil {
-		return nil, errors.Wrapf(err, "nil pre state for slot %d", b.Slot)
+	if preState == nil || preState.IsNil() {
+		return nil, errors.Wrapf(err, "nil pre state for slot %d", b.Slot())
 	}

 	// Verify block slot time is not from the future.
-	if err := helpers.VerifySlotTime(preState.GenesisTime(), b.Slot, params.BeaconNetworkConfig().MaximumGossipClockDisparity); err != nil {
+	if err := slots.VerifyTime(uint64(s.genesisTime.Unix()), b.Slot(), params.BeaconNetworkConfig().MaximumGossipClockDisparity); err != nil {
 		return nil, err
 	}

@@ -57,11 +57,11 @@ func (s *Service) getBlockPreState(ctx context.Context, b *ethpb.BeaconBlock) (i
 }

 // verifyBlkPreState validates input block has a valid pre-state.
-func (s *Service) verifyBlkPreState(ctx context.Context, b *ethpb.BeaconBlock) error {
+func (s *Service) verifyBlkPreState(ctx context.Context, b block.BeaconBlock) error {
 	ctx, span := trace.StartSpan(ctx, "blockChain.verifyBlkPreState")
 	defer span.End()

-	parentRoot := bytesutil.ToBytes32(b.ParentRoot)
+	parentRoot := bytesutil.ToBytes32(b.ParentRoot())
 	// Loosen the check to HasBlock because state summary gets saved in batches
 	// during initial syncing. There's no risk given a state summary object is just a
 	// a subset of the block object.
@@ -69,7 +69,7 @@ func (s *Service) verifyBlkPreState(ctx context.Context, b *ethpb.BeaconBlock) e
 		return errors.New("could not reconstruct parent state")
 	}

-	if err := s.VerifyBlkDescendant(ctx, bytesutil.ToBytes32(b.ParentRoot)); err != nil {
+	if err := s.VerifyBlkDescendant(ctx, bytesutil.ToBytes32(b.ParentRoot())); err != nil {
 		return err
 	}

@@ -91,16 +91,20 @@ func (s *Service) verifyBlkPreState(ctx context.Context, b *ethpb.BeaconBlock) e
 func (s *Service) VerifyBlkDescendant(ctx context.Context, root [32]byte) error {
 	ctx, span := trace.StartSpan(ctx, "blockChain.VerifyBlkDescendant")
 	defer span.End()
-	fRoot := s.ensureRootNotZeros(bytesutil.ToBytes32(s.finalizedCheckpt.Root))
+	finalized := s.store.FinalizedCheckpt()
+	if finalized == nil {
+		return errNilFinalizedInStore
+	}
+	fRoot := s.ensureRootNotZeros(bytesutil.ToBytes32(finalized.Root))
 	finalizedBlkSigned, err := s.cfg.BeaconDB.Block(ctx, fRoot)
 	if err != nil {
 		return err
 	}
-	if finalizedBlkSigned == nil || finalizedBlkSigned.Block == nil {
+	if finalizedBlkSigned == nil || finalizedBlkSigned.IsNil() || finalizedBlkSigned.Block().IsNil() {
 		return errors.New("nil finalized block")
 	}
-	finalizedBlk := finalizedBlkSigned.Block
-	bFinalizedRoot, err := s.ancestor(ctx, root[:], finalizedBlk.Slot)
+	finalizedBlk := finalizedBlkSigned.Block()
+	bFinalizedRoot, err := s.ancestor(ctx, root[:], finalizedBlk.Slot())
 	if err != nil {
 		return errors.Wrap(err, "could not get finalized block root")
 	}
@@ -110,9 +114,9 @@ func (s *Service) VerifyBlkDescendant(ctx context.Context, root [32]byte) error

 	if !bytes.Equal(bFinalizedRoot, fRoot[:]) {
 		err := fmt.Errorf("block %#x is not a descendent of the current finalized block slot %d, %#x != %#x",
-			bytesutil.Trunc(root[:]), finalizedBlk.Slot, bytesutil.Trunc(bFinalizedRoot),
+			bytesutil.Trunc(root[:]), finalizedBlk.Slot(), bytesutil.Trunc(bFinalizedRoot),
 			bytesutil.Trunc(fRoot[:]))
-		traceutil.AnnotateError(span, err)
+		tracing.AnnotateError(span, err)
 		return err
 	}
 	return nil
@@ -120,13 +124,17 @@ func (s *Service) VerifyBlkDescendant(ctx context.Context, root [32]byte) error

 // verifyBlkFinalizedSlot validates input block is not less than or equal
 // to current finalized slot.
-func (s *Service) verifyBlkFinalizedSlot(b *ethpb.BeaconBlock) error {
-	finalizedSlot, err := helpers.StartSlot(s.finalizedCheckpt.Epoch)
+func (s *Service) verifyBlkFinalizedSlot(b block.BeaconBlock) error {
+	finalized := s.store.FinalizedCheckpt()
+	if finalized == nil {
+		return errNilFinalizedInStore
+	}
+	finalizedSlot, err := slots.EpochStart(finalized.Epoch)
 	if err != nil {
 		return err
 	}
-	if finalizedSlot >= b.Slot {
-		return fmt.Errorf("block is equal or earlier than finalized block, slot %d < slot %d", b.Slot, finalizedSlot)
+	if finalizedSlot >= b.Slot() {
+		return fmt.Errorf("block is equal or earlier than finalized block, slot %d < slot %d", b.Slot(), finalizedSlot)
 	}
 	return nil
 }
@@ -134,63 +142,59 @@ func (s *Service) verifyBlkFinalizedSlot(b *ethpb.BeaconBlock) error {
 // shouldUpdateCurrentJustified prevents bouncing attack, by only update conflicting justified
 // checkpoints in the fork choice if in the early slots of the epoch.
 // Otherwise, delay incorporation of new justified checkpoint until next epoch boundary.
-// See https://ethresear.ch/t/prevention-of-bouncing-attack-on-ffg/6114 for more detailed analysis and discussion.
+//
+// Spec code:
+// def should_update_justified_checkpoint(store: Store, new_justified_checkpoint: Checkpoint) -> bool:
+//    """
+//    To address the bouncing attack, only update conflicting justified
+//    checkpoints in the fork choice if in the early slots of the epoch.
+//    Otherwise, delay incorporation of new justified checkpoint until next epoch boundary.
+//
+//    See https://ethresear.ch/t/prevention-of-bouncing-attack-on-ffg/6114 for more detailed analysis and discussion.
+//    """
+//    if compute_slots_since_epoch_start(get_current_slot(store)) < SAFE_SLOTS_TO_UPDATE_JUSTIFIED:
+//        return True
+//
+//    justified_slot = compute_start_slot_at_epoch(store.justified_checkpoint.epoch)
+//    if not get_ancestor(store, new_justified_checkpoint.root, justified_slot) == store.justified_checkpoint.root:
+//        return False
+//
+//    return True
 func (s *Service) shouldUpdateCurrentJustified(ctx context.Context, newJustifiedCheckpt *ethpb.Checkpoint) (bool, error) {
-	if helpers.SlotsSinceEpochStarts(s.CurrentSlot()) < params.BeaconConfig().SafeSlotsToUpdateJustified {
+	ctx, span := trace.StartSpan(ctx, "blockChain.shouldUpdateCurrentJustified")
+	defer span.End()
+
+	if slots.SinceEpochStarts(s.CurrentSlot()) < params.BeaconConfig().SafeSlotsToUpdateJustified {
 		return true, nil
 	}
-	var newJustifiedBlockSigned *ethpb.SignedBeaconBlock
+	justified := s.store.JustifiedCheckpt()
+	jSlot, err := slots.EpochStart(justified.Epoch)
+	if err != nil {
+		return false, err
+	}
 	justifiedRoot := s.ensureRootNotZeros(bytesutil.ToBytes32(newJustifiedCheckpt.Root))
-	var err error
-	if s.hasInitSyncBlock(justifiedRoot) {
-		newJustifiedBlockSigned = s.getInitSyncBlock(justifiedRoot)
-	} else {
-		newJustifiedBlockSigned, err = s.cfg.BeaconDB.Block(ctx, justifiedRoot)
-		if err != nil {
-			return false, err
-		}
-	}
-	if newJustifiedBlockSigned == nil || newJustifiedBlockSigned.Block == nil {
-		return false, errors.New("nil new justified block")
-	}
-
-	newJustifiedBlock := newJustifiedBlockSigned.Block
-	jSlot, err := helpers.StartSlot(s.justifiedCheckpt.Epoch)
+	b, err := s.ancestor(ctx, justifiedRoot[:], jSlot)
 	if err != nil {
 		return false, err
 	}
-	if newJustifiedBlock.Slot <= jSlot {
+	if !bytes.Equal(b, justified.Root) {
 		return false, nil
 	}
-	var justifiedBlockSigned *ethpb.SignedBeaconBlock
-	cachedJustifiedRoot := s.ensureRootNotZeros(bytesutil.ToBytes32(s.justifiedCheckpt.Root))
-	if s.hasInitSyncBlock(cachedJustifiedRoot) {
-		justifiedBlockSigned = s.getInitSyncBlock(cachedJustifiedRoot)
-	} else {
-		justifiedBlockSigned, err = s.cfg.BeaconDB.Block(ctx, cachedJustifiedRoot)
-		if err != nil {
-			return false, err
-		}
-	}

-	if justifiedBlockSigned == nil || justifiedBlockSigned.Block == nil {
-		return false, errors.New("nil justified block")
-	}
-	justifiedBlock := justifiedBlockSigned.Block
-	b, err := s.ancestor(ctx, justifiedRoot[:], justifiedBlock.Slot)
-	if err != nil {
-		return false, err
-	}
-	if !bytes.Equal(b, s.justifiedCheckpt.Root) {
-		return false, nil
-	}
 	return true, nil
 }

-func (s *Service) updateJustified(ctx context.Context, state iface.ReadOnlyBeaconState) error {
+func (s *Service) updateJustified(ctx context.Context, state state.ReadOnlyBeaconState) error {
+	ctx, span := trace.StartSpan(ctx, "blockChain.updateJustified")
+	defer span.End()
+
 	cpt := state.CurrentJustifiedCheckpoint()
-	if cpt.Epoch > s.bestJustifiedCheckpt.Epoch {
-		s.bestJustifiedCheckpt = cpt
+	bestJustified := s.store.BestJustifiedCheckpt()
+	if bestJustified == nil {
+		return errNilBestJustifiedInStore
+	}
+	if cpt.Epoch > bestJustified.Epoch {
+		s.store.SetBestJustifiedCheckpt(cpt)
 	}
 	canUpdate, err := s.shouldUpdateCurrentJustified(ctx, cpt)
 	if err != nil {
@@ -198,30 +202,39 @@ func (s *Service) updateJustified(ctx context.Context, state iface.ReadOnlyBeaco
 	}

 	if canUpdate {
-		s.prevJustifiedCheckpt = s.justifiedCheckpt
-		s.justifiedCheckpt = cpt
-		if err := s.cacheJustifiedStateBalances(ctx, bytesutil.ToBytes32(s.justifiedCheckpt.Root)); err != nil {
-			return err
+		justified := s.store.JustifiedCheckpt()
+		if justified == nil {
+			return errNilJustifiedInStore
 		}
+		s.store.SetPrevJustifiedCheckpt(justified)
+		s.store.SetJustifiedCheckpt(cpt)
 	}

-	return s.cfg.BeaconDB.SaveJustifiedCheckpoint(ctx, cpt)
+	return nil
 }

 // This caches input checkpoint as justified for the service struct. It rotates current justified to previous justified,
 // caches justified checkpoint balances for fork choice and save justified checkpoint in DB.
 // This method does not have defense against fork choice bouncing attack, which is why it's only recommend to be used during initial syncing.
 func (s *Service) updateJustifiedInitSync(ctx context.Context, cp *ethpb.Checkpoint) error {
-	s.prevJustifiedCheckpt = s.justifiedCheckpt
-	s.justifiedCheckpt = cp
-	if err := s.cacheJustifiedStateBalances(ctx, bytesutil.ToBytes32(s.justifiedCheckpt.Root)); err != nil {
+	justified := s.store.JustifiedCheckpt()
+	if justified == nil {
+		return errNilJustifiedInStore
+	}
+	s.store.SetPrevJustifiedCheckpt(justified)
+
+	if err := s.cfg.BeaconDB.SaveJustifiedCheckpoint(ctx, cp); err != nil {
 		return err
 	}
+	s.store.SetJustifiedCheckpt(cp)

-	return s.cfg.BeaconDB.SaveJustifiedCheckpoint(ctx, cp)
+	return nil
 }

 func (s *Service) updateFinalized(ctx context.Context, cp *ethpb.Checkpoint) error {
+	ctx, span := trace.StartSpan(ctx, "blockChain.updateFinalized")
+	defer span.End()
+
 	// Blocks need to be saved so that we can retrieve finalized block from
 	// DB when migrating states.
 	if err := s.cfg.BeaconDB.SaveBlocks(ctx, s.getInitSyncBlocks()); err != nil {
@@ -232,10 +245,6 @@ func (s *Service) updateFinalized(ctx context.Context, cp *ethpb.Checkpoint) err
 	if err := s.cfg.BeaconDB.SaveFinalizedCheckpoint(ctx, cp); err != nil {
 		return err
 	}
-	if !featureconfig.Get().UpdateHeadTimely {
-		s.prevFinalizedCheckpt = s.finalizedCheckpt
-		s.finalizedCheckpt = cp
-	}

 	fRoot := bytesutil.ToBytes32(cp.Root)
 	if err := s.cfg.StateGen.MigrateToCold(ctx, fRoot); err != nil {
@@ -307,71 +316,32 @@ func (s *Service) ancestorByDB(ctx context.Context, r [32]byte, slot types.Slot)
 		signed = s.getInitSyncBlock(r)
 	}

-	if signed == nil || signed.Block == nil {
+	if signed == nil || signed.IsNil() || signed.Block().IsNil() {
 		return nil, errors.New("nil block")
 	}
-	b := signed.Block
-	if b.Slot == slot || b.Slot < slot {
+	b := signed.Block()
+	if b.Slot() == slot || b.Slot() < slot {
 		return r[:], nil
 	}

-	return s.ancestorByDB(ctx, bytesutil.ToBytes32(b.ParentRoot), slot)
-}
-
-// This updates justified check point in store, if the new justified is later than stored justified or
-// the store's justified is not in chain with finalized check point.
-//
-// Spec definition:
-//   # Potentially update justified if different from store
-//        if store.justified_checkpoint != state.current_justified_checkpoint:
-//            # Update justified if new justified is later than store justified
-//            if state.current_justified_checkpoint.epoch > store.justified_checkpoint.epoch:
-//                store.justified_checkpoint = state.current_justified_checkpoint
-//                return
-//            # Update justified if store justified is not in chain with finalized checkpoint
-//            finalized_slot = compute_start_slot_at_epoch(store.finalized_checkpoint.epoch)
-//            ancestor_at_finalized_slot = get_ancestor(store, store.justified_checkpoint.root, finalized_slot)
-//            if ancestor_at_finalized_slot != store.finalized_checkpoint.root:
-//                store.justified_checkpoint = state.current_justified_checkpoint
-func (s *Service) finalizedImpliesNewJustified(ctx context.Context, state iface.BeaconState) error {
-	// Update justified if it's different than the one cached in the store.
-	if !attestationutil.CheckPointIsEqual(s.justifiedCheckpt, state.CurrentJustifiedCheckpoint()) {
-		if state.CurrentJustifiedCheckpoint().Epoch > s.justifiedCheckpt.Epoch {
-			s.justifiedCheckpt = state.CurrentJustifiedCheckpoint()
-			return s.cacheJustifiedStateBalances(ctx, bytesutil.ToBytes32(s.justifiedCheckpt.Root))
-		}
-
-		// Update justified if store justified is not in chain with finalized check point.
-		finalizedSlot, err := helpers.StartSlot(s.finalizedCheckpt.Epoch)
-		if err != nil {
-			return err
-		}
-		justifiedRoot := s.ensureRootNotZeros(bytesutil.ToBytes32(s.justifiedCheckpt.Root))
-		anc, err := s.ancestor(ctx, justifiedRoot[:], finalizedSlot)
-		if err != nil {
-			return err
-		}
-		if !bytes.Equal(anc, s.finalizedCheckpt.Root) {
-			s.justifiedCheckpt = state.CurrentJustifiedCheckpoint()
-			if err := s.cacheJustifiedStateBalances(ctx, bytesutil.ToBytes32(s.justifiedCheckpt.Root)); err != nil {
-				return err
-			}
-		}
-	}
-	return nil
+	return s.ancestorByDB(ctx, bytesutil.ToBytes32(b.ParentRoot()), slot)
 }

 // This retrieves missing blocks from DB (ie. the blocks that couldn't be received over sync) and inserts them to fork choice store.
 // This is useful for block tree visualizer and additional vote accounting.
-func (s *Service) fillInForkChoiceMissingBlocks(ctx context.Context, blk *ethpb.BeaconBlock,
+func (s *Service) fillInForkChoiceMissingBlocks(ctx context.Context, blk block.BeaconBlock,
 	fCheckpoint, jCheckpoint *ethpb.Checkpoint) error {
-	pendingNodes := make([]*ethpb.BeaconBlock, 0)
+	pendingNodes := make([]block.BeaconBlock, 0)
 	pendingRoots := make([][32]byte, 0)

-	parentRoot := bytesutil.ToBytes32(blk.ParentRoot)
-	slot := blk.Slot
+	parentRoot := bytesutil.ToBytes32(blk.ParentRoot())
+	slot := blk.Slot()
 	// Fork choice only matters from last finalized slot.
-	fSlot, err := helpers.StartSlot(s.finalizedCheckpt.Epoch)
+	finalized := s.store.FinalizedCheckpt()
+	if finalized == nil {
+		return errNilFinalizedInStore
+	}
+	fSlot, err := slots.EpochStart(finalized.Epoch)
 	if err != nil {
 		return err
 	}
@@ -383,11 +353,11 @@ func (s *Service) fillInForkChoiceMissingBlocks(ctx context.Context, blk *ethpb.
 			return err
 		}

-		pendingNodes = append(pendingNodes, b.Block)
+		pendingNodes = append(pendingNodes, b.Block())
 		copiedRoot := parentRoot
 		pendingRoots = append(pendingRoots, copiedRoot)
-		parentRoot = bytesutil.ToBytes32(b.Block.ParentRoot)
-		slot = b.Block.Slot
+		parentRoot = bytesutil.ToBytes32(b.Block().ParentRoot())
+		slot = b.Block().Slot()
 		higherThanFinalized = slot > fSlot
 	}

