fix up faulty slasher ticker

* Move necessary functions beacon-chain/core/time -> time/slots

* Fix fuzz

* Fix build

* Update slot_epoch.go

.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
@@ -46,4 +46,4 @@ test:fuzz --flaky_test_attempts=1
 
 # Better caching
 build:nostamp --nostamp
-build:nostamp --workspace_status_command=./hack/workspace_status_ci.sh
+build:nostamp --workspace_status_command=./hack/workspace_status_ci.sh

api/gateway/apimiddleware/api_middleware.go

@@ -59,8 +59,8 @@ type CustomHandler = func(m *ApiProxyMiddleware, endpoint Endpoint, w http.Respo
 
 // 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
+	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)
 }
@@ -170,7 +170,7 @@ func (m *ApiProxyMiddleware) handleApiPath(gatewayRouter *mux.Router, path strin
 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)
+		run, errJson := endpoint.Hooks.OnPreDeserializeRequestBodyIntoContainer(endpoint, w, req)
 		if errJson != nil {
 			return errJson
 		}
@@ -184,7 +184,7 @@ func deserializeRequestBodyIntoContainerWrapped(endpoint *Endpoint, req *http.Re
 		}
 	}
 	if endpoint.Hooks.OnPostDeserializeRequestBodyIntoContainer != nil {
-		if errJson := endpoint.Hooks.OnPostDeserializeRequestBodyIntoContainer(*endpoint, w, req); errJson != nil {
+		if errJson := endpoint.Hooks.OnPostDeserializeRequestBodyIntoContainer(endpoint, w, req); errJson != nil {
 			return errJson
 		}
 	}

api/gateway/apimiddleware/process_request.go

@@ -10,12 +10,22 @@ import (
 	"strings"
 	"time"
 
+	"github.com/pkg/errors"
 	"github.com/prysmaticlabs/prysm/api/grpc"
 )
 
 // DeserializeRequestBodyIntoContainer deserializes the request's body into an endpoint-specific struct.
 func DeserializeRequestBodyIntoContainer(body io.Reader, requestContainer interface{}) ErrorJson {
-	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

api/gateway/apimiddleware/process_request_test.go

@@ -83,6 +83,15 @@ 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) {

beacon-chain/blockchain/BUILD.bazel

@@ -23,18 +23,20 @@ go_library(
     visibility = [
         "//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: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/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/blockchain/head.go

@@ -7,10 +7,10 @@ import (
 
 	"github.com/pkg/errors"
 	types "github.com/prysmaticlabs/eth2-types"
-	"github.com/prysmaticlabs/prysm/beacon-chain/core"
 	"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"
 	"github.com/prysmaticlabs/prysm/beacon-chain/state"
 	"github.com/prysmaticlabs/prysm/config/features"
@@ -141,7 +141,7 @@ func (s *Service) saveHead(ctx context.Context, headRoot [32]byte) error {
 				NewHeadBlock: headRoot[:],
 				OldHeadState: oldStateRoot,
 				NewHeadState: newStateRoot,
-				Epoch:        core.SlotToEpoch(newHeadSlot),
+				Epoch:        slots.ToEpoch(newHeadSlot),
 			},
 		})
 
@@ -298,7 +298,7 @@ func (s *Service) cacheJustifiedStateBalances(ctx context.Context, justifiedRoot
 		return errors.New("justified state can't be nil")
 	}
 
