more progress on refactor

modif test files
separate out into specific files
2026-01-10 13:58:09 -05:00 · 2021-11-09 14:09:59 -05:00 · 2021-11-09 13:53:21 -05:00 · 2021-11-09 13:22:43 -05:00 · 2021-11-09 10:36:37 -05:00 · 2021-11-08 19:08:17 +00:00
2129 changed files with 114371 additions and 82255 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
--- a/.bazelversion
+++ b/.bazelversion
@@ -1 +1 @@
-3.7.0
+4.2.1
--- 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
@@ -43,3 +43,7 @@ build --flaky_test_attempts=5

 # 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/workflows/go.yml
+++ b/.github/workflows/go.yml
@@ -24,13 +24,23 @@ jobs:
        uses: ./.github/actions/gofmt
        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
+
  build:
    name: Build
    runs-on: ubuntu-latest
--- a/BUILD.bazel
+++ b/BUILD.bazel
@@ -144,12 +144,6 @@ 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 = "",
--- 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/README.md
+++ b/README.md
@@ -2,7 +2,7 @@

 [![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)
+[![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/consensus-specs/tree/v1.0.0)
 [![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 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.
--- 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/132
+++ b/132
@@ -76,9 +76,9 @@ 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(
@@ -139,6 +139,34 @@ 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",
@@ -197,8 +225,12 @@ filegroup(
    url = "https://github.com/eth2-clients/slashing-protection-interchange-tests/archive/b8413ca42dc92308019d0d4db52c87e9e125c4e9.tar.gz",
 )

+consensus_spec_version = "v1.1.3"
+
+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",
@@ -209,12 +241,12 @@ 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 = "e572f8c57e2dbbaeee056a600dc9d08396010dd5134a3a95e43c540470acf6f5",
+    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",
@@ -225,12 +257,12 @@ 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 = "7e2f62eaae9fd541690cc61d252556d0c5deb585ca1873aacbeb5b02d06f1362",
+    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",
@@ -241,8 +273,55 @@ 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 = "05cbb89810c8acd6c57c4773ddfd167305cd4539960e9b4d7b69e1a988b35ad2",
+    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 = "0cef67b08448f7eb43bf66c464451c9e7a4852df8ef90555cca6d440e3436882",
+    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 = "9dc47bf6b14aed7fac8833e35ab83a69131b43fa5789b3256bf1ac3d4861aeb8",
+    strip_prefix = "eth2-networks-7fa1b868985ee24aad65567f9250cf7fa86f97b1",
+    url = "https://github.com/eth2-clients/eth2-networks/archive/7fa1b868985ee24aad65567f9250cf7fa86f97b1.tar.gz",
 )

 http_archive(
@@ -262,27 +341,6 @@ git_repository(
 # 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",
@@ -304,9 +362,9 @@ filegroup(
    visibility = ["//visibility:public"],
 )
 """,
-    sha256 = "54ce527b83d092da01127f2e3816f4d5cfbab69354caba8537f1ea55889b6d7c",
+    sha256 = "0a3d94428ea28916276694c517b82b364122063fdbf924f54ee9ae0bc500289f",
    urls = [
-        "https://github.com/prysmaticlabs/prysm-web-ui/releases/download/v1.0.0-beta.4/prysm-web-ui.tar.gz",
+        "https://github.com/prysmaticlabs/prysm-web-ui/releases/download/v1.0.1/prysm-web-ui.tar.gz",
    ],
 )

@@ -337,10 +395,6 @@ load(

 _cc_image_repos()

-load("@com_github_ethereum_go_ethereum//:deps.bzl", "geth_dependencies")
-
-geth_dependencies()
-
 load("@io_bazel_rules_go//extras:embed_data_deps.bzl", "go_embed_data_dependencies")

 go_embed_data_dependencies()
--- a/shared/gateway/BUILD.bazel
+++ b/shared/gateway/BUILD.bazel
@@ -3,29 +3,22 @@ load("@prysm//tools/go:def.bzl", "go_library", "go_test")
 go_library(
    name = "go_default_library",
    srcs = [
-        "api_middleware.go",
-        "api_middleware_processing.go",
-        "api_middleware_structs.go",
        "gateway.go",
        "log.go",
-        "param_handling.go",
    ],
-    importpath = "github.com/prysmaticlabs/prysm/shared/gateway",
+    importpath = "github.com/prysmaticlabs/prysm/api/gateway",
    visibility = [
        "//beacon-chain:__subpackages__",
        "//validator:__subpackages__",
    ],
    deps = [
-        "//shared:go_default_library",
-        "//shared/bytesutil:go_default_library",
-        "//shared/grpcutils:go_default_library",
-        "@com_github_ethereum_go_ethereum//common/hexutil:go_default_library",
+        "//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",
-        "@com_github_wealdtech_go_bytesutil//: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",
@@ -34,17 +27,13 @@ go_library(

 go_test(
    name = "go_default_test",
-    srcs = [
-        "api_middleware_processing_test.go",
-        "gateway_test.go",
-        "param_handling_test.go",
-    ],
+    srcs = ["gateway_test.go"],
    embed = [":go_default_library"],
    deps = [
+        "//api/gateway/apimiddleware:go_default_library",
        "//cmd/beacon-chain/flags:go_default_library",
-        "//shared/grpcutils:go_default_library",
-        "//shared/testutil/assert:go_default_library",
-        "//shared/testutil/require: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 +1,233 @@
+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
+}
+
+// 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.
+	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() {
+		m.handleApiPath(gatewayRouter, path, m.EndpointCreator)
+	}
+}
+
+func (m *ApiProxyMiddleware) handleApiPath(gatewayRouter *mux.Router, path string, endpointFactory EndpointFactory) {
+	gatewayRouter.HandleFunc(path, func(w http.ResponseWriter, req *http.Request) {
+		endpoint, err := endpointFactory.Create(path)
+		if err != nil {
+			errJson := InternalServerErrorWithMessage(err, "could not create endpoint")
+			WriteError(w, errJson, nil)
+		}
+
+		for _, handler := range endpoint.CustomHandlers {
+			if handler(m, *endpoint, w, req) {
+				return
+			}
+		}
+
+		if req.Method == "POST" {
+			if errJson := deserializeRequestBodyIntoContainerWrapped(endpoint, req, w); errJson != nil {
+				WriteError(w, errJson, nil)
+				return
+			}
+
+			if errJson := ProcessRequestContainerFields(endpoint.PostRequest); errJson != nil {
+				WriteError(w, errJson, nil)
+				return
+			}
+			if errJson := SetRequestBodyToRequestContainer(endpoint.PostRequest, 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 {
+				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 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
@@ -1,4 +1,4 @@
-package gateway
+package apimiddleware

 import (
 	"encoding/base64"
@@ -7,7 +7,7 @@ import (
 	"strings"

 	"github.com/gorilla/mux"
-	butil "github.com/prysmaticlabs/prysm/shared/bytesutil"
+	butil "github.com/prysmaticlabs/prysm/encoding/bytesutil"
 	"github.com/wealdtech/go-bytesutil"
 )

@@ -28,11 +28,8 @@ segmentsLoop:

 			routeVar := mux.Vars(req)[s[1:len(s)-1]]
 			bRouteVar := []byte(routeVar)
-			isHex, err := butil.IsHex(bRouteVar)
-			if err != nil {
-				return InternalServerErrorWithMessage(err, "could not process URL parameter")
-			}
-			if isHex {
+			if butil.IsHex(bRouteVar) {
+				var err error
 				bRouteVar, err = bytesutil.FromHexString(string(bRouteVar))
 				if err != nil {
 					return InternalServerErrorWithMessage(err, "could not process URL parameter")
@@ -64,11 +61,8 @@ func HandleQueryParameters(req *http.Request, params []QueryParam) ErrorJson {
 					queryParams.Del(key)
 					for _, v := range vals {
 						b := []byte(v)
-						isHex, err := butil.IsHex(b)
-						if err != nil {
-							return InternalServerErrorWithMessage(err, "could not process query parameter")
-						}
-						if isHex {
+						if butil.IsHex(b) {
+							var err error
 							b, err = bytesutil.FromHexString(v)
 							if err != nil {
 								return InternalServerErrorWithMessage(err, "could not process query parameter")
--- a/api/gateway/apimiddleware/param_handling_test.go
+++ b/api/gateway/apimiddleware/param_handling_test.go
@@ -1,4 +1,4 @@
-package gateway
+package apimiddleware

 import (
 	"bytes"
@@ -6,8 +6,8 @@ import (
 	"testing"

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

 func TestHandleURLParameters(t *testing.T) {
--- 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
@@ -1,27 +1,31 @@
-package gateway
+package apimiddleware

 import (
 	"bytes"
-	"encoding/base64"
 	"encoding/json"
-	"fmt"
 	"io"
 	"io/ioutil"
 	"net/http"
-	"reflect"
 	"strconv"
 	"strings"
 	"time"

-	"github.com/ethereum/go-ethereum/common/hexutil"
 	"github.com/pkg/errors"
-	"github.com/prysmaticlabs/prysm/shared/grpcutils"
-	"github.com/wealdtech/go-bytesutil"
+	"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 {
-	if err := json.NewDecoder(body).Decode(&requestContainer); err != nil {
+	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
@@ -59,10 +63,15 @@ func (m *ApiProxyMiddleware) PrepareRequestForProxying(endpoint Endpoint, req *h
 	req.URL.Scheme = "http"
 	req.URL.Host = m.GatewayAddress
 	req.RequestURI = ""
-	if errJson := HandleURLParameters(endpoint.Path, req, endpoint.GetRequestURLLiterals); errJson != nil {
+	if errJson := HandleURLParameters(endpoint.Path, req, endpoint.RequestURLLiterals); errJson != nil {
 		return errJson
 	}
-	return HandleQueryParameters(req, endpoint.GetRequestQueryParams)
+	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.
@@ -88,31 +97,30 @@ func ReadGrpcResponseBody(r io.Reader) ([]byte, ErrorJson) {
 	return body, nil
 }

-// DeserializeGrpcResponseBodyIntoErrorJson deserializes the body from the grpc-gateway's response into an error struct.
-// The struct can be later examined to check if the request resulted in an error.
-func DeserializeGrpcResponseBodyIntoErrorJson(errJson ErrorJson, body []byte) ErrorJson {
-	if err := json.Unmarshal(body, errJson); err != nil {
-		return InternalServerErrorWithMessage(err, "could not unmarshal error")
-	}
-	return nil
-}
-
 // HandleGrpcResponseError acts on an error that resulted from a grpc-gateway's response.
-func HandleGrpcResponseError(errJson ErrorJson, resp *http.Response, w http.ResponseWriter) {
-	// 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)
-		}
+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")
 	}
-	// Set code to HTTP code because unmarshalled body contained gRPC code.
-	errJson.SetCode(resp.StatusCode)
-	WriteError(w, errJson, resp.Header)
+	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
 }

-// GrpcResponseIsStatusCodeOnly checks whether a grpc-gateway's response contained no body.
-func GrpcResponseIsStatusCodeOnly(req *http.Request, responseContainer interface{}) bool {
-	return req.Method == "GET" && responseContainer == 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.
@@ -154,12 +162,12 @@ func SerializeMiddlewareResponseIntoJson(responseContainer interface{}) (jsonRes
 }

 // WriteMiddlewareResponseHeadersAndBody populates headers and the body of the final response.
-func WriteMiddlewareResponseHeadersAndBody(req *http.Request, grpcResp *http.Response, responseJson []byte, w http.ResponseWriter) ErrorJson {
+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-"+grpcutils.HttpCodeMetadataKey {
+			if h == "Grpc-Metadata-"+grpc.HttpCodeMetadataKey {
 				statusCodeHeader = vs[0]
 			}
 		} else {
@@ -168,7 +176,7 @@ func WriteMiddlewareResponseHeadersAndBody(req *http.Request, grpcResp *http.Res
 			}
 		}
 	}
-	if req.Method == "GET" {
+	if !GrpcResponseIsEmpty(responseJson) {
 		w.Header().Set("Content-Length", strconv.Itoa(len(responseJson)))
 		if statusCodeHeader != "" {
 			code, err := strconv.Atoi(statusCodeHeader)
@@ -182,7 +190,8 @@ func WriteMiddlewareResponseHeadersAndBody(req *http.Request, grpcResp *http.Res
 		if _, err := io.Copy(w, ioutil.NopCloser(bytes.NewReader(responseJson))); err != nil {
 			return InternalServerErrorWithMessage(err, "could not write response message")
 		}
-	} else if req.Method == "POST" {
+	} else {
+		w.Header().Set("Content-Length", "0")
 		w.WriteHeader(grpcResp.StatusCode)
 	}
 	return nil
@@ -191,9 +200,11 @@ func WriteMiddlewareResponseHeadersAndBody(req *http.Request, grpcResp *http.Res
 // 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-"+grpcutils.CustomErrorMetadataKey]
+		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")
@@ -202,10 +213,29 @@ func WriteError(w http.ResponseWriter, errJson ErrorJson, responseHeader http.He
 		}
 	}

-	j, err := json.Marshal(errJson)
-	if err != nil {
-		log.WithError(err).Error("Could not marshal 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)))
@@ -223,94 +253,3 @@ func Cleanup(grpcResponseBody io.ReadCloser) ErrorJson {
 	}
 	return nil
 }
-
-// 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 {
-	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_test.go
+++ b/api/gateway/apimiddleware/process_request_test.go
@@ -1,4 +1,4 @@
-package gateway
+package apimiddleware

 import (
 	"bytes"
@@ -8,9 +8,9 @@ import (
 	"strings"
 	"testing"

-	"github.com/prysmaticlabs/prysm/shared/grpcutils"
-	"github.com/prysmaticlabs/prysm/shared/testutil/assert"
-	"github.com/prysmaticlabs/prysm/shared/testutil/require"
+	"github.com/prysmaticlabs/prysm/api/grpc"
+	"github.com/prysmaticlabs/prysm/testing/assert"
+	"github.com/prysmaticlabs/prysm/testing/require"
 	"github.com/sirupsen/logrus/hooks/test"
 )

@@ -63,6 +63,11 @@ 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
@@ -83,6 +88,15 @@ func TestDeserializeRequestBodyIntoContainer(t *testing.T) {
 		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) {
@@ -124,9 +138,9 @@ func TestPrepareRequestForProxying(t *testing.T) {
 	}
 	// We will set some params to make the request more interesting.
 	endpoint := Endpoint{
-		Path:                  "/{url_param}",
-		GetRequestURLLiterals: []string{"url_param"},
-		GetRequestQueryParams: []QueryParam{{Name: "query_param"}},
+		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)
@@ -147,29 +161,6 @@ func TestReadGrpcResponseBody(t *testing.T) {
 	assert.Equal(t, "foo", string(body))
 }

-func TestDeserializeGrpcResponseBodyIntoErrorJson(t *testing.T) {
-	t.Run("ok", func(t *testing.T) {
-		e := &testErrorJson{
-			Message: "foo",
-			Code:    500,
-		}
-		body, err := json.Marshal(e)
-		require.NoError(t, err)
-
-		eToDeserialize := &testErrorJson{}
-		errJson := DeserializeGrpcResponseBodyIntoErrorJson(eToDeserialize, body)
-		require.Equal(t, true, errJson == nil)
-		assert.Equal(t, "foo", eToDeserialize.Msg())
-		assert.Equal(t, 500, eToDeserialize.StatusCode())
-	})
-
-	t.Run("error", func(t *testing.T) {
-		errJson := DeserializeGrpcResponseBodyIntoErrorJson(nil, nil)
-		require.NotNil(t, errJson)
-		assert.Equal(t, true, strings.Contains(errJson.Msg(), "could not unmarshal error"))
-	})
-}
-
 func TestHandleGrpcResponseError(t *testing.T) {
 	response := &http.Response{
 		StatusCode: 400,
@@ -181,10 +172,14 @@ func TestHandleGrpcResponseError(t *testing.T) {
 	writer := httptest.NewRecorder()
 	errJson := &testErrorJson{
 		Message: "foo",
-		Code:    500,
+		Code:    400,
 	}
+	b, err := json.Marshal(errJson)
+	require.NoError(t, err)

-	HandleGrpcResponseError(errJson, response, writer)
+	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")
@@ -196,25 +191,18 @@ func TestHandleGrpcResponseError(t *testing.T) {
 	assert.Equal(t, 400, errJson.StatusCode())
 }

-func TestGrpcResponseIsStatusCodeOnly(t *testing.T) {
-	var body bytes.Buffer
-
-	t.Run("status_code_only", func(t *testing.T) {
-		request := httptest.NewRequest("GET", "http://foo.example", &body)
-		result := GrpcResponseIsStatusCodeOnly(request, nil)
-		assert.Equal(t, true, result)
+func TestGrpcResponseIsEmpty(t *testing.T) {
+	t.Run("nil", func(t *testing.T) {
+		assert.Equal(t, true, GrpcResponseIsEmpty(nil))
 	})
-
-	t.Run("different_method", func(t *testing.T) {
-		request := httptest.NewRequest("POST", "http://foo.example", &body)
-		result := GrpcResponseIsStatusCodeOnly(request, nil)
-		assert.Equal(t, false, result)
+	t.Run("empty_slice", func(t *testing.T) {
+		assert.Equal(t, true, GrpcResponseIsEmpty(make([]byte, 0)))
 	})
-
-	t.Run("non_empty_response", func(t *testing.T) {
-		request := httptest.NewRequest("GET", "http://foo.example", &body)
-		result := GrpcResponseIsStatusCodeOnly(request, &testRequestContainer{})
-		assert.Equal(t, false, result)
+	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\"})")))
 	})
 }

@@ -268,14 +256,11 @@ func TestSerializeMiddlewareResponseIntoJson(t *testing.T) {
 }

 func TestWriteMiddlewareResponseHeadersAndBody(t *testing.T) {
-	var body bytes.Buffer
-
 	t.Run("GET", func(t *testing.T) {
-		request := httptest.NewRequest("GET", "http://foo.example", &body)
 		response := &http.Response{
 			Header: http.Header{
 				"Foo": []string{"foo"},
-				"Grpc-Metadata-" + grpcutils.HttpCodeMetadataKey: []string{"204"},
+				"Grpc-Metadata-" + grpc.HttpCodeMetadataKey: []string{"204"},
 			},
 		}
 		container := defaultResponseContainer()
@@ -284,7 +269,7 @@ func TestWriteMiddlewareResponseHeadersAndBody(t *testing.T) {
 		writer := httptest.NewRecorder()
 		writer.Body = &bytes.Buffer{}

-		errJson := WriteMiddlewareResponseHeadersAndBody(request, response, responseJson, writer)
+		errJson := WriteMiddlewareResponseHeadersAndBody(response, responseJson, writer)
 		require.Equal(t, true, errJson == nil)
 		v, ok := writer.Header()["Foo"]
 		require.Equal(t, true, ok, "header not found")
@@ -299,7 +284,6 @@ func TestWriteMiddlewareResponseHeadersAndBody(t *testing.T) {
 	})

 	t.Run("GET_no_grpc_status_code_header", func(t *testing.T) {
-		request := httptest.NewRequest("GET", "http://foo.example", &body)
 		response := &http.Response{
 			Header:     http.Header{},
 			StatusCode: 204,
@@ -309,33 +293,31 @@ func TestWriteMiddlewareResponseHeadersAndBody(t *testing.T) {
 		require.NoError(t, err)
 		writer := httptest.NewRecorder()

-		errJson := WriteMiddlewareResponseHeadersAndBody(request, response, responseJson, writer)
+		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) {
-		request := httptest.NewRequest("GET", "http://foo.example", &body)
 		response := &http.Response{
 			Header: http.Header{},
 		}

 		// Set invalid status code.
-		response.Header["Grpc-Metadata-"+grpcutils.HttpCodeMetadataKey] = []string{"invalid"}
+		response.Header["Grpc-Metadata-"+grpc.HttpCodeMetadataKey] = []string{"invalid"}

 		container := defaultResponseContainer()
 		responseJson, err := json.Marshal(container)
 		require.NoError(t, err)
 		writer := httptest.NewRecorder()

-		errJson := WriteMiddlewareResponseHeadersAndBody(request, response, responseJson, writer)
+		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) {
-		request := httptest.NewRequest("POST", "http://foo.example", &body)
 		response := &http.Response{
 			Header:     http.Header{},
 			StatusCode: 204,
@@ -345,16 +327,50 @@ func TestWriteMiddlewareResponseHeadersAndBody(t *testing.T) {
 		require.NoError(t, err)
 		writer := httptest.NewRecorder()

-		errJson := WriteMiddlewareResponseHeadersAndBody(request, response, responseJson, writer)
+		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-" + grpcutils.CustomErrorMetadataKey: []string{"{\"CustomField\":\"bar\"}"},
+			"Grpc-Metadata-" + grpc.CustomErrorMetadataKey: []string{"{\"CustomField\":\"bar\"}"},
 		}
 		errJson := &testErrorJson{
 			Message: "foo",
@@ -384,7 +400,7 @@ func TestWriteError(t *testing.T) {
 		logHook := test.NewGlobal()

 		responseHeader := http.Header{
-			"Grpc-Metadata-" + grpcutils.CustomErrorMetadataKey: []string{"invalid"},
+			"Grpc-Metadata-" + grpc.CustomErrorMetadataKey: []string{"invalid"},
 		}

 		WriteError(httptest.NewRecorder(), &testErrorJson{}, responseHeader)
--- a/shared/gateway/api_middleware_structs.go
+++ b/shared/gateway/api_middleware_structs.go
@@ -1,4 +1,4 @@
-package gateway
+package apimiddleware

 import (
 	"net/http"
@@ -15,6 +15,7 @@ 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.
@@ -54,3 +55,8 @@ func (e *DefaultErrorJson) Msg() string {
 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/shared/gateway/gateway.go
+++ b/shared/gateway/gateway.go
@@ -10,22 +10,24 @@ import (
 	"strings"
 	"time"

+	"github.com/gorilla/mux"
 	gwruntime "github.com/grpc-ecosystem/grpc-gateway/v2/runtime"
 	"github.com/pkg/errors"
-	"github.com/prysmaticlabs/prysm/shared"
+	"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 _ shared.Service = (*Gateway)(nil)
+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 mux that will be used for grpc-gateway requests.
+	Mux           *gwruntime.ServeMux     // The router that will be used for grpc-gateway requests.
 }

 // PbHandlerRegistration is a function that registers a protobuf handler.
@@ -37,16 +39,15 @@ type MuxHandler func(http.Handler, http.ResponseWriter, *http.Request)
 // Gateway is the gRPC gateway to serve HTTP JSON traffic as a proxy and forward it to the gRPC server.
 type Gateway struct {
 	conn                         *grpc.ClientConn
-	pbHandlers                   []PbMux
+	pbHandlers                   []*PbMux
 	muxHandler                   MuxHandler
 	maxCallRecvMsgSize           uint64
-	mux                          *http.ServeMux
+	router                       *mux.Router
 	server                       *http.Server
 	cancel                       context.CancelFunc
 	remoteCert                   string
 	gatewayAddr                  string
-	apiMiddlewareAddr            string
-	apiMiddlewareEndpointFactory EndpointFactory
+	apiMiddlewareEndpointFactory apimiddleware.EndpointFactory
 	ctx                          context.Context
 	startFailure                 error
 	remoteAddr                   string
@@ -56,7 +57,7 @@ type Gateway struct {
 // New returns a new instance of the Gateway.
 func New(
 	ctx context.Context,
-	pbHandlers []PbMux,
+	pbHandlers []*PbMux,
 	muxHandler MuxHandler,
 	remoteAddr,
 	gatewayAddress string,
@@ -64,7 +65,7 @@ func New(
 	g := &Gateway{
 		pbHandlers:     pbHandlers,
 		muxHandler:     muxHandler,
-		mux:            http.NewServeMux(),
+		router:         mux.NewRouter(),
 		gatewayAddr:    gatewayAddress,
 		ctx:            ctx,
 		remoteAddr:     remoteAddr,
@@ -73,9 +74,9 @@ func New(
 	return g
 }

-// WithMux allows adding a custom http.ServeMux to the gateway.
-func (g *Gateway) WithMux(m *http.ServeMux) *Gateway {
-	g.mux = m
+// WithRouter allows adding a custom mux router to the gateway.
+func (g *Gateway) WithRouter(r *mux.Router) *Gateway {
+	g.router = r
 	return g
 }

@@ -98,8 +99,7 @@ func (g *Gateway) WithMaxCallRecvMsgSize(size uint64) *Gateway {
 }

 // WithApiMiddleware allows adding API Middleware proxy to the gateway.
-func (g *Gateway) WithApiMiddleware(address string, endpointFactory EndpointFactory) *Gateway {
-	g.apiMiddlewareAddr = address
+func (g *Gateway) WithApiMiddleware(endpointFactory apimiddleware.EndpointFactory) *Gateway {
 	g.apiMiddlewareEndpointFactory = endpointFactory
 	return g
 }
@@ -126,18 +126,25 @@ func (g *Gateway) Start() {
 			}
 		}
 		for _, p := range h.Patterns {
-			g.mux.Handle(p, h.Mux)
+			g.router.PathPrefix(p).Handler(h.Mux)
 		}
 	}

-	corsMux := g.corsMiddleware(g.mux)
-	g.mux.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
-		g.muxHandler(corsMux, w, r)
-	})
+	corsMux := g.corsMiddleware(g.router)
+
+	if g.muxHandler != nil {
+		g.router.PathPrefix("/").HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			g.muxHandler(corsMux, w, r)
+		})
+	}
+
+	if g.apiMiddlewareEndpointFactory != nil && !g.apiMiddlewareEndpointFactory.IsNil() {
+		go g.registerApiMiddleware()
+	}

 	g.server = &http.Server{
 		Addr:    g.gatewayAddr,
-		Handler: corsMux,
+		Handler: g.router,
 	}

 	go func() {
@@ -148,10 +155,6 @@ func (g *Gateway) Start() {
 			return
 		}
 	}()
-
-	if g.apiMiddlewareAddr != "" && g.apiMiddlewareEndpointFactory != nil && !g.apiMiddlewareEndpointFactory.IsNil() {
-		go g.registerApiMiddleware()
-	}
 }

 // Status of grpc gateway. Returns an error if this service is unhealthy.
@@ -199,7 +202,7 @@ func (g *Gateway) corsMiddleware(h http.Handler) http.Handler {
 	return c.Handler(h)
 }

-const swaggerDir = "proto/beacon/rpc/v1/"
+const swaggerDir = "proto/prysm/v1alpha1/"

 // SwaggerServer returns swagger specification files located under "/swagger/"
 func SwaggerServer() http.HandlerFunc {
@@ -269,15 +272,10 @@ func (g *Gateway) dialUnix(ctx context.Context, addr string) (*grpc.ClientConn,
 }

 func (g *Gateway) registerApiMiddleware() {
-	proxy := &ApiProxyMiddleware{
+	proxy := &apimiddleware.ApiProxyMiddleware{
 		GatewayAddress:  g.gatewayAddr,
-		ProxyAddress:    g.apiMiddlewareAddr,
 		EndpointCreator: g.apiMiddlewareEndpointFactory,
 	}
-	log.WithField("API middleware address", g.apiMiddlewareAddr).Info("Starting API middleware")
-	if err := proxy.Run(); err != http.ErrServerClosed {
-		log.WithError(err).Error("Failed to start API middleware")
-		g.startFailure = err
-		return
-	}
+	log.Info("Starting API middleware")
+	proxy.Run(g.router)
 }
--- a/shared/gateway/gateway_test.go
+++ b/shared/gateway/gateway_test.go
@@ -5,11 +5,15 @@ import (
 	"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/shared/testutil/assert"
-	"github.com/prysmaticlabs/prysm/shared/testutil/require"
+	"github.com/prysmaticlabs/prysm/testing/assert"
+	"github.com/prysmaticlabs/prysm/testing/require"
 	logTest "github.com/sirupsen/logrus/hooks/test"
 	"github.com/urfave/cli/v2"
 )
@@ -21,7 +25,7 @@ func (*mockEndpointFactory) Paths() []string {
 	return []string{}
 }