@@ -397,7 +367,7 @@ func (s *Service) fillInForkChoiceMissingBlocks(ctx context.Context, blk *ethpb.
 		b := pendingNodes[i]
 		r := pendingRoots[i]
 		if err := s.cfg.ForkChoiceStore.ProcessBlock(ctx,
-			b.Slot, r, bytesutil.ToBytes32(b.ParentRoot), bytesutil.ToBytes32(b.Body.Graffiti),
+			b.Slot(), r, bytesutil.ToBytes32(b.ParentRoot()), bytesutil.ToBytes32(b.Body().Graffiti()),
 			jCheckpoint.Epoch,
 			fCheckpoint.Epoch); err != nil {
 			return errors.Wrap(err, "could not process block for proto array fork choice")
@@ -450,7 +420,7 @@ func (s *Service) deletePoolAtts(atts []*ethpb.Attestation) error {
 // fork choice justification routine.
 func (s *Service) ensureRootNotZeros(root [32]byte) [32]byte {
 	if root == params.BeaconConfig().ZeroHash {
-		return s.genesisRoot
+		return s.originBlockRoot
 	}
 	return root
 }
--- a/beacon-chain/blockchain/process_block_test.go
+++ b/beacon-chain/blockchain/process_block_test.go
--- a/beacon-chain/blockchain/receive_attestation.go
+++ b/beacon-chain/blockchain/receive_attestation.go
@@ -7,21 +7,28 @@ import (
 	"time"

 	"github.com/pkg/errors"
-	ethpb "github.com/prysmaticlabs/ethereumapis/eth/v1alpha1"
+	"github.com/prysmaticlabs/prysm/async/event"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/feed"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/helpers"
-	iface "github.com/prysmaticlabs/prysm/beacon-chain/state/interface"
-	"github.com/prysmaticlabs/prysm/shared/bytesutil"
-	"github.com/prysmaticlabs/prysm/shared/params"
-	"github.com/prysmaticlabs/prysm/shared/slotutil"
+	"github.com/prysmaticlabs/prysm/beacon-chain/state"
+	"github.com/prysmaticlabs/prysm/config/params"
+	"github.com/prysmaticlabs/prysm/encoding/bytesutil"
+	ethpb "github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1"
+	"github.com/prysmaticlabs/prysm/time/slots"
 	"github.com/sirupsen/logrus"
 	"go.opencensus.io/trace"
 )

+// AttestationStateFetcher allows for retrieving a beacon state corresponding to the block
+// root of an attestation's target checkpoint.
+type AttestationStateFetcher interface {
+	AttestationTargetState(ctx context.Context, target *ethpb.Checkpoint) (state.BeaconState, error)
+}
+
 // AttestationReceiver interface defines the methods of chain service receive and processing new attestations.
 type AttestationReceiver interface {
+	AttestationStateFetcher
 	ReceiveAttestationNoPubsub(ctx context.Context, att *ethpb.Attestation) error
-	AttestationPreState(ctx context.Context, att *ethpb.Attestation) (iface.BeaconState, error)
 	VerifyLmdFfgConsistency(ctx context.Context, att *ethpb.Attestation) error
 	VerifyFinalizedConsistency(ctx context.Context, root []byte) error
 }
@@ -35,28 +42,28 @@ func (s *Service) ReceiveAttestationNoPubsub(ctx context.Context, att *ethpb.Att
 	ctx, span := trace.StartSpan(ctx, "beacon-chain.blockchain.ReceiveAttestationNoPubsub")
 	defer span.End()

-	if err := s.onAttestation(ctx, att); err != nil {
+	if err := s.OnAttestation(ctx, att); err != nil {
 		return errors.Wrap(err, "could not process attestation")
 	}

 	return nil
 }

-// AttestationPreState returns the pre state of attestation.
-func (s *Service) AttestationPreState(ctx context.Context, att *ethpb.Attestation) (iface.BeaconState, error) {
-	ss, err := helpers.StartSlot(att.Data.Target.Epoch)
+// AttestationTargetState returns the pre state of attestation.
+func (s *Service) AttestationTargetState(ctx context.Context, target *ethpb.Checkpoint) (state.BeaconState, error) {
+	ss, err := slots.EpochStart(target.Epoch)
 	if err != nil {
 		return nil, err
 	}
-	if err := helpers.ValidateSlotClock(ss, uint64(s.genesisTime.Unix())); err != nil {
+	if err := slots.ValidateClock(ss, uint64(s.genesisTime.Unix())); err != nil {
 		return nil, err
 	}
-	return s.getAttPreState(ctx, att.Data.Target)
+	return s.getAttPreState(ctx, target)
 }

 // VerifyLmdFfgConsistency verifies that attestation's LMD and FFG votes are consistency to each other.
 func (s *Service) VerifyLmdFfgConsistency(ctx context.Context, a *ethpb.Attestation) error {
-	targetSlot, err := helpers.StartSlot(a.Data.Target.Epoch)
+	targetSlot, err := slots.EpochStart(a.Data.Target.Epoch)
 	if err != nil {
 		return err
 	}
@@ -81,7 +88,10 @@ func (s *Service) VerifyFinalizedConsistency(ctx context.Context, root []byte) e
 	}

 	f := s.FinalizedCheckpt()
-	ss, err := helpers.StartSlot(f.Epoch)
+	if f == nil {
+		return errNilFinalizedInStore
+	}
+	ss, err := slots.EpochStart(f.Epoch)
 	if err != nil {
 		return err
 	}
@@ -97,39 +107,66 @@ func (s *Service) VerifyFinalizedConsistency(ctx context.Context, root []byte) e
 }

 // This routine processes fork choice attestations from the pool to account for validator votes and fork choice.
-func (s *Service) processAttestationsRoutine(subscribedToStateEvents chan<- struct{}) {
+func (s *Service) spawnProcessAttestationsRoutine(stateFeed *event.Feed) {
 	// Wait for state to be initialized.
 	stateChannel := make(chan *feed.Event, 1)
-	stateSub := s.cfg.StateNotifier.StateFeed().Subscribe(stateChannel)
-	subscribedToStateEvents <- struct{}{}
-	<-stateChannel
-	stateSub.Unsubscribe()
-
-	if s.genesisTime.IsZero() {
-		log.Warn("ProcessAttestations routine waiting for genesis time")
-		for s.genesisTime.IsZero() {
-			time.Sleep(1 * time.Second)
-		}
-		log.Warn("Genesis time received, now available to process attestations")
-	}
-
-	st := slotutil.NewSlotTicker(s.genesisTime, params.BeaconConfig().SecondsPerSlot)
-	for {
+	stateSub := stateFeed.Subscribe(stateChannel)
+	go func() {
 		select {
 		case <-s.ctx.Done():
+			stateSub.Unsubscribe()
 			return
-		case <-st.C():
-			// Continue when there's no fork choice attestation, there's nothing to process and update head.
-			// This covers the condition when the node is still initial syncing to the head of the chain.
-			if s.cfg.AttPool.ForkchoiceAttestationCount() == 0 {
-				continue
+		case <-stateChannel:
+			stateSub.Unsubscribe()
+			break
+		}
+
+		if s.genesisTime.IsZero() {
+			log.Warn("ProcessAttestations routine waiting for genesis time")
+			for s.genesisTime.IsZero() {
+				if err := s.ctx.Err(); err != nil {
+					log.WithError(err).Error("Giving up waiting for genesis time")
+					return
+				}
+				time.Sleep(1 * time.Second)
 			}
-			s.processAttestations(s.ctx)
-			if err := s.updateHead(s.ctx, s.getJustifiedBalances()); err != nil {
-				log.Warnf("Resolving fork due to new attestation: %v", err)
+			log.Warn("Genesis time received, now available to process attestations")
+		}
+
+		st := slots.NewSlotTicker(s.genesisTime, params.BeaconConfig().SecondsPerSlot)
+		for {
+			select {
+			case <-s.ctx.Done():
+				return
+			case <-st.C():
+				if err := s.NewSlot(s.ctx, s.CurrentSlot()); err != nil {
+					log.WithError(err).Error("Could not process new slot")
+					return
+				}
+
+				// Continue when there's no fork choice attestation, there's nothing to process and update head.
+				// This covers the condition when the node is still initial syncing to the head of the chain.
+				if s.cfg.AttPool.ForkchoiceAttestationCount() == 0 {
+					continue
+				}
+				s.processAttestations(s.ctx)
+
+				justified := s.store.JustifiedCheckpt()
+				if justified == nil {
+					log.WithError(errNilJustifiedInStore).Error("Could not get justified checkpoint")
+					continue
+				}
+				balances, err := s.justifiedBalances.get(s.ctx, bytesutil.ToBytes32(justified.Root))
+				if err != nil {
+					log.WithError(err).Errorf("Unable to get justified balances for root %v", justified.Root)
+					continue
+				}
+				if err := s.updateHead(s.ctx, balances); err != nil {
+					log.WithError(err).Warn("Resolving fork due to new attestation")
+				}
 			}
 		}
-	}
+	}()
 }

 // This processes fork choice attestations from the pool to account for validator votes and fork choice.
@@ -138,9 +175,9 @@ func (s *Service) processAttestations(ctx context.Context) {
 	for _, a := range atts {
 		// Based on the spec, don't process the attestation until the subsequent slot.
 		// This delays consideration in the fork choice until their slot is in the past.
-		// https://github.com/ethereum/eth2.0-specs/blob/dev/specs/phase0/fork-choice.md#validate_on_attestation
+		// https://github.com/ethereum/consensus-specs/blob/dev/specs/phase0/fork-choice.md#validate_on_attestation
 		nextSlot := a.Data.Slot + 1
-		if err := helpers.VerifySlotTime(uint64(s.genesisTime.Unix()), nextSlot, params.BeaconNetworkConfig().MaximumGossipClockDisparity); err != nil {
+		if err := slots.VerifyTime(uint64(s.genesisTime.Unix()), nextSlot, params.BeaconNetworkConfig().MaximumGossipClockDisparity); err != nil {
 			continue
 		}

--- a/beacon-chain/blockchain/receive_attestation_test.go
+++ b/beacon-chain/blockchain/receive_attestation_test.go
@@ -6,21 +6,26 @@ import (
 	"time"

 	types "github.com/prysmaticlabs/eth2-types"
-	ethpb "github.com/prysmaticlabs/ethereumapis/eth/v1alpha1"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/helpers"
-	"github.com/prysmaticlabs/prysm/beacon-chain/core/state"
+	"github.com/prysmaticlabs/prysm/beacon-chain/core/transition"
 	testDB "github.com/prysmaticlabs/prysm/beacon-chain/db/testing"
-	"github.com/prysmaticlabs/prysm/beacon-chain/forkchoice/protoarray"
 	"github.com/prysmaticlabs/prysm/beacon-chain/operations/attestations"
-	"github.com/prysmaticlabs/prysm/beacon-chain/state/stategen"
-	"github.com/prysmaticlabs/prysm/shared/bytesutil"
-	"github.com/prysmaticlabs/prysm/shared/params"
-	"github.com/prysmaticlabs/prysm/shared/testutil"
-	"github.com/prysmaticlabs/prysm/shared/testutil/require"
-	"github.com/prysmaticlabs/prysm/shared/timeutils"
+	"github.com/prysmaticlabs/prysm/config/params"
+	"github.com/prysmaticlabs/prysm/encoding/bytesutil"
+	ethpb "github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1"
+	"github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1/wrapper"
+	"github.com/prysmaticlabs/prysm/testing/require"
+	"github.com/prysmaticlabs/prysm/testing/util"
+	prysmTime "github.com/prysmaticlabs/prysm/time"
+	"github.com/prysmaticlabs/prysm/time/slots"
 	logTest "github.com/sirupsen/logrus/hooks/test"
 )

+var (
+	_ = AttestationReceiver(&Service{})
+	_ = AttestationStateFetcher(&Service{})
+)
+
 func TestAttestationCheckPtState_FarFutureSlot(t *testing.T) {
 	helpers.ClearCache()
 	beaconDB := testDB.SetupDB(t)
@@ -28,33 +33,32 @@ func TestAttestationCheckPtState_FarFutureSlot(t *testing.T) {
 	chainService := setupBeaconChain(t, beaconDB)
 	chainService.genesisTime = time.Now()

-	e := types.Epoch(helpers.MaxSlotBuffer/uint64(params.BeaconConfig().SlotsPerEpoch) + 1)
-	_, err := chainService.AttestationPreState(context.Background(), &ethpb.Attestation{Data: &ethpb.AttestationData{Target: &ethpb.Checkpoint{Epoch: e}}})
+	e := types.Epoch(slots.MaxSlotBuffer/uint64(params.BeaconConfig().SlotsPerEpoch) + 1)
+	_, err := chainService.AttestationTargetState(context.Background(), &ethpb.Checkpoint{Epoch: e})
 	require.ErrorContains(t, "exceeds max allowed value relative to the local clock", err)
 }

 func TestVerifyLMDFFGConsistent_NotOK(t *testing.T) {
 	ctx := context.Background()
-	beaconDB := testDB.SetupDB(t)
+	opts := testServiceOptsWithDB(t)

-	cfg := &Config{BeaconDB: beaconDB, ForkChoiceStore: protoarray.New(0, 0, [32]byte{})}
-	service, err := NewService(ctx, cfg)
+	service, err := NewService(ctx, opts...)
 	require.NoError(t, err)

-	b32 := testutil.NewBeaconBlock()
+	b32 := util.NewBeaconBlock()
 	b32.Block.Slot = 32
-	require.NoError(t, service.cfg.BeaconDB.SaveBlock(ctx, b32))
+	require.NoError(t, service.cfg.BeaconDB.SaveBlock(ctx, wrapper.WrappedPhase0SignedBeaconBlock(b32)))
 	r32, err := b32.Block.HashTreeRoot()
 	require.NoError(t, err)
-	b33 := testutil.NewBeaconBlock()
+	b33 := util.NewBeaconBlock()
 	b33.Block.Slot = 33
 	b33.Block.ParentRoot = r32[:]
-	require.NoError(t, service.cfg.BeaconDB.SaveBlock(ctx, b33))
+	require.NoError(t, service.cfg.BeaconDB.SaveBlock(ctx, wrapper.WrappedPhase0SignedBeaconBlock(b33)))
 	r33, err := b33.Block.HashTreeRoot()
 	require.NoError(t, err)

 	wanted := "FFG and LMD votes are not consistent"
-	a := testutil.NewAttestation()
+	a := util.NewAttestation()
 	a.Data.Target.Epoch = 1
 	a.Data.Target.Root = []byte{'a'}
 	a.Data.BeaconBlockRoot = r33[:]
@@ -63,25 +67,24 @@ func TestVerifyLMDFFGConsistent_NotOK(t *testing.T) {

 func TestVerifyLMDFFGConsistent_OK(t *testing.T) {
 	ctx := context.Background()
-	beaconDB := testDB.SetupDB(t)

-	cfg := &Config{BeaconDB: beaconDB, ForkChoiceStore: protoarray.New(0, 0, [32]byte{})}
-	service, err := NewService(ctx, cfg)
+	opts := testServiceOptsWithDB(t)
+	service, err := NewService(ctx, opts...)
 	require.NoError(t, err)

-	b32 := testutil.NewBeaconBlock()
+	b32 := util.NewBeaconBlock()
 	b32.Block.Slot = 32
-	require.NoError(t, service.cfg.BeaconDB.SaveBlock(ctx, b32))
+	require.NoError(t, service.cfg.BeaconDB.SaveBlock(ctx, wrapper.WrappedPhase0SignedBeaconBlock(b32)))
 	r32, err := b32.Block.HashTreeRoot()
 	require.NoError(t, err)
-	b33 := testutil.NewBeaconBlock()
+	b33 := util.NewBeaconBlock()
 	b33.Block.Slot = 33
 	b33.Block.ParentRoot = r32[:]
-	require.NoError(t, service.cfg.BeaconDB.SaveBlock(ctx, b33))
+	require.NoError(t, service.cfg.BeaconDB.SaveBlock(ctx, wrapper.WrappedPhase0SignedBeaconBlock(b33)))
 	r33, err := b33.Block.HashTreeRoot()
 	require.NoError(t, err)

-	a := testutil.NewAttestation()
+	a := util.NewAttestation()
 	a.Data.Target.Epoch = 1
 	a.Data.Target.Root = r32[:]
 	a.Data.BeaconBlockRoot = r33[:]
@@ -92,25 +95,20 @@ func TestVerifyLMDFFGConsistent_OK(t *testing.T) {
 func TestProcessAttestations_Ok(t *testing.T) {
 	hook := logTest.NewGlobal()
 	ctx := context.Background()
-	beaconDB := testDB.SetupDB(t)
+	opts := testServiceOptsWithDB(t)
+	opts = append(opts, WithAttestationPool(attestations.NewPool()))

-	cfg := &Config{
-		BeaconDB:        beaconDB,
-		ForkChoiceStore: protoarray.New(0, 0, [32]byte{}),
-		StateGen:        stategen.New(beaconDB),
-		AttPool:         attestations.NewPool(),
-	}
-	service, err := NewService(ctx, cfg)
-	service.genesisTime = timeutils.Now().Add(-1 * time.Duration(params.BeaconConfig().SecondsPerSlot) * time.Second)
+	service, err := NewService(ctx, opts...)
 	require.NoError(t, err)
-	genesisState, pks := testutil.DeterministicGenesisState(t, 64)
-	require.NoError(t, genesisState.SetGenesisTime(uint64(timeutils.Now().Unix())-params.BeaconConfig().SecondsPerSlot))
+	service.genesisTime = prysmTime.Now().Add(-1 * time.Duration(params.BeaconConfig().SecondsPerSlot) * time.Second)
+	genesisState, pks := util.DeterministicGenesisState(t, 64)
+	require.NoError(t, genesisState.SetGenesisTime(uint64(prysmTime.Now().Unix())-params.BeaconConfig().SecondsPerSlot))
 	require.NoError(t, service.saveGenesisData(ctx, genesisState))
-	atts, err := testutil.GenerateAttestations(genesisState, pks, 1, 0, false)
+	atts, err := util.GenerateAttestations(genesisState, pks, 1, 0, false)
 	require.NoError(t, err)
 	tRoot := bytesutil.ToBytes32(atts[0].Data.Target.Root)
 	copied := genesisState.Copy()
-	copied, err = state.ProcessSlots(ctx, copied, 1)
+	copied, err = transition.ProcessSlots(ctx, copied, 1)
 	require.NoError(t, err)
 	require.NoError(t, service.cfg.BeaconDB.SaveState(ctx, copied, tRoot))
 	require.NoError(t, service.cfg.ForkChoiceStore.ProcessBlock(ctx, 0, tRoot, tRoot, tRoot, 1, 1))
--- a/beacon-chain/blockchain/receive_block.go
+++ b/beacon-chain/blockchain/receive_block.go
@@ -5,14 +5,12 @@ import (

 	"github.com/pkg/errors"
 	types "github.com/prysmaticlabs/eth2-types"
-	ethpb "github.com/prysmaticlabs/ethereumapis/eth/v1alpha1"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/feed"
 	statefeed "github.com/prysmaticlabs/prysm/beacon-chain/core/feed/state"
-	"github.com/prysmaticlabs/prysm/beacon-chain/core/helpers"
-	"github.com/prysmaticlabs/prysm/beacon-chain/state/stateV0"
-	"github.com/prysmaticlabs/prysm/shared/featureconfig"
-	"github.com/prysmaticlabs/prysm/shared/timeutils"
-	"github.com/prysmaticlabs/prysm/shared/traceutil"
+	"github.com/prysmaticlabs/prysm/monitoring/tracing"
+	"github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1/block"
+	"github.com/prysmaticlabs/prysm/time"
+	"github.com/prysmaticlabs/prysm/time/slots"
 	"go.opencensus.io/trace"
 )