-	epoch := core.CurrentEpoch(justifiedState)
+	epoch := time.CurrentEpoch(justifiedState)
 
 	justifiedBalances := make([]uint64, justifiedState.NumValidators())
 	if err := justifiedState.ReadFromEveryValidator(func(idx int, val state.ReadOnlyValidator) error {
@@ -336,15 +336,15 @@ func (s *Service) notifyNewHeadEvent(
 	currentDutyDependentRoot := s.genesisRoot[:]
 
 	var previousDutyEpoch types.Epoch
-	currentDutyEpoch := core.SlotToEpoch(newHeadSlot)
+	currentDutyEpoch := slots.ToEpoch(newHeadSlot)
 	if currentDutyEpoch > 0 {
 		previousDutyEpoch = currentDutyEpoch.Sub(1)
 	}
-	currentDutySlot, err := core.StartSlot(currentDutyEpoch)
+	currentDutySlot, err := slots.EpochStart(currentDutyEpoch)
 	if err != nil {
 		return errors.Wrap(err, "could not get duty slot")
 	}
-	previousDutySlot, err := core.StartSlot(previousDutyEpoch)
+	previousDutySlot, err := slots.EpochStart(previousDutyEpoch)
 	if err != nil {
 		return errors.Wrap(err, "could not get duty slot")
 	}
@@ -366,7 +366,7 @@ func (s *Service) notifyNewHeadEvent(
 			Slot:                      newHeadSlot,
 			Block:                     newHeadRoot,
 			State:                     newHeadStateRoot,
-			EpochTransition:           core.IsEpochEnd(newHeadSlot),
+			EpochTransition:           slots.IsEpochStart(newHeadSlot),
 			PreviousDutyDependentRoot: previousDutyDependentRoot,
 			CurrentDutyDependentRoot:  currentDutyDependentRoot,
 		},

beacon-chain/blockchain/head_sync_committee_info.go

@@ -8,7 +8,6 @@ import (
 	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"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/altair"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/helpers"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/signing"
@@ -16,6 +15,7 @@ import (
 	"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.
@@ -62,14 +62,14 @@ func (s *Service) HeadSyncContributionProofDomain(ctx context.Context, slot type
 // 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 := core.SlotToEpoch(slot + 1)
-	currentEpoch := core.SlotToEpoch(slot)
+	nextSlotEpoch := slots.ToEpoch(slot + 1)
+	currentEpoch := slots.ToEpoch(slot)
 
 	switch {
-	case core.SyncCommitteePeriod(nextSlotEpoch) == core.SyncCommitteePeriod(currentEpoch):
+	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 core.SyncCommitteePeriod(nextSlotEpoch) == core.SyncCommitteePeriod(currentEpoch)+1:
+	case slots.SyncCommitteePeriod(nextSlotEpoch) == slots.SyncCommitteePeriod(currentEpoch)+1:
 		return s.headNextSyncCommitteeIndices(ctx, index, slot)
 	default:
 		// Impossible condition.
@@ -105,11 +105,11 @@ func (s *Service) HeadSyncCommitteePubKeys(ctx context.Context, slot types.Slot,
 		return nil, err
 	}
 
-	nextSlotEpoch := core.SlotToEpoch(headState.Slot() + 1)
-	currEpoch := core.SlotToEpoch(headState.Slot())
+	nextSlotEpoch := slots.ToEpoch(headState.Slot() + 1)
+	currEpoch := slots.ToEpoch(headState.Slot())
 
 	var syncCommittee *ethpb.SyncCommittee
-	if currEpoch == nextSlotEpoch || core.SyncCommitteePeriod(currEpoch) == core.SyncCommitteePeriod(nextSlotEpoch) {
+	if currEpoch == nextSlotEpoch || slots.SyncCommitteePeriod(currEpoch) == slots.SyncCommitteePeriod(nextSlotEpoch) {
 		syncCommittee, err = headState.CurrentSyncCommittee()
 		if err != nil {
 			return nil, err
@@ -130,7 +130,7 @@ func (s *Service) domainWithHeadState(ctx context.Context, slot types.Slot, doma
 	if err != nil {
 		return nil, err
 	}
-	return signing.Domain(headState.Fork(), core.SlotToEpoch(headState.Slot()), domain, headState.GenesisValidatorRoot())
+	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.