-func (*mockEndpointFactory) Create(_ string) (*Endpoint, error) {
+func (*mockEndpointFactory) Create(_ string) (*apimiddleware.Endpoint, error) {
 	return nil, nil
 }

@@ -30,33 +34,31 @@ func (*mockEndpointFactory) IsNil() bool {
 }

 func TestGateway_Customized(t *testing.T) {
-	mux := http.NewServeMux()
+	r := mux.NewRouter()
 	cert := "cert"
 	origins := []string{"origin"}
 	size := uint64(100)
-	middlewareAddr := "middleware"
 	endpointFactory := &mockEndpointFactory{}

 	g := New(
 		context.Background(),
-		[]PbMux{},
+		[]*PbMux{},
 		func(handler http.Handler, writer http.ResponseWriter, request *http.Request) {

 		},
 		"",
 		"",
-	).WithMux(mux).
+	).WithRouter(r).
 		WithRemoteCert(cert).
 		WithAllowedOrigins(origins).
 		WithMaxCallRecvMsgSize(size).
-		WithApiMiddleware(middlewareAddr, endpointFactory)
+		WithApiMiddleware(endpointFactory)

-	assert.Equal(t, mux, g.mux)
+	assert.Equal(t, r, g.router)
 	assert.Equal(t, cert, g.remoteCert)
 	require.Equal(t, 1, len(g.allowedOrigins))
 	assert.Equal(t, origins[0], g.allowedOrigins[0])
 	assert.Equal(t, size, g.maxCallRecvMsgSize)
-	assert.Equal(t, middlewareAddr, g.apiMiddlewareAddr)
 	assert.Equal(t, endpointFactory, g.apiMiddlewareEndpointFactory)
 }

@@ -75,7 +77,7 @@ func TestGateway_StartStop(t *testing.T) {

 	g := New(
 		ctx.Context,
-		[]PbMux{},
+		[]*PbMux{},
 		func(handler http.Handler, writer http.ResponseWriter, request *http.Request) {

 		},
@@ -92,3 +94,27 @@ func TestGateway_StartStop(t *testing.T) {
 	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)
+
+	g := New(
+		ctx.Context,
+		[]*PbMux{},
+		/* muxHandler */ nil,
+		selfAddress,
+		gatewayAddress,
+	)
+
+	writer := httptest.NewRecorder()
+	g.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/shared/grpcutils/BUILD.bazel
+++ b/shared/grpcutils/BUILD.bazel
@@ -6,7 +6,7 @@ go_library(
        "grpcutils.go",
        "parameters.go",
    ],
-    importpath = "github.com/prysmaticlabs/prysm/shared/grpcutils",
+    importpath = "github.com/prysmaticlabs/prysm/api/grpc",
    visibility = ["//visibility:public"],
    deps = [
        "@com_github_sirupsen_logrus//:go_default_library",
@@ -20,8 +20,8 @@ go_test(
    srcs = ["grpcutils_test.go"],
    embed = [":go_default_library"],
    deps = [
-        "//shared/testutil/assert:go_default_library",
-        "//shared/testutil/require:go_default_library",
+        "//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",
--- a/shared/grpcutils/grpcutils.go
+++ b/shared/grpcutils/grpcutils.go
@@ -1,4 +1,4 @@
-package grpcutils
+package grpc

 import (
 	"context"
--- a/shared/grpcutils/grpcutils_test.go
+++ b/shared/grpcutils/grpcutils_test.go
@@ -1,4 +1,4 @@
-package grpcutils
+package grpc

 import (
 	"context"
@@ -7,8 +7,8 @@ import (
 	"testing"

 	"github.com/grpc-ecosystem/grpc-gateway/v2/runtime"
-	"github.com/prysmaticlabs/prysm/shared/testutil/assert"
-	"github.com/prysmaticlabs/prysm/shared/testutil/require"
+	"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"
--- a/shared/grpcutils/parameters.go
+++ b/shared/grpcutils/parameters.go
@@ -1,4 +1,4 @@
-package grpcutils
+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.
--- a/shared/pagination/BUILD.bazel
+++ b/shared/pagination/BUILD.bazel
@@ -3,10 +3,10 @@ load("@prysm//tools/go:def.bzl", "go_library", "go_test")
 go_library(
    name = "go_default_library",
    srcs = ["pagination.go"],
-    importpath = "github.com/prysmaticlabs/prysm/shared/pagination",
+    importpath = "github.com/prysmaticlabs/prysm/api/pagination",
    visibility = ["//visibility:public"],
    deps = [
-        "//shared/params:go_default_library",
+        "//config/params:go_default_library",
        "@com_github_pkg_errors//:go_default_library",
    ],
 )
@@ -16,7 +16,7 @@ go_test(
    srcs = ["pagination_test.go"],
    deps = [
        ":go_default_library",
-        "//shared/testutil/assert:go_default_library",
-        "//shared/testutil/require: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/shared/mputil/BUILD.bazel
+++ b/shared/mputil/BUILD.bazel
@@ -3,25 +3,30 @@ 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/shared/mputil",
+    importpath = "github.com/prysmaticlabs/prysm/async",
    visibility = ["//visibility:public"],
+    deps = ["@com_github_sirupsen_logrus//:go_default_library"],
 )

 go_test(
    name = "go_default_test",
-    size = "small",
    srcs = [
        "benchmark_test.go",
+        "debounce_test.go",
+        "every_test.go",
        "multilock_test.go",
        "scatter_test.go",
    ],
    embed = [":go_default_library"],
    deps = [
-        "//shared/testutil/assert:go_default_library",
-        "//shared/testutil/require:go_default_library",
+        "//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/shared/abool/BUILD.bazel
+++ b/shared/abool/BUILD.bazel
@@ -3,7 +3,7 @@ load("@prysm//tools/go:def.bzl", "go_library", "go_test")
 go_library(
    name = "go_default_library",
    srcs = ["abool.go"],
-    importpath = "github.com/prysmaticlabs/prysm/shared/abool",
+    importpath = "github.com/prysmaticlabs/prysm/async/abool",
    visibility = ["//visibility:public"],
 )

--- a/shared/abool/abool.go
+++ b/shared/abool/abool.go
--- a/shared/abool/abool_test.go
+++ b/shared/abool/abool_test.go
--- a/shared/mputil/benchmark_test.go
+++ b/shared/mputil/benchmark_test.go
@@ -1,4 +1,4 @@
-package mputil_test
+package async_test

 import (
 	"crypto/rand"
@@ -6,8 +6,8 @@ import (
 	"sync"
 	"testing"

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

@@ -52,7 +52,7 @@ func BenchmarkHash(b *testing.B) {
 func BenchmarkHashMP(b *testing.B) {
 	output := make([][]byte, len(input))
 	for i := 0; i < b.N; i++ {
-		workerResults, err := mputil.Scatter(len(input), func(offset int, entries int, _ *sync.RWMutex) (interface{}, error) {
+		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)
--- 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/shared/event/BUILD.bazel
+++ b/shared/event/BUILD.bazel
@@ -6,9 +6,9 @@ go_library(
        "feed.go",
        "subscription.go",
    ],
-    importpath = "github.com/prysmaticlabs/prysm/shared/event",
+    importpath = "github.com/prysmaticlabs/prysm/async/event",
    visibility = ["//visibility:public"],
-    deps = ["//shared/mclockutil:go_default_library"],
+    deps = ["//time/mclock:go_default_library"],
 )

 go_test(
@@ -23,7 +23,7 @@ go_test(
    ],
    embed = [":go_default_library"],
    deps = [
-        "//shared/testutil/assert:go_default_library",
-        "//shared/testutil/require:go_default_library",
+        "//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/shared/event/feed_test.go
+++ b/shared/event/feed_test.go
@@ -23,7 +23,7 @@ import (
 	"testing"
 	"time"

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

 func TestFeedPanics(t *testing.T) {
@@ -159,7 +159,7 @@ func TestFeedSubscribeSameChannel(t *testing.T) {
 	done.Wait()
 }

-func TestFeedSubscribeBlockedPost(t *testing.T) {
+func TestFeedSubscribeBlockedPost(_ *testing.T) {
 	var (
 		feed   Feed
 		nsends = 2000
@@ -192,7 +192,7 @@ func TestFeedSubscribeBlockedPost(t *testing.T) {
 	}
 }

-func TestFeedUnsubscribeBlockedPost(t *testing.T) {
+func TestFeedUnsubscribeBlockedPost(_ *testing.T) {
 	var (
 		feed   Feed
 		nsends = 200
@@ -229,7 +229,7 @@ func TestFeedUnsubscribeBlockedPost(t *testing.T) {

 // Checks that unsubscribing a channel during Send works even if that
 // channel has already been sent on.
-func TestFeedUnsubscribeSentChan(t *testing.T) {
+func TestFeedUnsubscribeSentChan(_ *testing.T) {
 	var (
 		feed Feed
 		ch1  = make(chan int)
@@ -315,3 +315,193 @@ func BenchmarkFeedSend1000(b *testing.B) {
 	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
@@ -6,4 +6,4 @@ You can also read our main [README](https://github.com/prysmaticlabs/prysm/blob/

 [![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
@@ -5,10 +5,12 @@ go_library(
    srcs = [
        "chain_info.go",
        "head.go",
+        "head_sync_committee_info.go",
        "info.go",
        "init_sync_process_block.go",
        "log.go",
        "metrics.go",
+        "options.go",
        "process_attestation.go",
        "process_attestation_helpers.go",
        "process_block.go",
@@ -21,16 +23,23 @@ go_library(
    importpath = "github.com/prysmaticlabs/prysm/beacon-chain/blockchain",
    visibility = [
        "//beacon-chain:__subpackages__",
-        "//fuzz:__pkg__",
+        "//cmd/beacon-chain:__subpackages__",
+        "//testing/fuzz:__pkg__",
+        "//testing/slasher/simulator:__pkg__",
    ],
    deps = [
+        "//async:go_default_library",
+        "//async/event: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/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",
@@ -40,23 +49,21 @@ 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:go_default_library",
        "//beacon-chain/state/stategen:go_default_library",
        "//cmd/beacon-chain/flags:go_default_library",
-        "//proto/beacon/p2p/v1:go_default_library",
+        "//config/features: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/eth/v1alpha1:go_default_library",
-        "//proto/interfaces:go_default_library",
-        "//shared/attestationutil:go_default_library",
-        "//shared/bls:go_default_library",
-        "//shared/bytesutil:go_default_library",
-        "//shared/copyutil: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",
+        "//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_pkg_errors//:go_default_library",
        "@com_github_prometheus_client_golang//prometheus:go_default_library",
@@ -82,9 +89,11 @@ 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",
        "process_attestation_test.go",
        "process_block_test.go",
@@ -96,27 +105,25 @@ 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",
        "//beacon-chain/state/v1:go_default_library",
-        "//proto/beacon/db:go_default_library",
-        "//proto/beacon/p2p/v1:go_default_library",
-        "//proto/eth/v1alpha1:go_default_library",
-        "//proto/eth/v1alpha1/wrapper: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",
@@ -149,24 +156,23 @@ 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",
-        "//proto/eth/v1alpha1:go_default_library",
-        "//proto/eth/v1alpha1/wrapper: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",
--- a/beacon-chain/blockchain/chain_info.go
+++ b/beacon-chain/blockchain/chain_info.go
@@ -7,13 +7,11 @@ import (
 	types "github.com/prysmaticlabs/eth2-types"
 	"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"
-	pb "github.com/prysmaticlabs/prysm/proto/beacon/p2p/v1"
-	ethpb "github.com/prysmaticlabs/prysm/proto/eth/v1alpha1"
-	"github.com/prysmaticlabs/prysm/proto/interfaces"
-	"github.com/prysmaticlabs/prysm/shared/bytesutil"
-	"github.com/prysmaticlabs/prysm/shared/copyutil"
-	"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"
 	"go.opencensus.io/trace"
 )

@@ -25,6 +23,8 @@ type ChainInfoFetcher interface {
 	GenesisFetcher
 	CanonicalFetcher
 	ForkFetcher
+	TimeFetcher
+	HeadDomainFetcher
 }

 // TimeFetcher retrieves the Ethereum consensus data that's related to time.
@@ -43,19 +43,23 @@ type GenesisFetcher interface {
 type HeadFetcher interface {
 	HeadSlot() types.Slot
 	HeadRoot(ctx context.Context) ([]byte, error)
-	HeadBlock(ctx context.Context) (interfaces.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(ctx context.Context, pubKey [48]byte) (types.ValidatorIndex, bool)
+	HeadValidatorIndexToPublicKey(ctx context.Context, index types.ValidatorIndex) ([48]byte, error)
 	ProtoArrayStore() *protoarray.Store
 	ChainHeads() ([][32]byte, []types.Slot)
+	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.
@@ -78,7 +82,7 @@ func (s *Service) FinalizedCheckpt() *ethpb.Checkpoint {
 		return &ethpb.Checkpoint{Root: params.BeaconConfig().ZeroHash[:]}
 	}

-	return copyutil.CopyCheckpoint(s.finalizedCheckpt)
+	return ethpb.CopyCheckpoint(s.finalizedCheckpt)
 }

 // CurrentJustifiedCheckpt returns the current justified checkpoint from head state.
@@ -87,7 +91,7 @@ func (s *Service) CurrentJustifiedCheckpt() *ethpb.Checkpoint {
 		return &ethpb.Checkpoint{Root: params.BeaconConfig().ZeroHash[:]}
 	}

-	return copyutil.CopyCheckpoint(s.justifiedCheckpt)
+	return ethpb.CopyCheckpoint(s.justifiedCheckpt)
 }

 // PreviousJustifiedCheckpt returns the previous justified checkpoint from head state.
@@ -96,7 +100,7 @@ func (s *Service) PreviousJustifiedCheckpt() *ethpb.Checkpoint {
 		return &ethpb.Checkpoint{Root: params.BeaconConfig().ZeroHash[:]}
 	}

-	return copyutil.CopyCheckpoint(s.prevJustifiedCheckpt)
+	return ethpb.CopyCheckpoint(s.prevJustifiedCheckpt)
 }

 // HeadSlot returns the slot of the head of the chain.
@@ -140,7 +144,7 @@ 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) (interfaces.SignedBeaconBlock, error) {
+func (s *Service) HeadBlock(ctx context.Context) (block.SignedBeaconBlock, error) {
 	s.headLock.RLock()
 	defer s.headLock.RUnlock()

@@ -154,7 +158,7 @@ func (s *Service) HeadBlock(ctx context.Context) (interfaces.SignedBeaconBlock,
 // 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()
@@ -178,7 +182,7 @@ 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.
@@ -239,12 +243,12 @@ 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,
 		}
@@ -284,3 +288,27 @@ 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(ctx context.Context, pubKey [48]byte) (types.ValidatorIndex, bool) {
+	s.headLock.RLock()
+	defer s.headLock.RUnlock()
+	if !s.hasHeadState() {
+		return 0, false
+	}
+	return s.headState(ctx).ValidatorIndexByPubkey(pubKey)
+}
+
+// HeadValidatorIndexToPublicKey returns the pubkey of the validator `index`  in current head state.
+func (s *Service) HeadValidatorIndexToPublicKey(_ context.Context, index types.ValidatorIndex) ([48]byte, error) {
+	s.headLock.RLock()
+	defer s.headLock.RUnlock()
+	if !s.hasHeadState() {
+		return [48]byte{}, nil
+	}
+	v, err := s.headValidatorAtIndex(index)
+	if err != nil {
+		return [48]byte{}, err
+	}
+	return v.PublicKey(), nil
+}
--- a/beacon-chain/blockchain/chain_info_norace_test.go
+++ b/beacon-chain/blockchain/chain_info_norace_test.go
@@ -6,15 +6,15 @@ import (

 	testDB "github.com/prysmaticlabs/prysm/beacon-chain/db/testing"
 	"github.com/prysmaticlabs/prysm/beacon-chain/state/stategen"
-	ethpb "github.com/prysmaticlabs/prysm/proto/eth/v1alpha1"
-	"github.com/prysmaticlabs/prysm/proto/eth/v1alpha1/wrapper"
-	"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{}))
@@ -25,7 +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() {
@@ -38,7 +38,7 @@ 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)},
+		cfg:  &config{BeaconDB: beaconDB, StateGen: stategen.New(beaconDB)},
 		head: &head{block: wrapper.WrappedPhase0SignedBeaconBlock(&ethpb.SignedBeaconBlock{})},
 	}
 	go func() {
@@ -51,7 +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
@@ -9,15 +9,14 @@ import (
 	"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/v1"
-	pb "github.com/prysmaticlabs/prysm/proto/beacon/p2p/v1"
-	ethpb "github.com/prysmaticlabs/prysm/proto/eth/v1alpha1"
-	"github.com/prysmaticlabs/prysm/proto/eth/v1alpha1/wrapper"
-	"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"
+	"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"
 )

@@ -105,7 +104,7 @@ func TestPrevJustifiedCheckpt_GenesisRootOk(t *testing.T) {

 func TestHeadSlot_CanRetrieve(t *testing.T) {
 	c := &Service{}
-	s, err := v1.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())
@@ -121,13 +120,13 @@ 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(), wrapper.WrappedPhase0SignedBeaconBlock(b)))
-	require.NoError(t, beaconDB.SaveStateSummary(context.Background(), &pb.StateSummary{Root: br[:]}))
+	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)
@@ -135,9 +134,9 @@ func TestHeadRoot_UseDB(t *testing.T) {
 }

 func TestHeadBlock_CanRetrieve(t *testing.T) {
-	b := testutil.NewBeaconBlock()
+	b := util.NewBeaconBlock()
 	b.Block.Slot = 1
-	s, err := v1.InitializeFromProto(&pb.BeaconState{})
+	s, err := v1.InitializeFromProto(&ethpb.BeaconState{})
 	require.NoError(t, err)
 	c := &Service{}
 	c.head = &head{block: wrapper.WrappedPhase0SignedBeaconBlock(b), state: s}
@@ -148,7 +147,7 @@ func TestHeadBlock_CanRetrieve(t *testing.T) {
 }

 func TestHeadState_CanRetrieve(t *testing.T) {
-	s, err := v1.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}
@@ -164,8 +163,8 @@ func TestGenesisTime_CanRetrieve(t *testing.T) {
 }

 func TestCurrentFork_CanRetrieve(t *testing.T) {
-	f := &pb.Fork{Epoch: 999}
-	s, err := v1.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}
@@ -175,7 +174,7 @@ 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,
 	}
@@ -190,7 +189,7 @@ func TestGenesisValidatorRoot_CanRetrieve(t *testing.T) {
 	c := &Service{}
 	assert.Equal(t, [32]byte{}, c.GenesisValidatorRoot(), "Did not get correct genesis validator root")

-	s, err := v1.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")
@@ -204,7 +203,7 @@ func TestHeadETH1Data_Nil(t *testing.T) {

 func TestHeadETH1Data_CanRetrieve(t *testing.T) {
 	d := &ethpb.Eth1Data{DepositCount: 999}
-	s, err := v1.InitializeFromProto(&pb.BeaconState{Eth1Data: d})
+	s, err := v1.InitializeFromProto(&ethpb.BeaconState{Eth1Data: d})
 	require.NoError(t, err)
 	c := &Service{}
 	c.head = &head{state: s}
@@ -218,7 +217,7 @@ 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)
@@ -234,7 +233,7 @@ 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{}
@@ -249,7 +248,7 @@ 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)
@@ -266,7 +265,7 @@ 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{}
@@ -279,14 +278,14 @@ 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))
@@ -297,3 +296,61 @@ 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(context.Background(), [48]byte{})
+	require.Equal(t, false, e)
+
+	v, err := s.ValidatorAtIndex(0)
+	require.NoError(t, err)
+
+	i, e := c.HeadPublicKeyToValidatorIndex(context.Background(), 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(context.Background(), [48]byte{})
+	require.Equal(t, false, e)
+	require.Equal(t, types.ValidatorIndex(0), idx)
+
+	c.head = &head{state: nil}
+	i, e := c.HeadPublicKeyToValidatorIndex(context.Background(), [48]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, [48]byte{}, p)
+
+	c.head = &head{state: nil}
+	p, err = c.HeadValidatorIndexToPublicKey(context.Background(), 0)
+	require.NoError(t, err)
+	require.Equal(t, [48]byte{}, p)
+}
--- a/beacon-chain/blockchain/head.go
+++ b/beacon-chain/blockchain/head.go
@@ -10,23 +10,25 @@ import (
 	"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/time"
 	"github.com/prysmaticlabs/prysm/beacon-chain/forkchoice/protoarray"
-	iface "github.com/prysmaticlabs/prysm/beacon-chain/state/interface"
+	"github.com/prysmaticlabs/prysm/beacon-chain/state"
+	"github.com/prysmaticlabs/prysm/config/features"
+	"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/interfaces"
-	"github.com/prysmaticlabs/prysm/shared/bytesutil"
-	"github.com/prysmaticlabs/prysm/shared/params"
-	"github.com/prysmaticlabs/prysm/shared/slotutil"
+	"github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1/block"
+	"github.com/prysmaticlabs/prysm/time/slots"
 	"github.com/sirupsen/logrus"
 	"go.opencensus.io/trace"
 )

 // 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 interfaces.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
@@ -105,8 +107,8 @@ func (s *Service) saveHead(ctx context.Context, headRoot [32]byte) error {
 	if err != nil {
 		return err
 	}
-	if newHeadBlock == nil || newHeadBlock.IsNil() || newHeadBlock.Block().IsNil() {
-		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.
@@ -129,7 +131,7 @@ func (s *Service) saveHead(ctx context.Context, headRoot [32]byte) error {
 			"newSlot": fmt.Sprintf("%d", newHeadSlot),
 			"oldSlot": fmt.Sprintf("%d", headSlot),
 		}).Debug("Chain reorg occurred")
-		absoluteSlotDifference := slotutil.AbsoluteValueSlotDifference(newHeadSlot, headSlot)
+		absoluteSlotDifference := slots.AbsoluteValueSlotDifference(newHeadSlot, headSlot)
 		s.cfg.StateNotifier.StateFeed().Send(&feed.Event{
 			Type: statefeed.Reorg,
 			Data: &ethpbv1.EventChainReorg{
@@ -139,10 +141,14 @@ func (s *Service) saveHead(ctx context.Context, headRoot [32]byte) error {
 				NewHeadBlock: headRoot[:],
 				OldHeadState: oldStateRoot,
 				NewHeadState: newStateRoot,
-				Epoch:        helpers.SlotToEpoch(newHeadSlot),
+				Epoch:        slots.ToEpoch(newHeadSlot),
 			},
 		})

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

@@ -168,8 +174,8 @@ func (s *Service) saveHead(ctx context.Context, headRoot [32]byte) error {
 // 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 interfaces.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)
@@ -185,7 +191,7 @@ func (s *Service) saveHeadNoDB(ctx context.Context, b interfaces.SignedBeaconBlo
 }

 // 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 interfaces.SignedBeaconBlock, state iface.BeaconState) {
+func (s *Service) setHead(root [32]byte, block block.SignedBeaconBlock, state state.BeaconState) {
 	s.headLock.Lock()
 	defer s.headLock.Unlock()

@@ -201,7 +207,7 @@ func (s *Service) setHead(root [32]byte, block interfaces.SignedBeaconBlock, sta
 // 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 interfaces.SignedBeaconBlock, state iface.BeaconState) {
+func (s *Service) setHeadInitialSync(root [32]byte, block block.SignedBeaconBlock, state state.BeaconState) {
 	s.headLock.Lock()
 	defer s.headLock.Unlock()

@@ -234,14 +240,14 @@ 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() interfaces.SignedBeaconBlock {
+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 {
+func (s *Service) headState(ctx context.Context) state.BeaconState {
 	ctx, span := trace.StartSpan(ctx, "blockChain.headState")
 	defer span.End()

@@ -254,6 +260,13 @@ 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)
+}
+
 // Returns true if head state exists.
 // This is the lock free version.
 func (s *Service) hasHeadState() bool {
@@ -268,7 +281,7 @@ func (s *Service) cacheJustifiedStateBalances(ctx context.Context, justifiedRoot

 	s.clearInitSyncBlocks()

-	var justifiedState iface.BeaconState
+	var justifiedState state.BeaconState
 	var err error
 	if justifiedRoot == s.genesisRoot {
 		justifiedState, err = s.cfg.BeaconDB.GenesisState(ctx)
@@ -285,10 +298,10 @@ func (s *Service) cacheJustifiedStateBalances(ctx context.Context, justifiedRoot
 		return errors.New("justified state can't be nil")
 	}

-	epoch := helpers.CurrentEpoch(justifiedState)
+	epoch := time.CurrentEpoch(justifiedState)

 	justifiedBalances := make([]uint64, justifiedState.NumValidators())
-	if err := justifiedState.ReadFromEveryValidator(func(idx int, val iface.ReadOnlyValidator) error {
+	if err := justifiedState.ReadFromEveryValidator(func(idx int, val state.ReadOnlyValidator) error {
 		if helpers.IsActiveValidatorUsingTrie(val, epoch) {
 			justifiedBalances[idx] = val.EffectiveBalance()
 		} else {
@@ -315,7 +328,7 @@ func (s *Service) getJustifiedBalances() []uint64 {
 // chain head is determined, set, and saved to disk.
 func (s *Service) notifyNewHeadEvent(
 	newHeadSlot types.Slot,
-	newHeadState iface.BeaconState,
+	newHeadState state.BeaconState,
 	newHeadStateRoot,
 	newHeadRoot []byte,
 ) error {
@@ -323,15 +336,15 @@ func (s *Service) notifyNewHeadEvent(
 	currentDutyDependentRoot := s.genesisRoot[:]

 	var previousDutyEpoch types.Epoch
-	currentDutyEpoch := helpers.SlotToEpoch(newHeadSlot)
+	currentDutyEpoch := slots.ToEpoch(newHeadSlot)
 	if currentDutyEpoch > 0 {
 		previousDutyEpoch = currentDutyEpoch.Sub(1)
 	}
-	currentDutySlot, err := helpers.StartSlot(currentDutyEpoch)
+	currentDutySlot, err := slots.EpochStart(currentDutyEpoch)
 	if err != nil {
 		return errors.Wrap(err, "could not get duty slot")
 	}
-	previousDutySlot, err := helpers.StartSlot(previousDutyEpoch)
+	previousDutySlot, err := slots.EpochStart(previousDutyEpoch)
 	if err != nil {
 		return errors.Wrap(err, "could not get duty slot")
 	}
@@ -353,10 +366,47 @@ func (s *Service) notifyNewHeadEvent(
 			Slot:                      newHeadSlot,
 			Block:                     newHeadRoot,
 			State:                     newHeadStateRoot,
-			EpochTransition:           helpers.IsEpochEnd(newHeadSlot),
+			EpochTransition:           slots.IsEpochStart(newHeadSlot),
 			PreviousDutyDependentRoot: previousDutyDependentRoot,
 			CurrentDutyDependentRoot:  currentDutyDependentRoot,
 		},
 	})
 	return nil
 }
+
+// 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 +1,174 @@
+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")
+		}
+		if slot > headState.Slot() {
+			headState, err = transition.ProcessSlots(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
@@ -4,18 +4,20 @@ import (
 	"bytes"
 	"context"
 	"testing"
+	"time"

 	types "github.com/prysmaticlabs/eth2-types"
 	mock "github.com/prysmaticlabs/prysm/beacon-chain/blockchain/testing"
-	"github.com/prysmaticlabs/prysm/beacon-chain/core/helpers"
 	testDB "github.com/prysmaticlabs/prysm/beacon-chain/db/testing"
-	pb "github.com/prysmaticlabs/prysm/proto/beacon/p2p/v1"
+	"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/eth/v1alpha1"
-	"github.com/prysmaticlabs/prysm/proto/eth/v1alpha1/wrapper"
-	"github.com/prysmaticlabs/prysm/shared/testutil"
-	"github.com/prysmaticlabs/prysm/shared/testutil/assert"
-	"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/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"
 )