@@ -21,8 +19,8 @@ var epochsSinceFinalitySaveHotStateDB = types.Epoch(100)

 // BlockReceiver interface defines the methods of chain service receive and processing new blocks.
 type BlockReceiver interface {
-	ReceiveBlock(ctx context.Context, block *ethpb.SignedBeaconBlock, blockRoot [32]byte) error
-	ReceiveBlockBatch(ctx context.Context, blocks []*ethpb.SignedBeaconBlock, blkRoots [][32]byte) error
+	ReceiveBlock(ctx context.Context, block block.SignedBeaconBlock, blockRoot [32]byte) error
+	ReceiveBlockBatch(ctx context.Context, blocks []block.SignedBeaconBlock, blkRoots [][32]byte) error
 	HasInitSyncBlock(root [32]byte) bool
 }

@@ -31,38 +29,21 @@ type BlockReceiver interface {
 //   1. Validate block, apply state transition and update check points
 //   2. Apply fork choice to the processed block
 //   3. Save latest head info
-func (s *Service) ReceiveBlock(ctx context.Context, block *ethpb.SignedBeaconBlock, blockRoot [32]byte) error {
+func (s *Service) ReceiveBlock(ctx context.Context, block block.SignedBeaconBlock, blockRoot [32]byte) error {
 	ctx, span := trace.StartSpan(ctx, "blockChain.ReceiveBlock")
 	defer span.End()
-	receivedTime := timeutils.Now()
-	blockCopy := stateV0.CopySignedBeaconBlock(block)
+	receivedTime := time.Now()
+	blockCopy := block.Copy()

 	// Apply state transition on the new block.
 	if err := s.onBlock(ctx, blockCopy, blockRoot); err != nil {
 		err := errors.Wrap(err, "could not process block")
-		traceutil.AnnotateError(span, err)
+		tracing.AnnotateError(span, err)
 		return err
 	}

-	// Update and save head block after fork choice.
-	if !featureconfig.Get().UpdateHeadTimely {
-		if err := s.updateHead(ctx, s.getJustifiedBalances()); err != nil {
-			log.WithError(err).Warn("Could not update head")
-		}
-		// Send notification of the processed block to the state feed.
-		s.cfg.StateNotifier.StateFeed().Send(&feed.Event{
-			Type: statefeed.BlockProcessed,
-			Data: &statefeed.BlockProcessedData{
-				Slot:        blockCopy.Block.Slot,
-				BlockRoot:   blockRoot,
-				SignedBlock: blockCopy,
-				Verified:    true,
-			},
-		})
-	}
-
 	// Handle post block operations such as attestations and exits.
-	if err := s.handlePostBlockOperations(blockCopy.Block); err != nil {
+	if err := s.handlePostBlockOperations(blockCopy.Block()); err != nil {
 		return err
 	}

@@ -72,14 +53,18 @@ func (s *Service) ReceiveBlock(ctx context.Context, block *ethpb.SignedBeaconBlo
 	}

 	// Reports on block and fork choice metrics.
-	reportSlotMetrics(blockCopy.Block.Slot, s.HeadSlot(), s.CurrentSlot(), s.finalizedCheckpt)
+	finalized := s.store.FinalizedCheckpt()
+	if finalized == nil {
+		return errNilFinalizedInStore
+	}
+	reportSlotMetrics(blockCopy.Block().Slot(), s.HeadSlot(), s.CurrentSlot(), finalized)

 	// Log block sync status.
-	if err := logBlockSyncStatus(blockCopy.Block, blockRoot, s.finalizedCheckpt, receivedTime, uint64(s.genesisTime.Unix())); err != nil {
+	if err := logBlockSyncStatus(blockCopy.Block(), blockRoot, finalized, receivedTime, uint64(s.genesisTime.Unix())); err != nil {
 		return err
 	}
 	// Log state transition data.
-	logStateTransitionData(blockCopy.Block)
+	logStateTransitionData(blockCopy.Block())

 	return nil
 }
@@ -87,7 +72,7 @@ func (s *Service) ReceiveBlock(ctx context.Context, block *ethpb.SignedBeaconBlo
 // ReceiveBlockBatch processes the whole block batch at once, assuming the block batch is linear ,transitioning
 // the state, performing batch verification of all collected signatures and then performing the appropriate
 // actions for a block post-transition.
-func (s *Service) ReceiveBlockBatch(ctx context.Context, blocks []*ethpb.SignedBeaconBlock, blkRoots [][32]byte) error {
+func (s *Service) ReceiveBlockBatch(ctx context.Context, blocks []block.SignedBeaconBlock, blkRoots [][32]byte) error {
 	ctx, span := trace.StartSpan(ctx, "blockChain.ReceiveBlockBatch")
 	defer span.End()

@@ -95,21 +80,21 @@ func (s *Service) ReceiveBlockBatch(ctx context.Context, blocks []*ethpb.SignedB
 	fCheckpoints, jCheckpoints, err := s.onBlockBatch(ctx, blocks, blkRoots)
 	if err != nil {
 		err := errors.Wrap(err, "could not process block in batch")
-		traceutil.AnnotateError(span, err)
+		tracing.AnnotateError(span, err)
 		return err
 	}

 	for i, b := range blocks {
-		blockCopy := stateV0.CopySignedBeaconBlock(b)
+		blockCopy := b.Copy()
 		if err = s.handleBlockAfterBatchVerify(ctx, blockCopy, blkRoots[i], fCheckpoints[i], jCheckpoints[i]); err != nil {
-			traceutil.AnnotateError(span, err)
+			tracing.AnnotateError(span, err)
 			return err
 		}
 		// Send notification of the processed block to the state feed.
 		s.cfg.StateNotifier.StateFeed().Send(&feed.Event{
 			Type: statefeed.BlockProcessed,
 			Data: &statefeed.BlockProcessedData{
-				Slot:        blockCopy.Block.Slot,
+				Slot:        blockCopy.Block().Slot(),
 				BlockRoot:   blkRoots[i],
 				SignedBlock: blockCopy,
 				Verified:    true,
@@ -117,10 +102,21 @@ func (s *Service) ReceiveBlockBatch(ctx context.Context, blocks []*ethpb.SignedB
 		})

 		// Reports on blockCopy and fork choice metrics.
-		reportSlotMetrics(blockCopy.Block.Slot, s.HeadSlot(), s.CurrentSlot(), s.finalizedCheckpt)
+		finalized := s.store.FinalizedCheckpt()
+		if finalized == nil {
+			return errNilFinalizedInStore
+		}
+		reportSlotMetrics(blockCopy.Block().Slot(), s.HeadSlot(), s.CurrentSlot(), finalized)
 	}

-	if err := s.VerifyWeakSubjectivityRoot(s.ctx); err != nil {
+	if err := s.cfg.BeaconDB.SaveBlocks(ctx, s.getInitSyncBlocks()); err != nil {
+		return err
+	}
+	finalized := s.store.FinalizedCheckpt()
+	if finalized == nil {
+		return errNilFinalizedInStore
+	}
+	if err := s.wsVerifier.VerifyWeakSubjectivity(s.ctx, finalized.Epoch); err != nil {
 		// log.Fatalf will prevent defer from being called
 		span.End()
 		// Exit run time if the node failed to verify weak subjectivity checkpoint.
@@ -135,24 +131,24 @@ func (s *Service) HasInitSyncBlock(root [32]byte) bool {
 	return s.hasInitSyncBlock(root)
 }

-func (s *Service) handlePostBlockOperations(b *ethpb.BeaconBlock) error {
+func (s *Service) handlePostBlockOperations(b block.BeaconBlock) error {
 	// Delete the processed block attestations from attestation pool.
-	if err := s.deletePoolAtts(b.Body.Attestations); err != nil {
+	if err := s.deletePoolAtts(b.Body().Attestations()); err != nil {
 		return err
 	}

 	// Add block attestations to the fork choice pool to compute head.
-	if err := s.cfg.AttPool.SaveBlockAttestations(b.Body.Attestations); err != nil {
+	if err := s.cfg.AttPool.SaveBlockAttestations(b.Body().Attestations()); err != nil {
 		log.Errorf("Could not save block attestations for fork choice: %v", err)
 		return nil
 	}
 	// Mark block exits as seen so we don't include same ones in future blocks.
-	for _, e := range b.Body.VoluntaryExits {
+	for _, e := range b.Body().VoluntaryExits() {
 		s.cfg.ExitPool.MarkIncluded(e)
 	}

 	//  Mark attester slashings as seen so we don't include same ones in future blocks.
-	for _, as := range b.Body.AttesterSlashings {
+	for _, as := range b.Body().AttesterSlashings() {
 		s.cfg.SlashingPool.MarkIncludedAttesterSlashing(as)
 	}
 	return nil
@@ -161,11 +157,15 @@ func (s *Service) handlePostBlockOperations(b *ethpb.BeaconBlock) error {
 // This checks whether it's time to start saving hot state to DB.
 // It's time when there's `epochsSinceFinalitySaveHotStateDB` epochs of non-finality.
 func (s *Service) checkSaveHotStateDB(ctx context.Context) error {
-	currentEpoch := helpers.SlotToEpoch(s.CurrentSlot())
+	currentEpoch := slots.ToEpoch(s.CurrentSlot())
 	// Prevent `sinceFinality` going underflow.
 	var sinceFinality types.Epoch
-	if currentEpoch > s.finalizedCheckpt.Epoch {
-		sinceFinality = currentEpoch - s.finalizedCheckpt.Epoch
+	finalized := s.store.FinalizedCheckpt()
+	if finalized == nil {
+		return errNilFinalizedInStore
+	}
+	if currentEpoch > finalized.Epoch {
+		sinceFinality = currentEpoch - finalized.Epoch
 	}

 	if sinceFinality >= epochsSinceFinalitySaveHotStateDB {
--- a/beacon-chain/blockchain/receive_block_test.go
+++ b/beacon-chain/blockchain/receive_block_test.go
@@ -7,30 +7,33 @@ import (
 	"time"

 	types "github.com/prysmaticlabs/eth2-types"
-	ethpb "github.com/prysmaticlabs/ethereumapis/eth/v1alpha1"
 	blockchainTesting "github.com/prysmaticlabs/prysm/beacon-chain/blockchain/testing"
 	testDB "github.com/prysmaticlabs/prysm/beacon-chain/db/testing"
 	"github.com/prysmaticlabs/prysm/beacon-chain/forkchoice/protoarray"
 	"github.com/prysmaticlabs/prysm/beacon-chain/operations/attestations"
 	"github.com/prysmaticlabs/prysm/beacon-chain/operations/voluntaryexits"
 	"github.com/prysmaticlabs/prysm/beacon-chain/state/stategen"
-	"github.com/prysmaticlabs/prysm/shared/bytesutil"
-	"github.com/prysmaticlabs/prysm/shared/params"
-	"github.com/prysmaticlabs/prysm/shared/testutil"
-	"github.com/prysmaticlabs/prysm/shared/testutil/assert"
-	"github.com/prysmaticlabs/prysm/shared/testutil/require"
+	"github.com/prysmaticlabs/prysm/config/params"
+	"github.com/prysmaticlabs/prysm/encoding/bytesutil"
+	ethpb "github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1"
+	"github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1/block"
+	"github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1/wrapper"
+	"github.com/prysmaticlabs/prysm/testing/assert"
+	"github.com/prysmaticlabs/prysm/testing/require"
+	"github.com/prysmaticlabs/prysm/testing/util"
 	logTest "github.com/sirupsen/logrus/hooks/test"
 )

 func TestService_ReceiveBlock(t *testing.T) {
 	ctx := context.Background()

-	genesis, keys := testutil.DeterministicGenesisState(t, 64)
-	genFullBlock := func(t *testing.T, conf *testutil.BlockGenConfig, slot types.Slot) *ethpb.SignedBeaconBlock {
-		blk, err := testutil.GenerateFullBlock(genesis, keys, conf, slot)
+	genesis, keys := util.DeterministicGenesisState(t, 64)
+	genFullBlock := func(t *testing.T, conf *util.BlockGenConfig, slot types.Slot) *ethpb.SignedBeaconBlock {
+		blk, err := util.GenerateFullBlock(genesis, keys, conf, slot)
 		assert.NoError(t, err)
 		return blk
 	}
+	params.SetupTestConfigCleanup(t)
 	bc := params.BeaconConfig()
 	bc.ShardCommitteePeriod = 0 // Required for voluntary exits test in reasonable time.
 	params.OverrideBeaconConfig(bc)
@@ -47,13 +50,13 @@ func TestService_ReceiveBlock(t *testing.T) {
 		{
 			name: "applies block with state transition",
 			args: args{
-				block: genFullBlock(t, testutil.DefaultBlockGenConfig(), 2 /*slot*/),
+				block: genFullBlock(t, util.DefaultBlockGenConfig(), 2 /*slot*/),
 			},
 			check: func(t *testing.T, s *Service) {
 				if hs := s.head.state.Slot(); hs != 2 {
 					t.Errorf("Unexpected state slot. Got %d but wanted %d", hs, 2)
 				}
-				if bs := s.head.block.Block.Slot; bs != 2 {
+				if bs := s.head.block.Block().Slot(); bs != 2 {
 					t.Errorf("Unexpected head block slot. Got %d but wanted %d", bs, 2)
 				}
 			},
@@ -62,7 +65,7 @@ func TestService_ReceiveBlock(t *testing.T) {
 			name: "saves attestations to pool",
 			args: args{
 				block: genFullBlock(t,
-					&testutil.BlockGenConfig{
+					&util.BlockGenConfig{
 						NumProposerSlashings: 0,
 						NumAttesterSlashings: 0,
 						NumAttestations:      2,
@@ -82,7 +85,7 @@ func TestService_ReceiveBlock(t *testing.T) {
 		{
 			name: "updates exit pool",
 			args: args{
-				block: genFullBlock(t, &testutil.BlockGenConfig{
+				block: genFullBlock(t, &util.BlockGenConfig{
 					NumProposerSlashings: 0,
 					NumAttesterSlashings: 0,
 					NumAttestations:      0,
@@ -106,7 +109,7 @@ func TestService_ReceiveBlock(t *testing.T) {
 		{
 			name: "notifies block processed on state feed",
 			args: args{
-				block: genFullBlock(t, testutil.DefaultBlockGenConfig(), 1 /*slot*/),
+				block: genFullBlock(t, util.DefaultBlockGenConfig(), 1 /*slot*/),
 			},
 			check: func(t *testing.T, s *Service) {
 				if recvd := len(s.cfg.StateNotifier.(*blockchainTesting.MockStateNotifier).ReceivedEvents()); recvd < 1 {
@@ -122,29 +125,25 @@ func TestService_ReceiveBlock(t *testing.T) {
 			genesisBlockRoot := bytesutil.ToBytes32(nil)
 			require.NoError(t, beaconDB.SaveState(ctx, genesis, genesisBlockRoot))

-			cfg := &Config{
-				BeaconDB: beaconDB,
-				ForkChoiceStore: protoarray.New(
-					0, // justifiedEpoch
-					0, // finalizedEpoch
-					genesisBlockRoot,
-				),
-				AttPool:       attestations.NewPool(),
-				ExitPool:      voluntaryexits.NewPool(),
-				StateNotifier: &blockchainTesting.MockStateNotifier{RecordEvents: true},
-				StateGen:      stategen.New(beaconDB),
+			opts := []Option{
+				WithDatabase(beaconDB),
+				WithForkChoiceStore(protoarray.New(0, 0, genesisBlockRoot)),
+				WithAttestationPool(attestations.NewPool()),
+				WithExitPool(voluntaryexits.NewPool()),
+				WithStateNotifier(&blockchainTesting.MockStateNotifier{RecordEvents: true}),
+				WithStateGen(stategen.New(beaconDB)),
 			}
-			s, err := NewService(ctx, cfg)
+			s, err := NewService(ctx, opts...)
 			require.NoError(t, err)
 			require.NoError(t, s.saveGenesisData(ctx, genesis))
 			gBlk, err := s.cfg.BeaconDB.GenesisBlock(ctx)
 			require.NoError(t, err)
-			gRoot, err := gBlk.Block.HashTreeRoot()
+			gRoot, err := gBlk.Block().HashTreeRoot()
 			require.NoError(t, err)
-			s.finalizedCheckpt = &ethpb.Checkpoint{Root: gRoot[:]}
+			s.store.SetFinalizedCheckpt(&ethpb.Checkpoint{Root: gRoot[:]})
 			root, err := tt.args.block.Block.HashTreeRoot()
 			require.NoError(t, err)
-			err = s.ReceiveBlock(ctx, tt.args.block, root)
+			err = s.ReceiveBlock(ctx, wrapper.WrappedPhase0SignedBeaconBlock(tt.args.block), root)
 			if tt.wantedErr != "" {
 				assert.ErrorContains(t, tt.wantedErr, err)
 			} else {
@@ -157,38 +156,35 @@ func TestService_ReceiveBlock(t *testing.T) {

 func TestService_ReceiveBlockUpdateHead(t *testing.T) {
 	ctx := context.Background()
-	genesis, keys := testutil.DeterministicGenesisState(t, 64)
-	b, err := testutil.GenerateFullBlock(genesis, keys, testutil.DefaultBlockGenConfig(), 1)
+	genesis, keys := util.DeterministicGenesisState(t, 64)
+	b, err := util.GenerateFullBlock(genesis, keys, util.DefaultBlockGenConfig(), 1)
 	assert.NoError(t, err)
 	beaconDB := testDB.SetupDB(t)
 	genesisBlockRoot := bytesutil.ToBytes32(nil)
 	require.NoError(t, beaconDB.SaveState(ctx, genesis, genesisBlockRoot))
-	cfg := &Config{
-		BeaconDB: beaconDB,
-		ForkChoiceStore: protoarray.New(
-			0, // justifiedEpoch
-			0, // finalizedEpoch
-			genesisBlockRoot,
-		),
-		AttPool:       attestations.NewPool(),
-		ExitPool:      voluntaryexits.NewPool(),
-		StateNotifier: &blockchainTesting.MockStateNotifier{RecordEvents: true},
-		StateGen:      stategen.New(beaconDB),
+	opts := []Option{
+		WithDatabase(beaconDB),
+		WithForkChoiceStore(protoarray.New(0, 0, genesisBlockRoot)),
+		WithAttestationPool(attestations.NewPool()),
+		WithExitPool(voluntaryexits.NewPool()),
+		WithStateNotifier(&blockchainTesting.MockStateNotifier{RecordEvents: true}),
+		WithStateGen(stategen.New(beaconDB)),
 	}
-	s, err := NewService(ctx, cfg)
+
+	s, err := NewService(ctx, opts...)
 	require.NoError(t, err)
 	require.NoError(t, s.saveGenesisData(ctx, genesis))
 	gBlk, err := s.cfg.BeaconDB.GenesisBlock(ctx)
 	require.NoError(t, err)
-	gRoot, err := gBlk.Block.HashTreeRoot()
+	gRoot, err := gBlk.Block().HashTreeRoot()
 	require.NoError(t, err)
-	s.finalizedCheckpt = &ethpb.Checkpoint{Root: gRoot[:]}
+	s.store.SetFinalizedCheckpt(&ethpb.Checkpoint{Root: gRoot[:]})
 	root, err := b.Block.HashTreeRoot()
 	require.NoError(t, err)
 	wg := sync.WaitGroup{}
 	wg.Add(1)
 	go func() {
-		require.NoError(t, s.ReceiveBlock(ctx, b, root))
+		require.NoError(t, s.ReceiveBlock(ctx, wrapper.WrappedPhase0SignedBeaconBlock(b), root))
 		wg.Done()
 	}()
 	wg.Wait()
@@ -202,9 +198,9 @@ func TestService_ReceiveBlockUpdateHead(t *testing.T) {
 func TestService_ReceiveBlockBatch(t *testing.T) {
 	ctx := context.Background()