beacon-chain/blockchain/head_sync_committee_info_test.go

@@ -6,13 +6,13 @@ import (
 
 	types "github.com/prysmaticlabs/eth2-types"
 	"github.com/prysmaticlabs/prysm/beacon-chain/cache"
-	"github.com/prysmaticlabs/prysm/beacon-chain/core"
 	"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) {
@@ -122,7 +122,7 @@ func TestService_HeadSyncCommitteeDomain(t *testing.T) {
 	c := &Service{}
 	c.head = &head{state: s}
 
-	wanted, err := signing.Domain(s.Fork(), core.SlotToEpoch(s.Slot()), params.BeaconConfig().DomainSyncCommittee, s.GenesisValidatorRoot())
+	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)
@@ -136,7 +136,7 @@ func TestService_HeadSyncContributionProofDomain(t *testing.T) {
 	c := &Service{}
 	c.head = &head{state: s}
 
-	wanted, err := signing.Domain(s.Fork(), core.SlotToEpoch(s.Slot()), params.BeaconConfig().DomainContributionAndProof, s.GenesisValidatorRoot())
+	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)
@@ -150,7 +150,7 @@ func TestService_HeadSyncSelectionProofDomain(t *testing.T) {
 	c := &Service{}
 	c.head = &head{state: s}
 
-	wanted, err := signing.Domain(s.Fork(), core.SlotToEpoch(s.Slot()), params.BeaconConfig().DomainSyncCommitteeSelectionProof, s.GenesisValidatorRoot())
+	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)

beacon-chain/blockchain/head_test.go

@@ -8,7 +8,6 @@ import (
 
 	types "github.com/prysmaticlabs/eth2-types"
 	mock "github.com/prysmaticlabs/prysm/beacon-chain/blockchain/testing"
-	"github.com/prysmaticlabs/prysm/beacon-chain/core"
 	testDB "github.com/prysmaticlabs/prysm/beacon-chain/db/testing"
 	"github.com/prysmaticlabs/prysm/config/features"
 	"github.com/prysmaticlabs/prysm/config/params"
@@ -18,6 +17,7 @@ import (
 	"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"
 )
 
@@ -187,9 +187,9 @@ func Test_notifyNewHeadEvent(t *testing.T) {
 			},
 			genesisRoot: genesisRoot,
 		}
-		epoch1Start, err := core.StartSlot(1)
+		epoch1Start, err := slots.EpochStart(1)
 		require.NoError(t, err)
-		epoch2Start, err := core.StartSlot(1)
+		epoch2Start, err := slots.EpochStart(1)
 		require.NoError(t, err)
 		require.NoError(t, bState.SetSlot(epoch1Start))
 
@@ -206,7 +206,7 @@ func Test_notifyNewHeadEvent(t *testing.T) {
 			Slot:                      epoch2Start,
 			Block:                     newHeadRoot[:],
 			State:                     newHeadStateRoot[:],
-			EpochTransition:           false,
+			EpochTransition:           true,
 			PreviousDutyDependentRoot: genesisRoot[:],
 			CurrentDutyDependentRoot:  make([]byte, 32),
 		}

beacon-chain/blockchain/log.go

@@ -5,12 +5,12 @@ import (
 	"fmt"
 	"time"
 
-	"github.com/prysmaticlabs/prysm/beacon-chain/core"
 	"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"
 )
 
@@ -44,7 +44,7 @@ func logStateTransitionData(b block.BeaconBlock) {
 }
 
 func logBlockSyncStatus(block block.BeaconBlock, blockRoot [32]byte, finalized *ethpb.Checkpoint, receivedTime time.Time, genesisTime uint64) error {
-	startTime, err := core.SlotToTime(genesisTime, block.Slot())
+	startTime, err := slots.ToTime(genesisTime, block.Slot())
 	if err != nil {
 		return err
 	}
@@ -52,7 +52,7 @@ func logBlockSyncStatus(block block.BeaconBlock, blockRoot [32]byte, finalized *
 		"slot":           block.Slot(),
 		"slotInEpoch":    block.Slot() % params.BeaconConfig().SlotsPerEpoch,
 		"block":          fmt.Sprintf("0x%s...", hex.EncodeToString(blockRoot[:])[:8]),
-		"epoch":          core.SlotToEpoch(block.Slot()),
+		"epoch":          slots.ToEpoch(block.Slot()),
 		"finalizedEpoch": finalized.Epoch,
 		"finalizedRoot":  fmt.Sprintf("0x%s...", hex.EncodeToString(finalized.Root)[:8]),
 	}).Info("Synced new block")