@@ -36,31 +38,30 @@ func TestSaveHead_Different(t *testing.T) {
 	beaconDB := testDB.SetupDB(t)
 	service := setupBeaconChain(t, beaconDB)

-	oldRoot := [32]byte{'A'}
+	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: wrapper.WrappedPhase0SignedBeaconBlock(
-			&ethpb.SignedBeaconBlock{
-				Block: &ethpb.BeaconBlock{
-					Slot:      0,
-					StateRoot: make([]byte, 32),
-				},
-			},
-		),
+		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(), 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))

@@ -79,22 +80,20 @@ func TestSaveHead_Different_Reorg(t *testing.T) {
 	beaconDB := testDB.SetupDB(t)
 	service := setupBeaconChain(t, beaconDB)

-	oldRoot := [32]byte{'A'}
+	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: wrapper.WrappedPhase0SignedBeaconBlock(
-			&ethpb.SignedBeaconBlock{
-				Block: &ethpb.BeaconBlock{
-					Slot:      0,
-					StateRoot: make([]byte, 32),
-				},
-			},
-		),
+		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
@@ -102,10 +101,10 @@ func TestSaveHead_Different_Reorg(t *testing.T) {
 	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))

@@ -125,9 +124,9 @@ func TestCacheJustifiedStateBalances_CanCache(t *testing.T) {
 	beaconDB := testDB.SetupDB(t)
 	service := setupBeaconChain(t, beaconDB)

-	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")
@@ -137,7 +136,7 @@ func TestUpdateHead_MissingJustifiedRoot(t *testing.T) {
 	beaconDB := testDB.SetupDB(t)
 	service := setupBeaconChain(t, beaconDB)

-	b := testutil.NewBeaconBlock()
+	b := util.NewBeaconBlock()
 	require.NoError(t, service.cfg.BeaconDB.SaveBlock(context.Background(), wrapper.WrappedPhase0SignedBeaconBlock(b)))
 	r, err := b.Block.HashTreeRoot()
 	require.NoError(t, err)
@@ -151,10 +150,10 @@ func TestUpdateHead_MissingJustifiedRoot(t *testing.T) {

 func Test_notifyNewHeadEvent(t *testing.T) {
 	t.Run("genesis_state_root", func(t *testing.T) {
-		bState, _ := testutil.DeterministicGenesisState(t, 10)
+		bState, _ := util.DeterministicGenesisState(t, 10)
 		notifier := &mock.MockStateNotifier{RecordEvents: true}
 		srv := &Service{
-			cfg: &Config{
+			cfg: &config{
 				StateNotifier: notifier,
 			},
 			genesisRoot: [32]byte{1},
@@ -179,18 +178,18 @@ func Test_notifyNewHeadEvent(t *testing.T) {
 		require.DeepSSZEqual(t, wanted, eventHead)
 	})
 	t.Run("non_genesis_values", func(t *testing.T) {
-		bState, _ := testutil.DeterministicGenesisState(t, 10)
+		bState, _ := util.DeterministicGenesisState(t, 10)
 		notifier := &mock.MockStateNotifier{RecordEvents: true}
 		genesisRoot := [32]byte{1}
 		srv := &Service{
-			cfg: &Config{
+			cfg: &config{
 				StateNotifier: notifier,
 			},
 			genesisRoot: genesisRoot,
 		}
-		epoch1Start, err := helpers.StartSlot(1)
+		epoch1Start, err := slots.EpochStart(1)
 		require.NoError(t, err)
-		epoch2Start, err := helpers.StartSlot(1)
+		epoch2Start, err := slots.EpochStart(1)
 		require.NoError(t, err)
 		require.NoError(t, bState.SetSlot(epoch1Start))

@@ -207,10 +206,62 @@ func Test_notifyNewHeadEvent(t *testing.T) {
 			Slot:                      epoch2Start,
 			Block:                     newHeadRoot[:],
 			State:                     newHeadStateRoot[:],
-			EpochTransition:           false,
+			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>
--- a/beacon-chain/blockchain/info_test.go
+++ b/beacon-chain/blockchain/info_test.go
@@ -9,11 +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/proto/eth/v1alpha1/wrapper"
-	"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) {
@@ -22,10 +22,10 @@ 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{
+	cfg := &config{
 		BeaconDB: beaconDB,
 		ForkChoiceStore: protoarray.New(
 			0, // justifiedEpoch
@@ -34,11 +34,12 @@ func TestService_TreeHandler(t *testing.T) {
 		),
 		StateGen: stategen.New(beaconDB),
 	}
-	s, err := NewService(ctx, cfg)
+	s, err := NewService(ctx)
 	require.NoError(t, err)
+	s.cfg = cfg
 	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'}, wrapper.WrappedPhase0SignedBeaconBlock(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 (
-	"github.com/prysmaticlabs/prysm/proto/interfaces"
+	"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 interfaces.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) interfaces.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) interfaces.SignedBeaconBlock {

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

-	blks := make([]interfaces.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() []interfaces.SignedBeaconBlock {
 func (s *Service) clearInitSyncBlocks() {
 	s.initSyncBlocksLock.Lock()
 	defer s.initSyncBlocksLock.Unlock()
-	s.initSyncBlocks = make(map[[32]byte]interfaces.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
@@ -5,19 +5,20 @@ import (
 	"fmt"
 	"time"

-	"github.com/prysmaticlabs/prysm/beacon-chain/core/helpers"
-	ethpb "github.com/prysmaticlabs/prysm/proto/eth/v1alpha1"
-	"github.com/prysmaticlabs/prysm/proto/interfaces"
-	"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 interfaces.BeaconBlock) {
-	log := log.WithField("slot", b.Slot)
+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()))
 	}
@@ -33,11 +34,17 @@ func logStateTransitionData(b interfaces.BeaconBlock) {
 	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 interfaces.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
 	}
@@ -45,14 +52,16 @@ func logBlockSyncStatus(block interfaces.BeaconBlock, blockRoot [32]byte, finali
 		"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
@@ -3,17 +3,17 @@ package blockchain
 import (
 	"testing"

-	ethpb "github.com/prysmaticlabs/prysm/proto/eth/v1alpha1"
-	"github.com/prysmaticlabs/prysm/proto/eth/v1alpha1/wrapper"
-	"github.com/prysmaticlabs/prysm/proto/interfaces"
-	"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    interfaces.BeaconBlock
+		b    block.BeaconBlock
 		want string
 	}{
 		{name: "empty block body",
--- a/beacon-chain/blockchain/metrics.go
+++ b/beacon-chain/blockchain/metrics.go
@@ -3,15 +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"
+	"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"
-	ethpb "github.com/prysmaticlabs/prysm/proto/eth/v1alpha1"
-	"github.com/prysmaticlabs/prysm/proto/interfaces"
-	"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 (
@@ -60,6 +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",
@@ -76,6 +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.",
@@ -97,9 +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",
@@ -107,6 +122,14 @@ 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.",
+	})
 )

 // reportSlotMetrics reports slot related metrics.
@@ -121,7 +144,7 @@ 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
@@ -179,6 +202,7 @@ 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))
@@ -205,15 +229,33 @@ 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:
+		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))
@@ -228,7 +270,7 @@ func reportEpochMetrics(ctx context.Context, postState, headState iface.BeaconSt
 	return nil
 }

-func reportAttestationInclusion(blk interfaces.BeaconBlock) {
+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"

-	pb "github.com/prysmaticlabs/prysm/proto/beacon/p2p/v1"
-	eth "github.com/prysmaticlabs/prysm/proto/eth/v1alpha1"
-	"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/options.go
+++ b/beacon-chain/blockchain/options.go
@@ -0,0 +1,139 @@
+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
+	}
+}
+
+// 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/process_attestation.go
+++ b/beacon-chain/blockchain/process_attestation.go
@@ -5,12 +5,12 @@ import (

 	"github.com/pkg/errors"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/helpers"
-	ethpb "github.com/prysmaticlabs/prysm/proto/eth/v1alpha1"
-	"github.com/prysmaticlabs/prysm/shared/attestationutil"
-	"github.com/prysmaticlabs/prysm/shared/bytesutil"
-	"github.com/prysmaticlabs/prysm/shared/copyutil"
-	"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"
+	"github.com/prysmaticlabs/prysm/time/slots"
 	"go.opencensus.io/trace"
 )

@@ -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 := copyutil.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
@@ -62,7 +62,7 @@ func (s *Service) onAttestation(ctx context.Context, a *ethpb.Attestation) error
 	genesisTime := baseState.GenesisTime()

 	// 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 := s.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
@@ -7,22 +7,22 @@ import (

 	"github.com/pkg/errors"
 	types "github.com/prysmaticlabs/eth2-types"
+	"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"
-	ethpb "github.com/prysmaticlabs/prysm/proto/eth/v1alpha1"
-	"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)
@@ -38,38 +38,23 @@ 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)
-			}
+		baseState, err = transition.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
 	}

-	// 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

@@ -78,7 +63,7 @@ func (s *Service) getAttPreState(ctx context.Context, c *ethpb.Checkpoint) (ifac
 // verifyAttTargetEpoch validates attestation is from the current or previous epoch.
 func (s *Service) 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 {
@@ -102,7 +87,7 @@ func (s *Service) verifyBeaconBlock(ctx context.Context, data *ethpb.Attestation
 	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 {
--- a/beacon-chain/blockchain/process_attestation_test.go
+++ b/beacon-chain/blockchain/process_attestation_test.go
@@ -5,63 +5,63 @@ import (
 	"testing"

 	types "github.com/prysmaticlabs/eth2-types"
-	"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"
-	ethpb "github.com/prysmaticlabs/prysm/proto/eth/v1alpha1"
-	"github.com/prysmaticlabs/prysm/proto/eth/v1alpha1/wrapper"
-	"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"
+	"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"
+	"github.com/prysmaticlabs/prysm/time/slots"
 )

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

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

 	_, 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, 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, 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, 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,
@@ -76,17 +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",
 		},
@@ -131,21 +131,22 @@ func TestStore_OnAttestation_Ok(t *testing.T) {
 	ctx := context.Background()
 	beaconDB := testDB.SetupDB(t)

-	cfg := &Config{
+	cfg := &config{
 		BeaconDB:        beaconDB,
 		ForkChoiceStore: protoarray.New(0, 0, [32]byte{}),
 		StateGen:        stategen.New(beaconDB),
 	}
-	service, err := NewService(ctx, cfg)
+	service, err := NewService(ctx)
 	require.NoError(t, err)
-	genesisState, pks := testutil.DeterministicGenesisState(t, 64)
-	require.NoError(t, genesisState.SetGenesisTime(uint64(timeutils.Now().Unix())-params.BeaconConfig().SecondsPerSlot))
+	service.cfg = cfg
+	genesisState, pks := util.DeterministicGenesisState(t, 64)
+	require.NoError(t, genesisState.SetGenesisTime(uint64(time.Now().Unix())-params.BeaconConfig().SecondsPerSlot))
 	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))
@@ -156,14 +157,15 @@ func TestStore_SaveCheckpointState(t *testing.T) {
 	ctx := context.Background()
 	beaconDB := testDB.SetupDB(t)

-	cfg := &Config{
+	cfg := &config{
 		BeaconDB: beaconDB,
 		StateGen: stategen.New(beaconDB),
 	}
-	service, err := NewService(ctx, cfg)
+	service, err := NewService(ctx)
 	require.NoError(t, err)
+	service.cfg = cfg

-	s, err := testutil.NewBeaconState()
+	s, err := util.NewBeaconState()
 	require.NoError(t, err)
 	err = s.SetFinalizedCheckpoint(&ethpb.Checkpoint{Root: bytesutil.PadTo([]byte{'A'}, 32)})
 	require.NoError(t, err)
@@ -186,7 +188,7 @@ func TestStore_SaveCheckpointState(t *testing.T) {
 	r = bytesutil.ToBytes32([]byte{'A'})
 	cp1 := &ethpb.Checkpoint{Epoch: 1, Root: bytesutil.PadTo([]byte{'A'}, 32)}
 	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'}, 32)}))

 	s1, err := service.getAttPreState(ctx, cp1)
 	require.NoError(t, err)
@@ -194,7 +196,7 @@ func TestStore_SaveCheckpointState(t *testing.T) {

 	cp2 := &ethpb.Checkpoint{Epoch: 2, Root: bytesutil.PadTo([]byte{'B'}, 32)}
 	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'}, 32)}))
 	s2, err := service.getAttPreState(ctx, cp2)
 	require.NoError(t, err)
 	assert.Equal(t, 2*params.BeaconConfig().SlotsPerEpoch, s2.Slot(), "Unexpected state slot")
@@ -218,7 +220,7 @@ func TestStore_SaveCheckpointState(t *testing.T) {
 	service.prevFinalizedCheckpt = &ethpb.Checkpoint{Root: r[:]}
 	cp3 := &ethpb.Checkpoint{Epoch: 1, Root: bytesutil.PadTo([]byte{'C'}, 32)}
 	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'}, 32)}))
 	s3, err := service.getAttPreState(ctx, cp3)
 	require.NoError(t, err)
 	assert.Equal(t, s.Slot(), s3.Slot(), "Unexpected state slot")
@@ -228,15 +230,16 @@ func TestStore_UpdateCheckpointState(t *testing.T) {
 	ctx := context.Background()
 	beaconDB := testDB.SetupDB(t)

-	cfg := &Config{
+	cfg := &config{
 		BeaconDB: beaconDB,
 		StateGen: stategen.New(beaconDB),
 	}
-	service, err := NewService(ctx, cfg)
+	service, err := NewService(ctx)
 	require.NoError(t, err)
+	service.cfg = cfg

 	epoch := types.Epoch(1)
-	baseState, _ := testutil.DeterministicGenesisState(t, 1)
+	baseState, _ := util.DeterministicGenesisState(t, 1)
 	checkpoint := &ethpb.Checkpoint{Epoch: epoch, Root: bytesutil.PadTo([]byte("hi"), 32)}
 	require.NoError(t, service.cfg.BeaconDB.SaveState(ctx, baseState, bytesutil.ToBytes32(checkpoint.Root)))
 	returned, err := service.getAttPreState(ctx, checkpoint)
@@ -252,9 +255,9 @@ func TestStore_UpdateCheckpointState(t *testing.T) {
 	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")

@@ -267,9 +270,10 @@ func TestAttEpoch_MatchPrevEpoch(t *testing.T) {
 	ctx := context.Background()
 	beaconDB := testDB.SetupDB(t)

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

 	nowTime := uint64(params.BeaconConfig().SlotsPerEpoch) * params.BeaconConfig().SecondsPerSlot
 	require.NoError(t, service.verifyAttTargetEpoch(ctx, 0, nowTime, &ethpb.Checkpoint{Root: make([]byte, 32)}))
@@ -279,9 +283,10 @@ func TestAttEpoch_MatchCurrentEpoch(t *testing.T) {
 	ctx := context.Background()
 	beaconDB := testDB.SetupDB(t)

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

 	nowTime := uint64(params.BeaconConfig().SlotsPerEpoch) * params.BeaconConfig().SecondsPerSlot
 	require.NoError(t, service.verifyAttTargetEpoch(ctx, 0, nowTime, &ethpb.Checkpoint{Epoch: 1}))
@@ -291,9 +296,10 @@ func TestAttEpoch_NotMatch(t *testing.T) {
 	ctx := context.Background()
 	beaconDB := testDB.SetupDB(t)

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

 	nowTime := 2 * uint64(params.BeaconConfig().SlotsPerEpoch) * params.BeaconConfig().SecondsPerSlot
 	err = service.verifyAttTargetEpoch(ctx, 0, nowTime, &ethpb.Checkpoint{Root: make([]byte, 32)})
@@ -304,11 +310,12 @@ func TestVerifyBeaconBlock_NoBlock(t *testing.T) {
 	ctx := context.Background()
 	beaconDB := testDB.SetupDB(t)

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

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

@@ -316,11 +323,12 @@ func TestVerifyBeaconBlock_futureBlock(t *testing.T) {
 	ctx := context.Background()
 	beaconDB := testDB.SetupDB(t)

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

-	b := testutil.NewBeaconBlock()
+	b := util.NewBeaconBlock()
 	b.Block.Slot = 2
 	require.NoError(t, service.cfg.BeaconDB.SaveBlock(ctx, wrapper.WrappedPhase0SignedBeaconBlock(b)))
 	r, err := b.Block.HashTreeRoot()
@@ -334,11 +342,12 @@ func TestVerifyBeaconBlock_OK(t *testing.T) {
 	ctx := context.Background()
 	beaconDB := testDB.SetupDB(t)

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

-	b := testutil.NewBeaconBlock()
+	b := util.NewBeaconBlock()
 	b.Block.Slot = 2
 	require.NoError(t, service.cfg.BeaconDB.SaveBlock(ctx, wrapper.WrappedPhase0SignedBeaconBlock(b)))
 	r, err := b.Block.HashTreeRoot()
@@ -352,11 +361,12 @@ 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)
+	cfg := &config{BeaconDB: beaconDB, ForkChoiceStore: protoarray.New(0, 0, [32]byte{})}
+	service, err := NewService(ctx)
 	require.NoError(t, err)
+	service.cfg = cfg

-	b32 := testutil.NewBeaconBlock()
+	b32 := util.NewBeaconBlock()
 	b32.Block.Slot = 32
 	require.NoError(t, service.cfg.BeaconDB.SaveBlock(ctx, wrapper.WrappedPhase0SignedBeaconBlock(b32)))
 	r32, err := b32.Block.HashTreeRoot()
@@ -364,7 +374,7 @@ func TestVerifyFinalizedConsistency_InconsistentRoot(t *testing.T) {

 	service.finalizedCheckpt = &ethpb.Checkpoint{Epoch: 1}

-	b33 := testutil.NewBeaconBlock()
+	b33 := util.NewBeaconBlock()
 	b33.Block.Slot = 33
 	b33.Block.ParentRoot = r32[:]
 	require.NoError(t, service.cfg.BeaconDB.SaveBlock(ctx, wrapper.WrappedPhase0SignedBeaconBlock(b33)))
@@ -379,11 +389,12 @@ 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)
+	cfg := &config{BeaconDB: beaconDB, ForkChoiceStore: protoarray.New(0, 0, [32]byte{})}
+	service, err := NewService(ctx)
 	require.NoError(t, err)
+	service.cfg = cfg

-	b32 := testutil.NewBeaconBlock()
+	b32 := util.NewBeaconBlock()
 	b32.Block.Slot = 32
 	require.NoError(t, service.cfg.BeaconDB.SaveBlock(ctx, wrapper.WrappedPhase0SignedBeaconBlock(b32)))
 	r32, err := b32.Block.HashTreeRoot()
@@ -391,7 +402,7 @@ func TestVerifyFinalizedConsistency_OK(t *testing.T) {

 	service.finalizedCheckpt = &ethpb.Checkpoint{Epoch: 1, Root: r32[:]}

-	b33 := testutil.NewBeaconBlock()
+	b33 := util.NewBeaconBlock()
 	b33.Block.Slot = 33
 	b33.Block.ParentRoot = r32[:]
 	require.NoError(t, service.cfg.BeaconDB.SaveBlock(ctx, wrapper.WrappedPhase0SignedBeaconBlock(b33)))
@@ -406,18 +417,19 @@ 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)
+	cfg := &config{BeaconDB: beaconDB, ForkChoiceStore: protoarray.New(0, 0, [32]byte{})}
+	service, err := NewService(ctx)
 	require.NoError(t, err)
+	service.cfg = cfg

-	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[:]}

-	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
@@ -9,17 +9,19 @@ import (
 	"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"
+	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/eth/v1alpha1"
-	"github.com/prysmaticlabs/prysm/proto/interfaces"
-	"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"
+	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"
 )

@@ -83,12 +85,11 @@ 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 interfaces.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.IsNil() || signed.Block().IsNil() {
-		return errors.New("nil block")
+	if err := helpers.BeaconBlockIsNil(signed); err != nil {
+		return err
 	}
 	b := signed.Block()

@@ -97,7 +98,7 @@ func (s *Service) onBlock(ctx context.Context, signed interfaces.SignedBeaconBlo
 		return err
 	}

-	postState, err := state.ExecuteStateTransition(ctx, preState, signed)
+	postState, err := transition.ExecuteStateTransition(ctx, preState, signed)
 	if err != nil {
 		return err
 	}
@@ -106,51 +107,88 @@ func (s *Service) onBlock(ctx context.Context, signed interfaces.SignedBeaconBlo
 		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 {
+	currJustifiedEpoch := s.justifiedCheckpt.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")
+	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()
+	}
+
+	if err := s.updateHead(ctx, s.getJustifiedBalances()); err != nil {
+		log.WithError(err).Warn("Could not update head")
+	}
+
+	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.
+	if features.Get().EnableNextSlotStateCache {
+		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")
 			}
-			s.prevFinalizedCheckpt = s.finalizedCheckpt
-			s.finalizedCheckpt = postState.FinalizedCheckpoint()
-		}
+		}()
+	}

-		if err := s.updateHead(ctx, s.getJustifiedBalances()); err != nil {
-			log.WithError(err).Warn("Could not update head")
+	// Save justified check point to db.
+	if postState.CurrentJustifiedCheckpoint().Epoch > currJustifiedEpoch {
+		if err := s.cfg.BeaconDB.SaveJustifiedCheckpoint(ctx, postState.CurrentJustifiedCheckpoint()); 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,
-			},
-		})
 	}

 	// Update finalized check point.
@@ -162,11 +200,6 @@ func (s *Service) onBlock(ctx context.Context, signed interfaces.SignedBeaconBlo
 		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{
@@ -195,7 +228,7 @@ func (s *Service) onBlock(ctx context.Context, signed interfaces.SignedBeaconBlo
 	return s.handleEpochBoundary(ctx, postState)
 }

-func (s *Service) onBlockBatch(ctx context.Context, blks []interfaces.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()
@@ -203,8 +236,8 @@ func (s *Service) onBlockBatch(ctx context.Context, blks []interfaces.SignedBeac
 	if len(blks) == 0 || len(blockRoots) == 0 {
 		return nil, nil, errors.New("no blocks provided")
 	}
-	if blks[0] == nil || blks[0].IsNil() || blks[0].Block().IsNil() {
-		return nil, nil, errors.New("nil block")
+	if err := helpers.BeaconBlockIsNil(blks[0]); err != nil {
+		return nil, nil, err
 	}
 	b := blks[0].Block()

@@ -228,14 +261,14 @@ func (s *Service) onBlockBatch(ctx context.Context, blks []interfaces.SignedBeac
 		Messages:   [][32]byte{},
 	}
 	var set *bls.SignatureSet
-	boundaries := make(map[[32]byte]iface.BeaconState)
+	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")
@@ -271,7 +304,7 @@ func (s *Service) onBlockBatch(ctx context.Context, blks []interfaces.SignedBeac

 // 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 interfaces.SignedBeaconBlock,
+func (s *Service) handleBlockAfterBatchVerify(ctx context.Context, signed block.SignedBeaconBlock,
 	blockRoot [32]byte, fCheckpoint, jCheckpoint *ethpb.Checkpoint) error {
 	b := signed.Block()

@@ -279,7 +312,7 @@ func (s *Service) handleBlockAfterBatchVerify(ctx context.Context, signed interf
 	if err := s.insertBlockToForkChoiceStore(ctx, b, blockRoot, fCheckpoint, jCheckpoint); err != nil {
 		return err
 	}
-	if err := s.cfg.BeaconDB.SaveStateSummary(ctx, &pb.StateSummary{
+	if err := s.cfg.BeaconDB.SaveStateSummary(ctx, &ethpb.StateSummary{
 		Slot: signed.Block().Slot(),
 		Root: blockRoot[:],
 	}); err != nil {
@@ -305,23 +338,28 @@ func (s *Service) handleBlockAfterBatchVerify(ctx context.Context, signed interf
 		if err := s.updateFinalized(ctx, fCheckpoint); err != nil {
 			return err
 		}
+		s.prevFinalizedCheckpt = s.finalizedCheckpt
+		s.finalizedCheckpt = 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 {
@@ -329,17 +367,17 @@ 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
 		}
 	}
@@ -349,8 +387,11 @@ 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 interfaces.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 {
@@ -358,11 +399,11 @@ func (s *Service) insertBlockAndAttestationsToForkChoiceStore(ctx context.Contex
 	}
 	// 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)
+		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
 		}
@@ -371,7 +412,7 @@ func (s *Service) insertBlockAndAttestationsToForkChoiceStore(ctx context.Contex
 	return nil
 }

-func (s *Service) insertBlockToForkChoiceStore(ctx context.Context, blk interfaces.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
@@ -388,7 +429,7 @@ func (s *Service) insertBlockToForkChoiceStore(ctx context.Context, blk interfac

 // 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 interfaces.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 {
@@ -404,3 +445,33 @@ func (s *Service) savePostStateInfo(ctx context.Context, r [32]byte, b interface
 	}
 	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
+}
--- a/beacon-chain/blockchain/process_block_helpers.go
+++ b/beacon-chain/blockchain/process_block_helpers.go
@@ -8,26 +8,26 @@ import (
 	"github.com/pkg/errors"
 	types "github.com/prysmaticlabs/eth2-types"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/helpers"
-	iface "github.com/prysmaticlabs/prysm/beacon-chain/state/interface"
-	ethpb "github.com/prysmaticlabs/prysm/proto/eth/v1alpha1"
-	"github.com/prysmaticlabs/prysm/proto/interfaces"
-	"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/attestation"
+	"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 interfaces.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()

@@ -45,7 +45,7 @@ func (s *Service) getBlockPreState(ctx context.Context, b interfaces.BeaconBlock
 	}

 	// 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(preState.GenesisTime(), b.Slot(), params.BeaconNetworkConfig().MaximumGossipClockDisparity); err != nil {
 		return nil, err
 	}

@@ -58,7 +58,7 @@ func (s *Service) getBlockPreState(ctx context.Context, b interfaces.BeaconBlock
 }

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

@@ -113,7 +113,7 @@ func (s *Service) VerifyBlkDescendant(ctx context.Context, root [32]byte) error
 		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(fRoot[:]))
-		traceutil.AnnotateError(span, err)
+		tracing.AnnotateError(span, err)
 		return err
 	}
 	return nil
@@ -121,8 +121,8 @@ 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 interfaces.BeaconBlock) error {
-	finalizedSlot, err := helpers.StartSlot(s.finalizedCheckpt.Epoch)
+func (s *Service) verifyBlkFinalizedSlot(b block.BeaconBlock) error {
+	finalizedSlot, err := slots.EpochStart(s.finalizedCheckpt.Epoch)
 	if err != nil {
 		return err
 	}
@@ -135,60 +135,52 @@ func (s *Service) verifyBlkFinalizedSlot(b interfaces.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 interfaces.SignedBeaconBlock
-	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.IsNil() || newJustifiedBlockSigned.Block().IsNil() {
-		return false, errors.New("nil new justified block")
-	}

-	newJustifiedBlock := newJustifiedBlockSigned.Block()
-	jSlot, err := helpers.StartSlot(s.justifiedCheckpt.Epoch)
+	jSlot, err := slots.EpochStart(s.justifiedCheckpt.Epoch)
 	if err != nil {
 		return false, err
 	}
-	if newJustifiedBlock.Slot() <= jSlot {
-		return false, nil
-	}
-	var justifiedBlockSigned interfaces.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.IsNil() || justifiedBlockSigned.Block().IsNil() {
-		return false, errors.New("nil justified block")
-	}
-	justifiedBlock := justifiedBlockSigned.Block()
-	b, err := s.ancestor(ctx, justifiedRoot[:], justifiedBlock.Slot())
+	justifiedRoot := s.ensureRootNotZeros(bytesutil.ToBytes32(newJustifiedCheckpt.Root))
+	b, err := s.ancestor(ctx, justifiedRoot[:], jSlot)
 	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
@@ -206,7 +198,7 @@ func (s *Service) updateJustified(ctx context.Context, state iface.ReadOnlyBeaco
 		}
 	}

-	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,
@@ -223,6 +215,9 @@ func (s *Service) updateJustifiedInitSync(ctx context.Context, cp *ethpb.Checkpo
 }

 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 {
@@ -233,10 +228,6 @@ 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 {
@@ -334,16 +325,16 @@ func (s *Service) ancestorByDB(ctx context.Context, r [32]byte, slot types.Slot)
 //            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 {
+func (s *Service) finalizedImpliesNewJustified(ctx context.Context, state state.BeaconState) error {
 	// Update justified if it's different than the one cached in the store.
-	if !attestationutil.CheckPointIsEqual(s.justifiedCheckpt, state.CurrentJustifiedCheckpoint()) {
+	if !attestation.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)
+		finalizedSlot, err := slots.EpochStart(s.finalizedCheckpt.Epoch)
 		if err != nil {
 			return err
 		}
@@ -364,15 +355,15 @@ func (s *Service) finalizedImpliesNewJustified(ctx context.Context, state iface.