-	genesis, keys := testutil.DeterministicGenesisState(t, 64)
-	genFullBlock := func(t *testing.T, conf *testutil.BlockGenConfig, slot types.Slot) *ethpb.SignedBeaconBlock {
-		blk, err := testutil.GenerateFullBlock(genesis, keys, conf, slot)
+	genesis, keys := util.DeterministicGenesisState(t, 64)
+	genFullBlock := func(t *testing.T, conf *util.BlockGenConfig, slot types.Slot) *ethpb.SignedBeaconBlock {
+		blk, err := util.GenerateFullBlock(genesis, keys, conf, slot)
 		assert.NoError(t, err)
 		return blk
 	}
@@ -221,17 +217,17 @@ func TestService_ReceiveBlockBatch(t *testing.T) {
 		{
 			name: "applies block with state transition",
 			args: args{
-				block: genFullBlock(t, testutil.DefaultBlockGenConfig(), 2 /*slot*/),
+				block: genFullBlock(t, util.DefaultBlockGenConfig(), 2 /*slot*/),
 			},
 			check: func(t *testing.T, s *Service) {
 				assert.Equal(t, types.Slot(2), s.head.state.Slot(), "Incorrect head state slot")
-				assert.Equal(t, types.Slot(2), s.head.block.Block.Slot, "Incorrect head block slot")
+				assert.Equal(t, types.Slot(2), s.head.block.Block().Slot(), "Incorrect head block slot")
 			},
 		},
 		{
 			name: "notifies block processed on state feed",
 			args: args{
-				block: genFullBlock(t, testutil.DefaultBlockGenConfig(), 1 /*slot*/),
+				block: genFullBlock(t, util.DefaultBlockGenConfig(), 1 /*slot*/),
 			},
 			check: func(t *testing.T, s *Service) {
 				if recvd := len(s.cfg.StateNotifier.(*blockchainTesting.MockStateNotifier).ReceivedEvents()); recvd < 1 {
@@ -246,29 +242,25 @@ func TestService_ReceiveBlockBatch(t *testing.T) {
 			beaconDB := testDB.SetupDB(t)
 			genesisBlockRoot, err := genesis.HashTreeRoot(ctx)
 			require.NoError(t, err)
-			cfg := &Config{
-				BeaconDB: beaconDB,
-				ForkChoiceStore: protoarray.New(
-					0, // justifiedEpoch
-					0, // finalizedEpoch
-					genesisBlockRoot,
-				),
-				StateNotifier: &blockchainTesting.MockStateNotifier{RecordEvents: true},
-				StateGen:      stategen.New(beaconDB),
+			opts := []Option{
+				WithDatabase(beaconDB),
+				WithForkChoiceStore(protoarray.New(0, 0, genesisBlockRoot)),
+				WithStateNotifier(&blockchainTesting.MockStateNotifier{RecordEvents: true}),
+				WithStateGen(stategen.New(beaconDB)),
 			}
-			s, err := NewService(ctx, cfg)
+			s, err := NewService(ctx, opts...)
 			require.NoError(t, err)
 			err = s.saveGenesisData(ctx, genesis)
 			require.NoError(t, err)
 			gBlk, err := s.cfg.BeaconDB.GenesisBlock(ctx)
 			require.NoError(t, err)

-			gRoot, err := gBlk.Block.HashTreeRoot()
+			gRoot, err := gBlk.Block().HashTreeRoot()
 			require.NoError(t, err)
-			s.finalizedCheckpt = &ethpb.Checkpoint{Root: gRoot[:]}
+			s.store.SetFinalizedCheckpt(&ethpb.Checkpoint{Root: gRoot[:]})
 			root, err := tt.args.block.Block.HashTreeRoot()
 			require.NoError(t, err)
-			blks := []*ethpb.SignedBeaconBlock{tt.args.block}
+			blks := []block.SignedBeaconBlock{wrapper.WrappedPhase0SignedBeaconBlock(tt.args.block)}
 			roots := [][32]byte{root}
 			err = s.ReceiveBlockBatch(ctx, blks, roots)
 			if tt.wantedErr != "" {
@@ -282,37 +274,39 @@ func TestService_ReceiveBlockBatch(t *testing.T) {
 }

 func TestService_HasInitSyncBlock(t *testing.T) {
-	s, err := NewService(context.Background(), &Config{StateNotifier: &blockchainTesting.MockStateNotifier{}})
+	opts := testServiceOptsNoDB()
+	opts = append(opts, WithStateNotifier(&blockchainTesting.MockStateNotifier{}))
+	s, err := NewService(context.Background(), opts...)
 	require.NoError(t, err)
 	r := [32]byte{'a'}
 	if s.HasInitSyncBlock(r) {
 		t.Error("Should not have block")
 	}
-	s.saveInitSyncBlock(r, testutil.NewBeaconBlock())
+	s.saveInitSyncBlock(r, wrapper.WrappedPhase0SignedBeaconBlock(util.NewBeaconBlock()))
 	if !s.HasInitSyncBlock(r) {
 		t.Error("Should have block")
 	}
 }

 func TestCheckSaveHotStateDB_Enabling(t *testing.T) {
-	beaconDB := testDB.SetupDB(t)
+	opts := testServiceOptsWithDB(t)
 	hook := logTest.NewGlobal()
-	s, err := NewService(context.Background(), &Config{StateGen: stategen.New(beaconDB)})
+	s, err := NewService(context.Background(), opts...)
 	require.NoError(t, err)
 	st := params.BeaconConfig().SlotsPerEpoch.Mul(uint64(epochsSinceFinalitySaveHotStateDB))
 	s.genesisTime = time.Now().Add(time.Duration(-1*int64(st)*int64(params.BeaconConfig().SecondsPerSlot)) * time.Second)
-	s.finalizedCheckpt = &ethpb.Checkpoint{}
+	s.store.SetFinalizedCheckpt(&ethpb.Checkpoint{})

 	require.NoError(t, s.checkSaveHotStateDB(context.Background()))
 	assert.LogsContain(t, hook, "Entering mode to save hot states in DB")
 }

 func TestCheckSaveHotStateDB_Disabling(t *testing.T) {
-	beaconDB := testDB.SetupDB(t)
 	hook := logTest.NewGlobal()
-	s, err := NewService(context.Background(), &Config{StateGen: stategen.New(beaconDB)})
+	opts := testServiceOptsWithDB(t)
+	s, err := NewService(context.Background(), opts...)
 	require.NoError(t, err)
-	s.finalizedCheckpt = &ethpb.Checkpoint{}
+	s.store.SetFinalizedCheckpt(&ethpb.Checkpoint{})
 	require.NoError(t, s.checkSaveHotStateDB(context.Background()))
 	s.genesisTime = time.Now()

@@ -321,11 +315,11 @@ func TestCheckSaveHotStateDB_Disabling(t *testing.T) {
 }

 func TestCheckSaveHotStateDB_Overflow(t *testing.T) {
-	beaconDB := testDB.SetupDB(t)
 	hook := logTest.NewGlobal()
-	s, err := NewService(context.Background(), &Config{StateGen: stategen.New(beaconDB)})
+	opts := testServiceOptsWithDB(t)
+	s, err := NewService(context.Background(), opts...)
 	require.NoError(t, err)
-	s.finalizedCheckpt = &ethpb.Checkpoint{Epoch: 10000000}
+	s.store.SetFinalizedCheckpt(&ethpb.Checkpoint{Epoch: 10000000})
 	s.genesisTime = time.Now()

 	require.NoError(t, s.checkSaveHotStateDB(context.Background()))
--- a/beacon-chain/blockchain/service.go
+++ b/beacon-chain/blockchain/service.go
@@ -1,6 +1,5 @@
 // Package blockchain defines the life-cycle of the blockchain at the core of
-// eth2, including processing of new blocks and attestations using casper
-// proof of stake.
+// Ethereum, including processing of new blocks and attestations using proof of stake.
 package blockchain

 import (
@@ -12,13 +11,14 @@ import (

 	"github.com/pkg/errors"
 	types "github.com/prysmaticlabs/eth2-types"
-	ethpb "github.com/prysmaticlabs/ethereumapis/eth/v1alpha1"
+	"github.com/prysmaticlabs/prysm/async/event"
+	"github.com/prysmaticlabs/prysm/beacon-chain/blockchain/store"
 	"github.com/prysmaticlabs/prysm/beacon-chain/cache"
 	"github.com/prysmaticlabs/prysm/beacon-chain/cache/depositcache"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/feed"
 	statefeed "github.com/prysmaticlabs/prysm/beacon-chain/core/feed/state"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/helpers"
-	"github.com/prysmaticlabs/prysm/beacon-chain/core/state"
+	"github.com/prysmaticlabs/prysm/beacon-chain/core/transition"
 	"github.com/prysmaticlabs/prysm/beacon-chain/db"
 	f "github.com/prysmaticlabs/prysm/beacon-chain/forkchoice"
 	"github.com/prysmaticlabs/prysm/beacon-chain/forkchoice/protoarray"
@@ -27,13 +27,15 @@ import (
 	"github.com/prysmaticlabs/prysm/beacon-chain/operations/voluntaryexits"
 	"github.com/prysmaticlabs/prysm/beacon-chain/p2p"
 	"github.com/prysmaticlabs/prysm/beacon-chain/powchain"
-	iface "github.com/prysmaticlabs/prysm/beacon-chain/state/interface"
-	"github.com/prysmaticlabs/prysm/beacon-chain/state/stateV0"
+	"github.com/prysmaticlabs/prysm/beacon-chain/state"
 	"github.com/prysmaticlabs/prysm/beacon-chain/state/stategen"
 	"github.com/prysmaticlabs/prysm/cmd/beacon-chain/flags"
-	"github.com/prysmaticlabs/prysm/shared/bytesutil"
-	"github.com/prysmaticlabs/prysm/shared/params"
-	"github.com/prysmaticlabs/prysm/shared/slotutil"
+	"github.com/prysmaticlabs/prysm/config/params"
+	"github.com/prysmaticlabs/prysm/encoding/bytesutil"
+	ethpb "github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1"
+	"github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1/block"
+	prysmTime "github.com/prysmaticlabs/prysm/time"
+	"github.com/prysmaticlabs/prysm/time/slots"
 	"github.com/sirupsen/logrus"
 	"go.opencensus.io/trace"
 )
@@ -45,30 +47,26 @@ const headSyncMinEpochsAfterCheckpoint = 128
 // Service represents a service that handles the internal
 // logic of managing the full PoS beacon chain.
 type Service struct {
-	cfg                   *Config
-	ctx                   context.Context
-	cancel                context.CancelFunc
-	genesisTime           time.Time
-	head                  *head
-	headLock              sync.RWMutex
-	genesisRoot           [32]byte
-	justifiedCheckpt      *ethpb.Checkpoint
-	prevJustifiedCheckpt  *ethpb.Checkpoint
-	bestJustifiedCheckpt  *ethpb.Checkpoint
-	finalizedCheckpt      *ethpb.Checkpoint
-	prevFinalizedCheckpt  *ethpb.Checkpoint
+	cfg         *config
+	ctx         context.Context
+	cancel      context.CancelFunc
+	genesisTime time.Time
+	head        *head
+	headLock    sync.RWMutex
+	// originBlockRoot is the genesis root, or weak subjectivity checkpoint root, depending on how the node is initialized
+	originBlockRoot       [32]byte
 	nextEpochBoundarySlot types.Slot
 	boundaryRoots         [][32]byte
 	checkpointStateCache  *cache.CheckpointStateCache
-	initSyncBlocks        map[[32]byte]*ethpb.SignedBeaconBlock
+	initSyncBlocks        map[[32]byte]block.SignedBeaconBlock
 	initSyncBlocksLock    sync.RWMutex
-	justifiedBalances     []uint64
-	justifiedBalancesLock sync.RWMutex
-	wsVerified            bool
+	justifiedBalances     *stateBalanceCache
+	wsVerifier            *WeakSubjectivityVerifier
+	store                 *store.Store
 }

-// Config options for the service.
-type Config struct {
+// config options for the service.
+type config struct {
 	BeaconBlockBuf          int
 	ChainStartFetcher       powchain.ChainStartFetcher
 	BeaconDB                db.HeadAccessDatabase
@@ -80,229 +78,58 @@ type Config struct {
 	MaxRoutines             int
 	StateNotifier           statefeed.Notifier
 	ForkChoiceStore         f.ForkChoicer
-	OpsService              *attestations.Service
+	AttService              *attestations.Service
 	StateGen                *stategen.State
+	SlasherAttestationsFeed *event.Feed
 	WeakSubjectivityCheckpt *ethpb.Checkpoint
+	FinalizedStateAtStartUp state.BeaconState
 }

 // NewService instantiates a new block service instance that will
 // be registered into a running beacon node.
-func NewService(ctx context.Context, cfg *Config) (*Service, error) {
+func NewService(ctx context.Context, opts ...Option) (*Service, error) {
 	ctx, cancel := context.WithCancel(ctx)
-	return &Service{
-		cfg:                  cfg,
+	srv := &Service{
 		ctx:                  ctx,
 		cancel:               cancel,
 		boundaryRoots:        [][32]byte{},
 		checkpointStateCache: cache.NewCheckpointStateCache(),
-		initSyncBlocks:       make(map[[32]byte]*ethpb.SignedBeaconBlock),
-		justifiedBalances:    make([]uint64, 0),
-	}, nil
+		initSyncBlocks:       make(map[[32]byte]block.SignedBeaconBlock),
+		cfg:                  &config{},
+		store:                &store.Store{},
+	}
+	for _, opt := range opts {
+		if err := opt(srv); err != nil {
+			return nil, err
+		}
+	}
+	var err error
+	if srv.justifiedBalances == nil {
+		srv.justifiedBalances, err = newStateBalanceCache(srv.cfg.StateGen)
+		if err != nil {
+			return nil, err
+		}
+	}
+	srv.wsVerifier, err = NewWeakSubjectivityVerifier(srv.cfg.WeakSubjectivityCheckpt, srv.cfg.BeaconDB)
+	if err != nil {
+		return nil, err
+	}
+	return srv, nil
 }

 // Start a blockchain service's main event loop.
 func (s *Service) Start() {
-	// For running initial sync with state cache, in an event of restart, we use
-	// last finalized check point as start point to sync instead of head
-	// state. This is because we no longer save state every slot during sync.
-	cp, err := s.cfg.BeaconDB.FinalizedCheckpoint(s.ctx)
-	if err != nil {
-		log.Fatalf("Could not fetch finalized cp: %v", err)
-	}
+	saved := s.cfg.FinalizedStateAtStartUp