beacon-chain/blockchain/process_attestation.go

@@ -4,13 +4,13 @@ import (
 	"context"
 
 	"github.com/pkg/errors"
-	"github.com/prysmaticlabs/prysm/beacon-chain/core"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/helpers"
 	"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"
 )
 
@@ -75,7 +75,7 @@ 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 := core.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
 	}
 

beacon-chain/blockchain/process_attestation_helpers.go

@@ -8,13 +8,13 @@ import (
 	"github.com/pkg/errors"
 	types "github.com/prysmaticlabs/eth2-types"
 	"github.com/prysmaticlabs/prysm/async"
-	"github.com/prysmaticlabs/prysm/beacon-chain/core"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/helpers"
 	"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.
@@ -38,7 +38,7 @@ func (s *Service) getAttPreState(ctx context.Context, c *ethpb.Checkpoint) (stat
 		return nil, errors.Wrapf(err, "could not get pre state for epoch %d", c.Epoch)
 	}
 
-	epochStartSlot, err := core.StartSlot(c.Epoch)
+	epochStartSlot, err := slots.EpochStart(c.Epoch)
 	if err != nil {
 		return nil, err
 	}
@@ -63,7 +63,7 @@ func (s *Service) getAttPreState(ctx context.Context, c *ethpb.Checkpoint) (stat
 // 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 := core.SlotToEpoch(currentSlot)
+	currentEpoch := slots.ToEpoch(currentSlot)
 	var prevEpoch types.Epoch
 	// Prevents previous epoch under flow
 	if currentEpoch > 1 {

beacon-chain/blockchain/process_attestation_test.go

@@ -5,7 +5,6 @@ import (
 	"testing"
 
 	types "github.com/prysmaticlabs/eth2-types"
-	"github.com/prysmaticlabs/prysm/beacon-chain/core"
 	"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"
@@ -18,6 +17,7 @@ import (
 	"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) {
@@ -251,7 +251,7 @@ 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 := core.StartSlot(newCheckpoint.Epoch)
+	s, err := slots.EpochStart(newCheckpoint.Epoch)
 	require.NoError(t, err)
 	baseState, err = transition.ProcessSlots(ctx, baseState, s)
 	require.NoError(t, err)

beacon-chain/blockchain/process_block.go

@@ -6,20 +6,22 @@ import (
 	"time"
 
 	"github.com/pkg/errors"
-	"github.com/prysmaticlabs/prysm/beacon-chain/core"
 	"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"
+	coreTime "github.com/prysmaticlabs/prysm/beacon-chain/core/time"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/transition"
 	"github.com/prysmaticlabs/prysm/beacon-chain/state"
 	"github.com/prysmaticlabs/prysm/config/features"
 	"github.com/prysmaticlabs/prysm/config/params"
 	"github.com/prysmaticlabs/prysm/crypto/bls"
 	"github.com/prysmaticlabs/prysm/encoding/bytesutil"
+	"github.com/prysmaticlabs/prysm/monitoring/tracing"
 	ethpbv1 "github.com/prysmaticlabs/prysm/proto/eth/v1"
 	ethpb "github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1"
 	"github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1/attestation"
 	"github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1/block"
+	"github.com/prysmaticlabs/prysm/time/slots"
 	"go.opencensus.io/trace"
 )
 