 // 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 interfaces.BeaconBlock,
+func (s *Service) fillInForkChoiceMissingBlocks(ctx context.Context, blk block.BeaconBlock,
 	fCheckpoint, jCheckpoint *ethpb.Checkpoint) error {
-	pendingNodes := make([]interfaces.BeaconBlock, 0)
+	pendingNodes := make([]block.BeaconBlock, 0)
 	pendingRoots := make([][32]byte, 0)

 	parentRoot := bytesutil.ToBytes32(blk.ParentRoot())
 	slot := blk.Slot()
 	// Fork choice only matters from last finalized slot.
-	fSlot, err := helpers.StartSlot(s.finalizedCheckpt.Epoch)
+	fSlot, err := slots.EpochStart(s.finalizedCheckpt.Epoch)
 	if err != nil {
 		return err
 	}
--- a/beacon-chain/blockchain/process_block_test.go
+++ b/beacon-chain/blockchain/process_block_test.go
@@ -13,76 +13,77 @@ import (
 	mock "github.com/prysmaticlabs/prysm/beacon-chain/blockchain/testing"
 	"github.com/prysmaticlabs/prysm/beacon-chain/cache/depositcache"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/blocks"
-	"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"
-	iface "github.com/prysmaticlabs/prysm/beacon-chain/state/interface"
+	"github.com/prysmaticlabs/prysm/beacon-chain/state"
 	"github.com/prysmaticlabs/prysm/beacon-chain/state/stategen"
-	"github.com/prysmaticlabs/prysm/beacon-chain/state/v1"
-	pb "github.com/prysmaticlabs/prysm/proto/beacon/p2p/v1"
-	ethpb "github.com/prysmaticlabs/prysm/proto/eth/v1alpha1"
-	"github.com/prysmaticlabs/prysm/proto/eth/v1alpha1/wrapper"
-	"github.com/prysmaticlabs/prysm/proto/interfaces"
-	"github.com/prysmaticlabs/prysm/shared/attestationutil"
-	"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"
+	v1 "github.com/prysmaticlabs/prysm/beacon-chain/state/v1"
+	"github.com/prysmaticlabs/prysm/config/features"
+	"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/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"
+	prysmTime "github.com/prysmaticlabs/prysm/time"
 )

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

-	cfg := &Config{
+	cfg := &config{
 		BeaconDB:        beaconDB,
 		StateGen:        stategen.New(beaconDB),
 		ForkChoiceStore: protoarray.New(0, 0, [32]byte{}),
 	}
-	service, err := NewService(ctx, cfg)
+	service, err := NewService(ctx)
 	require.NoError(t, err)
+	service.cfg = cfg
 	genesisStateRoot := [32]byte{}
 	genesis := blocks.NewGenesisBlock(genesisStateRoot[:])
 	assert.NoError(t, beaconDB.SaveBlock(ctx, wrapper.WrappedPhase0SignedBeaconBlock(genesis)))
 	validGenesisRoot, err := genesis.Block.HashTreeRoot()
 	require.NoError(t, err)
-	st, err := testutil.NewBeaconState()
+	st, err := util.NewBeaconState()
 	require.NoError(t, err)
 	require.NoError(t, service.cfg.BeaconDB.SaveState(ctx, st.Copy(), validGenesisRoot))
 	roots, err := blockTree1(t, beaconDB, validGenesisRoot[:])
 	require.NoError(t, err)
-	random := testutil.NewBeaconBlock()
+	random := util.NewBeaconBlock()
 	random.Block.Slot = 1
 	random.Block.ParentRoot = validGenesisRoot[:]
 	assert.NoError(t, beaconDB.SaveBlock(ctx, wrapper.WrappedPhase0SignedBeaconBlock(random)))
 	randomParentRoot, err := random.Block.HashTreeRoot()
 	assert.NoError(t, err)
-	require.NoError(t, service.cfg.BeaconDB.SaveStateSummary(ctx, &pb.StateSummary{Slot: st.Slot(), Root: randomParentRoot[:]}))
+	require.NoError(t, service.cfg.BeaconDB.SaveStateSummary(ctx, &ethpb.StateSummary{Slot: st.Slot(), Root: randomParentRoot[:]}))
 	require.NoError(t, service.cfg.BeaconDB.SaveState(ctx, st.Copy(), randomParentRoot))
 	randomParentRoot2 := roots[1]
-	require.NoError(t, service.cfg.BeaconDB.SaveStateSummary(ctx, &pb.StateSummary{Slot: st.Slot(), Root: randomParentRoot2}))
+	require.NoError(t, service.cfg.BeaconDB.SaveStateSummary(ctx, &ethpb.StateSummary{Slot: st.Slot(), Root: randomParentRoot2}))
 	require.NoError(t, service.cfg.BeaconDB.SaveState(ctx, st.Copy(), bytesutil.ToBytes32(randomParentRoot2)))

 	tests := []struct {
 		name          string
 		blk           *ethpb.SignedBeaconBlock
-		s             iface.BeaconState
+		s             state.BeaconState
 		time          uint64
 		wantErrString string
 	}{
 		{
 			name:          "parent block root does not have a state",
-			blk:           testutil.NewBeaconBlock(),
+			blk:           util.NewBeaconBlock(),
 			s:             st.Copy(),
 			wantErrString: "could not reconstruct parent state",
 		},
 		{
 			name: "block is from the future",
 			blk: func() *ethpb.SignedBeaconBlock {
-				b := testutil.NewBeaconBlock()
+				b := util.NewBeaconBlock()
 				b.Block.ParentRoot = randomParentRoot2
 				b.Block.Slot = params.BeaconConfig().FarFutureSlot
 				return b
@@ -93,7 +94,7 @@ func TestStore_OnBlock(t *testing.T) {
 		{
 			name: "could not get finalized block",
 			blk: func() *ethpb.SignedBeaconBlock {
-				b := testutil.NewBeaconBlock()
+				b := util.NewBeaconBlock()
 				b.Block.ParentRoot = randomParentRoot[:]
 				return b
 			}(),
@@ -103,7 +104,7 @@ func TestStore_OnBlock(t *testing.T) {
 		{
 			name: "same slot as finalized block",
 			blk: func() *ethpb.SignedBeaconBlock {
-				b := testutil.NewBeaconBlock()
+				b := util.NewBeaconBlock()
 				b.Block.Slot = 0
 				b.Block.ParentRoot = randomParentRoot2
 				return b
@@ -133,12 +134,13 @@ func TestStore_OnBlockBatch(t *testing.T) {
 	ctx := context.Background()
 	beaconDB := testDB.SetupDB(t)

-	cfg := &Config{
+	cfg := &config{
 		BeaconDB: beaconDB,
 		StateGen: stategen.New(beaconDB),
 	}
-	service, err := NewService(ctx, cfg)
+	service, err := NewService(ctx)
 	require.NoError(t, err)
+	service.cfg = cfg

 	genesisStateRoot := [32]byte{}
 	genesis := blocks.NewGenesisBlock(genesisStateRoot[:])
@@ -151,17 +153,17 @@ func TestStore_OnBlockBatch(t *testing.T) {
 	service.cfg.ForkChoiceStore = protoarray.New(0, 0, [32]byte{})
 	service.saveInitSyncBlock(gRoot, wrapper.WrappedPhase0SignedBeaconBlock(genesis))

-	st, keys := testutil.DeterministicGenesisState(t, 64)
+	st, keys := util.DeterministicGenesisState(t, 64)

 	bState := st.Copy()

-	var blks []interfaces.SignedBeaconBlock
+	var blks []block.SignedBeaconBlock
 	var blkRoots [][32]byte
-	var firstState iface.BeaconState
+	var firstState state.BeaconState
 	for i := 1; i < 10; i++ {
-		b, err := testutil.GenerateFullBlock(bState, keys, testutil.DefaultBlockGenConfig(), types.Slot(i))
+		b, err := util.GenerateFullBlock(bState, keys, util.DefaultBlockGenConfig(), types.Slot(i))
 		require.NoError(t, err)
-		bState, err = state.ExecuteStateTransition(ctx, bState, wrapper.WrappedPhase0SignedBeaconBlock(b))
+		bState, err = transition.ExecuteStateTransition(ctx, bState, wrapper.WrappedPhase0SignedBeaconBlock(b))
 		require.NoError(t, err)
 		if i == 1 {
 			firstState = bState.Copy()
@@ -188,19 +190,20 @@ func TestRemoveStateSinceLastFinalized_EmptyStartSlot(t *testing.T) {
 	params.UseMinimalConfig()
 	defer params.UseMainnetConfig()

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

 	update, err := service.shouldUpdateCurrentJustified(ctx, &ethpb.Checkpoint{Root: make([]byte, 32)})
 	require.NoError(t, err)
 	assert.Equal(t, true, update, "Should be able to update justified")
-	lastJustifiedBlk := testutil.NewBeaconBlock()
+	lastJustifiedBlk := util.NewBeaconBlock()
 	lastJustifiedBlk.Block.ParentRoot = bytesutil.PadTo([]byte{'G'}, 32)
 	lastJustifiedRoot, err := lastJustifiedBlk.Block.HashTreeRoot()
 	require.NoError(t, err)
-	newJustifiedBlk := testutil.NewBeaconBlock()
+	newJustifiedBlk := util.NewBeaconBlock()
 	newJustifiedBlk.Block.Slot = 1
 	newJustifiedBlk.Block.ParentRoot = bytesutil.PadTo(lastJustifiedRoot[:], 32)
 	newJustifiedRoot, err := newJustifiedBlk.Block.HashTreeRoot()
@@ -222,14 +225,17 @@ func TestShouldUpdateJustified_ReturnFalse(t *testing.T) {
 	params.UseMinimalConfig()
 	defer params.UseMainnetConfig()

-	cfg := &Config{BeaconDB: beaconDB}
-	service, err := NewService(ctx, cfg)
+	cfg := &config{BeaconDB: beaconDB}
+	service, err := NewService(ctx)
 	require.NoError(t, err)
-	lastJustifiedBlk := testutil.NewBeaconBlock()
+	service.cfg = cfg
+	service.cfg.ForkChoiceStore = protoarray.New(0, 0, [32]byte{})
+
+	lastJustifiedBlk := util.NewBeaconBlock()
 	lastJustifiedBlk.Block.ParentRoot = bytesutil.PadTo([]byte{'G'}, 32)
 	lastJustifiedRoot, err := lastJustifiedBlk.Block.HashTreeRoot()
 	require.NoError(t, err)
-	newJustifiedBlk := testutil.NewBeaconBlock()
+	newJustifiedBlk := util.NewBeaconBlock()
 	newJustifiedBlk.Block.ParentRoot = bytesutil.PadTo(lastJustifiedRoot[:], 32)
 	newJustifiedRoot, err := newJustifiedBlk.Block.HashTreeRoot()
 	require.NoError(t, err)
@@ -249,14 +255,15 @@ func TestCachedPreState_CanGetFromStateSummary(t *testing.T) {
 	ctx := context.Background()
 	beaconDB := testDB.SetupDB(t)

-	cfg := &Config{
+	cfg := &config{
 		BeaconDB: beaconDB,
 		StateGen: stategen.New(beaconDB),
 	}
-	service, err := NewService(ctx, cfg)
+	service, err := NewService(ctx)
 	require.NoError(t, err)
+	service.cfg = cfg

-	s, err := v1.InitializeFromProto(&pb.BeaconState{Slot: 1, GenesisValidatorsRoot: params.BeaconConfig().ZeroHash[:]})
+	s, err := v1.InitializeFromProto(&ethpb.BeaconState{Slot: 1, GenesisValidatorsRoot: params.BeaconConfig().ZeroHash[:]})
 	require.NoError(t, err)

 	genesisStateRoot := [32]byte{}
@@ -270,10 +277,10 @@ func TestCachedPreState_CanGetFromStateSummary(t *testing.T) {
 	service.cfg.ForkChoiceStore = protoarray.New(0, 0, [32]byte{})
 	service.saveInitSyncBlock(gRoot, wrapper.WrappedPhase0SignedBeaconBlock(genesis))

-	b := testutil.NewBeaconBlock()
+	b := util.NewBeaconBlock()
 	b.Block.Slot = 1
 	b.Block.ParentRoot = gRoot[:]
-	require.NoError(t, service.cfg.BeaconDB.SaveStateSummary(ctx, &pb.StateSummary{Slot: 1, Root: gRoot[:]}))
+	require.NoError(t, service.cfg.BeaconDB.SaveStateSummary(ctx, &ethpb.StateSummary{Slot: 1, Root: gRoot[:]}))
 	require.NoError(t, service.cfg.StateGen.SaveState(ctx, gRoot, s))
 	require.NoError(t, service.verifyBlkPreState(ctx, wrapper.WrappedPhase0BeaconBlock(b.Block)))
 }
@@ -282,12 +289,13 @@ func TestCachedPreState_CanGetFromDB(t *testing.T) {
 	ctx := context.Background()
 	beaconDB := testDB.SetupDB(t)

-	cfg := &Config{
+	cfg := &config{
 		BeaconDB: beaconDB,
 		StateGen: stategen.New(beaconDB),
 	}
-	service, err := NewService(ctx, cfg)
+	service, err := NewService(ctx)
 	require.NoError(t, err)
+	service.cfg = cfg

 	genesisStateRoot := [32]byte{}
 	genesis := blocks.NewGenesisBlock(genesisStateRoot[:])
@@ -300,7 +308,7 @@ func TestCachedPreState_CanGetFromDB(t *testing.T) {
 	service.cfg.ForkChoiceStore = protoarray.New(0, 0, [32]byte{})
 	service.saveInitSyncBlock(gRoot, wrapper.WrappedPhase0SignedBeaconBlock(genesis))

-	b := testutil.NewBeaconBlock()
+	b := util.NewBeaconBlock()
 	b.Block.Slot = 1
 	service.finalizedCheckpt = &ethpb.Checkpoint{Root: gRoot[:]}
 	err = service.verifyBlkPreState(ctx, wrapper.WrappedPhase0BeaconBlock(b.Block))
@@ -308,9 +316,9 @@ func TestCachedPreState_CanGetFromDB(t *testing.T) {
 	assert.ErrorContains(t, wanted, err)

 	b.Block.ParentRoot = gRoot[:]
-	s, err := v1.InitializeFromProto(&pb.BeaconState{Slot: 1})
+	s, err := v1.InitializeFromProto(&ethpb.BeaconState{Slot: 1})
 	require.NoError(t, err)
-	require.NoError(t, service.cfg.BeaconDB.SaveStateSummary(ctx, &pb.StateSummary{Slot: 1, Root: gRoot[:]}))
+	require.NoError(t, service.cfg.BeaconDB.SaveStateSummary(ctx, &ethpb.StateSummary{Slot: 1, Root: gRoot[:]}))
 	require.NoError(t, service.cfg.StateGen.SaveState(ctx, gRoot, s))
 	require.NoError(t, service.verifyBlkPreState(ctx, wrapper.WrappedPhase0SignedBeaconBlock(b).Block()))
 }
@@ -319,22 +327,23 @@ func TestUpdateJustified_CouldUpdateBest(t *testing.T) {
 	ctx := context.Background()
 	beaconDB := testDB.SetupDB(t)

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

-	signedBlock := testutil.NewBeaconBlock()
+	signedBlock := util.NewBeaconBlock()
 	require.NoError(t, beaconDB.SaveBlock(ctx, wrapper.WrappedPhase0SignedBeaconBlock(signedBlock)))
 	r, err := signedBlock.Block.HashTreeRoot()
 	require.NoError(t, err)
 	service.justifiedCheckpt = &ethpb.Checkpoint{Root: []byte{'A'}}
 	service.bestJustifiedCheckpt = &ethpb.Checkpoint{Root: []byte{'A'}}
-	st, err := testutil.NewBeaconState()
+	st, err := util.NewBeaconState()
 	require.NoError(t, err)
 	require.NoError(t, beaconDB.SaveState(ctx, st.Copy(), r))

 	// Could update
-	s, err := testutil.NewBeaconState()
+	s, err := util.NewBeaconState()
 	require.NoError(t, err)
 	require.NoError(t, s.SetCurrentJustifiedCheckpoint(&ethpb.Checkpoint{Epoch: 1, Root: r[:]}))
 	require.NoError(t, service.updateJustified(context.Background(), s))
@@ -352,9 +361,10 @@ func TestFillForkChoiceMissingBlocks_CanSave(t *testing.T) {
 	ctx := context.Background()
 	beaconDB := testDB.SetupDB(t)

-	cfg := &Config{BeaconDB: beaconDB}
-	service, err := NewService(ctx, cfg)
+	cfg := &config{BeaconDB: beaconDB}
+	service, err := NewService(ctx)
 	require.NoError(t, err)
+	service.cfg = cfg
 	service.cfg.ForkChoiceStore = protoarray.New(0, 0, [32]byte{'A'})
 	service.finalizedCheckpt = &ethpb.Checkpoint{Root: make([]byte, 32)}

@@ -363,15 +373,15 @@ func TestFillForkChoiceMissingBlocks_CanSave(t *testing.T) {
 	require.NoError(t, beaconDB.SaveBlock(ctx, wrapper.WrappedPhase0SignedBeaconBlock(genesis)))
 	validGenesisRoot, err := genesis.Block.HashTreeRoot()
 	require.NoError(t, err)
-	st, err := testutil.NewBeaconState()
+	st, err := util.NewBeaconState()
 	require.NoError(t, err)

 	require.NoError(t, service.cfg.BeaconDB.SaveState(ctx, st.Copy(), validGenesisRoot))
 	roots, err := blockTree1(t, beaconDB, validGenesisRoot[:])
 	require.NoError(t, err)

-	beaconState, _ := testutil.DeterministicGenesisState(t, 32)
-	block := testutil.NewBeaconBlock()
+	beaconState, _ := util.DeterministicGenesisState(t, 32)
+	block := util.NewBeaconBlock()
 	block.Block.Slot = 9
 	block.Block.ParentRoot = roots[8]

@@ -390,9 +400,10 @@ func TestFillForkChoiceMissingBlocks_RootsMatch(t *testing.T) {
 	ctx := context.Background()
 	beaconDB := testDB.SetupDB(t)

-	cfg := &Config{BeaconDB: beaconDB}
-	service, err := NewService(ctx, cfg)
+	cfg := &config{BeaconDB: beaconDB}
+	service, err := NewService(ctx)
 	require.NoError(t, err)
+	service.cfg = cfg
 	service.cfg.ForkChoiceStore = protoarray.New(0, 0, [32]byte{'A'})
 	service.finalizedCheckpt = &ethpb.Checkpoint{Root: make([]byte, 32)}

@@ -401,15 +412,15 @@ func TestFillForkChoiceMissingBlocks_RootsMatch(t *testing.T) {
 	require.NoError(t, beaconDB.SaveBlock(ctx, wrapper.WrappedPhase0SignedBeaconBlock(genesis)))
 	validGenesisRoot, err := genesis.Block.HashTreeRoot()
 	require.NoError(t, err)
-	st, err := testutil.NewBeaconState()
+	st, err := util.NewBeaconState()
 	require.NoError(t, err)

 	require.NoError(t, service.cfg.BeaconDB.SaveState(ctx, st.Copy(), validGenesisRoot))
 	roots, err := blockTree1(t, beaconDB, validGenesisRoot[:])
 	require.NoError(t, err)

-	beaconState, _ := testutil.DeterministicGenesisState(t, 32)
-	block := testutil.NewBeaconBlock()
+	beaconState, _ := util.DeterministicGenesisState(t, 32)
+	block := util.NewBeaconBlock()
 	block.Block.Slot = 9
 	block.Block.ParentRoot = roots[8]

@@ -431,9 +442,10 @@ func TestFillForkChoiceMissingBlocks_FilterFinalized(t *testing.T) {
 	ctx := context.Background()
 	beaconDB := testDB.SetupDB(t)

-	cfg := &Config{BeaconDB: beaconDB}
-	service, err := NewService(ctx, cfg)
+	cfg := &config{BeaconDB: beaconDB}
+	service, err := NewService(ctx)
 	require.NoError(t, err)
+	service.cfg = cfg
 	service.cfg.ForkChoiceStore = protoarray.New(0, 0, [32]byte{'A'})
 	// Set finalized epoch to 1.
 	service.finalizedCheckpt = &ethpb.Checkpoint{Epoch: 1}
@@ -443,29 +455,29 @@ func TestFillForkChoiceMissingBlocks_FilterFinalized(t *testing.T) {
 	assert.NoError(t, beaconDB.SaveBlock(ctx, wrapper.WrappedPhase0SignedBeaconBlock(genesis)))
 	validGenesisRoot, err := genesis.Block.HashTreeRoot()
 	assert.NoError(t, err)
-	st, err := testutil.NewBeaconState()
+	st, err := util.NewBeaconState()
 	require.NoError(t, err)

 	require.NoError(t, service.cfg.BeaconDB.SaveState(ctx, st.Copy(), validGenesisRoot))

 	// Define a tree branch, slot 63 <- 64 <- 65
-	b63 := testutil.NewBeaconBlock()
+	b63 := util.NewBeaconBlock()
 	b63.Block.Slot = 63
 	require.NoError(t, service.cfg.BeaconDB.SaveBlock(ctx, wrapper.WrappedPhase0SignedBeaconBlock(b63)))
 	r63, err := b63.Block.HashTreeRoot()
 	require.NoError(t, err)
-	b64 := testutil.NewBeaconBlock()
+	b64 := util.NewBeaconBlock()
 	b64.Block.Slot = 64
 	b64.Block.ParentRoot = r63[:]
 	require.NoError(t, service.cfg.BeaconDB.SaveBlock(ctx, wrapper.WrappedPhase0SignedBeaconBlock(b64)))
 	r64, err := b64.Block.HashTreeRoot()
 	require.NoError(t, err)
-	b65 := testutil.NewBeaconBlock()
+	b65 := util.NewBeaconBlock()
 	b65.Block.Slot = 65
 	b65.Block.ParentRoot = r64[:]
 	require.NoError(t, service.cfg.BeaconDB.SaveBlock(ctx, wrapper.WrappedPhase0SignedBeaconBlock(b65)))

-	beaconState, _ := testutil.DeterministicGenesisState(t, 32)
+	beaconState, _ := util.DeterministicGenesisState(t, 32)
 	err = service.fillInForkChoiceMissingBlocks(
 		context.Background(), wrapper.WrappedPhase0SignedBeaconBlock(b65).Block(), beaconState.FinalizedCheckpoint(), beaconState.CurrentJustifiedCheckpoint())
 	require.NoError(t, err)
@@ -484,67 +496,67 @@ func TestFillForkChoiceMissingBlocks_FilterFinalized(t *testing.T) {
 // (B1, and B3 are all from the same slots)
 func blockTree1(t *testing.T, beaconDB db.Database, genesisRoot []byte) ([][]byte, error) {
 	genesisRoot = bytesutil.PadTo(genesisRoot, 32)
-	b0 := testutil.NewBeaconBlock()
+	b0 := util.NewBeaconBlock()
 	b0.Block.Slot = 0
 	b0.Block.ParentRoot = genesisRoot
 	r0, err := b0.Block.HashTreeRoot()
 	if err != nil {
 		return nil, err
 	}
-	b1 := testutil.NewBeaconBlock()
+	b1 := util.NewBeaconBlock()
 	b1.Block.Slot = 1
 	b1.Block.ParentRoot = r0[:]
 	r1, err := b1.Block.HashTreeRoot()
 	if err != nil {
 		return nil, err
 	}
-	b3 := testutil.NewBeaconBlock()
+	b3 := util.NewBeaconBlock()
 	b3.Block.Slot = 3
 	b3.Block.ParentRoot = r0[:]
 	r3, err := b3.Block.HashTreeRoot()
 	if err != nil {
 		return nil, err
 	}
-	b4 := testutil.NewBeaconBlock()
+	b4 := util.NewBeaconBlock()
 	b4.Block.Slot = 4
 	b4.Block.ParentRoot = r3[:]
 	r4, err := b4.Block.HashTreeRoot()
 	if err != nil {
 		return nil, err
 	}
-	b5 := testutil.NewBeaconBlock()
+	b5 := util.NewBeaconBlock()
 	b5.Block.Slot = 5
 	b5.Block.ParentRoot = r4[:]
 	r5, err := b5.Block.HashTreeRoot()
 	if err != nil {
 		return nil, err
 	}
-	b6 := testutil.NewBeaconBlock()
+	b6 := util.NewBeaconBlock()
 	b6.Block.Slot = 6
 	b6.Block.ParentRoot = r4[:]
 	r6, err := b6.Block.HashTreeRoot()
 	if err != nil {
 		return nil, err
 	}
-	b7 := testutil.NewBeaconBlock()
+	b7 := util.NewBeaconBlock()
 	b7.Block.Slot = 7
 	b7.Block.ParentRoot = r5[:]
 	r7, err := b7.Block.HashTreeRoot()
 	if err != nil {
 		return nil, err
 	}
-	b8 := testutil.NewBeaconBlock()
+	b8 := util.NewBeaconBlock()
 	b8.Block.Slot = 8
 	b8.Block.ParentRoot = r6[:]
 	r8, err := b8.Block.HashTreeRoot()
 	if err != nil {
 		return nil, err
 	}
-	st, err := testutil.NewBeaconState()
+	st, err := util.NewBeaconState()
 	require.NoError(t, err)

 	for _, b := range []*ethpb.SignedBeaconBlock{b0, b1, b3, b4, b5, b6, b7, b8} {
-		beaconBlock := testutil.NewBeaconBlock()
+		beaconBlock := util.NewBeaconBlock()
 		beaconBlock.Block.Slot = b.Block.Slot
 		beaconBlock.Block.ParentRoot = bytesutil.PadTo(b.Block.ParentRoot, 32)
 		if err := beaconDB.SaveBlock(context.Background(), wrapper.WrappedPhase0SignedBeaconBlock(beaconBlock)); err != nil {
@@ -567,14 +579,14 @@ func blockTree1(t *testing.T, beaconDB db.Database, genesisRoot []byte) ([][]byt
 }

 func TestCurrentSlot_HandlesOverflow(t *testing.T) {
-	svc := Service{genesisTime: timeutils.Now().Add(1 * time.Hour)}
+	svc := Service{genesisTime: prysmTime.Now().Add(1 * time.Hour)}

 	slot := svc.CurrentSlot()
 	require.Equal(t, types.Slot(0), slot, "Unexpected slot")
 }
 func TestAncestorByDB_CtxErr(t *testing.T) {
 	ctx, cancel := context.WithCancel(context.Background())
-	service, err := NewService(ctx, &Config{})
+	service, err := NewService(ctx)
 	require.NoError(t, err)

 	cancel()
@@ -586,27 +598,28 @@ func TestAncestor_HandleSkipSlot(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)
+	cfg := &config{BeaconDB: beaconDB, ForkChoiceStore: protoarray.New(0, 0, [32]byte{})}
+	service, err := NewService(ctx)
 	require.NoError(t, err)
+	service.cfg = cfg