-	r := bytesutil.ToBytes32(cp.Root)
-	// Before the first finalized epoch, in the current epoch,
-	// the finalized root is defined as zero hashes instead of genesis root hash.
-	// We want to use genesis root to retrieve for state.
-	if r == params.BeaconConfig().ZeroHash {
-		genesisBlock, err := s.cfg.BeaconDB.GenesisBlock(s.ctx)
-		if err != nil {
-			log.Fatalf("Could not fetch finalized cp: %v", err)
+	if saved != nil && !saved.IsNil() {
+		if err := s.startFromSavedState(saved); err != nil {
+			log.Fatal(err)
 		}
-		if genesisBlock != nil {
-			r, err = genesisBlock.Block.HashTreeRoot()
-			if err != nil {
-				log.Fatalf("Could not tree hash genesis block: %v", err)
-			}
-		}
-	}
-	beaconState, err := s.cfg.StateGen.StateByRoot(s.ctx, r)
-	if err != nil {
-		log.Fatalf("Could not fetch beacon state by root: %v", err)
-	}
-
-	// Make sure that attestation processor is subscribed and ready for state initializing event.
-	attestationProcessorSubscribed := make(chan struct{}, 1)
-
-	// If the chain has already been initialized, simply start the block processing routine.
-	if beaconState != nil {
-		log.Info("Blockchain data already exists in DB, initializing...")
-		s.genesisTime = time.Unix(int64(beaconState.GenesisTime()), 0)
-		s.cfg.OpsService.SetGenesisTime(beaconState.GenesisTime())
-		if err := s.initializeChainInfo(s.ctx); err != nil {
-			log.Fatalf("Could not set up chain info: %v", err)
-		}
-
-		// We start a counter to genesis, if needed.
-		gState, err := s.cfg.BeaconDB.GenesisState(s.ctx)
-		if err != nil {
-			log.Fatalf("Could not retrieve genesis state: %v", err)
-		}
-		gRoot, err := gState.HashTreeRoot(s.ctx)
-		if err != nil {
-			log.Fatalf("Could not hash tree root genesis state: %v", err)
-		}
-		go slotutil.CountdownToGenesis(s.ctx, s.genesisTime, uint64(gState.NumValidators()), gRoot)
-
-		justifiedCheckpoint, err := s.cfg.BeaconDB.JustifiedCheckpoint(s.ctx)
-		if err != nil {
-			log.Fatalf("Could not get justified checkpoint: %v", err)
-		}
-		finalizedCheckpoint, err := s.cfg.BeaconDB.FinalizedCheckpoint(s.ctx)
-		if err != nil {
-			log.Fatalf("Could not get finalized checkpoint: %v", err)
-		}
-
-		// Resume fork choice.
-		s.justifiedCheckpt = stateV0.CopyCheckpoint(justifiedCheckpoint)
-		if err := s.cacheJustifiedStateBalances(s.ctx, s.ensureRootNotZeros(bytesutil.ToBytes32(s.justifiedCheckpt.Root))); err != nil {
-			log.Fatalf("Could not cache justified state balances: %v", err)
-		}
-		s.prevJustifiedCheckpt = stateV0.CopyCheckpoint(justifiedCheckpoint)
-		s.bestJustifiedCheckpt = stateV0.CopyCheckpoint(justifiedCheckpoint)
-		s.finalizedCheckpt = stateV0.CopyCheckpoint(finalizedCheckpoint)
-		s.prevFinalizedCheckpt = stateV0.CopyCheckpoint(finalizedCheckpoint)
-		s.resumeForkChoice(justifiedCheckpoint, finalizedCheckpoint)
-
-		ss, err := helpers.StartSlot(s.finalizedCheckpt.Epoch)
-		if err != nil {
-			log.Fatalf("Could not get start slot of finalized epoch: %v", err)
-		}
-		h := s.headBlock().Block
-		if h.Slot > ss {
-			log.WithFields(logrus.Fields{
-				"startSlot": ss,
-				"endSlot":   h.Slot,
-			}).Info("Loading blocks to fork choice store, this may take a while.")
-			if err := s.fillInForkChoiceMissingBlocks(s.ctx, h, s.finalizedCheckpt, s.justifiedCheckpt); err != nil {
-				log.Fatalf("Could not fill in fork choice store missing blocks: %v", err)
-			}
-		}
-
-		if err := s.VerifyWeakSubjectivityRoot(s.ctx); err != nil {
-			// Exit run time if the node failed to verify weak subjectivity checkpoint.
-			log.Fatalf("Could not verify weak subjectivity checkpoint: %v", err)
-		}
-
-		s.cfg.StateNotifier.StateFeed().Send(&feed.Event{
-			Type: statefeed.Initialized,
-			Data: &statefeed.InitializedData{
-				StartTime:             s.genesisTime,
-				GenesisValidatorsRoot: beaconState.GenesisValidatorRoot(),
-			},
-		})
 	} else {
-		log.Info("Waiting to reach the validator deposit threshold to start the beacon chain...")
-		if s.cfg.ChainStartFetcher == nil {
-			log.Fatal("Not configured web3Service for POW chain")
-			return // return need for TestStartUninitializedChainWithoutConfigPOWChain.
+		if err := s.startFromPOWChain(); err != nil {
+			log.Fatal(err)
 		}
-		go func() {
-			stateChannel := make(chan *feed.Event, 1)
-			stateSub := s.cfg.StateNotifier.StateFeed().Subscribe(stateChannel)
-			defer stateSub.Unsubscribe()
-			<-attestationProcessorSubscribed
-			for {
-				select {
-				case event := <-stateChannel:
-					if event.Type == statefeed.ChainStarted {
-						data, ok := event.Data.(*statefeed.ChainStartedData)
-						if !ok {
-							log.Error("event data is not type *statefeed.ChainStartedData")
-							return
-						}
-						log.WithField("starttime", data.StartTime).Debug("Received chain start event")
-						s.processChainStartTime(s.ctx, data.StartTime)
-						return
-					}
-				case <-s.ctx.Done():
-					log.Debug("Context closed, exiting goroutine")
-					return
-				case err := <-stateSub.Err():
-					log.WithError(err).Error("Subscription to state notifier failed")
-					return
-				}
-			}
-		}()
 	}
-
-	go s.processAttestationsRoutine(attestationProcessorSubscribed)
-}
-
-// processChainStartTime initializes a series of deposits from the ChainStart deposits in the eth1
-// deposit contract, initializes the beacon chain's state, and kicks off the beacon chain.
-func (s *Service) processChainStartTime(ctx context.Context, genesisTime time.Time) {
-	preGenesisState := s.cfg.ChainStartFetcher.PreGenesisState()
-	initializedState, err := s.initializeBeaconChain(ctx, genesisTime, preGenesisState, s.cfg.ChainStartFetcher.ChainStartEth1Data())
-	if err != nil {
-		log.Fatalf("Could not initialize beacon chain: %v", err)
-	}
-	// We start a counter to genesis, if needed.
-	gRoot, err := initializedState.HashTreeRoot(s.ctx)
-	if err != nil {
-		log.Fatalf("Could not hash tree root genesis state: %v", err)
-	}
-	go slotutil.CountdownToGenesis(ctx, genesisTime, uint64(initializedState.NumValidators()), gRoot)
-
-	// We send out a state initialized event to the rest of the services
-	// running in the beacon node.
-	s.cfg.StateNotifier.StateFeed().Send(&feed.Event{
-		Type: statefeed.Initialized,
-		Data: &statefeed.InitializedData{
-			StartTime:             genesisTime,
-			GenesisValidatorsRoot: initializedState.GenesisValidatorRoot(),
-		},
-	})
-}
-
-// initializes the state and genesis block of the beacon chain to persistent storage
-// based on a genesis timestamp value obtained from the ChainStart event emitted
-// by the ETH1.0 Deposit Contract and the POWChain service of the node.
-func (s *Service) initializeBeaconChain(
-	ctx context.Context,
-	genesisTime time.Time,
-	preGenesisState iface.BeaconState,
-	eth1data *ethpb.Eth1Data) (iface.BeaconState, error) {
-	ctx, span := trace.StartSpan(ctx, "beacon-chain.Service.initializeBeaconChain")
-	defer span.End()
-	s.genesisTime = genesisTime
-	unixTime := uint64(genesisTime.Unix())
-
-	genesisState, err := state.OptimizedGenesisBeaconState(unixTime, preGenesisState, eth1data)
-	if err != nil {
-		return nil, errors.Wrap(err, "could not initialize genesis state")
-	}
-
-	if err := s.saveGenesisData(ctx, genesisState); err != nil {
-		return nil, errors.Wrap(err, "could not save genesis data")
-	}
-
-	log.Info("Initialized beacon chain genesis state")
-
-	// Clear out all pre-genesis data now that the state is initialized.
-	s.cfg.ChainStartFetcher.ClearPreGenesisData()
-
-	// Update committee shuffled indices for genesis epoch.
-	if err := helpers.UpdateCommitteeCache(genesisState, 0 /* genesis epoch */); err != nil {
-		return nil, err
-	}
-	if err := helpers.UpdateProposerIndicesInCache(genesisState); err != nil {
-		return nil, err
-	}
-
-	s.cfg.OpsService.SetGenesisTime(genesisState.GenesisTime())
-
-	return genesisState, nil
 }

 // Stop the blockchain service's main event loop and associated goroutines.
@@ -322,7 +149,7 @@ func (s *Service) Stop() error {
 // Status always returns nil unless there is an error condition that causes
 // this service to be unhealthy.
 func (s *Service) Status() error {
-	if s.genesisRoot == params.BeaconConfig().ZeroHash {
+	if s.originBlockRoot == params.BeaconConfig().ZeroHash {
 		return errors.New("genesis state has not been created")
 	}
 	if runtime.NumGoroutine() > s.cfg.MaxRoutines {
@@ -331,64 +158,104 @@ func (s *Service) Status() error {
 	return nil
 }

-// This gets called when beacon chain is first initialized to save genesis data (state, block, and more) in db.
-func (s *Service) saveGenesisData(ctx context.Context, genesisState iface.BeaconState) error {
-	if err := s.cfg.BeaconDB.SaveGenesisData(ctx, genesisState); err != nil {
-		return errors.Wrap(err, "could not save genesis data")
-	}
-	genesisBlk, err := s.cfg.BeaconDB.GenesisBlock(ctx)
-	if err != nil || genesisBlk == nil {
-		return fmt.Errorf("could not load genesis block: %v", err)
-	}
-	genesisBlkRoot, err := genesisBlk.Block.HashTreeRoot()
+func (s *Service) startFromSavedState(saved state.BeaconState) error {
+	log.Info("Blockchain data already exists in DB, initializing...")
+	s.genesisTime = time.Unix(int64(saved.GenesisTime()), 0)
+	s.cfg.AttService.SetGenesisTime(saved.GenesisTime())
+
+	originRoot, err := s.originRootFromSavedState(s.ctx)
 	if err != nil {
-		return errors.Wrap(err, "could not get genesis block root")
-	}
-
-	s.genesisRoot = genesisBlkRoot
-	s.cfg.StateGen.SaveFinalizedState(0 /*slot*/, genesisBlkRoot, genesisState)
-
-	// Finalized checkpoint at genesis is a zero hash.
-	genesisCheckpoint := genesisState.FinalizedCheckpoint()
-
-	s.justifiedCheckpt = stateV0.CopyCheckpoint(genesisCheckpoint)
-	if err := s.cacheJustifiedStateBalances(ctx, genesisBlkRoot); err != nil {
 		return err
 	}
-	s.prevJustifiedCheckpt = stateV0.CopyCheckpoint(genesisCheckpoint)
-	s.bestJustifiedCheckpt = stateV0.CopyCheckpoint(genesisCheckpoint)
-	s.finalizedCheckpt = stateV0.CopyCheckpoint(genesisCheckpoint)
-	s.prevFinalizedCheckpt = stateV0.CopyCheckpoint(genesisCheckpoint)
+	s.originBlockRoot = originRoot

-	if err := s.cfg.ForkChoiceStore.ProcessBlock(ctx,
-		genesisBlk.Block.Slot,
-		genesisBlkRoot,
-		params.BeaconConfig().ZeroHash,
-		[32]byte{},
-		genesisCheckpoint.Epoch,
-		genesisCheckpoint.Epoch); err != nil {
-		log.Fatalf("Could not process genesis block for fork choice: %v", err)
+	if err := s.initializeHeadFromDB(s.ctx); err != nil {
+		return errors.Wrap(err, "could not set up chain info")
+	}
+	spawnCountdownIfPreGenesis(s.ctx, s.genesisTime, s.cfg.BeaconDB)
+
+	justified, err := s.cfg.BeaconDB.JustifiedCheckpoint(s.ctx)
+	if err != nil {
+		return errors.Wrap(err, "could not get justified checkpoint")
+	}
+	finalized, err := s.cfg.BeaconDB.FinalizedCheckpoint(s.ctx)
+	if err != nil {
+		return errors.Wrap(err, "could not get finalized checkpoint")
+	}
+	s.store = store.New(justified, finalized)
+
+	store := protoarray.New(justified.Epoch, finalized.Epoch, bytesutil.ToBytes32(finalized.Root))
+	s.cfg.ForkChoiceStore = store
+
+	if err := s.loadSyncedTips(originRoot, saved.Slot()); err != nil {
+		return err
 	}

-	s.setHead(genesisBlkRoot, genesisBlk, genesisState)
+	ss, err := slots.EpochStart(finalized.Epoch)
+	if err != nil {
+		return errors.Wrap(err, "could not get start slot of finalized epoch")
+	}
+	h := s.headBlock().Block()
+	if h.Slot() > ss {
+		log.WithFields(logrus.Fields{
+			"startSlot": ss,
+			"endSlot":   h.Slot(),
+		}).Info("Loading blocks to fork choice store, this may take a while.")
+		if err := s.fillInForkChoiceMissingBlocks(s.ctx, h, finalized, justified); err != nil {
+			return errors.Wrap(err, "could not fill in fork choice store missing blocks")
+		}
+	}
+
+	// not attempting to save initial sync blocks here, because there shouldn't be any until
+	// after the statefeed.Initialized event is fired (below)
+	if err := s.wsVerifier.VerifyWeakSubjectivity(s.ctx, finalized.Epoch); err != nil {
+		// Exit run time if the node failed to verify weak subjectivity checkpoint.
+		return errors.Wrap(err, "could not verify initial checkpoint provided for chain sync")
+	}
+
+	s.cfg.StateNotifier.StateFeed().Send(&feed.Event{
+		Type: statefeed.Initialized,
+		Data: &statefeed.InitializedData{
+			StartTime:             s.genesisTime,
+			GenesisValidatorsRoot: saved.GenesisValidatorRoot(),
+		},
+	})
+
+	s.spawnProcessAttestationsRoutine(s.cfg.StateNotifier.StateFeed())
+
 	return nil
 }

-// This gets called to initialize chain info variables using the finalized checkpoint stored in DB
-func (s *Service) initializeChainInfo(ctx context.Context) error {
+func (s *Service) originRootFromSavedState(ctx context.Context) ([32]byte, error) {
+	// first check if we have started from checkpoint sync and have a root
+	originRoot, err := s.cfg.BeaconDB.OriginBlockRoot(ctx)
+	if err == nil {
+		return originRoot, nil
+	}
+	if !errors.Is(err, db.ErrNotFound) {
+		return originRoot, errors.Wrap(err, "could not retrieve checkpoint sync chain origin data from db")
+	}
+
+	// we got here because OriginBlockRoot gave us an ErrNotFound. this means the node was started from a genesis state,
+	// so we should have a value for GenesisBlock
 	genesisBlock, err := s.cfg.BeaconDB.GenesisBlock(ctx)
 	if err != nil {
-		return errors.Wrap(err, "could not get genesis block from db")
+		return originRoot, errors.Wrap(err, "could not get genesis block from db")
 	}
-	if genesisBlock == nil {
-		return errors.New("no genesis block in db")
+	if err := helpers.BeaconBlockIsNil(genesisBlock); err != nil {
+		return originRoot, err
 	}
-	genesisBlkRoot, err := genesisBlock.Block.HashTreeRoot()
+	genesisBlkRoot, err := genesisBlock.Block().HashTreeRoot()
 	if err != nil {
-		return errors.Wrap(err, "could not get signing root of genesis block")
+		return genesisBlkRoot, errors.Wrap(err, "could not get signing root of genesis block")
 	}
-	s.genesisRoot = genesisBlkRoot
+	return genesisBlkRoot, nil
+}

+// initializeHeadFromDB uses the finalized checkpoint and head block found in the database to set the current head
+// note that this may block until stategen replays blocks between the finalized and head blocks
+// if the head sync flag was specified and the gap between the finalized and head blocks is at least 128 epochs long
+func (s *Service) initializeHeadFromDB(ctx context.Context) error {
 	finalized, err := s.cfg.BeaconDB.FinalizedCheckpoint(ctx)
 	if err != nil {
 		return errors.Wrap(err, "could not get finalized checkpoint from db")
@@ -399,9 +266,9 @@ func (s *Service) initializeChainInfo(ctx context.Context) error {
 		return errors.New("no finalized epoch in the database")
 	}
 	finalizedRoot := s.ensureRootNotZeros(bytesutil.ToBytes32(finalized.Root))
-	var finalizedState iface.BeaconState
+	var finalizedState state.BeaconState

-	finalizedState, err = s.cfg.StateGen.Resume(ctx)
+	finalizedState, err = s.cfg.StateGen.Resume(ctx, s.cfg.FinalizedStateAtStartUp)
 	if err != nil {
 		return errors.Wrap(err, "could not get finalized state from db")
 	}
@@ -411,7 +278,7 @@ func (s *Service) initializeChainInfo(ctx context.Context) error {
 		if err != nil {
 			return errors.Wrap(err, "could not retrieve head block")
 		}
-		headEpoch := helpers.SlotToEpoch(headBlock.Block.Slot)
+		headEpoch := slots.ToEpoch(headBlock.Block().Slot())
 		var epochsSinceFinality types.Epoch
 		if headEpoch > finalized.Epoch {
 			epochsSinceFinality = headEpoch - finalized.Epoch
@@ -419,16 +286,16 @@ func (s *Service) initializeChainInfo(ctx context.Context) error {
 		// Head sync when node is far enough beyond known finalized epoch,
 		// this becomes really useful during long period of non-finality.
 		if epochsSinceFinality >= headSyncMinEpochsAfterCheckpoint {
-			headRoot, err := headBlock.Block.HashTreeRoot()
+			headRoot, err := headBlock.Block().HashTreeRoot()
 			if err != nil {
 				return errors.Wrap(err, "could not hash head block")
 			}
-			finalizedState, err := s.cfg.StateGen.Resume(ctx)
+			finalizedState, err := s.cfg.StateGen.Resume(ctx, s.cfg.FinalizedStateAtStartUp)
 			if err != nil {
 				return errors.Wrap(err, "could not get finalized state from db")
 			}
 			log.Infof("Regenerating state from the last checkpoint at slot %d to current head slot of %d."+
-				"This process may take a while, please wait.", finalizedState.Slot(), headBlock.Block.Slot)
+				"This process may take a while, please wait.", finalizedState.Slot(), headBlock.Block().Slot())
 			headState, err := s.cfg.StateGen.StateByRoot(ctx, headRoot)
 			if err != nil {
 				return errors.Wrap(err, "could not retrieve head state")
@@ -447,7 +314,7 @@ func (s *Service) initializeChainInfo(ctx context.Context) error {
 		return errors.Wrap(err, "could not get finalized block from db")
 	}

-	if finalizedState == nil || finalizedBlock == nil {
+	if finalizedState == nil || finalizedState.IsNil() || finalizedBlock == nil || finalizedBlock.IsNil() {
 		return errors.New("finalized state and block can't be nil")
 	}
 	s.setHead(finalizedRoot, finalizedBlock, finalizedState)
@@ -455,11 +322,141 @@ func (s *Service) initializeChainInfo(ctx context.Context) error {
 	return nil
 }