-	b1 := testutil.NewBeaconBlock()
+	b1 := util.NewBeaconBlock()
 	b1.Block.Slot = 1
 	b1.Block.ParentRoot = bytesutil.PadTo([]byte{'a'}, 32)
 	r1, err := b1.Block.HashTreeRoot()
 	require.NoError(t, err)
-	b100 := testutil.NewBeaconBlock()
+	b100 := util.NewBeaconBlock()
 	b100.Block.Slot = 100
 	b100.Block.ParentRoot = r1[:]
 	r100, err := b100.Block.HashTreeRoot()
 	require.NoError(t, err)
-	b200 := testutil.NewBeaconBlock()
+	b200 := util.NewBeaconBlock()
 	b200.Block.Slot = 200
 	b200.Block.ParentRoot = r100[:]
 	r200, err := b200.Block.HashTreeRoot()
 	require.NoError(t, err)
 	for _, b := range []*ethpb.SignedBeaconBlock{b1, b100, b200} {
-		beaconBlock := testutil.NewBeaconBlock()
+		beaconBlock := util.NewBeaconBlock()
 		beaconBlock.Block.Slot = b.Block.Slot
 		beaconBlock.Block.ParentRoot = bytesutil.PadTo(b.Block.ParentRoot, 32)
 		require.NoError(t, beaconDB.SaveBlock(context.Background(), wrapper.WrappedPhase0SignedBeaconBlock(beaconBlock)))
@@ -629,27 +642,28 @@ func TestAncestor_HandleSkipSlot(t *testing.T) {

 func TestAncestor_CanUseForkchoice(t *testing.T) {
 	ctx := context.Background()
-	cfg := &Config{ForkChoiceStore: protoarray.New(0, 0, [32]byte{})}
-	service, err := NewService(ctx, cfg)
+	cfg := &config{ForkChoiceStore: protoarray.New(0, 0, [32]byte{})}
+	service, err := NewService(ctx)
 	require.NoError(t, err)
+	service.cfg = cfg

-	b1 := testutil.NewBeaconBlock()
+	b1 := util.NewBeaconBlock()
 	b1.Block.Slot = 1
 	b1.Block.ParentRoot = bytesutil.PadTo([]byte{'a'}, 32)
 	r1, err := b1.Block.HashTreeRoot()
 	require.NoError(t, err)
-	b100 := testutil.NewBeaconBlock()
+	b100 := util.NewBeaconBlock()
 	b100.Block.Slot = 100
 	b100.Block.ParentRoot = r1[:]
 	r100, err := b100.Block.HashTreeRoot()
 	require.NoError(t, err)
-	b200 := testutil.NewBeaconBlock()
+	b200 := util.NewBeaconBlock()
 	b200.Block.Slot = 200
 	b200.Block.ParentRoot = r100[:]
 	r200, err := b200.Block.HashTreeRoot()
 	require.NoError(t, err)
 	for _, b := range []*ethpb.SignedBeaconBlock{b1, b100, b200} {
-		beaconBlock := testutil.NewBeaconBlock()
+		beaconBlock := util.NewBeaconBlock()
 		beaconBlock.Block.Slot = b.Block.Slot
 		beaconBlock.Block.ParentRoot = bytesutil.PadTo(b.Block.ParentRoot, 32)
 		r, err := b.Block.HashTreeRoot()
@@ -668,27 +682,28 @@ func TestAncestor_CanUseDB(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)
+	cfg := &config{BeaconDB: beaconDB, ForkChoiceStore: protoarray.New(0, 0, [32]byte{})}
+	service, err := NewService(ctx)
 	require.NoError(t, err)
+	service.cfg = cfg

-	b1 := testutil.NewBeaconBlock()
+	b1 := util.NewBeaconBlock()
 	b1.Block.Slot = 1
 	b1.Block.ParentRoot = bytesutil.PadTo([]byte{'a'}, 32)
 	r1, err := b1.Block.HashTreeRoot()
 	require.NoError(t, err)
-	b100 := testutil.NewBeaconBlock()
+	b100 := util.NewBeaconBlock()
 	b100.Block.Slot = 100
 	b100.Block.ParentRoot = r1[:]
 	r100, err := b100.Block.HashTreeRoot()
 	require.NoError(t, err)
-	b200 := testutil.NewBeaconBlock()
+	b200 := util.NewBeaconBlock()
 	b200.Block.Slot = 200
 	b200.Block.ParentRoot = r100[:]
 	r200, err := b200.Block.HashTreeRoot()
 	require.NoError(t, err)
 	for _, b := range []*ethpb.SignedBeaconBlock{b1, b100, b200} {
-		beaconBlock := testutil.NewBeaconBlock()
+		beaconBlock := util.NewBeaconBlock()
 		beaconBlock.Block.Slot = b.Block.Slot
 		beaconBlock.Block.ParentRoot = bytesutil.PadTo(b.Block.ParentRoot, 32)
 		require.NoError(t, beaconDB.SaveBlock(context.Background(), wrapper.WrappedPhase0SignedBeaconBlock(beaconBlock))) // Saves blocks to DB.
@@ -705,9 +720,10 @@ func TestAncestor_CanUseDB(t *testing.T) {

 func TestEnsureRootNotZeroHashes(t *testing.T) {
 	ctx := context.Background()
-	cfg := &Config{}
-	service, err := NewService(ctx, cfg)
+	cfg := &config{}
+	service, err := NewService(ctx)
 	require.NoError(t, err)
+	service.cfg = cfg
 	service.genesisRoot = [32]byte{'a'}

 	r := service.ensureRootNotZeros(params.BeaconConfig().ZeroHash)
@@ -757,30 +773,31 @@ func TestFinalizedImpliesNewJustified(t *testing.T) {
 		},
 	}
 	for _, test := range tests {
-		beaconState, err := testutil.NewBeaconState()
+		beaconState, err := util.NewBeaconState()
 		require.NoError(t, err)
 		require.NoError(t, beaconState.SetCurrentJustifiedCheckpoint(test.args.stateCheckPoint))
-		service, err := NewService(ctx, &Config{BeaconDB: beaconDB, StateGen: stategen.New(beaconDB), ForkChoiceStore: protoarray.New(0, 0, [32]byte{})})
+		service, err := NewService(ctx)
 		require.NoError(t, err)
+		service.cfg = &config{BeaconDB: beaconDB, StateGen: stategen.New(beaconDB), ForkChoiceStore: protoarray.New(0, 0, [32]byte{})}
 		service.justifiedCheckpt = test.args.cachedCheckPoint
-		require.NoError(t, service.cfg.BeaconDB.SaveStateSummary(ctx, &pb.StateSummary{Root: bytesutil.PadTo(test.want.Root, 32)}))
-		genesisState, err := testutil.NewBeaconState()
+		require.NoError(t, service.cfg.BeaconDB.SaveStateSummary(ctx, &ethpb.StateSummary{Root: bytesutil.PadTo(test.want.Root, 32)}))
+		genesisState, err := util.NewBeaconState()
 		require.NoError(t, err)
 		require.NoError(t, service.cfg.BeaconDB.SaveState(ctx, genesisState, bytesutil.ToBytes32(test.want.Root)))

 		if test.args.diffFinalizedCheckPoint {
-			b1 := testutil.NewBeaconBlock()
+			b1 := util.NewBeaconBlock()
 			b1.Block.Slot = 1
 			b1.Block.ParentRoot = bytesutil.PadTo([]byte{'a'}, 32)
 			r1, err := b1.Block.HashTreeRoot()
 			require.NoError(t, err)
-			b100 := testutil.NewBeaconBlock()
+			b100 := util.NewBeaconBlock()
 			b100.Block.Slot = 100
 			b100.Block.ParentRoot = r1[:]
 			r100, err := b100.Block.HashTreeRoot()
 			require.NoError(t, err)
 			for _, b := range []*ethpb.SignedBeaconBlock{b1, b100} {
-				beaconBlock := testutil.NewBeaconBlock()
+				beaconBlock := util.NewBeaconBlock()
 				beaconBlock.Block.Slot = b.Block.Slot
 				beaconBlock.Block.ParentRoot = bytesutil.PadTo(b.Block.ParentRoot, 32)
 				require.NoError(t, service.cfg.BeaconDB.SaveBlock(context.Background(), wrapper.WrappedPhase0SignedBeaconBlock(beaconBlock)))
@@ -790,7 +807,7 @@ func TestFinalizedImpliesNewJustified(t *testing.T) {
 		}

 		require.NoError(t, service.finalizedImpliesNewJustified(ctx, beaconState))
-		assert.Equal(t, true, attestationutil.CheckPointIsEqual(test.want, service.justifiedCheckpt), "Did not get wanted check point")
+		assert.Equal(t, true, attestation.CheckPointIsEqual(test.want, service.justifiedCheckpt), "Did not get wanted check point")
 	}
 }

@@ -798,13 +815,13 @@ func TestVerifyBlkDescendant(t *testing.T) {
 	beaconDB := testDB.SetupDB(t)
 	ctx := context.Background()

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

-	b1 := testutil.NewBeaconBlock()
+	b1 := util.NewBeaconBlock()
 	b1.Block.Slot = 1
 	b1.Block.Body.Graffiti = bytesutil.PadTo([]byte{'a'}, 32)
 	r1, err := b1.Block.HashTreeRoot()
@@ -852,8 +869,9 @@ func TestVerifyBlkDescendant(t *testing.T) {
 		},
 	}
 	for _, tt := range tests {
-		service, err := NewService(ctx, &Config{BeaconDB: beaconDB, StateGen: stategen.New(beaconDB), ForkChoiceStore: protoarray.New(0, 0, [32]byte{})})
+		service, err := NewService(ctx)
 		require.NoError(t, err)
+		service.cfg = &config{BeaconDB: beaconDB, StateGen: stategen.New(beaconDB), ForkChoiceStore: protoarray.New(0, 0, [32]byte{})}
 		service.finalizedCheckpt = &ethpb.Checkpoint{
 			Root: tt.args.finalizedRoot[:],
 		}
@@ -869,17 +887,18 @@ func TestVerifyBlkDescendant(t *testing.T) {
 func TestUpdateJustifiedInitSync(t *testing.T) {
 	beaconDB := testDB.SetupDB(t)
 	ctx := context.Background()
-	cfg := &Config{BeaconDB: beaconDB}
-	service, err := NewService(ctx, cfg)
+	cfg := &config{BeaconDB: beaconDB}
+	service, err := NewService(ctx)
 	require.NoError(t, err)
+	service.cfg = cfg

-	gBlk := testutil.NewBeaconBlock()
+	gBlk := util.NewBeaconBlock()
 	gRoot, err := gBlk.Block.HashTreeRoot()
 	require.NoError(t, err)
 	require.NoError(t, service.cfg.BeaconDB.SaveBlock(ctx, wrapper.WrappedPhase0SignedBeaconBlock(gBlk)))
 	require.NoError(t, service.cfg.BeaconDB.SaveGenesisBlockRoot(ctx, gRoot))
-	require.NoError(t, service.cfg.BeaconDB.SaveStateSummary(ctx, &pb.StateSummary{Root: gRoot[:]}))
-	beaconState, _ := testutil.DeterministicGenesisState(t, 32)
+	require.NoError(t, service.cfg.BeaconDB.SaveStateSummary(ctx, &ethpb.StateSummary{Root: gRoot[:]}))
+	beaconState, _ := util.DeterministicGenesisState(t, 32)
 	require.NoError(t, service.cfg.BeaconDB.SaveState(ctx, beaconState, gRoot))
 	service.genesisRoot = gRoot
 	currentCp := &ethpb.Checkpoint{Epoch: 1}
@@ -897,11 +916,12 @@ func TestUpdateJustifiedInitSync(t *testing.T) {

 func TestHandleEpochBoundary_BadMetrics(t *testing.T) {
 	ctx := context.Background()
-	cfg := &Config{}
-	service, err := NewService(ctx, cfg)
+	cfg := &config{}
+	service, err := NewService(ctx)
 	require.NoError(t, err)
+	service.cfg = cfg

-	s, err := testutil.NewBeaconState()
+	s, err := util.NewBeaconState()
 	require.NoError(t, err)
 	require.NoError(t, s.SetSlot(1))
 	service.head = &head{state: (*v1.BeaconState)(nil)}
@@ -911,11 +931,12 @@ func TestHandleEpochBoundary_BadMetrics(t *testing.T) {

 func TestHandleEpochBoundary_UpdateFirstSlot(t *testing.T) {
 	ctx := context.Background()
-	cfg := &Config{}
-	service, err := NewService(ctx, cfg)
+	cfg := &config{}
+	service, err := NewService(ctx)
 	require.NoError(t, err)
+	service.cfg = cfg

-	s, _ := testutil.DeterministicGenesisState(t, 1024)
+	s, _ := util.DeterministicGenesisState(t, 1024)
 	service.head = &head{state: s}
 	require.NoError(t, s.SetSlot(2*params.BeaconConfig().SlotsPerEpoch))
 	require.NoError(t, service.handleEpochBoundary(ctx, s))
@@ -927,17 +948,18 @@ func TestOnBlock_CanFinalize(t *testing.T) {
 	beaconDB := testDB.SetupDB(t)
 	depositCache, err := depositcache.New()
 	require.NoError(t, err)
-	cfg := &Config{
+	cfg := &config{
 		BeaconDB:        beaconDB,
 		StateGen:        stategen.New(beaconDB),
 		ForkChoiceStore: protoarray.New(0, 0, [32]byte{}),
 		DepositCache:    depositCache,
 		StateNotifier:   &mock.MockStateNotifier{},
 	}
-	service, err := NewService(ctx, cfg)
+	service, err := NewService(ctx)
 	require.NoError(t, err)
+	service.cfg = cfg

-	gs, keys := testutil.DeterministicGenesisState(t, 32)
+	gs, keys := util.DeterministicGenesisState(t, 32)
 	require.NoError(t, service.saveGenesisData(ctx, gs))
 	gBlk, err := service.cfg.BeaconDB.GenesisBlock(ctx)
 	require.NoError(t, err)
@@ -947,7 +969,7 @@ func TestOnBlock_CanFinalize(t *testing.T) {

 	testState := gs.Copy()
 	for i := types.Slot(1); i <= 4*params.BeaconConfig().SlotsPerEpoch; i++ {
-		blk, err := testutil.GenerateFullBlock(testState, keys, testutil.DefaultBlockGenConfig(), i)
+		blk, err := util.GenerateFullBlock(testState, keys, util.DefaultBlockGenConfig(), i)
 		require.NoError(t, err)
 		r, err := blk.Block.HashTreeRoot()
 		require.NoError(t, err)
@@ -957,6 +979,14 @@ func TestOnBlock_CanFinalize(t *testing.T) {
 	}
 	require.Equal(t, types.Epoch(3), service.CurrentJustifiedCheckpt().Epoch)
 	require.Equal(t, types.Epoch(2), service.FinalizedCheckpt().Epoch)
+
+	// The update should persist in DB.
+	j, err := service.cfg.BeaconDB.JustifiedCheckpoint(ctx)
+	require.NoError(t, err)
+	require.Equal(t, j.Epoch, service.CurrentJustifiedCheckpt().Epoch)
+	f, err := service.cfg.BeaconDB.FinalizedCheckpoint(ctx)
+	require.NoError(t, err)
+	require.Equal(t, f.Epoch, service.FinalizedCheckpt().Epoch)
 }

 func TestInsertFinalizedDeposits(t *testing.T) {
@@ -964,16 +994,17 @@ func TestInsertFinalizedDeposits(t *testing.T) {
 	beaconDB := testDB.SetupDB(t)
 	depositCache, err := depositcache.New()
 	require.NoError(t, err)
-	cfg := &Config{
+	cfg := &config{
 		BeaconDB:        beaconDB,
 		StateGen:        stategen.New(beaconDB),
 		ForkChoiceStore: protoarray.New(0, 0, [32]byte{}),
 		DepositCache:    depositCache,
 	}
-	service, err := NewService(ctx, cfg)
+	service, err := NewService(ctx)
 	require.NoError(t, err)
+	service.cfg = cfg

-	gs, _ := testutil.DeterministicGenesisState(t, 32)
+	gs, _ := util.DeterministicGenesisState(t, 32)
 	require.NoError(t, service.saveGenesisData(ctx, gs))
 	gBlk, err := service.cfg.BeaconDB.GenesisBlock(ctx)
 	require.NoError(t, err)
@@ -1001,3 +1032,49 @@ func TestInsertFinalizedDeposits(t *testing.T) {
 		assert.DeepEqual(t, [][]byte(nil), d.Proof, "Proofs are not empty")
 	}
 }
+
+func TestRemoveBlockAttestationsInPool_Canonical(t *testing.T) {
+	resetCfg := features.InitWithReset(&features.Flags{
+		CorrectlyPruneCanonicalAtts: 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)
+	require.NoError(t, service.cfg.BeaconDB.SaveStateSummary(ctx, &ethpb.StateSummary{Root: r[:]}))
+	require.NoError(t, service.cfg.BeaconDB.SaveGenesisBlockRoot(ctx, r))
+
+	atts := b.Block.Body.Attestations
+	require.NoError(t, service.cfg.AttPool.SaveAggregatedAttestations(atts))
+	require.NoError(t, service.pruneCanonicalAttsFromPool(ctx, r, wrapper.WrappedPhase0SignedBeaconBlock(b)))
+	require.Equal(t, 0, service.cfg.AttPool.AggregatedAttestationCount())
+}
+
+func TestRemoveBlockAttestationsInPool_NonCanonical(t *testing.T) {
+	resetCfg := features.InitWithReset(&features.Flags{
+		CorrectlyPruneCanonicalAtts: 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)
+
+	atts := b.Block.Body.Attestations
+	require.NoError(t, service.cfg.AttPool.SaveAggregatedAttestations(atts))
+	require.NoError(t, service.pruneCanonicalAttsFromPool(ctx, r, wrapper.WrappedPhase0SignedBeaconBlock(b)))
+	require.Equal(t, 1, service.cfg.AttPool.AggregatedAttestationCount())
+}
--- a/beacon-chain/blockchain/receive_attestation.go
+++ b/beacon-chain/blockchain/receive_attestation.go
@@ -9,19 +9,25 @@ import (
 	"github.com/pkg/errors"
 	"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"
-	ethpb "github.com/prysmaticlabs/prysm/proto/eth/v1alpha1"
-	"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
 }
@@ -42,21 +48,21 @@ func (s *Service) ReceiveAttestationNoPubsub(ctx context.Context, att *ethpb.Att
 	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 +87,7 @@ func (s *Service) VerifyFinalizedConsistency(ctx context.Context, root []byte) e
 	}

 	f := s.FinalizedCheckpt()
-	ss, err := helpers.StartSlot(f.Epoch)
+	ss, err := slots.EpochStart(f.Epoch)
 	if err != nil {
 		return err
 	}
@@ -113,7 +119,7 @@ func (s *Service) processAttestationsRoutine(subscribedToStateEvents chan<- stru
 		log.Warn("Genesis time received, now available to process attestations")
 	}

-	st := slotutil.NewSlotTicker(s.genesisTime, params.BeaconConfig().SecondsPerSlot)
+	st := slots.NewSlotTicker(s.genesisTime, params.BeaconConfig().SecondsPerSlot)
 	for {
 		select {
 		case <-s.ctx.Done():
@@ -138,9 +144,9 @@ 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
@@ -7,21 +7,27 @@ import (

 	types "github.com/prysmaticlabs/eth2-types"
 	"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"
-	ethpb "github.com/prysmaticlabs/prysm/proto/eth/v1alpha1"
-	"github.com/prysmaticlabs/prysm/proto/eth/v1alpha1/wrapper"
-	"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)
@@ -29,8 +35,8 @@ 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)
 }

@@ -38,16 +44,17 @@ func TestVerifyLMDFFGConsistent_NotOK(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)
+	cfg := &config{BeaconDB: beaconDB, ForkChoiceStore: protoarray.New(0, 0, [32]byte{})}
+	service, err := NewService(ctx)
 	require.NoError(t, err)
+	service.cfg = cfg

-	b32 := testutil.NewBeaconBlock()
+	b32 := util.NewBeaconBlock()
 	b32.Block.Slot = 32
 	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, wrapper.WrappedPhase0SignedBeaconBlock(b33)))
@@ -55,7 +62,7 @@ func TestVerifyLMDFFGConsistent_NotOK(t *testing.T) {
 	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[:]
@@ -66,23 +73,24 @@ 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)
+	cfg := &config{BeaconDB: beaconDB, ForkChoiceStore: protoarray.New(0, 0, [32]byte{})}
+	service, err := NewService(ctx)
 	require.NoError(t, err)
+	service.cfg = cfg

-	b32 := testutil.NewBeaconBlock()
+	b32 := util.NewBeaconBlock()
 	b32.Block.Slot = 32
 	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, 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[:]
@@ -95,23 +103,24 @@ func TestProcessAttestations_Ok(t *testing.T) {
 	ctx := context.Background()
 	beaconDB := testDB.SetupDB(t)

-	cfg := &Config{
+	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)
 	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)
+	service.cfg = cfg
+	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
@@ -7,11 +7,10 @@ import (
 	types "github.com/prysmaticlabs/eth2-types"
 	"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/proto/interfaces"
-	"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"
 )

@@ -20,8 +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 interfaces.SignedBeaconBlock, blockRoot [32]byte) error
-	ReceiveBlockBatch(ctx context.Context, blocks []interfaces.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
 }

@@ -30,36 +29,19 @@ 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 interfaces.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()
+	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 {
 		return err
@@ -86,7 +68,7 @@ func (s *Service) ReceiveBlock(ctx context.Context, block interfaces.SignedBeaco
 // 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 []interfaces.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()

@@ -94,14 +76,14 @@ func (s *Service) ReceiveBlockBatch(ctx context.Context, blocks []interfaces.Sig
 	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 := 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.
@@ -119,7 +101,10 @@ func (s *Service) ReceiveBlockBatch(ctx context.Context, blocks []interfaces.Sig
 		reportSlotMetrics(blockCopy.Block().Slot(), s.HeadSlot(), s.CurrentSlot(), s.finalizedCheckpt)
 	}

-	if err := s.VerifyWeakSubjectivityRoot(s.ctx); err != nil {
+	if err := s.cfg.BeaconDB.SaveBlocks(ctx, s.getInitSyncBlocks()); err != nil {
+		return err
+	}
+	if err := s.wsVerifier.VerifyWeakSubjectivity(s.ctx, s.finalizedCheckpt.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.
@@ -134,7 +119,7 @@ func (s *Service) HasInitSyncBlock(root [32]byte) bool {
 	return s.hasInitSyncBlock(root)
 }

-func (s *Service) handlePostBlockOperations(b interfaces.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 {
 		return err
@@ -160,7 +145,7 @@ func (s *Service) handlePostBlockOperations(b interfaces.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 {
--- a/beacon-chain/blockchain/receive_block_test.go
+++ b/beacon-chain/blockchain/receive_block_test.go
@@ -13,23 +13,23 @@ import (
 	"github.com/prysmaticlabs/prysm/beacon-chain/operations/attestations"
 	"github.com/prysmaticlabs/prysm/beacon-chain/operations/voluntaryexits"
 	"github.com/prysmaticlabs/prysm/beacon-chain/state/stategen"
-	ethpb "github.com/prysmaticlabs/prysm/proto/eth/v1alpha1"
-	"github.com/prysmaticlabs/prysm/proto/eth/v1alpha1/wrapper"
-	"github.com/prysmaticlabs/prysm/proto/interfaces"
-	"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
 	}
@@ -49,7 +49,7 @@ 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 {
@@ -64,7 +64,7 @@ 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,
@@ -84,7 +84,7 @@ 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,
@@ -108,7 +108,7 @@ 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 {
@@ -124,7 +124,7 @@ func TestService_ReceiveBlock(t *testing.T) {
 			genesisBlockRoot := bytesutil.ToBytes32(nil)
 			require.NoError(t, beaconDB.SaveState(ctx, genesis, genesisBlockRoot))

-			cfg := &Config{
+			cfg := &config{
 				BeaconDB: beaconDB,
 				ForkChoiceStore: protoarray.New(
 					0, // justifiedEpoch
@@ -136,8 +136,9 @@ func TestService_ReceiveBlock(t *testing.T) {
 				StateNotifier: &blockchainTesting.MockStateNotifier{RecordEvents: true},
 				StateGen:      stategen.New(beaconDB),
 			}
-			s, err := NewService(ctx, cfg)
+			s, err := NewService(ctx)
 			require.NoError(t, err)
+			s.cfg = cfg
 			require.NoError(t, s.saveGenesisData(ctx, genesis))
 			gBlk, err := s.cfg.BeaconDB.GenesisBlock(ctx)
 			require.NoError(t, err)
@@ -159,13 +160,13 @@ 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{
+	cfg := &config{
 		BeaconDB: beaconDB,
 		ForkChoiceStore: protoarray.New(
 			0, // justifiedEpoch
@@ -177,8 +178,9 @@ func TestService_ReceiveBlockUpdateHead(t *testing.T) {
 		StateNotifier: &blockchainTesting.MockStateNotifier{RecordEvents: true},
 		StateGen:      stategen.New(beaconDB),
 	}
-	s, err := NewService(ctx, cfg)
+	s, err := NewService(ctx)
 	require.NoError(t, err)
+	s.cfg = cfg
 	require.NoError(t, s.saveGenesisData(ctx, genesis))
 	gBlk, err := s.cfg.BeaconDB.GenesisBlock(ctx)
 	require.NoError(t, err)
@@ -204,9 +206,9 @@ 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
 	}
@@ -223,7 +225,7 @@ 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")
@@ -233,7 +235,7 @@ func TestService_ReceiveBlockBatch(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 {
@@ -248,7 +250,7 @@ func TestService_ReceiveBlockBatch(t *testing.T) {
 			beaconDB := testDB.SetupDB(t)
 			genesisBlockRoot, err := genesis.HashTreeRoot(ctx)
 			require.NoError(t, err)
-			cfg := &Config{
+			cfg := &config{
 				BeaconDB: beaconDB,
 				ForkChoiceStore: protoarray.New(
 					0, // justifiedEpoch
@@ -258,8 +260,9 @@ func TestService_ReceiveBlockBatch(t *testing.T) {
 				StateNotifier: &blockchainTesting.MockStateNotifier{RecordEvents: true},
 				StateGen:      stategen.New(beaconDB),
 			}
-			s, err := NewService(ctx, cfg)
+			s, err := NewService(ctx)
 			require.NoError(t, err)
+			s.cfg = cfg
 			err = s.saveGenesisData(ctx, genesis)
 			require.NoError(t, err)
 			gBlk, err := s.cfg.BeaconDB.GenesisBlock(ctx)
@@ -270,7 +273,7 @@ func TestService_ReceiveBlockBatch(t *testing.T) {
 			s.finalizedCheckpt = &ethpb.Checkpoint{Root: gRoot[:]}
 			root, err := tt.args.block.Block.HashTreeRoot()
 			require.NoError(t, err)
-			blks := []interfaces.SignedBeaconBlock{wrapper.WrappedPhase0SignedBeaconBlock(tt.args.block)}
+			blks := []block.SignedBeaconBlock{wrapper.WrappedPhase0SignedBeaconBlock(tt.args.block)}
 			roots := [][32]byte{root}
 			err = s.ReceiveBlockBatch(ctx, blks, roots)
 			if tt.wantedErr != "" {
@@ -284,13 +287,14 @@ func TestService_ReceiveBlockBatch(t *testing.T) {
 }

 func TestService_HasInitSyncBlock(t *testing.T) {
-	s, err := NewService(context.Background(), &Config{StateNotifier: &blockchainTesting.MockStateNotifier{}})
+	s, err := NewService(context.Background())
 	require.NoError(t, err)
+	s.cfg = &config{StateNotifier: &blockchainTesting.MockStateNotifier{}}
 	r := [32]byte{'a'}
 	if s.HasInitSyncBlock(r) {
 		t.Error("Should not have block")
 	}
-	s.saveInitSyncBlock(r, wrapper.WrappedPhase0SignedBeaconBlock(testutil.NewBeaconBlock()))
+	s.saveInitSyncBlock(r, wrapper.WrappedPhase0SignedBeaconBlock(util.NewBeaconBlock()))
 	if !s.HasInitSyncBlock(r) {
 		t.Error("Should have block")
 	}
@@ -299,8 +303,9 @@ func TestService_HasInitSyncBlock(t *testing.T) {
 func TestCheckSaveHotStateDB_Enabling(t *testing.T) {
 	beaconDB := testDB.SetupDB(t)
 	hook := logTest.NewGlobal()
-	s, err := NewService(context.Background(), &Config{StateGen: stategen.New(beaconDB)})
+	s, err := NewService(context.Background())
 	require.NoError(t, err)
+	s.cfg = &config{StateGen: stategen.New(beaconDB)}
 	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{}
@@ -312,8 +317,9 @@ func TestCheckSaveHotStateDB_Enabling(t *testing.T) {
 func TestCheckSaveHotStateDB_Disabling(t *testing.T) {
 	beaconDB := testDB.SetupDB(t)
 	hook := logTest.NewGlobal()
-	s, err := NewService(context.Background(), &Config{StateGen: stategen.New(beaconDB)})
+	s, err := NewService(context.Background())
 	require.NoError(t, err)
+	s.cfg = &config{StateGen: stategen.New(beaconDB)}
 	s.finalizedCheckpt = &ethpb.Checkpoint{}
 	require.NoError(t, s.checkSaveHotStateDB(context.Background()))
 	s.genesisTime = time.Now()
@@ -325,8 +331,9 @@ 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)})
+	s, err := NewService(context.Background())
 	require.NoError(t, err)
+	s.cfg = &config{StateGen: stategen.New(beaconDB)}
 	s.finalizedCheckpt = &ethpb.Checkpoint{Epoch: 10000000}
 	s.genesisTime = time.Now()

--- a/beacon-chain/blockchain/service.go
+++ b/beacon-chain/blockchain/service.go
@@ -11,12 +11,13 @@ import (

 	"github.com/pkg/errors"
 	types "github.com/prysmaticlabs/eth2-types"
+	"github.com/prysmaticlabs/prysm/async/event"
 	"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"
@@ -25,15 +26,14 @@ 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"
 	"github.com/prysmaticlabs/prysm/beacon-chain/state/stategen"
 	"github.com/prysmaticlabs/prysm/cmd/beacon-chain/flags"
-	ethpb "github.com/prysmaticlabs/prysm/proto/eth/v1alpha1"
-	"github.com/prysmaticlabs/prysm/proto/interfaces"
-	"github.com/prysmaticlabs/prysm/shared/bytesutil"
-	"github.com/prysmaticlabs/prysm/shared/copyutil"
-	"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"
+	"github.com/prysmaticlabs/prysm/time/slots"
 	"github.com/sirupsen/logrus"
 	"go.opencensus.io/trace"
 )
@@ -45,7 +45,7 @@ const headSyncMinEpochsAfterCheckpoint = 128
 // Service represents a service that handles the internal
 // logic of managing the full PoS beacon chain.
 type Service struct {
-	cfg                   *Config
+	cfg                   *config
 	ctx                   context.Context
 	cancel                context.CancelFunc
 	genesisTime           time.Time
@@ -60,15 +60,15 @@ type Service struct {
 	nextEpochBoundarySlot types.Slot
 	boundaryRoots         [][32]byte
 	checkpointStateCache  *cache.CheckpointStateCache
-	initSyncBlocks        map[[32]byte]interfaces.SignedBeaconBlock
+	initSyncBlocks        map[[32]byte]block.SignedBeaconBlock
 	initSyncBlocksLock    sync.RWMutex
 	justifiedBalances     []uint64
 	justifiedBalancesLock sync.RWMutex
-	wsVerified            bool
+	wsVerifier            *WeakSubjectivityVerifier
 }

-// Config options for the service.
-type Config struct {
+// config options for the service.
+type config struct {
 	BeaconBlockBuf          int
 	ChainStartFetcher       powchain.ChainStartFetcher
 	BeaconDB                db.HeadAccessDatabase
@@ -82,54 +82,40 @@ type Config struct {
 	ForkChoiceStore         f.ForkChoicer
 	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]interfaces.SignedBeaconBlock),
+		initSyncBlocks:       make(map[[32]byte]block.SignedBeaconBlock),
 		justifiedBalances:    make([]uint64, 0),
-	}, nil
+		cfg:                  &config{},
+	}
+	for _, opt := range opts {
+		if err := opt(srv); err != nil {
+			return nil, err
+		}
+	}
+	var err error
+	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)
-	}
-
-	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 genesisBlock != nil && !genesisBlock.IsNil() {
-			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)
-	}
+	beaconState := s.cfg.FinalizedStateAtStartUp

 	// Make sure that attestation processor is subscribed and ready for state initializing event.
 	attestationProcessorSubscribed := make(chan struct{}, 1)
@@ -152,7 +138,7 @@ func (s *Service) Start() {
 		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)
+		go slots.CountdownToGenesis(s.ctx, s.genesisTime, uint64(gState.NumValidators()), gRoot)

 		justifiedCheckpoint, err := s.cfg.BeaconDB.JustifiedCheckpoint(s.ctx)
 		if err != nil {
@@ -164,17 +150,17 @@ func (s *Service) Start() {
 		}

 		// Resume fork choice.
-		s.justifiedCheckpt = copyutil.CopyCheckpoint(justifiedCheckpoint)
+		s.justifiedCheckpt = ethpb.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 = copyutil.CopyCheckpoint(justifiedCheckpoint)
-		s.bestJustifiedCheckpt = copyutil.CopyCheckpoint(justifiedCheckpoint)
-		s.finalizedCheckpt = copyutil.CopyCheckpoint(finalizedCheckpoint)
-		s.prevFinalizedCheckpt = copyutil.CopyCheckpoint(finalizedCheckpoint)
+		s.prevJustifiedCheckpt = ethpb.CopyCheckpoint(justifiedCheckpoint)
+		s.bestJustifiedCheckpt = ethpb.CopyCheckpoint(justifiedCheckpoint)
+		s.finalizedCheckpt = ethpb.CopyCheckpoint(finalizedCheckpoint)
+		s.prevFinalizedCheckpt = ethpb.CopyCheckpoint(finalizedCheckpoint)
 		s.resumeForkChoice(justifiedCheckpoint, finalizedCheckpoint)

-		ss, err := helpers.StartSlot(s.finalizedCheckpt.Epoch)
+		ss, err := slots.EpochStart(s.finalizedCheckpt.Epoch)
 		if err != nil {
 			log.Fatalf("Could not get start slot of finalized epoch: %v", err)
 		}
@@ -189,9 +175,11 @@ func (s *Service) Start() {
 			}
 		}

-		if err := s.VerifyWeakSubjectivityRoot(s.ctx); err != nil {
+		// not attempting to save initial sync blocks here, because there shouldn't be until
+		// after the statefeed.Initialized event is fired (below)
+		if err := s.wsVerifier.VerifyWeakSubjectivity(s.ctx, s.finalizedCheckpt.Epoch); err != nil {
 			// Exit run time if the node failed to verify weak subjectivity checkpoint.
-			log.Fatalf("Could not verify weak subjectivity checkpoint: %v", err)
+			log.Fatalf("could not verify initial checkpoint provided for chain sync, with err=: %v", err)
 		}

 		s.cfg.StateNotifier.StateFeed().Send(&feed.Event{
@@ -252,7 +240,7 @@ func (s *Service) processChainStartTime(ctx context.Context, genesisTime time.Ti
 	if err != nil {
 		log.Fatalf("Could not hash tree root genesis state: %v", err)
 	}
-	go slotutil.CountdownToGenesis(ctx, genesisTime, uint64(initializedState.NumValidators()), gRoot)
+	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.
@@ -271,14 +259,14 @@ func (s *Service) processChainStartTime(ctx context.Context, genesisTime time.Ti
 func (s *Service) initializeBeaconChain(
 	ctx context.Context,
 	genesisTime time.Time,
-	preGenesisState iface.BeaconState,
-	eth1data *ethpb.Eth1Data) (iface.BeaconState, error) {
+	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 := state.OptimizedGenesisBeaconState(unixTime, preGenesisState, eth1data)
+	genesisState, err := transition.OptimizedGenesisBeaconState(unixTime, preGenesisState, eth1data)
 	if err != nil {
 		return nil, errors.Wrap(err, "could not initialize genesis state")
 	}
@@ -296,7 +284,7 @@ func (s *Service) initializeBeaconChain(
 	if err := helpers.UpdateCommitteeCache(genesisState, 0 /* genesis epoch */); err != nil {
 		return nil, err
 	}
-	if err := helpers.UpdateProposerIndicesInCache(genesisState); err != nil {
+	if err := helpers.UpdateProposerIndicesInCache(ctx, genesisState); err != nil {
 		return nil, err
 	}

@@ -332,7 +320,7 @@ func (s *Service) Status() error {
 }

 // 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 {
+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")
 	}
@@ -351,14 +339,14 @@ func (s *Service) saveGenesisData(ctx context.Context, genesisState iface.Beacon
 	// Finalized checkpoint at genesis is a zero hash.
 	genesisCheckpoint := genesisState.FinalizedCheckpoint()

-	s.justifiedCheckpt = copyutil.CopyCheckpoint(genesisCheckpoint)
+	s.justifiedCheckpt = ethpb.CopyCheckpoint(genesisCheckpoint)
 	if err := s.cacheJustifiedStateBalances(ctx, genesisBlkRoot); err != nil {
 		return err
 	}
-	s.prevJustifiedCheckpt = copyutil.CopyCheckpoint(genesisCheckpoint)
-	s.bestJustifiedCheckpt = copyutil.CopyCheckpoint(genesisCheckpoint)
-	s.finalizedCheckpt = copyutil.CopyCheckpoint(genesisCheckpoint)
-	s.prevFinalizedCheckpt = copyutil.CopyCheckpoint(genesisCheckpoint)
+	s.prevJustifiedCheckpt = ethpb.CopyCheckpoint(genesisCheckpoint)
+	s.bestJustifiedCheckpt = ethpb.CopyCheckpoint(genesisCheckpoint)
+	s.finalizedCheckpt = ethpb.CopyCheckpoint(genesisCheckpoint)
+	s.prevFinalizedCheckpt = ethpb.CopyCheckpoint(genesisCheckpoint)

 	if err := s.cfg.ForkChoiceStore.ProcessBlock(ctx,
 		genesisBlk.Block().Slot(),
@@ -380,8 +368,8 @@ func (s *Service) initializeChainInfo(ctx context.Context) error {
 	if err != nil {
 		return errors.Wrap(err, "could not get genesis block from db")
 	}
-	if genesisBlock == nil || genesisBlock.IsNil() {
-		return errors.New("no genesis block in db")
+	if err := helpers.BeaconBlockIsNil(genesisBlock); err != nil {
+		return err
 	}
 	genesisBlkRoot, err := genesisBlock.Block().HashTreeRoot()
 	if err != nil {
@@ -399,9 +387,9 @@ 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 +399,7 @@ 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
@@ -423,7 +411,7 @@ func (s *Service) initializeChainInfo(ctx context.Context) error {
 			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")
 			}
--- 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
@@ -8,12 +8,13 @@ import (
 	"time"

 	"github.com/ethereum/go-ethereum/common"
+	"github.com/prysmaticlabs/prysm/async/event"
 	"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"
@@ -21,19 +22,17 @@ import (
 	"github.com/prysmaticlabs/prysm/beacon-chain/p2p"
 	"github.com/prysmaticlabs/prysm/beacon-chain/powchain"
 	"github.com/prysmaticlabs/prysm/beacon-chain/state/stategen"
-	"github.com/prysmaticlabs/prysm/beacon-chain/state/v1"
+	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"
-	ethpb "github.com/prysmaticlabs/prysm/proto/eth/v1alpha1"
-	"github.com/prysmaticlabs/prysm/proto/eth/v1alpha1/wrapper"
-	"github.com/prysmaticlabs/prysm/proto/interfaces"
-	"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"
 )
@@ -64,6 +63,11 @@ 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 {
@@ -71,30 +75,31 @@ func setupBeaconChain(t *testing.T, beaconDB db.Database) *Service {
 	ctx := context.Background()
 	var web3Service *powchain.Service
 	var err error
-	bState, _ := testutil.DeterministicGenesisState(t, 10)
+	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")

 	attService, err := attestations.NewService(ctx, &attestations.Config{Pool: attestations.NewPool()})
@@ -103,7 +108,7 @@ func setupBeaconChain(t *testing.T, beaconDB db.Database) *Service {
 	depositCache, err := depositcache.New()
 	require.NoError(t, err)

-	cfg := &Config{
+	cfg := &config{
 		BeaconBlockBuf:    0,
 		BeaconDB:          beaconDB,
 		DepositCache:      depositCache,
@@ -119,8 +124,9 @@ func setupBeaconChain(t *testing.T, beaconDB db.Database) *Service {
 	// 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)
 	require.NoError(t, err, "Unable to setup chain service")
+	chainService.cfg = cfg
 	chainService.genesisTime = time.Unix(1, 0) // non-zero time

 	return chainService
@@ -133,11 +139,11 @@ 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, wrapper.WrappedPhase0SignedBeaconBlock(genesisBlk)))
-	s, err := testutil.NewBeaconState()
+	s, err := util.NewBeaconState()
 	require.NoError(t, err)
 	require.NoError(t, s.SetSlot(1))
 	require.NoError(t, beaconDB.SaveState(ctx, s, blkRoot))
@@ -145,7 +151,7 @@ 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()

@@ -163,16 +169,16 @@ 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, wrapper.WrappedPhase0SignedBeaconBlock(genesisBlk)))
-	s, err := testutil.NewBeaconState()
+	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()

@@ -193,12 +199,12 @@ 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[:],
@@ -232,18 +238,18 @@ 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, wrapper.WrappedPhase0SignedBeaconBlock(genesisBlk)))
-	s, err := testutil.NewBeaconState()
+	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()

@@ -258,17 +264,17 @@ 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, 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[:]))
@@ -277,8 +283,9 @@ func TestChainService_InitializeChainInfo(t *testing.T) {
 	require.NoError(t, beaconDB.SaveState(ctx, headState, headRoot))
 	require.NoError(t, beaconDB.SaveState(ctx, headState, genesisRoot))
 	require.NoError(t, beaconDB.SaveBlock(ctx, wrapper.WrappedPhase0SignedBeaconBlock(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, beaconDB.SaveFinalizedCheckpoint(ctx, &ethpb.Checkpoint{Epoch: slots.ToEpoch(finalizedSlot), Root: headRoot[:]}))
+	c := &Service{cfg: &config{BeaconDB: beaconDB, StateGen: stategen.New(beaconDB)}}
+	c.cfg.FinalizedStateAtStartUp = headState
 	require.NoError(t, c.initializeChainInfo(ctx))
 	headBlk, err := c.HeadBlock(ctx)
 	require.NoError(t, err)
@@ -299,17 +306,17 @@ 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, 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[:]))
@@ -318,7 +325,7 @@ func TestChainService_InitializeChainInfo_SetHeadAtGenesis(t *testing.T) {
 	require.NoError(t, beaconDB.SaveState(ctx, headState, headRoot))
 	require.NoError(t, beaconDB.SaveState(ctx, headState, genesisRoot))
 	require.NoError(t, beaconDB.SaveBlock(ctx, wrapper.WrappedPhase0SignedBeaconBlock(headBlock)))
-	c := &Service{cfg: &Config{BeaconDB: beaconDB, StateGen: stategen.New(beaconDB)}}
+	c := &Service{cfg: &config{BeaconDB: beaconDB, StateGen: stategen.New(beaconDB)}}
 	require.NoError(t, c.initializeChainInfo(ctx))
 	s, err := c.HeadState(ctx)
 	require.NoError(t, err)
@@ -341,13 +348,13 @@ 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, wrapper.WrappedPhase0SignedBeaconBlock(genesisBlock)))

-	finalizedBlock := testutil.NewBeaconBlock()
+	finalizedBlock := util.NewBeaconBlock()
 	finalizedBlock.Block.Slot = finalizedSlot
 	finalizedBlock.Block.ParentRoot = genesisRoot[:]
 	finalizedRoot, err := finalizedBlock.Block.HashTreeRoot()
@@ -355,14 +362,14 @@ func TestChainService_InitializeChainInfo_HeadSync(t *testing.T) {
 	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, 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[:]))
@@ -371,12 +378,12 @@ 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)}}
-
+	c := &Service{cfg: &config{BeaconDB: beaconDB, StateGen: stategen.New(beaconDB)}}
+	c.cfg.FinalizedStateAtStartUp = headState
 	require.NoError(t, c.initializeChainInfo(ctx))
 	s, err := c.HeadState(ctx)
 	require.NoError(t, err)
@@ -388,7 +395,7 @@ func TestChainService_InitializeChainInfo_HeadSync(t *testing.T) {
 	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()
@@ -413,13 +420,13 @@ 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, wrapper.WrappedPhase0SignedBeaconBlock(blk), r, newState))
@@ -435,13 +442,13 @@ 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},
+		cfg:              &config{ForkChoiceStore: protoarray.New(0, 0, [32]byte{}), BeaconDB: beaconDB},
 		finalizedCheckpt: &ethpb.Checkpoint{Root: make([]byte, 32)},
 	}
-	block := testutil.NewBeaconBlock()
+	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, wrapper.WrappedPhase0SignedBeaconBlock(block).Block(), r, beaconState))

@@ -453,12 +460,12 @@ 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]interfaces.SignedBeaconBlock),
+		initSyncBlocks: make(map[[32]byte]block.SignedBeaconBlock),
 	}
-	block := testutil.NewBeaconBlock()
+	block := util.NewBeaconBlock()
 	r, err := block.Block.HashTreeRoot()
 	require.NoError(t, err)
 	s.saveInitSyncBlock(r, wrapper.WrappedPhase0SignedBeaconBlock(block))
@@ -484,9 +491,9 @@ 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()
+	block := util.NewBeaconBlock()
 	require.NoError(b, s.cfg.BeaconDB.SaveBlock(ctx, wrapper.WrappedPhase0SignedBeaconBlock(block)))
 	r, err := block.Block.HashTreeRoot()
 	require.NoError(b, err)
@@ -501,13 +508,13 @@ 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},
+		cfg:              &config{ForkChoiceStore: protoarray.New(0, 0, [32]byte{}), BeaconDB: beaconDB},
 		finalizedCheckpt: &ethpb.Checkpoint{Root: make([]byte, 32)},
 	}
 	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)}}
+	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, wrapper.WrappedPhase0SignedBeaconBlock(block).Block(), r, beaconState))
--- a/beacon-chain/blockchain/testing/BUILD.bazel
+++ b/beacon-chain/blockchain/testing/BUILD.bazel
@@ -7,9 +7,11 @@ go_library(
    importpath = "github.com/prysmaticlabs/prysm/beacon-chain/blockchain/testing",
    visibility = [
        "//beacon-chain:__subpackages__",
-        "//fuzz:__pkg__",
+        "//testing:__subpackages__",
+        "//testing/fuzz:__pkg__",
    ],
    deps = [
+        "//async/event:go_default_library",
        "//beacon-chain/core/epoch/precompute:go_default_library",
        "//beacon-chain/core/feed:go_default_library",
        "//beacon-chain/core/feed/block:go_default_library",
@@ -18,14 +20,12 @@ go_library(
        "//beacon-chain/core/helpers:go_default_library",
        "//beacon-chain/db:go_default_library",
        "//beacon-chain/forkchoice/protoarray:go_default_library",
-        "//beacon-chain/state/interface:go_default_library",
+        "//beacon-chain/state:go_default_library",
        "//beacon-chain/state/v1:go_default_library",
-        "//proto/beacon/p2p/v1:go_default_library",
-        "//proto/eth/v1alpha1:go_default_library",
-        "//proto/interfaces:go_default_library",
-        "//shared/bytesutil:go_default_library",
-        "//shared/event:go_default_library",
-        "//shared/params:go_default_library",
+        "//config/params:go_default_library",
+        "//encoding/bytesutil:go_default_library",
+        "//proto/prysm/v1alpha1:go_default_library",
+        "//proto/prysm/v1alpha1/block:go_default_library",
        "@com_github_pkg_errors//:go_default_library",
        "@com_github_prysmaticlabs_eth2_types//:go_default_library",
        "@com_github_sirupsen_logrus//:go_default_library",
--- a/beacon-chain/blockchain/testing/mock.go
+++ b/beacon-chain/blockchain/testing/mock.go
@@ -10,6 +10,7 @@ import (

 	"github.com/pkg/errors"
 	types "github.com/prysmaticlabs/eth2-types"
+	"github.com/prysmaticlabs/prysm/async/event"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/epoch/precompute"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/feed"
 	blockfeed "github.com/prysmaticlabs/prysm/beacon-chain/core/feed/block"
@@ -18,31 +19,29 @@ import (
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/helpers"
 	"github.com/prysmaticlabs/prysm/beacon-chain/db"
 	"github.com/prysmaticlabs/prysm/beacon-chain/forkchoice/protoarray"
-	iface "github.com/prysmaticlabs/prysm/beacon-chain/state/interface"
-	"github.com/prysmaticlabs/prysm/beacon-chain/state/v1"
-	pb "github.com/prysmaticlabs/prysm/proto/beacon/p2p/v1"
-	ethpb "github.com/prysmaticlabs/prysm/proto/eth/v1alpha1"
-	"github.com/prysmaticlabs/prysm/proto/interfaces"
-	"github.com/prysmaticlabs/prysm/shared/bytesutil"
-	"github.com/prysmaticlabs/prysm/shared/event"
-	"github.com/prysmaticlabs/prysm/shared/params"
+	"github.com/prysmaticlabs/prysm/beacon-chain/state"
+	v1 "github.com/prysmaticlabs/prysm/beacon-chain/state/v1"
+	"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/sirupsen/logrus"
 )

 // ChainService defines the mock interface for testing
 type ChainService struct {
-	State                       iface.BeaconState
+	State                       state.BeaconState
 	Root                        []byte
-	Block                       interfaces.SignedBeaconBlock
+	Block                       block.SignedBeaconBlock
 	FinalizedCheckPoint         *ethpb.Checkpoint
 	CurrentJustifiedCheckPoint  *ethpb.Checkpoint
 	PreviousJustifiedCheckPoint *ethpb.Checkpoint
-	BlocksReceived              []interfaces.SignedBeaconBlock
+	BlocksReceived              []block.SignedBeaconBlock
 	Balance                     *precompute.Balance
 	Genesis                     time.Time
 	ValidatorsRoot              [32]byte
 	CanonicalRoots              map[[32]byte]bool
-	Fork                        *pb.Fork
+	Fork                        *ethpb.Fork
 	ETH1Data                    *ethpb.Eth1Data
 	DB                          db.Database
 	stateNotifier               statefeed.Notifier
@@ -52,6 +51,13 @@ type ChainService struct {
 	ForkChoiceStore             *protoarray.Store
 	VerifyBlkDescendantErr      error
 	Slot                        *types.Slot // Pointer because 0 is a useful value, so checking against it can be incorrect.
+	SyncCommitteeIndices        []types.CommitteeIndex
+	SyncCommitteeDomain         []byte
+	SyncSelectionProofDomain    []byte
+	SyncContributionProofDomain []byte
+	PublicKey                   [48]byte
+	SyncCommitteePubkeys        [][]byte
+	InitSyncBlockRoots          map[[32]byte]bool
 }

 // StateNotifier mocks the same method in the chain service.
@@ -150,7 +156,7 @@ func (mon *MockOperationNotifier) OperationFeed() *event.Feed {
 }

 // ReceiveBlockInitialSync mocks ReceiveBlockInitialSync method in chain service.
-func (s *ChainService) ReceiveBlockInitialSync(ctx context.Context, block interfaces.SignedBeaconBlock, _ [32]byte) error {
+func (s *ChainService) ReceiveBlockInitialSync(ctx context.Context, block block.SignedBeaconBlock, _ [32]byte) error {
 	if s.State == nil {
 		s.State = &v1.BeaconState{}
 	}
@@ -177,7 +183,7 @@ func (s *ChainService) ReceiveBlockInitialSync(ctx context.Context, block interf
 }

 // ReceiveBlockBatch processes blocks in batches from initial-sync.
-func (s *ChainService) ReceiveBlockBatch(ctx context.Context, blks []interfaces.SignedBeaconBlock, _ [][32]byte) error {
+func (s *ChainService) ReceiveBlockBatch(ctx context.Context, blks []block.SignedBeaconBlock, _ [][32]byte) error {
 	if s.State == nil {
 		s.State = &v1.BeaconState{}
 	}
@@ -206,7 +212,7 @@ func (s *ChainService) ReceiveBlockBatch(ctx context.Context, blks []interfaces.
 }

 // ReceiveBlock mocks ReceiveBlock method in chain service.
-func (s *ChainService) ReceiveBlock(ctx context.Context, block interfaces.SignedBeaconBlock, _ [32]byte) error {
+func (s *ChainService) ReceiveBlock(ctx context.Context, block block.SignedBeaconBlock, _ [32]byte) error {
 	if s.State == nil {
 		s.State = &v1.BeaconState{}
 	}
@@ -249,17 +255,17 @@ func (s *ChainService) HeadRoot(_ context.Context) ([]byte, error) {
 }

 // HeadBlock mocks HeadBlock method in chain service.
-func (s *ChainService) HeadBlock(context.Context) (interfaces.SignedBeaconBlock, error) {
+func (s *ChainService) HeadBlock(context.Context) (block.SignedBeaconBlock, error) {
 	return s.Block, nil
 }

 // HeadState mocks HeadState method in chain service.
-func (s *ChainService) HeadState(context.Context) (iface.BeaconState, error) {
+func (s *ChainService) HeadState(context.Context) (state.BeaconState, error) {
 	return s.State, nil
 }

 // CurrentFork mocks HeadState method in chain service.
-func (s *ChainService) CurrentFork() *pb.Fork {
+func (s *ChainService) CurrentFork() *ethpb.Fork {
 	return s.Fork
 }

@@ -288,17 +294,17 @@ func (s *ChainService) ReceiveAttestationNoPubsub(context.Context, *ethpb.Attest
 	return nil
 }

-// AttestationPreState mocks AttestationPreState method in chain service.
-func (s *ChainService) AttestationPreState(_ context.Context, _ *ethpb.Attestation) (iface.BeaconState, error) {
+// AttestationTargetState mocks AttestationTargetState method in chain service.
+func (s *ChainService) AttestationTargetState(_ context.Context, _ *ethpb.Checkpoint) (state.BeaconState, error) {
 	return s.State, nil
 }

 // HeadValidatorsIndices mocks the same method in the chain service.
-func (s *ChainService) HeadValidatorsIndices(_ context.Context, epoch types.Epoch) ([]types.ValidatorIndex, error) {
+func (s *ChainService) HeadValidatorsIndices(ctx context.Context, epoch types.Epoch) ([]types.ValidatorIndex, error) {
 	if s.State == nil {
 		return []types.ValidatorIndex{}, nil
 	}
-	return helpers.ActiveValidatorIndices(s.State, epoch)
+	return helpers.ActiveValidatorIndices(ctx, s.State, epoch)
 }