-// This is called when a client starts from non-genesis slot. This passes last justified and finalized
-// information to fork choice service to initializes fork choice store.
-func (s *Service) resumeForkChoice(justifiedCheckpoint, finalizedCheckpoint *ethpb.Checkpoint) {
-	store := protoarray.New(justifiedCheckpoint.Epoch, finalizedCheckpoint.Epoch, bytesutil.ToBytes32(finalizedCheckpoint.Root))
-	s.cfg.ForkChoiceStore = store
+func (s *Service) startFromPOWChain() error {
+	log.Info("Waiting to reach the validator deposit threshold to start the beacon chain...")
+	if s.cfg.ChainStartFetcher == nil {
+		return errors.New("not configured web3Service for POW chain")
+	}
+	go func() {
+		stateChannel := make(chan *feed.Event, 1)
+		stateSub := s.cfg.StateNotifier.StateFeed().Subscribe(stateChannel)
+		defer stateSub.Unsubscribe()
+		s.spawnProcessAttestationsRoutine(s.cfg.StateNotifier.StateFeed())
+		for {
+			select {
+			case event := <-stateChannel:
+				if event.Type == statefeed.ChainStarted {
+					data, ok := event.Data.(*statefeed.ChainStartedData)
+					if !ok {
+						log.Error("event data is not type *statefeed.ChainStartedData")
+						return
+					}
+					log.WithField("starttime", data.StartTime).Debug("Received chain start event")
+					s.onPowchainStart(s.ctx, data.StartTime)
+					return
+				}
+			case <-s.ctx.Done():
+				log.Debug("Context closed, exiting goroutine")
+				return
+			case err := <-stateSub.Err():
+				log.WithError(err).Error("Subscription to state notifier failed")
+				return
+			}
+		}
+	}()
+
+	return nil
+}
+
+// onPowchainStart initializes a series of deposits from the ChainStart deposits in the eth1
+// deposit contract, initializes the beacon chain's state, and kicks off the beacon chain.
+func (s *Service) onPowchainStart(ctx context.Context, genesisTime time.Time) {
+	preGenesisState := s.cfg.ChainStartFetcher.PreGenesisState()
+	initializedState, err := s.initializeBeaconChain(ctx, genesisTime, preGenesisState, s.cfg.ChainStartFetcher.ChainStartEth1Data())
+	if err != nil {
+		log.Fatalf("Could not initialize beacon chain: %v", err)
+	}
+	// We start a counter to genesis, if needed.
+	gRoot, err := initializedState.HashTreeRoot(s.ctx)
+	if err != nil {
+		log.Fatalf("Could not hash tree root genesis state: %v", err)
+	}
+	go slots.CountdownToGenesis(ctx, genesisTime, uint64(initializedState.NumValidators()), gRoot)
+
+	// We send out a state initialized event to the rest of the services
+	// running in the beacon node.
+	s.cfg.StateNotifier.StateFeed().Send(&feed.Event{
+		Type: statefeed.Initialized,
+		Data: &statefeed.InitializedData{
+			StartTime:             genesisTime,
+			GenesisValidatorsRoot: initializedState.GenesisValidatorRoot(),
+		},
+	})
+}
+
+// initializes the state and genesis block of the beacon chain to persistent storage
+// based on a genesis timestamp value obtained from the ChainStart event emitted
+// by the ETH1.0 Deposit Contract and the POWChain service of the node.
+func (s *Service) initializeBeaconChain(
+	ctx context.Context,
+	genesisTime time.Time,
+	preGenesisState state.BeaconState,
+	eth1data *ethpb.Eth1Data) (state.BeaconState, error) {
+	ctx, span := trace.StartSpan(ctx, "beacon-chain.Service.initializeBeaconChain")
+	defer span.End()
+	s.genesisTime = genesisTime
+	unixTime := uint64(genesisTime.Unix())
+
+	genesisState, err := transition.OptimizedGenesisBeaconState(unixTime, preGenesisState, eth1data)
+	if err != nil {
+		return nil, errors.Wrap(err, "could not initialize genesis state")
+	}
+
+	if err := s.saveGenesisData(ctx, genesisState); err != nil {
+		return nil, errors.Wrap(err, "could not save genesis data")
+	}
+
+	log.Info("Initialized beacon chain genesis state")
+
+	// Clear out all pre-genesis data now that the state is initialized.
+	s.cfg.ChainStartFetcher.ClearPreGenesisData()
+
+	// Update committee shuffled indices for genesis epoch.
+	if err := helpers.UpdateCommitteeCache(genesisState, 0 /* genesis epoch */); err != nil {
+		return nil, err
+	}
+	if err := helpers.UpdateProposerIndicesInCache(ctx, genesisState); err != nil {
+		return nil, err
+	}
+
+	s.cfg.AttService.SetGenesisTime(genesisState.GenesisTime())
+
+	return genesisState, nil
+}
+
+// This gets called when beacon chain is first initialized to save genesis data (state, block, and more) in db.
+func (s *Service) saveGenesisData(ctx context.Context, genesisState state.BeaconState) error {
+	if err := s.cfg.BeaconDB.SaveGenesisData(ctx, genesisState); err != nil {
+		return errors.Wrap(err, "could not save genesis data")
+	}
+	genesisBlk, err := s.cfg.BeaconDB.GenesisBlock(ctx)
+	if err != nil || genesisBlk == nil || genesisBlk.IsNil() {
+		return fmt.Errorf("could not load genesis block: %v", err)
+	}
+	genesisBlkRoot, err := genesisBlk.Block().HashTreeRoot()
+	if err != nil {
+		return errors.Wrap(err, "could not get genesis block root")
+	}
+
+	s.originBlockRoot = genesisBlkRoot
+	s.cfg.StateGen.SaveFinalizedState(0 /*slot*/, genesisBlkRoot, genesisState)
+
+	// Finalized checkpoint at genesis is a zero hash.
+	genesisCheckpoint := genesisState.FinalizedCheckpoint()
+	s.store = store.New(genesisCheckpoint, genesisCheckpoint)
+
+	if err := s.cfg.ForkChoiceStore.ProcessBlock(ctx,
+		genesisBlk.Block().Slot(),
+		genesisBlkRoot,
+		params.BeaconConfig().ZeroHash,
+		[32]byte{},
+		genesisCheckpoint.Epoch,
+		genesisCheckpoint.Epoch); err != nil {
+		log.Fatalf("Could not process genesis block for fork choice: %v", err)
+	}
+
+	s.setHead(genesisBlkRoot, genesisBlk, genesisState)
+	return nil
 }

 // This returns true if block has been processed before. Two ways to verify the block has been processed:
@@ -473,3 +470,20 @@ func (s *Service) hasBlock(ctx context.Context, root [32]byte) bool {

 	return s.cfg.BeaconDB.HasBlock(ctx, root)
 }
+
+func spawnCountdownIfPreGenesis(ctx context.Context, genesisTime time.Time, db db.HeadAccessDatabase) {
+	currentTime := prysmTime.Now()
+	if currentTime.After(genesisTime) {
+		return
+	}
+
+	gState, err := db.GenesisState(ctx)
+	if err != nil {
+		log.Fatalf("Could not retrieve genesis state: %v", err)
+	}
+	gRoot, err := gState.HashTreeRoot(ctx)
+	if err != nil {
+		log.Fatalf("Could not hash tree root genesis state: %v", err)
+	}
+	go slots.CountdownToGenesis(ctx, genesisTime, uint64(gState.NumValidators()), gRoot)
+}
--- a/beacon-chain/blockchain/service_norace_test.go
+++ b/beacon-chain/blockchain/service_norace_test.go
@@ -6,7 +6,7 @@ import (
 	"testing"

 	testDB "github.com/prysmaticlabs/prysm/beacon-chain/db/testing"
-	"github.com/prysmaticlabs/prysm/shared/testutil/require"
+	"github.com/prysmaticlabs/prysm/testing/require"
 	"github.com/sirupsen/logrus"
 )

@@ -18,7 +18,7 @@ func init() {
 func TestChainService_SaveHead_DataRace(t *testing.T) {
 	beaconDB := testDB.SetupDB(t)
 	s := &Service{
-		cfg: &Config{BeaconDB: beaconDB},
+		cfg: &config{BeaconDB: beaconDB},
 	}
 	go func() {
 		require.NoError(t, s.saveHead(context.Background(), [32]byte{}))
--- a/beacon-chain/blockchain/service_test.go
+++ b/beacon-chain/blockchain/service_test.go
@@ -8,32 +8,36 @@ import (
 	"time"

 	"github.com/ethereum/go-ethereum/common"
-	"github.com/gogo/protobuf/proto"
-	ethpb "github.com/prysmaticlabs/ethereumapis/eth/v1alpha1"
+	types "github.com/prysmaticlabs/eth2-types"
+	"github.com/prysmaticlabs/prysm/async/event"
+	"github.com/prysmaticlabs/prysm/beacon-chain/blockchain/store"
+	mock "github.com/prysmaticlabs/prysm/beacon-chain/blockchain/testing"
 	"github.com/prysmaticlabs/prysm/beacon-chain/cache/depositcache"
 	b "github.com/prysmaticlabs/prysm/beacon-chain/core/blocks"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/feed"
 	statefeed "github.com/prysmaticlabs/prysm/beacon-chain/core/feed/state"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/helpers"
-	"github.com/prysmaticlabs/prysm/beacon-chain/core/state"
+	"github.com/prysmaticlabs/prysm/beacon-chain/core/transition"
 	"github.com/prysmaticlabs/prysm/beacon-chain/db"
 	testDB "github.com/prysmaticlabs/prysm/beacon-chain/db/testing"
 	"github.com/prysmaticlabs/prysm/beacon-chain/forkchoice/protoarray"
 	"github.com/prysmaticlabs/prysm/beacon-chain/operations/attestations"
 	"github.com/prysmaticlabs/prysm/beacon-chain/p2p"
 	"github.com/prysmaticlabs/prysm/beacon-chain/powchain"
-	"github.com/prysmaticlabs/prysm/beacon-chain/state/stateV0"
 	"github.com/prysmaticlabs/prysm/beacon-chain/state/stategen"
+	v1 "github.com/prysmaticlabs/prysm/beacon-chain/state/v1"
 	"github.com/prysmaticlabs/prysm/cmd/beacon-chain/flags"
-	protodb "github.com/prysmaticlabs/prysm/proto/beacon/db"
-	pb "github.com/prysmaticlabs/prysm/proto/beacon/p2p/v1"
-	"github.com/prysmaticlabs/prysm/shared/bytesutil"
-	"github.com/prysmaticlabs/prysm/shared/event"
-	"github.com/prysmaticlabs/prysm/shared/params"
-	"github.com/prysmaticlabs/prysm/shared/testutil"
-	"github.com/prysmaticlabs/prysm/shared/testutil/assert"
-	"github.com/prysmaticlabs/prysm/shared/testutil/require"
+	"github.com/prysmaticlabs/prysm/config/params"
+	"github.com/prysmaticlabs/prysm/encoding/bytesutil"
+	ethpb "github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1"
+	"github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1/block"
+	"github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1/wrapper"
+	"github.com/prysmaticlabs/prysm/testing/assert"
+	"github.com/prysmaticlabs/prysm/testing/require"
+	"github.com/prysmaticlabs/prysm/testing/util"
+	"github.com/prysmaticlabs/prysm/time/slots"
 	logTest "github.com/sirupsen/logrus/hooks/test"
+	"google.golang.org/protobuf/proto"
 )

 type mockBeaconNode struct {
@@ -62,6 +66,11 @@ func (mb *mockBroadcaster) BroadcastAttestation(_ context.Context, _ uint64, _ *
 	return nil
 }

+func (mb *mockBroadcaster) BroadcastSyncCommitteeMessage(_ context.Context, _ uint64, _ *ethpb.SyncCommitteeMessage) error {
+	mb.broadcastCalled = true
+	return nil
+}
+
 var _ p2p.Broadcaster = (*mockBroadcaster)(nil)

 func setupBeaconChain(t *testing.T, beaconDB db.Database) *Service {
@@ -69,55 +78,56 @@ func setupBeaconChain(t *testing.T, beaconDB db.Database) *Service {
 	ctx := context.Background()
 	var web3Service *powchain.Service
 	var err error
-	bState, _ := testutil.DeterministicGenesisState(t, 10)
-	pbState, err := stateV0.ProtobufBeaconState(bState.InnerStateUnsafe())
+	bState, _ := util.DeterministicGenesisState(t, 10)
+	pbState, err := v1.ProtobufBeaconState(bState.InnerStateUnsafe())
 	require.NoError(t, err)
-	err = beaconDB.SavePowchainData(ctx, &protodb.ETH1ChainData{
+	err = beaconDB.SavePowchainData(ctx, &ethpb.ETH1ChainData{
 		BeaconState: pbState,
-		Trie:        &protodb.SparseMerkleTrie{},
-		CurrentEth1Data: &protodb.LatestETH1Data{
+		Trie:        &ethpb.SparseMerkleTrie{},
+		CurrentEth1Data: &ethpb.LatestETH1Data{
 			BlockHash: make([]byte, 32),
 		},
-		ChainstartData: &protodb.ChainStartData{
+		ChainstartData: &ethpb.ChainStartData{
 			Eth1Data: &ethpb.Eth1Data{
 				DepositRoot:  make([]byte, 32),
 				DepositCount: 0,
 				BlockHash:    make([]byte, 32),
 			},
 		},
-		DepositContainers: []*protodb.DepositContainer{},
+		DepositContainers: []*ethpb.DepositContainer{},
 	})
 	require.NoError(t, err)
-	web3Service, err = powchain.NewService(ctx, &powchain.Web3ServiceConfig{
-		BeaconDB:        beaconDB,
-		HttpEndpoints:   []string{endpoint},
-		DepositContract: common.Address{},
-	})
+	web3Service, err = powchain.NewService(
+		ctx,
+		powchain.WithDatabase(beaconDB),
+		powchain.WithHttpEndpoints([]string{endpoint}),
+		powchain.WithDepositContractAddress(common.Address{}),
+	)
 	require.NoError(t, err, "Unable to set up web3 service")

-	opsService, err := attestations.NewService(ctx, &attestations.Config{Pool: attestations.NewPool()})
+	attService, err := attestations.NewService(ctx, &attestations.Config{Pool: attestations.NewPool()})
 	require.NoError(t, err)

 	depositCache, err := depositcache.New()
 	require.NoError(t, err)

-	cfg := &Config{
-		BeaconBlockBuf:    0,
-		BeaconDB:          beaconDB,
-		DepositCache:      depositCache,
-		ChainStartFetcher: web3Service,
-		P2p:               &mockBroadcaster{},
-		StateNotifier:     &mockBeaconNode{},
-		AttPool:           attestations.NewPool(),
-		StateGen:          stategen.New(beaconDB),
-		ForkChoiceStore:   protoarray.New(0, 0, params.BeaconConfig().ZeroHash),
-		OpsService:        opsService,
+	stateGen := stategen.New(beaconDB)
+	// Safe a state in stategen to purposes of testing a service stop / shutdown.
+	require.NoError(t, stateGen.SaveState(ctx, bytesutil.ToBytes32(bState.FinalizedCheckpoint().Root), bState))
+
+	opts := []Option{
+		WithDatabase(beaconDB),
+		WithDepositCache(depositCache),
+		WithChainStartFetcher(web3Service),
+		WithAttestationPool(attestations.NewPool()),
+		WithP2PBroadcaster(&mockBroadcaster{}),
+		WithStateNotifier(&mockBeaconNode{}),
+		WithForkChoiceStore(protoarray.New(0, 0, params.BeaconConfig().ZeroHash)),
+		WithAttestationService(attService),
+		WithStateGen(stateGen),
 	}

-	// Safe a state in stategen to purposes of testing a service stop / shutdown.
-	require.NoError(t, cfg.StateGen.SaveState(ctx, bytesutil.ToBytes32(bState.FinalizedCheckpoint().Root), bState))
-
-	chainService, err := NewService(ctx, cfg)
+	chainService, err := NewService(ctx, opts...)
 	require.NoError(t, err, "Unable to setup chain service")
 	chainService.genesisTime = time.Unix(1, 0) // non-zero time

@@ -131,11 +141,11 @@ func TestChainStartStop_Initialized(t *testing.T) {

 	chainService := setupBeaconChain(t, beaconDB)

-	genesisBlk := testutil.NewBeaconBlock()
+	genesisBlk := util.NewBeaconBlock()
 	blkRoot, err := genesisBlk.Block.HashTreeRoot()
 	require.NoError(t, err)
-	require.NoError(t, beaconDB.SaveBlock(ctx, genesisBlk))
-	s, err := testutil.NewBeaconState()
+	require.NoError(t, beaconDB.SaveBlock(ctx, wrapper.WrappedPhase0SignedBeaconBlock(genesisBlk)))
+	s, err := util.NewBeaconState()
 	require.NoError(t, err)
 	require.NoError(t, s.SetSlot(1))
 	require.NoError(t, beaconDB.SaveState(ctx, s, blkRoot))
@@ -143,7 +153,7 @@ func TestChainStartStop_Initialized(t *testing.T) {
 	require.NoError(t, beaconDB.SaveGenesisBlockRoot(ctx, blkRoot))
 	require.NoError(t, beaconDB.SaveJustifiedCheckpoint(ctx, &ethpb.Checkpoint{Root: blkRoot[:]}))
 	require.NoError(t, beaconDB.SaveFinalizedCheckpoint(ctx, &ethpb.Checkpoint{Root: blkRoot[:]}))
-
+	chainService.cfg.FinalizedStateAtStartUp = s
 	// Test the start function.
 	chainService.Start()

@@ -154,6 +164,74 @@ func TestChainStartStop_Initialized(t *testing.T) {
 	require.LogsContain(t, hook, "data already exists")
 }

+func TestChainStart_SyncedTipsInDB(t *testing.T) {
+	ctx := context.Background()
+	beaconDB := testDB.SetupDB(t)
+
+	chainService := setupBeaconChain(t, beaconDB)
+
+	genesisBlk := util.NewBeaconBlock()
+	blkRoot, err := genesisBlk.Block.HashTreeRoot()
+	require.NoError(t, err)
+	require.NoError(t, beaconDB.SaveBlock(ctx, wrapper.WrappedPhase0SignedBeaconBlock(genesisBlk)))
+	s, err := util.NewBeaconState()
+	require.NoError(t, err)
+	require.NoError(t, s.SetSlot(1))
+	require.NoError(t, beaconDB.SaveState(ctx, s, blkRoot))
+	require.NoError(t, beaconDB.SaveHeadBlockRoot(ctx, blkRoot))
+	require.NoError(t, beaconDB.SaveGenesisBlockRoot(ctx, blkRoot))
+	require.NoError(t, beaconDB.SaveJustifiedCheckpoint(ctx, &ethpb.Checkpoint{Root: blkRoot[:]}))
+	require.NoError(t, beaconDB.SaveFinalizedCheckpoint(ctx, &ethpb.Checkpoint{Root: blkRoot[:]}))
+	chainService.cfg.FinalizedStateAtStartUp = s
+
+	tips := make(map[[32]byte]types.Slot)
+	tips[bytesutil.ToBytes32([]byte{'a'})] = 1
+	tips[bytesutil.ToBytes32([]byte{'b'})] = 2
+	require.NoError(t, beaconDB.UpdateValidatedTips(ctx, tips))
+
+	// Test the start function.
+	chainService.Start()
+
+	// Test synced Tips in DB
+	tips2 := chainService.cfg.ForkChoiceStore.SyncedTips()
+	require.Equal(t, len(tips2), len(tips))
+	for k, v := range tips {
+		v2, ok := tips2[k]
+		require.Equal(t, true, ok)
+		require.Equal(t, v, v2)
+	}
+}
+
+func TestChainStart_SyncedTipsNotInDB(t *testing.T) {
+	ctx := context.Background()
+	beaconDB := testDB.SetupDB(t)
+
+	chainService := setupBeaconChain(t, beaconDB)
+
+	genesisBlk := util.NewBeaconBlock()
+	blkRoot, err := genesisBlk.Block.HashTreeRoot()
+	require.NoError(t, err)
+	require.NoError(t, beaconDB.SaveBlock(ctx, wrapper.WrappedPhase0SignedBeaconBlock(genesisBlk)))
+	s, err := util.NewBeaconState()
+	require.NoError(t, err)
+	require.NoError(t, s.SetSlot(1))
+	require.NoError(t, beaconDB.SaveState(ctx, s, blkRoot))
+	require.NoError(t, beaconDB.SaveHeadBlockRoot(ctx, blkRoot))
+	require.NoError(t, beaconDB.SaveGenesisBlockRoot(ctx, blkRoot))
+	require.NoError(t, beaconDB.SaveJustifiedCheckpoint(ctx, &ethpb.Checkpoint{Root: blkRoot[:]}))
+	require.NoError(t, beaconDB.SaveFinalizedCheckpoint(ctx, &ethpb.Checkpoint{Root: blkRoot[:]}))
+	chainService.cfg.FinalizedStateAtStartUp = s
+	// Test the start function.
+	chainService.Start()
+
+	// Test synced Tips in DB
+	tips := chainService.cfg.ForkChoiceStore.SyncedTips()
+	require.Equal(t, 1, len(tips))
+	slot, ok := tips[blkRoot]
+	require.Equal(t, true, ok)
+	require.Equal(t, types.Slot(1), slot)
+}
+
 func TestChainStartStop_GenesisZeroHashes(t *testing.T) {
 	hook := logTest.NewGlobal()
 	ctx := context.Background()
@@ -161,16 +239,16 @@ func TestChainStartStop_GenesisZeroHashes(t *testing.T) {

 	chainService := setupBeaconChain(t, beaconDB)