 // HeadSeed mocks the same method in the chain service.
@@ -355,8 +361,11 @@ func (s *ChainService) IsCanonical(_ context.Context, r [32]byte) (bool, error)
 }

 // HasInitSyncBlock mocks the same method in the chain service.
-func (s *ChainService) HasInitSyncBlock(_ [32]byte) bool {
-	return false
+func (s *ChainService) HasInitSyncBlock(rt [32]byte) bool {
+	if s.InitSyncBlockRoots == nil {
+		return false
+	}
+	return s.InitSyncBlockRoots[rt]
 }

 // HeadGenesisValidatorRoot mocks HeadGenesisValidatorRoot method in chain service.
@@ -393,3 +402,38 @@ func (s *ChainService) ChainHeads() ([][32]byte, []types.Slot) {
 		},
 		[]types.Slot{0, 1}
 }
+
+// HeadPublicKeyToValidatorIndex mocks HeadPublicKeyToValidatorIndex and always return 0 and true.
+func (s *ChainService) HeadPublicKeyToValidatorIndex(_ context.Context, _ [48]byte) (types.ValidatorIndex, bool) {
+	return 0, true
+}
+
+// HeadValidatorIndexToPublicKey mocks HeadValidatorIndexToPublicKey and always return empty and nil.
+func (s *ChainService) HeadValidatorIndexToPublicKey(_ context.Context, _ types.ValidatorIndex) ([48]byte, error) {
+	return s.PublicKey, nil
+}
+
+// HeadSyncCommitteeIndices mocks HeadSyncCommitteeIndices and always return `HeadNextSyncCommitteeIndices`.
+func (s *ChainService) HeadSyncCommitteeIndices(_ context.Context, index types.ValidatorIndex, slot types.Slot) ([]types.CommitteeIndex, error) {
+	return s.SyncCommitteeIndices, nil
+}
+
+// HeadSyncCommitteePubKeys mocks HeadSyncCommitteePubKeys and always return empty nil.
+func (s *ChainService) HeadSyncCommitteePubKeys(_ context.Context, _ types.Slot, _ types.CommitteeIndex) ([][]byte, error) {
+	return s.SyncCommitteePubkeys, nil
+}
+
+// HeadSyncCommitteeDomain mocks HeadSyncCommitteeDomain and always return empty nil.
+func (s *ChainService) HeadSyncCommitteeDomain(_ context.Context, _ types.Slot) ([]byte, error) {
+	return s.SyncCommitteeDomain, nil
+}
+
+// HeadSyncSelectionProofDomain mocks HeadSyncSelectionProofDomain and always return empty nil.
+func (s *ChainService) HeadSyncSelectionProofDomain(_ context.Context, _ types.Slot) ([]byte, error) {
+	return s.SyncSelectionProofDomain, nil
+}
+
+// HeadSyncContributionProofDomain mocks HeadSyncContributionProofDomain and always return empty nil.
+func (s *ChainService) HeadSyncContributionProofDomain(_ context.Context, _ types.Slot) ([]byte, error) {
+	return s.SyncContributionProofDomain, nil
+}
--- a/beacon-chain/blockchain/weak_subjectivity_checks.go
+++ b/beacon-chain/blockchain/weak_subjectivity_checks.go
@@ -4,57 +4,94 @@ import (
 	"context"
 	"fmt"

-	"github.com/prysmaticlabs/prysm/beacon-chain/core/helpers"
+	"github.com/pkg/errors"
+	types "github.com/prysmaticlabs/eth2-types"
 	"github.com/prysmaticlabs/prysm/beacon-chain/db/filters"
-	"github.com/prysmaticlabs/prysm/shared/bytesutil"
-	"github.com/prysmaticlabs/prysm/shared/params"
+	"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"
 )

-// VerifyWeakSubjectivityRoot verifies the weak subjectivity root in the service struct.
-// Reference design: https://github.com/ethereum/eth2.0-specs/blob/master/specs/phase0/weak-subjectivity.md#weak-subjectivity-sync-procedure
-func (s *Service) VerifyWeakSubjectivityRoot(ctx context.Context) error {
-	// TODO(7342): Remove the following to fully use weak subjectivity in production.
-	if s.cfg.WeakSubjectivityCheckpt == nil || len(s.cfg.WeakSubjectivityCheckpt.Root) == 0 || s.cfg.WeakSubjectivityCheckpt.Epoch == 0 {
-		return nil
-	}
+var errWSBlockNotFound = errors.New("weak subjectivity root not found in db")
+var errWSBlockNotFoundInEpoch = errors.New("weak subjectivity root not found in db within epoch")

-	// Do nothing if the weak subjectivity has previously been verified,
-	// or weak subjectivity epoch is higher than last finalized epoch.
-	if s.wsVerified {
-		return nil
-	}
-	if s.cfg.WeakSubjectivityCheckpt.Epoch > s.finalizedCheckpt.Epoch {
-		return nil
-	}
+type weakSubjectivityDB interface {
+	HasBlock(ctx context.Context, blockRoot [32]byte) bool
+	BlockRoots(ctx context.Context, f *filters.QueryFilter) ([][32]byte, error)
+}

-	r := bytesutil.ToBytes32(s.cfg.WeakSubjectivityCheckpt.Root)
-	log.Infof("Performing weak subjectivity check for root %#x in epoch %d", r, s.cfg.WeakSubjectivityCheckpt.Epoch)
-	// Save initial sync cached blocks to DB.
-	if err := s.cfg.BeaconDB.SaveBlocks(ctx, s.getInitSyncBlocks()); err != nil {
-		return err
-	}
-	// A node should have the weak subjectivity block in the DB.
-	if !s.cfg.BeaconDB.HasBlock(ctx, r) {
-		return fmt.Errorf("node does not have root in DB: %#x", r)
-	}
+type WeakSubjectivityVerifier struct {
+	enabled  bool
+	verified bool
+	root     [32]byte
+	epoch    types.Epoch
+	slot     types.Slot
+	db       weakSubjectivityDB
+}

-	startSlot, err := helpers.StartSlot(s.cfg.WeakSubjectivityCheckpt.Epoch)
+// NewWeakSubjectivityVerifier validates a checkpoint, and if valid, uses it to initialize a weak subjectivity verifier
+func NewWeakSubjectivityVerifier(wsc *ethpb.Checkpoint, db weakSubjectivityDB) (*WeakSubjectivityVerifier, error) {
+	// TODO(7342): Weak subjectivity checks are currently optional. When we require the flag to be specified
+	// per 7342, a nil checkpoint, zero-root or zero-epoch should all fail validation
+	// and return an error instead of creating a WeakSubjectivityVerifier that permits any chain history.
+	if wsc == nil || len(wsc.Root) == 0 || wsc.Epoch == 0 {
+		return &WeakSubjectivityVerifier{
+			enabled: false,
+		}, nil
+	}
+	startSlot, err := slots.EpochStart(wsc.Epoch)
 	if err != nil {
-		return err
+		return nil, err
 	}
+	return &WeakSubjectivityVerifier{
+		enabled:  true,
+		verified: false,
+		root:     bytesutil.ToBytes32(wsc.Root),
+		epoch:    wsc.Epoch,
+		db:       db,
+		slot:     startSlot,
+	}, nil
+}
+
+// VerifyWeakSubjectivity verifies the weak subjectivity root in the service struct.
+// Reference design: https://github.com/ethereum/consensus-specs/blob/master/specs/phase0/weak-subjectivity.md#weak-subjectivity-sync-procedure
+func (v *WeakSubjectivityVerifier) VerifyWeakSubjectivity(ctx context.Context, finalizedEpoch types.Epoch) error {
+	if v.verified || !v.enabled {
+		return nil
+	}
+
+	// Two conditions are described in the specs:
+	// IF epoch_number > store.finalized_checkpoint.epoch,
+	// then ASSERT during block sync that block with root block_root
+	// is in the sync path at epoch epoch_number. Emit descriptive critical error if this assert fails,
+	// then exit client process.
+	// we do not handle this case ^, because we can only blocks that have been processed / are currently
+	// in line for finalization, we don't have the ability to look ahead. so we only satisfy the following:
+	// IF epoch_number <= store.finalized_checkpoint.epoch,
+	// then ASSERT that the block in the canonical chain at epoch epoch_number has root block_root.
+	// Emit descriptive critical error if this assert fails, then exit client process.
+	if v.epoch > finalizedEpoch {
+		return nil
+	}
+	log.Infof("Performing weak subjectivity check for root %#x in epoch %d", v.root, v.epoch)
+
+	if !v.db.HasBlock(ctx, v.root) {
+		return errors.Wrap(errWSBlockNotFound, fmt.Sprintf("missing root %#x", v.root))
+	}
+	filter := filters.NewFilter().SetStartSlot(v.slot).SetEndSlot(v.slot + params.BeaconConfig().SlotsPerEpoch)
 	// A node should have the weak subjectivity block corresponds to the correct epoch in the DB.
-	filter := filters.NewFilter().SetStartSlot(startSlot).SetEndSlot(startSlot + params.BeaconConfig().SlotsPerEpoch)
-	roots, err := s.cfg.BeaconDB.BlockRoots(ctx, filter)
+	roots, err := v.db.BlockRoots(ctx, filter)
 	if err != nil {
-		return err
+		return errors.Wrap(err, "error while retrieving block roots to verify weak subjectivity")
 	}
 	for _, root := range roots {
-		if r == root {
+		if v.root == root {
 			log.Info("Weak subjectivity check has passed")
-			s.wsVerified = true
+			v.verified = true
 			return nil
 		}
 	}

-	return fmt.Errorf("node does not have root in db corresponding to epoch: %#x %d", r, s.cfg.WeakSubjectivityCheckpt.Epoch)
+	return errors.Wrap(errWSBlockNotFoundInEpoch, fmt.Sprintf("root=%#x, epoch=%d", v.root, v.epoch))
 }
--- a/beacon-chain/blockchain/weak_subjectivity_checks_test.go
+++ b/beacon-chain/blockchain/weak_subjectivity_checks_test.go
@@ -4,78 +4,77 @@ import (
 	"context"
 	"testing"

+	"github.com/pkg/errors"
 	types "github.com/prysmaticlabs/eth2-types"
 	testDB "github.com/prysmaticlabs/prysm/beacon-chain/db/testing"
-	ethpb "github.com/prysmaticlabs/prysm/proto/eth/v1alpha1"
-	"github.com/prysmaticlabs/prysm/proto/eth/v1alpha1/wrapper"
-	"github.com/prysmaticlabs/prysm/shared/bytesutil"
-	"github.com/prysmaticlabs/prysm/shared/testutil"
-	"github.com/prysmaticlabs/prysm/shared/testutil/require"
+	"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"
 )

 func TestService_VerifyWeakSubjectivityRoot(t *testing.T) {
 	beaconDB := testDB.SetupDB(t)

-	b := testutil.NewBeaconBlock()
+	b := util.NewBeaconBlock()
 	b.Block.Slot = 32
 	require.NoError(t, beaconDB.SaveBlock(context.Background(), wrapper.WrappedPhase0SignedBeaconBlock(b)))
 	r, err := b.Block.HashTreeRoot()
 	require.NoError(t, err)
 	tests := []struct {
 		wsVerified     bool
-		wantErr        bool
+		wantErr        error
 		checkpt        *ethpb.Checkpoint
 		finalizedEpoch types.Epoch
-		errString      string
 		name           string
 	}{
 		{
-			name:    "nil root and epoch",
-			wantErr: false,
+			name: "nil root and epoch",
 		},
 		{
 			name:           "already verified",
 			checkpt:        &ethpb.Checkpoint{Epoch: 2},
 			finalizedEpoch: 2,
 			wsVerified:     true,
-			wantErr:        false,
 		},
 		{
 			name:           "not yet to verify, ws epoch higher than finalized epoch",
 			checkpt:        &ethpb.Checkpoint{Epoch: 2},
 			finalizedEpoch: 1,
-			wantErr:        false,
 		},
 		{
 			name:           "can't find the block in DB",
 			checkpt:        &ethpb.Checkpoint{Root: bytesutil.PadTo([]byte{'a'}, 32), Epoch: 1},
 			finalizedEpoch: 3,
-			wantErr:        true,
-			errString:      "node does not have root in DB",
+			wantErr:        errWSBlockNotFound,
 		},
 		{
 			name:           "can't find the block corresponds to ws epoch in DB",
 			checkpt:        &ethpb.Checkpoint{Root: r[:], Epoch: 2}, // Root belongs in epoch 1.
 			finalizedEpoch: 3,
-			wantErr:        true,
-			errString:      "node does not have root in db corresponding to epoch",
+			wantErr:        errWSBlockNotFoundInEpoch,
 		},
 		{
 			name:           "can verify and pass",
 			checkpt:        &ethpb.Checkpoint{Root: r[:], Epoch: 1},
 			finalizedEpoch: 3,
-			wantErr:        false,
 		},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
+			wv, err := NewWeakSubjectivityVerifier(tt.checkpt, beaconDB)
+			require.NoError(t, err)
 			s := &Service{
-				cfg:              &Config{BeaconDB: beaconDB, WeakSubjectivityCheckpt: tt.checkpt},
-				wsVerified:       tt.wsVerified,
+				cfg:              &config{BeaconDB: beaconDB, WeakSubjectivityCheckpt: tt.checkpt},
 				finalizedCheckpt: &ethpb.Checkpoint{Epoch: tt.finalizedEpoch},
+				wsVerifier:       wv,
 			}
-			if err := s.VerifyWeakSubjectivityRoot(context.Background()); (err != nil) != tt.wantErr {
-				require.ErrorContains(t, tt.errString, err)
+			err = s.wsVerifier.VerifyWeakSubjectivity(context.Background(), s.finalizedCheckpt.Epoch)
+			if tt.wantErr == nil {
+				require.NoError(t, err)
+			} else {
+				require.Equal(t, true, errors.Is(err, tt.wantErr))
 			}
 		})
 	}
--- a/beacon-chain/cache/BUILD.bazel
+++ b/beacon-chain/cache/BUILD.bazel
@@ -10,34 +10,47 @@ go_library(
        "committees.go",
        "common.go",
        "doc.go",
+        "error.go",
        "proposer_indices_type.go",
        "skip_slot_cache.go",
        "subnet_ids.go",
+        "sync_committee_head_state.go",
+        "sync_subnet_ids.go",
    ] + select({
-        "//fuzz:fuzzing_enabled": [
+        "//testing/fuzz:fuzzing_enabled": [
+            "active_balance_disabled.go",
            "committee_disabled.go",
            "proposer_indices_disabled.go",
+            "sync_committee_disabled.go",
        ],
        "//conditions:default": [
+            "active_balance.go",
            "committee.go",
            "proposer_indices.go",
+            "sync_committee.go",
        ],
    }),
    importpath = "github.com/prysmaticlabs/prysm/beacon-chain/cache",
    visibility = [
        "//beacon-chain:__subpackages__",
-        "//fuzz:__pkg__",
+        "//testing/fuzz:__pkg__",
        "//tools:__subpackages__",
    ],
    deps = [
-        "//beacon-chain/state/interface:go_default_library",
-        "//proto/eth/v1alpha1:go_default_library",
-        "//shared/copyutil:go_default_library",
-        "//shared/hashutil:go_default_library",
-        "//shared/params:go_default_library",
-        "//shared/sliceutil:go_default_library",
+        "//beacon-chain/state:go_default_library",
+        "//beacon-chain/state/v2:go_default_library",
+        "//cache/lru:go_default_library",
+        "//config/features:go_default_library",
+        "//config/params:go_default_library",
+        "//container/slice:go_default_library",
+        "//crypto/hash:go_default_library",
+        "//crypto/rand:go_default_library",
+        "//encoding/bytesutil:go_default_library",
+        "//math:go_default_library",
+        "//proto/prysm/v1alpha1:go_default_library",
        "@com_github_hashicorp_golang_lru//:go_default_library",
        "@com_github_patrickmn_go_cache//: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",
@@ -50,6 +63,7 @@ go_test(
    name = "go_default_test",
    size = "small",
    srcs = [
+        "active_balance_test.go",
        "attestation_data_test.go",
        "cache_test.go",
        "checkpoint_state_test.go",
@@ -58,17 +72,22 @@ go_test(
        "proposer_indices_test.go",
        "skip_slot_cache_test.go",
        "subnet_ids_test.go",
+        "sync_committee_head_state_test.go",
+        "sync_committee_test.go",
+        "sync_subnet_ids_test.go",
    ],
    embed = [":go_default_library"],
    deps = [
-        "//beacon-chain/state/interface:go_default_library",
+        "//beacon-chain/state:go_default_library",
        "//beacon-chain/state/v1:go_default_library",
-        "//proto/beacon/p2p/v1:go_default_library",
-        "//proto/eth/v1alpha1:go_default_library",
-        "//shared/bytesutil:go_default_library",
-        "//shared/params:go_default_library",
-        "//shared/testutil/assert:go_default_library",
-        "//shared/testutil/require:go_default_library",
+        "//beacon-chain/state/v2:go_default_library",
+        "//config/features:go_default_library",
+        "//config/params:go_default_library",
+        "//encoding/bytesutil:go_default_library",
+        "//proto/prysm/v1alpha1:go_default_library",
+        "//testing/assert:go_default_library",
+        "//testing/require:go_default_library",
+        "//testing/util:go_default_library",
        "@com_github_google_gofuzz//:go_default_library",
        "@com_github_prysmaticlabs_eth2_types//:go_default_library",
        "@org_golang_google_protobuf//proto:go_default_library",
--- a/beacon-chain/cache/active_balance.go
+++ b/beacon-chain/cache/active_balance.go
@@ -0,0 +1,119 @@
+// +build !libfuzzer
+
+package cache
+
+import (
+	"encoding/binary"
+	"sync"
+
+	lru "github.com/hashicorp/golang-lru"
+	"github.com/pkg/errors"
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/client_golang/prometheus/promauto"
+	ethTypes "github.com/prysmaticlabs/eth2-types"
+	"github.com/prysmaticlabs/prysm/beacon-chain/state"
+	lruwrpr "github.com/prysmaticlabs/prysm/cache/lru"
+	"github.com/prysmaticlabs/prysm/config/features"
+	"github.com/prysmaticlabs/prysm/config/params"
+)
+
+var (
+	// maxBalanceCacheSize defines the max number of active balances can cache.
+	maxBalanceCacheSize = uint64(4)
+
+	// BalanceCacheMiss tracks the number of balance requests that aren't present in the cache.
+	balanceCacheMiss = promauto.NewCounter(prometheus.CounterOpts{
+		Name: "total_effective_balance_cache_miss",
+		Help: "The number of get requests that aren't present in the cache.",
+	})
+	// BalanceCacheHit tracks the number of balance requests that are in the cache.
+	balanceCacheHit = promauto.NewCounter(prometheus.CounterOpts{
+		Name: "total_effective_balance_cache_hit",
+		Help: "The number of get requests that are present in the cache.",
+	})
+)
+
+// BalanceCache is a struct with 1 LRU cache for looking up balance by epoch.
+type BalanceCache struct {
+	cache *lru.Cache
+	lock  sync.RWMutex
+}
+
+// NewEffectiveBalanceCache creates a new effective balance cache for storing/accessing total balance by epoch.
+func NewEffectiveBalanceCache() *BalanceCache {
+	return &BalanceCache{
+		cache: lruwrpr.New(int(maxBalanceCacheSize)),
+	}
+}
+
+// AddTotalEffectiveBalance adds a new total effective balance entry for current balance for state `st` into the cache.
+func (c *BalanceCache) AddTotalEffectiveBalance(st state.ReadOnlyBeaconState, balance uint64) error {
+	if !features.Get().EnableActiveBalanceCache {
+		return nil
+	}
+	key, err := balanceCacheKey(st)
+	if err != nil {
+		return err
+	}
+
+	c.lock.Lock()
+	defer c.lock.Unlock()
+
+	_ = c.cache.Add(key, balance)
+	return nil
+}
+
+// Get returns the current epoch's effective balance for state `st` in cache.
+func (c *BalanceCache) Get(st state.ReadOnlyBeaconState) (uint64, error) {
+	if !features.Get().EnableActiveBalanceCache {
+		return 0, ErrNotFound
+	}
+	key, err := balanceCacheKey(st)
+	if err != nil {
+		return 0, err
+	}
+
+	c.lock.RLock()
+	defer c.lock.RUnlock()
+
+	value, exists := c.cache.Get(key)
+	if !exists {
+		balanceCacheMiss.Inc()
+		return 0, ErrNotFound
+	}
+	balanceCacheHit.Inc()
+	return value.(uint64), nil
+}
+
+// Given input state `st`, balance key is constructed as:
+// (block_root in `st` at epoch_start_slot - 1) + current_epoch + validator_count
+func balanceCacheKey(st state.ReadOnlyBeaconState) (string, error) {
+	slotsPerEpoch := params.BeaconConfig().SlotsPerEpoch
+	currentEpoch := st.Slot().DivSlot(slotsPerEpoch)
+	epochStartSlot, err := slotsPerEpoch.SafeMul(uint64(currentEpoch))
+	if err != nil {
+		// impossible condition due to early division
+		return "", errors.Errorf("start slot calculation overflows: %v", err)
+	}
+	prevSlot := ethTypes.Slot(0)
+	if epochStartSlot > 1 {
+		prevSlot = epochStartSlot - 1
+	}
+	r, err := st.BlockRootAtIndex(uint64(prevSlot % params.BeaconConfig().SlotsPerHistoricalRoot))
+	if err != nil {
+		// impossible condition because index is always constrained within state
+		return "", err
+	}
+
+	// Mix in current epoch
+	b := make([]byte, 8)
+	binary.LittleEndian.PutUint64(b, uint64(currentEpoch))
+	key := append(r, b...)
+
+	// Mix in validator count
+	b = make([]byte, 8)
+	binary.LittleEndian.PutUint64(b, uint64(st.NumValidators()))
+	key = append(key, b...)
+
+	return string(key), nil
+}
--- a/beacon-chain/cache/active_balance_disabled.go
+++ b/beacon-chain/cache/active_balance_disabled.go
@@ -0,0 +1,31 @@
+// +build libfuzzer
+
+package cache
+
+import (
+	"sync"
+
+	lru "github.com/hashicorp/golang-lru"
+	"github.com/prysmaticlabs/prysm/beacon-chain/state"
+)
+
+// FakeBalanceCache is a fake struct with 1 LRU cache for looking up balance by epoch.
+type FakeBalanceCache struct {
+	cache *lru.Cache
+	lock  sync.RWMutex
+}
+
+// NewEffectiveBalanceCache creates a new effective balance cache for storing/accessing total balance by epoch.
+func NewEffectiveBalanceCache() *FakeBalanceCache {
+	return &FakeBalanceCache{}
+}
+
+// AddTotalEffectiveBalance adds a new total effective balance entry for current balance for state `st` into the cache.
+func (c *FakeBalanceCache) AddTotalEffectiveBalance(st state.ReadOnlyBeaconState, balance uint64) error {
+	return nil
+}
+
+// Get returns the current epoch's effective balance for state `st` in cache.
+func (c *FakeBalanceCache) Get(st state.ReadOnlyBeaconState) (uint64, error) {
+	return 0, nil
+}
--- a/beacon-chain/cache/active_balance_test.go
+++ b/beacon-chain/cache/active_balance_test.go
@@ -0,0 +1,81 @@
+package cache
+
+import (
+	"encoding/binary"
+	"math"
+	"testing"
+
+	types "github.com/prysmaticlabs/eth2-types"
+	state "github.com/prysmaticlabs/prysm/beacon-chain/state/v1"
+	"github.com/prysmaticlabs/prysm/config/features"
+	"github.com/prysmaticlabs/prysm/config/params"
+	ethpb "github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1"
+	"github.com/prysmaticlabs/prysm/testing/require"
+)
+
+func TestBalanceCache_AddGetBalance(t *testing.T) {
+	resetCfg := features.InitWithReset(&features.Flags{
+		EnableActiveBalanceCache: true,
+	})
+	defer resetCfg()
+
+	blockRoots := make([][]byte, params.BeaconConfig().SlotsPerHistoricalRoot)
+	for i := 0; i < len(blockRoots); i++ {
+		b := make([]byte, 8)
+		binary.LittleEndian.PutUint64(b, uint64(i))
+		blockRoots[i] = b
+	}
+	raw := &ethpb.BeaconState{
+		BlockRoots: blockRoots,
+	}
+	st, err := state.InitializeFromProto(raw)
+	require.NoError(t, err)
+
+	cache := NewEffectiveBalanceCache()
+	_, err = cache.Get(st)
+	require.ErrorContains(t, ErrNotFound.Error(), err)
+
+	b := uint64(100)
+	require.NoError(t, cache.AddTotalEffectiveBalance(st, b))
+	cachedB, err := cache.Get(st)
+	require.NoError(t, err)
+	require.Equal(t, b, cachedB)
+
+	require.NoError(t, st.SetSlot(1000))
+	_, err = cache.Get(st)
+	require.ErrorContains(t, ErrNotFound.Error(), err)
+
+	b = uint64(200)
+	require.NoError(t, cache.AddTotalEffectiveBalance(st, b))
+	cachedB, err = cache.Get(st)
+	require.NoError(t, err)
+	require.Equal(t, b, cachedB)
+
+	require.NoError(t, st.SetSlot(1000+params.BeaconConfig().SlotsPerHistoricalRoot))
+	_, err = cache.Get(st)
+	require.ErrorContains(t, ErrNotFound.Error(), err)
+
+	b = uint64(300)
+	require.NoError(t, cache.AddTotalEffectiveBalance(st, b))
+	cachedB, err = cache.Get(st)
+	require.NoError(t, err)
+	require.Equal(t, b, cachedB)
+}
+
+func TestBalanceCache_BalanceKey(t *testing.T) {
+	blockRoots := make([][]byte, params.BeaconConfig().SlotsPerHistoricalRoot)
+	for i := 0; i < len(blockRoots); i++ {
+		b := make([]byte, 8)
+		binary.LittleEndian.PutUint64(b, uint64(i))
+		blockRoots[i] = b
+	}
+	raw := &ethpb.BeaconState{
+		BlockRoots: blockRoots,
+	}
+	st, err := state.InitializeFromProto(raw)
+	require.NoError(t, err)
+	require.NoError(t, st.SetSlot(types.Slot(math.MaxUint64)))
+
+	_, err = balanceCacheKey(st)
+	require.NoError(t, err)
+}
--- a/beacon-chain/cache/attestation_data.go
+++ b/beacon-chain/cache/attestation_data.go
@@ -10,8 +10,7 @@ import (

 	"github.com/prometheus/client_golang/prometheus"
 	"github.com/prometheus/client_golang/prometheus/promauto"
-	ethpb "github.com/prysmaticlabs/prysm/proto/eth/v1alpha1"
-	"github.com/prysmaticlabs/prysm/shared/copyutil"
+	ethpb "github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1"
 	"k8s.io/client-go/tools/cache"
 )

@@ -98,7 +97,7 @@ func (c *AttestationCache) Get(ctx context.Context, req *ethpb.AttestationDataRe

 	if exists && item != nil && item.(*attestationReqResWrapper).res != nil {
 		attestationCacheHit.Inc()
-		return copyutil.CopyAttestationData(item.(*attestationReqResWrapper).res), nil
+		return ethpb.CopyAttestationData(item.(*attestationReqResWrapper).res), nil
 	}
 	attestationCacheMiss.Inc()
 	return nil, nil
--- a/beacon-chain/cache/attestation_data_test.go
+++ b/beacon-chain/cache/attestation_data_test.go
@@ -5,8 +5,8 @@ import (
 	"testing"

 	"github.com/prysmaticlabs/prysm/beacon-chain/cache"
-	ethpb "github.com/prysmaticlabs/prysm/proto/eth/v1alpha1"
-	"github.com/prysmaticlabs/prysm/shared/testutil/assert"
+	ethpb "github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1"
+	"github.com/prysmaticlabs/prysm/testing/assert"
 	"google.golang.org/protobuf/proto"
 )

--- a/beacon-chain/cache/checkpoint_state.go
+++ b/beacon-chain/cache/checkpoint_state.go
@@ -6,9 +6,10 @@ import (
 	lru "github.com/hashicorp/golang-lru"
 	"github.com/prometheus/client_golang/prometheus"
 	"github.com/prometheus/client_golang/prometheus/promauto"
-	iface "github.com/prysmaticlabs/prysm/beacon-chain/state/interface"
-	ethpb "github.com/prysmaticlabs/prysm/proto/eth/v1alpha1"
-	"github.com/prysmaticlabs/prysm/shared/hashutil"
+	"github.com/prysmaticlabs/prysm/beacon-chain/state"
+	lruwrpr "github.com/prysmaticlabs/prysm/cache/lru"
+	"github.com/prysmaticlabs/prysm/crypto/hash"
+	ethpb "github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1"
 )

 var (
@@ -36,21 +37,17 @@ type CheckpointStateCache struct {

 // NewCheckpointStateCache creates a new checkpoint state cache for storing/accessing processed state.
 func NewCheckpointStateCache() *CheckpointStateCache {
-	cache, err := lru.New(maxCheckpointStateSize)
-	if err != nil {
-		panic(err)
-	}
 	return &CheckpointStateCache{
-		cache: cache,
+		cache: lruwrpr.New(maxCheckpointStateSize),
 	}
 }

 // StateByCheckpoint fetches state by checkpoint. Returns true with a
 // reference to the CheckpointState info, if exists. Otherwise returns false, nil.
-func (c *CheckpointStateCache) StateByCheckpoint(cp *ethpb.Checkpoint) (iface.BeaconState, error) {
+func (c *CheckpointStateCache) StateByCheckpoint(cp *ethpb.Checkpoint) (state.BeaconState, error) {
 	c.lock.RLock()
 	defer c.lock.RUnlock()
-	h, err := hashutil.HashProto(cp)
+	h, err := hash.HashProto(cp)
 	if err != nil {
 		return nil, err
 	}
@@ -60,7 +57,7 @@ func (c *CheckpointStateCache) StateByCheckpoint(cp *ethpb.Checkpoint) (iface.Be
 	if exists && item != nil {
 		checkpointStateHit.Inc()
 		// Copy here is unnecessary since the return will only be used to verify attestation signature.
-		return item.(iface.BeaconState), nil
+		return item.(state.BeaconState), nil
 	}

 	checkpointStateMiss.Inc()
@@ -69,10 +66,10 @@ func (c *CheckpointStateCache) StateByCheckpoint(cp *ethpb.Checkpoint) (iface.Be

 // AddCheckpointState adds CheckpointState object to the cache. This method also trims the least
 // recently added CheckpointState object if the cache size has ready the max cache size limit.
-func (c *CheckpointStateCache) AddCheckpointState(cp *ethpb.Checkpoint, s iface.ReadOnlyBeaconState) error {
+func (c *CheckpointStateCache) AddCheckpointState(cp *ethpb.Checkpoint, s state.ReadOnlyBeaconState) error {
 	c.lock.Lock()
 	defer c.lock.Unlock()
-	h, err := hashutil.HashProto(cp)
+	h, err := hash.HashProto(cp)
 	if err != nil {
 		return err
 	}
--- a/beacon-chain/cache/checkpoint_state_test.go
+++ b/beacon-chain/cache/checkpoint_state_test.go
@@ -4,14 +4,13 @@ import (
 	"testing"

 	types "github.com/prysmaticlabs/eth2-types"
-	iface "github.com/prysmaticlabs/prysm/beacon-chain/state/interface"
-	"github.com/prysmaticlabs/prysm/beacon-chain/state/v1"
-	pb "github.com/prysmaticlabs/prysm/proto/beacon/p2p/v1"
-	ethpb "github.com/prysmaticlabs/prysm/proto/eth/v1alpha1"
-	"github.com/prysmaticlabs/prysm/shared/bytesutil"
-	"github.com/prysmaticlabs/prysm/shared/params"
-	"github.com/prysmaticlabs/prysm/shared/testutil/assert"
-	"github.com/prysmaticlabs/prysm/shared/testutil/require"
+	"github.com/prysmaticlabs/prysm/beacon-chain/state"
+	v1 "github.com/prysmaticlabs/prysm/beacon-chain/state/v1"
+	"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/assert"
+	"github.com/prysmaticlabs/prysm/testing/require"
 	"google.golang.org/protobuf/proto"
 )

@@ -19,48 +18,48 @@ func TestCheckpointStateCache_StateByCheckpoint(t *testing.T) {
 	cache := NewCheckpointStateCache()

 	cp1 := &ethpb.Checkpoint{Epoch: 1, Root: bytesutil.PadTo([]byte{'A'}, 32)}
-	st, err := v1.InitializeFromProto(&pb.BeaconState{
+	st, err := v1.InitializeFromProto(&ethpb.BeaconState{
 		GenesisValidatorsRoot: params.BeaconConfig().ZeroHash[:],
 		Slot:                  64,
 	})
 	require.NoError(t, err)

-	state, err := cache.StateByCheckpoint(cp1)
+	s, err := cache.StateByCheckpoint(cp1)
 	require.NoError(t, err)
-	assert.Equal(t, iface.BeaconState(nil), state, "Expected state not to exist in empty cache")
+	assert.Equal(t, state.BeaconState(nil), s, "Expected state not to exist in empty cache")

 	require.NoError(t, cache.AddCheckpointState(cp1, st))

-	state, err = cache.StateByCheckpoint(cp1)
+	s, err = cache.StateByCheckpoint(cp1)
 	require.NoError(t, err)

-	pbState1, err := v1.ProtobufBeaconState(state.InnerStateUnsafe())
+	pbState1, err := v1.ProtobufBeaconState(s.InnerStateUnsafe())
 	require.NoError(t, err)
-	pbState2, err := v1.ProtobufBeaconState(st.InnerStateUnsafe())
+	pbstate, err := v1.ProtobufBeaconState(st.InnerStateUnsafe())
 	require.NoError(t, err)
-	if !proto.Equal(pbState1, pbState2) {
+	if !proto.Equal(pbState1, pbstate) {
 		t.Error("incorrectly cached state")
 	}

 	cp2 := &ethpb.Checkpoint{Epoch: 2, Root: bytesutil.PadTo([]byte{'B'}, 32)}
-	st2, err := v1.InitializeFromProto(&pb.BeaconState{
+	st2, err := v1.InitializeFromProto(&ethpb.BeaconState{
 		Slot: 128,
 	})
 	require.NoError(t, err)
 	require.NoError(t, cache.AddCheckpointState(cp2, st2))

-	state, err = cache.StateByCheckpoint(cp2)
+	s, err = cache.StateByCheckpoint(cp2)
 	require.NoError(t, err)
-	assert.DeepEqual(t, st2.CloneInnerState(), state.CloneInnerState(), "incorrectly cached state")
+	assert.DeepEqual(t, st2.CloneInnerState(), s.CloneInnerState(), "incorrectly cached state")

-	state, err = cache.StateByCheckpoint(cp1)
+	s, err = cache.StateByCheckpoint(cp1)
 	require.NoError(t, err)
-	assert.DeepEqual(t, st.CloneInnerState(), state.CloneInnerState(), "incorrectly cached state")
+	assert.DeepEqual(t, st.CloneInnerState(), s.CloneInnerState(), "incorrectly cached state")
 }

 func TestCheckpointStateCache_MaxSize(t *testing.T) {
 	c := NewCheckpointStateCache()
-	st, err := v1.InitializeFromProto(&pb.BeaconState{
+	st, err := v1.InitializeFromProto(&ethpb.BeaconState{
 		Slot: 0,
 	})
 	require.NoError(t, err)
--- a/beacon-chain/cache/committee.go
+++ b/beacon-chain/cache/committee.go
@@ -3,15 +3,20 @@
 package cache

 import (
+	"context"
 	"errors"
+	"math"
 	"sync"
+	"time"

 	lru "github.com/hashicorp/golang-lru"
 	"github.com/prometheus/client_golang/prometheus"
 	"github.com/prometheus/client_golang/prometheus/promauto"
 	types "github.com/prysmaticlabs/eth2-types"
-	"github.com/prysmaticlabs/prysm/shared/params"
-	"github.com/prysmaticlabs/prysm/shared/sliceutil"
+	lruwrpr "github.com/prysmaticlabs/prysm/cache/lru"
+	"github.com/prysmaticlabs/prysm/config/params"
+	"github.com/prysmaticlabs/prysm/container/slice"
+	mathutil "github.com/prysmaticlabs/prysm/math"
 )

 var (
@@ -35,6 +40,7 @@ var (
 type CommitteeCache struct {
 	CommitteeCache *lru.Cache
 	lock           sync.RWMutex
+	inProgress     map[string]bool
 }

 // committeeKeyFn takes the seed as the key to retrieve shuffled indices of a committee in a given epoch.
@@ -48,22 +54,18 @@ func committeeKeyFn(obj interface{}) (string, error) {

 // NewCommitteesCache creates a new committee cache for storing/accessing shuffled indices of a committee.
 func NewCommitteesCache() *CommitteeCache {
-	cCache, err := lru.New(int(maxCommitteesCacheSize))
-	// An error is only returned if the size of the cache is
-	// <= 0.
-	if err != nil {
-		panic(err)
-	}
 	return &CommitteeCache{
-		CommitteeCache: cCache,
+		CommitteeCache: lruwrpr.New(int(maxCommitteesCacheSize)),
+		inProgress:     make(map[string]bool),
 	}
 }

 // Committee fetches the shuffled indices by slot and committee index. Every list of indices
 // represent one committee. Returns true if the list exists with slot and committee index. Otherwise returns false, nil.
-func (c *CommitteeCache) Committee(slot types.Slot, seed [32]byte, index types.CommitteeIndex) ([]types.ValidatorIndex, error) {
-	c.lock.RLock()
-	defer c.lock.RUnlock()
+func (c *CommitteeCache) Committee(ctx context.Context, slot types.Slot, seed [32]byte, index types.CommitteeIndex) ([]types.ValidatorIndex, error) {
+	if err := c.checkInProgress(ctx, seed); err != nil {
+		return nil, err
+	}

 	obj, exists := c.CommitteeCache.Get(key(seed))
 	if exists {
@@ -83,7 +85,10 @@ func (c *CommitteeCache) Committee(slot types.Slot, seed [32]byte, index types.C
 		committeeCountPerSlot = item.CommitteeCount / uint64(params.BeaconConfig().SlotsPerEpoch)
 	}

-	indexOffSet := uint64(index) + uint64(slot.ModSlot(params.BeaconConfig().SlotsPerEpoch).Mul(committeeCountPerSlot))
+	indexOffSet, err := mathutil.Add64(uint64(index), uint64(slot.ModSlot(params.BeaconConfig().SlotsPerEpoch).Mul(committeeCountPerSlot)))
+	if err != nil {
+		return nil, err
+	}
 	start, end := startEndIndices(item, indexOffSet)

 	if end > uint64(len(item.ShuffledIndices)) || end < start {
@@ -107,9 +112,10 @@ func (c *CommitteeCache) AddCommitteeShuffledList(committees *Committees) error
 }

 // ActiveIndices returns the active indices of a given seed stored in cache.
-func (c *CommitteeCache) ActiveIndices(seed [32]byte) ([]types.ValidatorIndex, error) {
-	c.lock.RLock()
-	defer c.lock.RUnlock()
+func (c *CommitteeCache) ActiveIndices(ctx context.Context, seed [32]byte) ([]types.ValidatorIndex, error) {
+	if err := c.checkInProgress(ctx, seed); err != nil {
+		return nil, err
+	}
 	obj, exists := c.CommitteeCache.Get(key(seed))

 	if exists {
@@ -128,9 +134,11 @@ func (c *CommitteeCache) ActiveIndices(seed [32]byte) ([]types.ValidatorIndex, e
 }

 // ActiveIndicesCount returns the active indices count of a given seed stored in cache.
-func (c *CommitteeCache) ActiveIndicesCount(seed [32]byte) (int, error) {
-	c.lock.RLock()
-	defer c.lock.RUnlock()
+func (c *CommitteeCache) ActiveIndicesCount(ctx context.Context, seed [32]byte) (int, error) {
+	if err := c.checkInProgress(ctx, seed); err != nil {
+		return 0, err
+	}
+
 	obj, exists := c.CommitteeCache.Get(key(seed))
 	if exists {
 		CommitteeCacheHit.Inc()
@@ -153,17 +161,65 @@ func (c *CommitteeCache) HasEntry(seed string) bool {
 	return ok
 }

+// MarkInProgress a request so that any other similar requests will block on
+// Get until MarkNotInProgress is called.
+func (c *CommitteeCache) MarkInProgress(seed [32]byte) error {
+	c.lock.Lock()
+	defer c.lock.Unlock()
+	s := key(seed)
+	if c.inProgress[s] {
+		return ErrAlreadyInProgress
+	}
+	c.inProgress[s] = true
+	return nil
+}
+
+// MarkNotInProgress will release the lock on a given request. This should be
+// called after put.
+func (c *CommitteeCache) MarkNotInProgress(seed [32]byte) error {
+	c.lock.Lock()
+	defer c.lock.Unlock()
+	s := key(seed)
+	delete(c.inProgress, s)
+	return nil
+}
+
 func startEndIndices(c *Committees, index uint64) (uint64, uint64) {
 	validatorCount := uint64(len(c.ShuffledIndices))
-	start := sliceutil.SplitOffset(validatorCount, c.CommitteeCount, index)
-	end := sliceutil.SplitOffset(validatorCount, c.CommitteeCount, index+1)
+	start := slice.SplitOffset(validatorCount, c.CommitteeCount, index)
+	end := slice.SplitOffset(validatorCount, c.CommitteeCount, index+1)
 	return start, end
 }

 // Using seed as source for key to handle reorgs in the same epoch.
 // The seed is derived from state's array of randao mixes and epoch value
 // hashed together. This avoids collisions on different validator set. Spec definition:
-// https://github.com/ethereum/eth2.0-specs/blob/v0.9.3/specs/core/0_beacon-chain.md#get_seed
+// https://github.com/ethereum/consensus-specs/blob/v0.9.3/specs/core/0_beacon-chain.md#get_seed
 func key(seed [32]byte) string {
 	return string(seed[:])
 }
+
+func (c *CommitteeCache) checkInProgress(ctx context.Context, seed [32]byte) error {
+	delay := minDelay
+	// Another identical request may be in progress already. Let's wait until
+	// any in progress request resolves or our timeout is exceeded.
+	for {
+		if ctx.Err() != nil {
+			return ctx.Err()
+		}
+
+		c.lock.RLock()
+		if !c.inProgress[key(seed)] {
+			c.lock.RUnlock()
+			break
+		}
+		c.lock.RUnlock()
+
+		// This increasing backoff is to decrease the CPU cycles while waiting
+		// for the in progress boolean to flip to false.
+		time.Sleep(time.Duration(delay) * time.Nanosecond)
+		delay *= delayFactor
+		delay = math.Min(delay, maxDelay)
+	}
+	return nil
+}
--- a/beacon-chain/cache/committee_disabled.go
+++ b/beacon-chain/cache/committee_disabled.go
@@ -3,7 +3,11 @@
 // This file is used in fuzzer builds to bypass global committee caches.
 package cache

-import types "github.com/prysmaticlabs/eth2-types"
+import (
+	"context"
+
+	types "github.com/prysmaticlabs/eth2-types"
+)

 // FakeCommitteeCache is a struct with 1 queue for looking up shuffled indices list by seed.
 type FakeCommitteeCache struct {
@@ -16,7 +20,7 @@ func NewCommitteesCache() *FakeCommitteeCache {

 // Committee fetches the shuffled indices by slot and committee index. Every list of indices
 // represent one committee. Returns true if the list exists with slot and committee index. Otherwise returns false, nil.
-func (c *FakeCommitteeCache) Committee(slot types.Slot, seed [32]byte, index types.CommitteeIndex) ([]types.ValidatorIndex, error) {
+func (c *FakeCommitteeCache) Committee(ctx context.Context, slot types.Slot, seed [32]byte, index types.CommitteeIndex) ([]types.ValidatorIndex, error) {
 	return nil, nil
 }

@@ -32,12 +36,17 @@ func (c *FakeCommitteeCache) AddProposerIndicesList(seed [32]byte, indices []typ
 }

 // ActiveIndices returns the active indices of a given seed stored in cache.
-func (c *FakeCommitteeCache) ActiveIndices(seed [32]byte) ([]types.ValidatorIndex, error) {
+func (c *FakeCommitteeCache) ActiveIndices(ctx context.Context, seed [32]byte) ([]types.ValidatorIndex, error) {
 	return nil, nil
 }

 // ActiveIndicesCount returns the active indices count of a given seed stored in cache.
-func (c *FakeCommitteeCache) ActiveIndicesCount(seed [32]byte) (int, error) {
+func (c *FakeCommitteeCache) ActiveIndicesCount(ctx context.Context, seed [32]byte) (int, error) {
+	return 0, nil
+}
+
+// ActiveBalance returns the active balance of a given seed stored in cache.
+func (c *FakeCommitteeCache) ActiveBalance(seed [32]byte) (uint64, error) {
 	return 0, nil
 }

@@ -50,3 +59,13 @@ func (c *FakeCommitteeCache) ProposerIndices(seed [32]byte) ([]types.ValidatorIn
 func (c *FakeCommitteeCache) HasEntry(string) bool {
 	return false
 }
+
+// MarkInProgress is a stub.
+func (c *FakeCommitteeCache) MarkInProgress(seed [32]byte) error {
+	return nil
+}
+
+// MarkNotInProgress is a stub.
+func (c *FakeCommitteeCache) MarkNotInProgress(seed [32]byte) error {
+	return nil
+}
--- a/beacon-chain/cache/committee_fuzz_test.go
+++ b/beacon-chain/cache/committee_fuzz_test.go
@@ -1,11 +1,12 @@
 package cache

 import (
+	"context"
 	"testing"

 	fuzz "github.com/google/gofuzz"
-	"github.com/prysmaticlabs/prysm/shared/testutil/assert"
-	"github.com/prysmaticlabs/prysm/shared/testutil/require"
+	"github.com/prysmaticlabs/prysm/testing/assert"
+	"github.com/prysmaticlabs/prysm/testing/require"
 )

 func TestCommitteeKeyFuzz_OK(t *testing.T) {
@@ -28,7 +29,7 @@ func TestCommitteeCache_FuzzCommitteesByEpoch(t *testing.T) {
 	for i := 0; i < 100000; i++ {
 		fuzzer.Fuzz(c)
 		require.NoError(t, cache.AddCommitteeShuffledList(c))
-		_, err := cache.Committee(0, c.Seed, 0)
+		_, err := cache.Committee(context.Background(), 0, c.Seed, 0)
 		require.NoError(t, err)
 	}

@@ -44,7 +45,7 @@ func TestCommitteeCache_FuzzActiveIndices(t *testing.T) {
 		fuzzer.Fuzz(c)
 		require.NoError(t, cache.AddCommitteeShuffledList(c))

-		indices, err := cache.ActiveIndices(c.Seed)
+		indices, err := cache.ActiveIndices(context.Background(), c.Seed)
 		require.NoError(t, err)
 		assert.DeepEqual(t, c.SortedIndices, indices)
 	}
--- a/beacon-chain/cache/committee_test.go
+++ b/beacon-chain/cache/committee_test.go
@@ -1,16 +1,17 @@
 package cache

 import (
+	"context"
 	"math"
 	"sort"
 	"strconv"
 	"testing"

 	types "github.com/prysmaticlabs/eth2-types"
-	"github.com/prysmaticlabs/prysm/shared/bytesutil"
-	"github.com/prysmaticlabs/prysm/shared/params"
-	"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"
+	"github.com/prysmaticlabs/prysm/testing/assert"
+	"github.com/prysmaticlabs/prysm/testing/require"
 )

 func TestCommitteeKeyFn_OK(t *testing.T) {
@@ -41,7 +42,7 @@ func TestCommitteeCache_CommitteesByEpoch(t *testing.T) {

 	slot := params.BeaconConfig().SlotsPerEpoch
 	committeeIndex := types.CommitteeIndex(1)
-	indices, err := cache.Committee(slot, item.Seed, committeeIndex)
+	indices, err := cache.Committee(context.Background(), slot, item.Seed, committeeIndex)
 	require.NoError(t, err)
 	if indices != nil {
 		t.Error("Expected committee not to exist in empty cache")
@@ -49,7 +50,7 @@ func TestCommitteeCache_CommitteesByEpoch(t *testing.T) {
 	require.NoError(t, cache.AddCommitteeShuffledList(item))

 	wantedIndex := types.CommitteeIndex(0)
-	indices, err = cache.Committee(slot, item.Seed, wantedIndex)
+	indices, err = cache.Committee(context.Background(), slot, item.Seed, wantedIndex)
 	require.NoError(t, err)

 	start, end := startEndIndices(item, uint64(wantedIndex))
@@ -60,7 +61,7 @@ func TestCommitteeCache_ActiveIndices(t *testing.T) {
 	cache := NewCommitteesCache()

 	item := &Committees{Seed: [32]byte{'A'}, SortedIndices: []types.ValidatorIndex{1, 2, 3, 4, 5, 6}}
-	indices, err := cache.ActiveIndices(item.Seed)
+	indices, err := cache.ActiveIndices(context.Background(), item.Seed)
 	require.NoError(t, err)
 	if indices != nil {
 		t.Error("Expected committee not to exist in empty cache")
@@ -68,7 +69,7 @@ func TestCommitteeCache_ActiveIndices(t *testing.T) {

 	require.NoError(t, cache.AddCommitteeShuffledList(item))

-	indices, err = cache.ActiveIndices(item.Seed)
+	indices, err = cache.ActiveIndices(context.Background(), item.Seed)
 	require.NoError(t, err)
 	assert.DeepEqual(t, item.SortedIndices, indices)
 }
@@ -77,13 +78,13 @@ func TestCommitteeCache_ActiveCount(t *testing.T) {
 	cache := NewCommitteesCache()

 	item := &Committees{Seed: [32]byte{'A'}, SortedIndices: []types.ValidatorIndex{1, 2, 3, 4, 5, 6}}
-	count, err := cache.ActiveIndicesCount(item.Seed)
+	count, err := cache.ActiveIndicesCount(context.Background(), item.Seed)
 	require.NoError(t, err)
 	assert.Equal(t, 0, count, "Expected active count not to exist in empty cache")

 	require.NoError(t, cache.AddCommitteeShuffledList(item))

-	count, err = cache.ActiveIndicesCount(item.Seed)
+	count, err = cache.ActiveIndicesCount(context.Background(), item.Seed)
 	require.NoError(t, err)
 	assert.Equal(t, len(item.SortedIndices), count)
 }
@@ -127,6 +128,6 @@ func TestCommitteeCacheOutOfRange(t *testing.T) {
 	assert.NoError(t, err)
 	_ = cache.CommitteeCache.Add(key, comms)

-	_, err = cache.Committee(0, seed, math.MaxUint64) // Overflow!
+	_, err = cache.Committee(context.Background(), 0, seed, math.MaxUint64) // Overflow!
 	require.NotNil(t, err, "Did not fail as expected")
 }
--- a/beacon-chain/cache/common.go
+++ b/beacon-chain/cache/common.go
@@ -1,7 +1,7 @@
 package cache

 import (
-	"github.com/prysmaticlabs/prysm/shared/params"
+	"github.com/prysmaticlabs/prysm/config/params"
 	"k8s.io/client-go/tools/cache"
 )

--- a/beacon-chain/cache/depositcache/BUILD.bazel
+++ b/beacon-chain/cache/depositcache/BUILD.bazel
@@ -10,12 +10,11 @@ go_library(
    importpath = "github.com/prysmaticlabs/prysm/beacon-chain/cache/depositcache",
    visibility = ["//beacon-chain:__subpackages__"],
    deps = [
-        "//proto/beacon/db:go_default_library",
-        "//proto/eth/v1alpha1:go_default_library",
-        "//shared/bytesutil:go_default_library",
-        "//shared/hashutil:go_default_library",
-        "//shared/params:go_default_library",
-        "//shared/trieutil:go_default_library",
+        "//config/params:go_default_library",
+        "//container/trie:go_default_library",
+        "//crypto/hash:go_default_library",
+        "//encoding/bytesutil:go_default_library",
+        "//proto/prysm/v1alpha1: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",
@@ -32,13 +31,12 @@ go_test(
    ],
    embed = [":go_default_library"],
    deps = [
-        "//proto/beacon/db:go_default_library",
-        "//proto/eth/v1alpha1:go_default_library",
-        "//shared/bytesutil:go_default_library",
-        "//shared/params:go_default_library",
-        "//shared/testutil/assert:go_default_library",
-        "//shared/testutil/require:go_default_library",
-        "//shared/trieutil:go_default_library",
+        "//config/params:go_default_library",
+        "//container/trie:go_default_library",
+        "//encoding/bytesutil:go_default_library",
+        "//proto/prysm/v1alpha1:go_default_library",
+        "//testing/assert:go_default_library",
+        "//testing/require:go_default_library",
        "@com_github_sirupsen_logrus//hooks/test:go_default_library",
        "@org_golang_google_protobuf//proto:go_default_library",
    ],
--- a/beacon-chain/cache/depositcache/deposits_cache.go
+++ b/beacon-chain/cache/depositcache/deposits_cache.go
@@ -15,11 +15,11 @@ import (
 	"github.com/pkg/errors"
 	"github.com/prometheus/client_golang/prometheus"
 	"github.com/prometheus/client_golang/prometheus/promauto"
-	dbpb "github.com/prysmaticlabs/prysm/proto/beacon/db"
-	ethpb "github.com/prysmaticlabs/prysm/proto/eth/v1alpha1"
-	"github.com/prysmaticlabs/prysm/shared/bytesutil"
-	"github.com/prysmaticlabs/prysm/shared/params"
-	"github.com/prysmaticlabs/prysm/shared/trieutil"
+	"github.com/prysmaticlabs/prysm/config/params"
+	"github.com/prysmaticlabs/prysm/container/trie"
+	"github.com/prysmaticlabs/prysm/encoding/bytesutil"
+	dbpb "github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1"
+	ethpb "github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1"
 	"github.com/sirupsen/logrus"
 	"go.opencensus.io/trace"
 )
@@ -43,7 +43,7 @@ type DepositFetcher interface {
 // FinalizedDeposits stores the trie of deposits that have been included
 // in the beacon state up to the latest finalized checkpoint.
 type FinalizedDeposits struct {
-	Deposits        *trieutil.SparseMerkleTrie
+	Deposits        *trie.SparseMerkleTrie
 	MerkleTrieIndex int64
 }

@@ -59,7 +59,7 @@ type DepositCache struct {

 // New instantiates a new deposit cache
 func New() (*DepositCache, error) {
-	finalizedDepositsTrie, err := trieutil.NewTrie(params.BeaconConfig().DepositContractTreeDepth)
+	finalizedDepositsTrie, err := trie.NewTrie(params.BeaconConfig().DepositContractTreeDepth)
 	if err != nil {
 		return nil, err
 	}
@@ -136,7 +136,10 @@ func (dc *DepositCache) InsertFinalizedDeposits(ctx context.Context, eth1Deposit
 			log.WithError(err).Error("Could not hash deposit data. Finalized deposit cache not updated.")
 			return
 		}
-		depositTrie.Insert(depHash[:], insertIndex)
+		if err = depositTrie.Insert(depHash[:], insertIndex); err != nil {
+			log.WithError(err).Error("Could not insert deposit hash")
+			return
+		}
 		insertIndex++
 	}

--- a/Show More
+++ b/Show More
@@ -1 +1 @@
 .7.0
 .2.1