-	genesisBlk := testutil.NewBeaconBlock()
+	genesisBlk := util.NewBeaconBlock()
 	blkRoot, err := genesisBlk.Block.HashTreeRoot()
 	require.NoError(t, err)
-	require.NoError(t, beaconDB.SaveBlock(ctx, genesisBlk))
-	s, err := testutil.NewBeaconState()
+	require.NoError(t, beaconDB.SaveBlock(ctx, wrapper.WrappedPhase0SignedBeaconBlock(genesisBlk)))
+	s, err := util.NewBeaconState()
 	require.NoError(t, err)
 	require.NoError(t, beaconDB.SaveState(ctx, s, blkRoot))
 	require.NoError(t, beaconDB.SaveGenesisBlockRoot(ctx, blkRoot))
 	require.NoError(t, beaconDB.SaveJustifiedCheckpoint(ctx, &ethpb.Checkpoint{Root: params.BeaconConfig().ZeroHash[:]}))
-
+	chainService.cfg.FinalizedStateAtStartUp = s
 	// Test the start function.
 	chainService.Start()

@@ -191,12 +269,12 @@ func TestChainService_InitializeBeaconChain(t *testing.T) {

 	// Set up 10 deposits pre chain start for validators to register
 	count := uint64(10)
-	deposits, _, err := testutil.DeterministicDepositsAndKeys(count)
+	deposits, _, err := util.DeterministicDepositsAndKeys(count)
 	require.NoError(t, err)
-	trie, _, err := testutil.DepositTrieFromDeposits(deposits)
+	trie, _, err := util.DepositTrieFromDeposits(deposits)
 	require.NoError(t, err)
 	hashTreeRoot := trie.HashTreeRoot()
-	genState, err := state.EmptyGenesisState()
+	genState, err := transition.EmptyGenesisState()
 	require.NoError(t, err)
 	err = genState.SetEth1Data(&ethpb.Eth1Data{
 		DepositRoot:  hashTreeRoot[:],
@@ -230,23 +308,23 @@ func TestChainService_CorrectGenesisRoots(t *testing.T) {

 	chainService := setupBeaconChain(t, beaconDB)

-	genesisBlk := testutil.NewBeaconBlock()
+	genesisBlk := util.NewBeaconBlock()
 	blkRoot, err := genesisBlk.Block.HashTreeRoot()
 	require.NoError(t, err)
-	require.NoError(t, beaconDB.SaveBlock(ctx, genesisBlk))
-	s, err := testutil.NewBeaconState()
+	require.NoError(t, beaconDB.SaveBlock(ctx, wrapper.WrappedPhase0SignedBeaconBlock(genesisBlk)))
+	s, err := util.NewBeaconState()
 	require.NoError(t, err)
 	require.NoError(t, s.SetSlot(0))
 	require.NoError(t, beaconDB.SaveState(ctx, s, blkRoot))
 	require.NoError(t, beaconDB.SaveHeadBlockRoot(ctx, blkRoot))
 	require.NoError(t, beaconDB.SaveGenesisBlockRoot(ctx, blkRoot))
 	require.NoError(t, beaconDB.SaveFinalizedCheckpoint(ctx, &ethpb.Checkpoint{Root: blkRoot[:]}))
-
+	chainService.cfg.FinalizedStateAtStartUp = s
 	// Test the start function.
 	chainService.Start()

-	require.DeepEqual(t, blkRoot[:], chainService.finalizedCheckpt.Root, "Finalize Checkpoint root is incorrect")
-	require.DeepEqual(t, params.BeaconConfig().ZeroHash[:], chainService.justifiedCheckpt.Root, "Justified Checkpoint root is incorrect")
+	require.DeepEqual(t, blkRoot[:], chainService.store.FinalizedCheckpt().Root, "Finalize Checkpoint root is incorrect")
+	require.DeepEqual(t, params.BeaconConfig().ZeroHash[:], chainService.store.JustifiedCheckpt().Root, "Justified Checkpoint root is incorrect")

 	require.NoError(t, chainService.Stop(), "Unable to stop chain service")

@@ -256,17 +334,17 @@ func TestChainService_InitializeChainInfo(t *testing.T) {
 	beaconDB := testDB.SetupDB(t)
 	ctx := context.Background()

-	genesis := testutil.NewBeaconBlock()
+	genesis := util.NewBeaconBlock()
 	genesisRoot, err := genesis.Block.HashTreeRoot()
 	require.NoError(t, err)
 	require.NoError(t, beaconDB.SaveGenesisBlockRoot(ctx, genesisRoot))
-	require.NoError(t, beaconDB.SaveBlock(ctx, genesis))
+	require.NoError(t, beaconDB.SaveBlock(ctx, wrapper.WrappedPhase0SignedBeaconBlock(genesis)))

 	finalizedSlot := params.BeaconConfig().SlotsPerEpoch*2 + 1
-	headBlock := testutil.NewBeaconBlock()
+	headBlock := util.NewBeaconBlock()
 	headBlock.Block.Slot = finalizedSlot
 	headBlock.Block.ParentRoot = bytesutil.PadTo(genesisRoot[:], 32)
-	headState, err := testutil.NewBeaconState()
+	headState, err := util.NewBeaconState()
 	require.NoError(t, err)
 	require.NoError(t, headState.SetSlot(finalizedSlot))
 	require.NoError(t, headState.SetGenesisValidatorRoot(params.BeaconConfig().ZeroHash[:]))
@@ -274,13 +352,16 @@ func TestChainService_InitializeChainInfo(t *testing.T) {
 	require.NoError(t, err)
 	require.NoError(t, beaconDB.SaveState(ctx, headState, headRoot))
 	require.NoError(t, beaconDB.SaveState(ctx, headState, genesisRoot))
-	require.NoError(t, beaconDB.SaveBlock(ctx, headBlock))
-	require.NoError(t, beaconDB.SaveFinalizedCheckpoint(ctx, &ethpb.Checkpoint{Epoch: helpers.SlotToEpoch(finalizedSlot), Root: headRoot[:]}))
-	c := &Service{cfg: &Config{BeaconDB: beaconDB, StateGen: stategen.New(beaconDB)}}
-	require.NoError(t, c.initializeChainInfo(ctx))
+	require.NoError(t, beaconDB.SaveBlock(ctx, wrapper.WrappedPhase0SignedBeaconBlock(headBlock)))
+	require.NoError(t, beaconDB.SaveFinalizedCheckpoint(ctx, &ethpb.Checkpoint{Epoch: slots.ToEpoch(finalizedSlot), Root: headRoot[:]}))
+	attSrv, err := attestations.NewService(ctx, &attestations.Config{})
+	require.NoError(t, err)
+	c, err := NewService(ctx, WithDatabase(beaconDB), WithStateGen(stategen.New(beaconDB)), WithAttestationService(attSrv), WithStateNotifier(&mock.MockStateNotifier{}), WithFinalizedStateAtStartUp(headState))
+	require.NoError(t, err)
+	require.NoError(t, c.startFromSavedState(headState))
 	headBlk, err := c.HeadBlock(ctx)
 	require.NoError(t, err)
-	assert.DeepEqual(t, headBlock, headBlk, "Head block incorrect")
+	assert.DeepEqual(t, headBlock, headBlk.Proto(), "Head block incorrect")
 	s, err := c.HeadState(ctx)
 	require.NoError(t, err)
 	assert.DeepSSZEqual(t, headState.InnerStateUnsafe(), s.InnerStateUnsafe(), "Head state incorrect")
@@ -290,24 +371,24 @@ func TestChainService_InitializeChainInfo(t *testing.T) {
 	if !bytes.Equal(headRoot[:], r) {
 		t.Error("head slot incorrect")
 	}
-	assert.Equal(t, genesisRoot, c.genesisRoot, "Genesis block root incorrect")
+	assert.Equal(t, genesisRoot, c.originBlockRoot, "Genesis block root incorrect")
 }

 func TestChainService_InitializeChainInfo_SetHeadAtGenesis(t *testing.T) {
 	beaconDB := testDB.SetupDB(t)
 	ctx := context.Background()

-	genesis := testutil.NewBeaconBlock()
+	genesis := util.NewBeaconBlock()
 	genesisRoot, err := genesis.Block.HashTreeRoot()
 	require.NoError(t, err)
 	require.NoError(t, beaconDB.SaveGenesisBlockRoot(ctx, genesisRoot))
-	require.NoError(t, beaconDB.SaveBlock(ctx, genesis))
+	require.NoError(t, beaconDB.SaveBlock(ctx, wrapper.WrappedPhase0SignedBeaconBlock(genesis)))

 	finalizedSlot := params.BeaconConfig().SlotsPerEpoch*2 + 1
-	headBlock := testutil.NewBeaconBlock()
+	headBlock := util.NewBeaconBlock()
 	headBlock.Block.Slot = finalizedSlot
 	headBlock.Block.ParentRoot = bytesutil.PadTo(genesisRoot[:], 32)
-	headState, err := testutil.NewBeaconState()
+	headState, err := util.NewBeaconState()
 	require.NoError(t, err)
 	require.NoError(t, headState.SetSlot(finalizedSlot))
 	require.NoError(t, headState.SetGenesisValidatorRoot(params.BeaconConfig().ZeroHash[:]))
@@ -315,14 +396,17 @@ func TestChainService_InitializeChainInfo_SetHeadAtGenesis(t *testing.T) {
 	require.NoError(t, err)
 	require.NoError(t, beaconDB.SaveState(ctx, headState, headRoot))
 	require.NoError(t, beaconDB.SaveState(ctx, headState, genesisRoot))
-	require.NoError(t, beaconDB.SaveBlock(ctx, headBlock))
-	c := &Service{cfg: &Config{BeaconDB: beaconDB, StateGen: stategen.New(beaconDB)}}
-	require.NoError(t, c.initializeChainInfo(ctx))
+	require.NoError(t, beaconDB.SaveBlock(ctx, wrapper.WrappedPhase0SignedBeaconBlock(headBlock)))
+	attSrv, err := attestations.NewService(ctx, &attestations.Config{})
+	require.NoError(t, err)
+	c, err := NewService(ctx, WithDatabase(beaconDB), WithStateGen(stategen.New(beaconDB)), WithAttestationService(attSrv), WithStateNotifier(&mock.MockStateNotifier{}))
+	require.NoError(t, err)
+	require.NoError(t, c.startFromSavedState(headState))
 	s, err := c.HeadState(ctx)
 	require.NoError(t, err)
 	assert.DeepSSZEqual(t, headState.InnerStateUnsafe(), s.InnerStateUnsafe(), "Head state incorrect")
-	assert.Equal(t, genesisRoot, c.genesisRoot, "Genesis block root incorrect")
-	assert.DeepEqual(t, genesis, c.head.block)
+	assert.Equal(t, genesisRoot, c.originBlockRoot, "Genesis block root incorrect")
+	assert.DeepEqual(t, genesis, c.head.block.Proto())
 }

 func TestChainService_InitializeChainInfo_HeadSync(t *testing.T) {
@@ -339,28 +423,28 @@ func TestChainService_InitializeChainInfo_HeadSync(t *testing.T) {
 	beaconDB := testDB.SetupDB(t)
 	ctx := context.Background()

-	genesisBlock := testutil.NewBeaconBlock()
+	genesisBlock := util.NewBeaconBlock()
 	genesisRoot, err := genesisBlock.Block.HashTreeRoot()
 	require.NoError(t, err)
 	require.NoError(t, beaconDB.SaveGenesisBlockRoot(ctx, genesisRoot))
-	require.NoError(t, beaconDB.SaveBlock(ctx, genesisBlock))
+	require.NoError(t, beaconDB.SaveBlock(ctx, wrapper.WrappedPhase0SignedBeaconBlock(genesisBlock)))

-	finalizedBlock := testutil.NewBeaconBlock()
+	finalizedBlock := util.NewBeaconBlock()
 	finalizedBlock.Block.Slot = finalizedSlot
 	finalizedBlock.Block.ParentRoot = genesisRoot[:]
 	finalizedRoot, err := finalizedBlock.Block.HashTreeRoot()
 	require.NoError(t, err)
-	require.NoError(t, beaconDB.SaveBlock(ctx, finalizedBlock))
+	require.NoError(t, beaconDB.SaveBlock(ctx, wrapper.WrappedPhase0SignedBeaconBlock(finalizedBlock)))

 	// Set head slot close to the finalization point, no head sync is triggered.
-	headBlock := testutil.NewBeaconBlock()
+	headBlock := util.NewBeaconBlock()
 	headBlock.Block.Slot = finalizedSlot + params.BeaconConfig().SlotsPerEpoch*5
 	headBlock.Block.ParentRoot = finalizedRoot[:]
 	headRoot, err := headBlock.Block.HashTreeRoot()
 	require.NoError(t, err)
-	require.NoError(t, beaconDB.SaveBlock(ctx, headBlock))
+	require.NoError(t, beaconDB.SaveBlock(ctx, wrapper.WrappedPhase0SignedBeaconBlock(headBlock)))

-	headState, err := testutil.NewBeaconState()
+	headState, err := util.NewBeaconState()
 	require.NoError(t, err)
 	require.NoError(t, headState.SetSlot(headBlock.Block.Slot))
 	require.NoError(t, headState.SetGenesisValidatorRoot(params.BeaconConfig().ZeroHash[:]))
@@ -369,40 +453,42 @@ func TestChainService_InitializeChainInfo_HeadSync(t *testing.T) {
 	require.NoError(t, beaconDB.SaveState(ctx, headState, headRoot))
 	require.NoError(t, beaconDB.SaveHeadBlockRoot(ctx, headRoot))
 	require.NoError(t, beaconDB.SaveFinalizedCheckpoint(ctx, &ethpb.Checkpoint{
-		Epoch: helpers.SlotToEpoch(finalizedBlock.Block.Slot),
+		Epoch: slots.ToEpoch(finalizedBlock.Block.Slot),
 		Root:  finalizedRoot[:],
 	}))

-	c := &Service{cfg: &Config{BeaconDB: beaconDB, StateGen: stategen.New(beaconDB)}}
-
-	require.NoError(t, c.initializeChainInfo(ctx))
+	attSrv, err := attestations.NewService(ctx, &attestations.Config{})
+	require.NoError(t, err)
+	c, err := NewService(ctx, WithDatabase(beaconDB), WithStateGen(stategen.New(beaconDB)), WithAttestationService(attSrv), WithStateNotifier(&mock.MockStateNotifier{}), WithFinalizedStateAtStartUp(headState))
+	require.NoError(t, err)
+	require.NoError(t, c.startFromSavedState(headState))
 	s, err := c.HeadState(ctx)
 	require.NoError(t, err)
 	assert.DeepSSZEqual(t, headState.InnerStateUnsafe(), s.InnerStateUnsafe(), "Head state incorrect")
-	assert.Equal(t, genesisRoot, c.genesisRoot, "Genesis block root incorrect")
+	assert.Equal(t, genesisRoot, c.originBlockRoot, "Genesis block root incorrect")
 	// Since head sync is not triggered, chain is initialized to the last finalization checkpoint.
-	assert.DeepEqual(t, finalizedBlock, c.head.block)
+	assert.DeepEqual(t, finalizedBlock, c.head.block.Proto())
 	assert.LogsContain(t, hook, "resetting head from the checkpoint ('--head-sync' flag is ignored)")
 	assert.LogsDoNotContain(t, hook, "Regenerating state from the last checkpoint at slot")

 	// Set head slot far beyond the finalization point, head sync should be triggered.
-	headBlock = testutil.NewBeaconBlock()
+	headBlock = util.NewBeaconBlock()
 	headBlock.Block.Slot = finalizedSlot + params.BeaconConfig().SlotsPerEpoch*headSyncMinEpochsAfterCheckpoint
 	headBlock.Block.ParentRoot = finalizedRoot[:]
 	headRoot, err = headBlock.Block.HashTreeRoot()
 	require.NoError(t, err)
-	require.NoError(t, beaconDB.SaveBlock(ctx, headBlock))
+	require.NoError(t, beaconDB.SaveBlock(ctx, wrapper.WrappedPhase0SignedBeaconBlock(headBlock)))
 	require.NoError(t, beaconDB.SaveState(ctx, headState, headRoot))
 	require.NoError(t, beaconDB.SaveHeadBlockRoot(ctx, headRoot))

 	hook.Reset()
-	require.NoError(t, c.initializeChainInfo(ctx))
+	require.NoError(t, c.initializeHeadFromDB(ctx))
 	s, err = c.HeadState(ctx)
 	require.NoError(t, err)
 	assert.DeepSSZEqual(t, headState.InnerStateUnsafe(), s.InnerStateUnsafe(), "Head state incorrect")
-	assert.Equal(t, genesisRoot, c.genesisRoot, "Genesis block root incorrect")
+	assert.Equal(t, genesisRoot, c.originBlockRoot, "Genesis block root incorrect")
 	// Head slot is far beyond the latest finalized checkpoint, head sync is triggered.
-	assert.DeepEqual(t, headBlock, c.head.block)
+	assert.DeepEqual(t, headBlock, c.head.block.Proto())
 	assert.LogsContain(t, hook, "Regenerating state from the last checkpoint at slot 225")
 	assert.LogsDoNotContain(t, hook, "resetting head from the checkpoint ('--head-sync' flag is ignored)")
 }
@@ -411,16 +497,16 @@ func TestChainService_SaveHeadNoDB(t *testing.T) {
 	beaconDB := testDB.SetupDB(t)
 	ctx := context.Background()
 	s := &Service{
-		cfg: &Config{BeaconDB: beaconDB, StateGen: stategen.New(beaconDB)},
+		cfg: &config{BeaconDB: beaconDB, StateGen: stategen.New(beaconDB)},
 	}
-	blk := testutil.NewBeaconBlock()
+	blk := util.NewBeaconBlock()
 	blk.Block.Slot = 1
 	r, err := blk.HashTreeRoot()
 	require.NoError(t, err)
-	newState, err := testutil.NewBeaconState()
+	newState, err := util.NewBeaconState()
 	require.NoError(t, err)
 	require.NoError(t, s.cfg.StateGen.SaveState(ctx, r, newState))
-	require.NoError(t, s.saveHeadNoDB(ctx, blk, r, newState))
+	require.NoError(t, s.saveHeadNoDB(ctx, wrapper.WrappedPhase0SignedBeaconBlock(blk), r, newState))

 	newB, err := s.cfg.BeaconDB.HeadBlock(ctx)
 	require.NoError(t, err)
@@ -433,15 +519,16 @@ func TestHasBlock_ForkChoiceAndDB(t *testing.T) {
 	ctx := context.Background()
 	beaconDB := testDB.SetupDB(t)
 	s := &Service{
-		cfg:              &Config{ForkChoiceStore: protoarray.New(0, 0, [32]byte{}), BeaconDB: beaconDB},
-		finalizedCheckpt: &ethpb.Checkpoint{Root: make([]byte, 32)},
+		cfg:   &config{ForkChoiceStore: protoarray.New(0, 0, [32]byte{}), BeaconDB: beaconDB},
+		store: &store.Store{},
 	}
-	block := testutil.NewBeaconBlock()
+	s.store.SetFinalizedCheckpt(&ethpb.Checkpoint{Epoch: 0, Root: params.BeaconConfig().ZeroHash[:]})
+	block := util.NewBeaconBlock()
 	r, err := block.Block.HashTreeRoot()
 	require.NoError(t, err)
-	beaconState, err := testutil.NewBeaconState()
+	beaconState, err := util.NewBeaconState()
 	require.NoError(t, err)
-	require.NoError(t, s.insertBlockAndAttestationsToForkChoiceStore(ctx, block.Block, r, beaconState))
+	require.NoError(t, s.insertBlockAndAttestationsToForkChoiceStore(ctx, wrapper.WrappedPhase0SignedBeaconBlock(block).Block(), r, beaconState))

 	assert.Equal(t, false, s.hasBlock(ctx, [32]byte{}), "Should not have block")
 	assert.Equal(t, true, s.hasBlock(ctx, r), "Should have block")
@@ -451,15 +538,15 @@ func TestServiceStop_SaveCachedBlocks(t *testing.T) {
 	ctx, cancel := context.WithCancel(context.Background())
 	beaconDB := testDB.SetupDB(t)
 	s := &Service{
-		cfg:            &Config{BeaconDB: beaconDB, StateGen: stategen.New(beaconDB)},
+		cfg:            &config{BeaconDB: beaconDB, StateGen: stategen.New(beaconDB)},
 		ctx:            ctx,
 		cancel:         cancel,
-		initSyncBlocks: make(map[[32]byte]*ethpb.SignedBeaconBlock),
+		initSyncBlocks: make(map[[32]byte]block.SignedBeaconBlock),
 	}
-	b := testutil.NewBeaconBlock()
-	r, err := b.Block.HashTreeRoot()
+	block := util.NewBeaconBlock()
+	r, err := block.Block.HashTreeRoot()
 	require.NoError(t, err)
-	s.saveInitSyncBlock(r, b)
+	s.saveInitSyncBlock(r, wrapper.WrappedPhase0SignedBeaconBlock(block))
 	require.NoError(t, s.Stop())
 	require.Equal(t, true, s.cfg.BeaconDB.HasBlock(ctx, r))
 }
@@ -470,7 +557,7 @@ func TestProcessChainStartTime_ReceivedFeed(t *testing.T) {
 	stateChannel := make(chan *feed.Event, 1)
 	stateSub := service.cfg.StateNotifier.StateFeed().Subscribe(stateChannel)
 	defer stateSub.Unsubscribe()
-	service.processChainStartTime(context.Background(), time.Now())
+	service.onPowchainStart(context.Background(), time.Now())

 	stateEvent := <-stateChannel
 	require.Equal(t, int(stateEvent.Type), statefeed.Initialized)
@@ -482,10 +569,10 @@ func BenchmarkHasBlockDB(b *testing.B) {
 	beaconDB := testDB.SetupDB(b)
 	ctx := context.Background()
 	s := &Service{
-		cfg: &Config{BeaconDB: beaconDB},
+		cfg: &config{BeaconDB: beaconDB},
 	}
-	block := testutil.NewBeaconBlock()
-	require.NoError(b, s.cfg.BeaconDB.SaveBlock(ctx, block))
+	block := util.NewBeaconBlock()
+	require.NoError(b, s.cfg.BeaconDB.SaveBlock(ctx, wrapper.WrappedPhase0SignedBeaconBlock(block)))
 	r, err := block.Block.HashTreeRoot()
 	require.NoError(b, err)

@@ -499,16 +586,17 @@ func BenchmarkHasBlockForkChoiceStore(b *testing.B) {
 	ctx := context.Background()
 	beaconDB := testDB.SetupDB(b)
 	s := &Service{
-		cfg:              &Config{ForkChoiceStore: protoarray.New(0, 0, [32]byte{}), BeaconDB: beaconDB},
-		finalizedCheckpt: &ethpb.Checkpoint{Root: make([]byte, 32)},
+		cfg:   &config{ForkChoiceStore: protoarray.New(0, 0, [32]byte{}), BeaconDB: beaconDB},
+		store: &store.Store{},
 	}
+	s.store.SetFinalizedCheckpt(&ethpb.Checkpoint{Epoch: 0, Root: params.BeaconConfig().ZeroHash[:]})
 	block := &ethpb.SignedBeaconBlock{Block: &ethpb.BeaconBlock{Body: &ethpb.BeaconBlockBody{}}}
 	r, err := block.Block.HashTreeRoot()
 	require.NoError(b, err)
-	bs := &pb.BeaconState{FinalizedCheckpoint: &ethpb.Checkpoint{Root: make([]byte, 32)}, CurrentJustifiedCheckpoint: &ethpb.Checkpoint{Root: make([]byte, 32)}}
-	beaconState, err := stateV0.InitializeFromProto(bs)
+	bs := &ethpb.BeaconState{FinalizedCheckpoint: &ethpb.Checkpoint{Root: make([]byte, 32)}, CurrentJustifiedCheckpoint: &ethpb.Checkpoint{Root: make([]byte, 32)}}
+	beaconState, err := v1.InitializeFromProto(bs)
 	require.NoError(b, err)
-	require.NoError(b, s.insertBlockAndAttestationsToForkChoiceStore(ctx, block.Block, r, beaconState))
+	require.NoError(b, s.insertBlockAndAttestationsToForkChoiceStore(ctx, wrapper.WrappedPhase0SignedBeaconBlock(block).Block(), r, beaconState))

 	b.ResetTimer()
 	for i := 0; i < b.N; i++ {
--- a/beacon-chain/blockchain/state_balance_cache.go
+++ b/beacon-chain/blockchain/state_balance_cache.go
@@ -0,0 +1,83 @@
+package blockchain
+
+import (
+	"context"
+	"errors"
+	"sync"
+
+	"github.com/prysmaticlabs/prysm/beacon-chain/core/helpers"
+	"github.com/prysmaticlabs/prysm/beacon-chain/core/time"
+	"github.com/prysmaticlabs/prysm/beacon-chain/state"
+	"github.com/prysmaticlabs/prysm/beacon-chain/state/stategen"
+)
+
+var errNilStateFromStategen = errors.New("justified state can't be nil")
+
+type stateBalanceCache struct {
+	sync.Mutex
+	balances []uint64
+	root     [32]byte
+	stateGen stateByRooter
+}
+
+type stateByRooter interface {
+	StateByRoot(context.Context, [32]byte) (state.BeaconState, error)
+}
+
+// newStateBalanceCache exists to remind us that stateBalanceCache needs a stagegen
+// to avoid nil pointer bugs when updating the cache in the read path (get())
+func newStateBalanceCache(sg *stategen.State) (*stateBalanceCache, error) {
+	if sg == nil {
+		return nil, errors.New("can't initialize state balance cache without stategen")
+	}
+	return &stateBalanceCache{stateGen: sg}, nil
+}
+
+// update is called by get() when the requested root doesn't match
+// the previously read value. This cache assumes we only want to cache one
+// set of balances for a single root (the current justified root).
+//
+// warning: this is not thread-safe on its own, relies on get() for locking
+func (c *stateBalanceCache) update(ctx context.Context, justifiedRoot [32]byte) ([]uint64, error) {
+	stateBalanceCacheMiss.Inc()
+	justifiedState, err := c.stateGen.StateByRoot(ctx, justifiedRoot)
+	if err != nil {
+		return nil, err
+	}
+	if justifiedState == nil || justifiedState.IsNil() {
+		return nil, errNilStateFromStategen
+	}
+	epoch := time.CurrentEpoch(justifiedState)
+
+	justifiedBalances := make([]uint64, justifiedState.NumValidators())
+	var balanceAccumulator = func(idx int, val state.ReadOnlyValidator) error {
+		if helpers.IsActiveValidatorUsingTrie(val, epoch) {
+			justifiedBalances[idx] = val.EffectiveBalance()
+		} else {
+			justifiedBalances[idx] = 0
+		}
+		return nil
+	}
+	if err := justifiedState.ReadFromEveryValidator(balanceAccumulator); err != nil {
+		return nil, err
+	}
+
+	c.balances = justifiedBalances
+	c.root = justifiedRoot
+	return c.balances, nil
+}
+
+// getBalances takes an explicit justifiedRoot so it can invalidate the singleton cache key
+// when the justified root changes, and takes a context so that the long-running stategen
+// read path can connect to the upstream cancellation/timeout chain.
+func (c *stateBalanceCache) get(ctx context.Context, justifiedRoot [32]byte) ([]uint64, error) {
+	c.Lock()
+	defer c.Unlock()
+
+	if justifiedRoot != [32]byte{} && justifiedRoot == c.root {
+		stateBalanceCacheHit.Inc()
+		return c.balances, nil
+	}
+
+	return c.update(ctx, justifiedRoot)
+}
--- a/beacon-chain/blockchain/state_balance_cache_test.go
+++ b/beacon-chain/blockchain/state_balance_cache_test.go
@@ -0,0 +1,236 @@
+package blockchain
+
+import (
+	"context"
+	"encoding/binary"
+	"errors"
+	"testing"
+
+	types "github.com/prysmaticlabs/eth2-types"
+	"github.com/prysmaticlabs/prysm/beacon-chain/state"
+	v2 "github.com/prysmaticlabs/prysm/beacon-chain/state/v2"
+	"github.com/prysmaticlabs/prysm/encoding/bytesutil"
+	ethpb "github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1"
+	"github.com/prysmaticlabs/prysm/testing/require"
+	"github.com/prysmaticlabs/prysm/time/slots"
+)
+
+type mockStateByRoot struct {
+	state state.BeaconState
+	err   error
+}
+
+func (m *mockStateByRoot) StateByRoot(context.Context, [32]byte) (state.BeaconState, error) {
+	return m.state, m.err
+}
+
+type testStateOpt func(*ethpb.BeaconStateAltair)
+
+func testStateWithValidators(v []*ethpb.Validator) testStateOpt {
+	return func(a *ethpb.BeaconStateAltair) {
+		a.Validators = v
+	}
+}
+
+func testStateWithSlot(slot types.Slot) testStateOpt {
+	return func(a *ethpb.BeaconStateAltair) {
+		a.Slot = slot
+	}
+}
+
+func testStateFixture(opts ...testStateOpt) state.BeaconState {
+	a := &ethpb.BeaconStateAltair{}
+	for _, o := range opts {
+		o(a)
+	}
+	s, _ := v2.InitializeFromProtoUnsafe(a)
+	return s
+}
+
+func generateTestValidators(count int, opts ...func(*ethpb.Validator)) []*ethpb.Validator {
+	vs := make([]*ethpb.Validator, count)
+	var i uint32 = 0
+	for ; i < uint32(count); i++ {
+		pk := make([]byte, 48)
+		binary.LittleEndian.PutUint32(pk, i)
+		v := &ethpb.Validator{PublicKey: pk}
+		for _, o := range opts {
+			o(v)
+		}
+		vs[i] = v
+	}
+	return vs
+}
+
+func oddValidatorsExpired(currentSlot types.Slot) func(*ethpb.Validator) {
+	return func(v *ethpb.Validator) {
+		pki := binary.LittleEndian.Uint64(v.PublicKey)
+		if pki%2 == 0 {
+			v.ExitEpoch = types.Epoch(int(slots.ToEpoch(currentSlot)) + 1)
+		} else {
+			v.ExitEpoch = types.Epoch(int(slots.ToEpoch(currentSlot)) - 1)
+		}
+	}
+}
+
+func oddValidatorsQueued(currentSlot types.Slot) func(*ethpb.Validator) {
+	return func(v *ethpb.Validator) {
+		v.ExitEpoch = types.Epoch(int(slots.ToEpoch(currentSlot)) + 1)
+		pki := binary.LittleEndian.Uint64(v.PublicKey)
+		if pki%2 == 0 {
+			v.ActivationEpoch = types.Epoch(int(slots.ToEpoch(currentSlot)) - 1)
+		} else {
+			v.ActivationEpoch = types.Epoch(int(slots.ToEpoch(currentSlot)) + 1)
+		}
+	}
+}
+
+func allValidatorsValid(currentSlot types.Slot) func(*ethpb.Validator) {
+	return func(v *ethpb.Validator) {
+		v.ActivationEpoch = types.Epoch(int(slots.ToEpoch(currentSlot)) - 1)
+		v.ExitEpoch = types.Epoch(int(slots.ToEpoch(currentSlot)) + 1)
+	}
+}
+
+func balanceIsKeyTimes2(v *ethpb.Validator) {
+	pki := binary.LittleEndian.Uint64(v.PublicKey)
+	v.EffectiveBalance = uint64(pki) * 2
+}
+
+func testHalfExpiredValidators() ([]*ethpb.Validator, []uint64) {
+	balances := []uint64{0, 0, 4, 0, 8, 0, 12, 0, 16, 0}
+	return generateTestValidators(10,
+		oddValidatorsExpired(types.Slot(99)),
+		balanceIsKeyTimes2), balances
+}
+
+func testHalfQueuedValidators() ([]*ethpb.Validator, []uint64) {
+	balances := []uint64{0, 0, 4, 0, 8, 0, 12, 0, 16, 0}
+	return generateTestValidators(10,
+		oddValidatorsQueued(types.Slot(99)),
+		balanceIsKeyTimes2), balances
+}
+
+func testAllValidValidators() ([]*ethpb.Validator, []uint64) {
+	balances := []uint64{0, 2, 4, 6, 8, 10, 12, 14, 16, 18}
+	return generateTestValidators(10,
+		allValidatorsValid(types.Slot(99)),
+		balanceIsKeyTimes2), balances
+}
+
+func TestStateBalanceCache(t *testing.T) {
+	type sbcTestCase struct {
+		err      error
+		root     [32]byte
+		sbc      *stateBalanceCache
+		balances []uint64
+		name     string
+	}
+	sentinelCacheMiss := errors.New("Cache missed, as expected!")
+	sentinelBalances := []uint64{1, 2, 3, 4, 5}
+	halfExpiredValidators, halfExpiredBalances := testHalfExpiredValidators()
+	halfQueuedValidators, halfQueuedBalances := testHalfQueuedValidators()
+	allValidValidators, allValidBalances := testAllValidValidators()
+	cases := []sbcTestCase{
+		{
+			root:     bytesutil.ToBytes32([]byte{'A'}),
+			balances: sentinelBalances,
+			sbc: &stateBalanceCache{
+				stateGen: &mockStateByRooter{
+					err: sentinelCacheMiss,
+				},
+				root:     bytesutil.ToBytes32([]byte{'A'}),
+				balances: sentinelBalances,
+			},
+			name: "cache hit",
+		},
+		// this works by using a staterooter that returns a known error
+		// so really we're testing the miss by making sure stategen got called
+		// this also tells us stategen errors are propagated
+		{
+			sbc: &stateBalanceCache{
+				stateGen: &mockStateByRooter{
+					err: sentinelCacheMiss,
+				},
+				root: bytesutil.ToBytes32([]byte{'B'}),
+			},
+			err:  sentinelCacheMiss,
+			root: bytesutil.ToBytes32([]byte{'A'}),
+			name: "cache miss",
+		},
+		{
+			sbc: &stateBalanceCache{
+				stateGen: &mockStateByRooter{},
+				root:     bytesutil.ToBytes32([]byte{'B'}),
+			},
+			err:  errNilStateFromStategen,
+			root: bytesutil.ToBytes32([]byte{'A'}),
+			name: "error for nil state upon cache miss",
+		},
+		{
+			sbc: &stateBalanceCache{
+				stateGen: &mockStateByRooter{
+					state: testStateFixture(
+						testStateWithSlot(99),
+						testStateWithValidators(halfExpiredValidators)),
+				},
+			},
+			balances: halfExpiredBalances,
+			root:     bytesutil.ToBytes32([]byte{'A'}),
+			name:     "test filtering by exit epoch",
+		},
+		{
+			sbc: &stateBalanceCache{
+				stateGen: &mockStateByRooter{
+					state: testStateFixture(
+						testStateWithSlot(99),
+						testStateWithValidators(halfQueuedValidators)),
+				},
+			},
+			balances: halfQueuedBalances,
+			root:     bytesutil.ToBytes32([]byte{'A'}),
+			name:     "test filtering by activation epoch",
+		},
+		{
+			sbc: &stateBalanceCache{
+				stateGen: &mockStateByRooter{
+					state: testStateFixture(
+						testStateWithSlot(99),
+						testStateWithValidators(allValidValidators)),
+				},
+			},
+			balances: allValidBalances,
+			root:     bytesutil.ToBytes32([]byte{'A'}),
+			name:     "happy path",
+		},
+		{
+			sbc: &stateBalanceCache{
+				stateGen: &mockStateByRooter{
+					state: testStateFixture(
+						testStateWithSlot(99),
+						testStateWithValidators(allValidValidators)),
+				},
+			},
+			balances: allValidBalances,
+			root:     [32]byte{},
+			name:     "zero root",
+		},
+	}
+	ctx := context.Background()
+	for _, c := range cases {
+		t.Run(c.name, func(t *testing.T) {
+			cache := c.sbc
+			cacheRootStart := cache.root
+			b, err := cache.get(ctx, c.root)
+			require.ErrorIs(t, err, c.err)
+			require.DeepEqual(t, c.balances, b)
+			if c.err != nil {
+				// if there was an error somewhere, the root should not have changed (unless it already matched)
+				require.Equal(t, cacheRootStart, cache.root)
+			} else {
+				// when successful, the cache should always end with a root matching the request
+				require.Equal(t, c.root, cache.root)
+			}
+		})
+	}
+}
--- a/beacon-chain/blockchain/store/BUILD.bazel
+++ b/beacon-chain/blockchain/store/BUILD.bazel
@@ -0,0 +1,27 @@
+load("@prysm//tools/go:def.bzl", "go_library", "go_test")
+
+go_library(
+    name = "go_default_library",
+    srcs = [
+        "doc.go",
+        "new.go",
+        "setter_getter.go",
+        "type.go",
+    ],
+    importpath = "github.com/prysmaticlabs/prysm/beacon-chain/blockchain/store",
+    visibility = ["//beacon-chain:__subpackages__"],
+    deps = ["//proto/prysm/v1alpha1:go_default_library"],
+)
+
+go_test(
+    name = "go_default_test",
+    srcs = [
+        "new_test.go",
+        "setter_getter_test.go",
+    ],
+    embed = [":go_default_library"],
+    deps = [
+        "//proto/prysm/v1alpha1:go_default_library",
+        "//testing/require:go_default_library",
+    ],
+)
--- a/beacon-chain/blockchain/store/doc.go
+++ b/beacon-chain/blockchain/store/doc.go
@@ -0,0 +1,4 @@
+// Package store implements the store object defined in the phase0 fork choice spec.
+// It serves as a helpful middleware layer in between blockchain pkg and fork choice protoarray pkg.
+// All the getters and setters are concurrent thread safe
+package store
--- a/Show More
+++ b/Show More
@@ -1 +1 @@
 .7.0
 .2.2