@@ -106,22 +108,36 @@ func (s *Service) onBlock(ctx context.Context, signed block.SignedBeaconBlock, b
 		return err
 	}
 
-	// Updating next slot state cache can happen in the background. It shouldn't block rest of the process.
-	if features.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 := transition.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
 		}
@@ -155,6 +171,27 @@ func (s *Service) onBlock(ctx context.Context, signed block.SignedBeaconBlock, b
 		},
 	})
 
+	// 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")
+			}
+		}()
+	}
+
+	// Save justified check point to db.
+	if postState.CurrentJustifiedCheckpoint().Epoch > currJustifiedEpoch {
+		if err := s.cfg.BeaconDB.SaveJustifiedCheckpoint(ctx, postState.CurrentJustifiedCheckpoint()); err != nil {
+			return err
+		}
+	}
+
 	// Update finalized check point.
 	if newFinalized {
 		if err := s.updateFinalized(ctx, postState.FinalizedCheckpoint()); err != nil {
@@ -232,7 +269,7 @@ func (s *Service) onBlockBatch(ctx context.Context, blks []block.SignedBeaconBlo
 			return nil, nil, err
 		}
 		// Save potential boundary states.
-		if core.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")
@@ -315,7 +352,7 @@ func (s *Service) handleEpochBoundary(ctx context.Context, postState state.Beaco
 
 	if postState.Slot()+1 == s.nextEpochBoundarySlot {
 		// Update caches for the next epoch at epoch boundary slot - 1.
-		if err := helpers.UpdateCommitteeCache(postState, core.NextEpoch(postState)); err != nil {
+		if err := helpers.UpdateCommitteeCache(postState, coreTime.NextEpoch(postState)); err != nil {
 			return err
 		}
 		copied := postState.Copy()
@@ -331,14 +368,14 @@ func (s *Service) handleEpochBoundary(ctx context.Context, postState state.Beaco
 			return err
 		}
 		var err error
-		s.nextEpochBoundarySlot, err = core.StartSlot(core.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, core.CurrentEpoch(postState)); err != nil {
+		if err := helpers.UpdateCommitteeCache(postState, coreTime.CurrentEpoch(postState)); err != nil {
 			return err
 		}
 		if err := helpers.UpdateProposerIndicesInCache(ctx, postState); err != nil {

beacon-chain/blockchain/process_block_helpers.go

@@ -7,7 +7,6 @@ import (
 
 	"github.com/pkg/errors"
 	types "github.com/prysmaticlabs/eth2-types"
-	"github.com/prysmaticlabs/prysm/beacon-chain/core"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/helpers"
 	"github.com/prysmaticlabs/prysm/beacon-chain/state"
 	"github.com/prysmaticlabs/prysm/config/params"
@@ -16,12 +15,13 @@ import (
 	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 core.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
@@ -45,7 +45,7 @@ func (s *Service) getBlockPreState(ctx context.Context, b block.BeaconBlock) (st
 	}
 
 	// Verify block slot time is not from the future.
-	if err := core.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
 	}
 
@@ -122,7 +122,7 @@ 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 block.BeaconBlock) error {
-	finalizedSlot, err := core.StartSlot(s.finalizedCheckpt.Epoch)
+	finalizedSlot, err := slots.EpochStart(s.finalizedCheckpt.Epoch)
 	if err != nil {
 		return err
 	}
@@ -140,7 +140,7 @@ func (s *Service) shouldUpdateCurrentJustified(ctx context.Context, newJustified
 	ctx, span := trace.StartSpan(ctx, "blockChain.shouldUpdateCurrentJustified")
 	defer span.End()
 
-	if core.SlotsSinceEpochStarts(s.CurrentSlot()) < params.BeaconConfig().SafeSlotsToUpdateJustified {
+	if slots.SinceEpochStarts(s.CurrentSlot()) < params.BeaconConfig().SafeSlotsToUpdateJustified {
 		return true, nil
 	}
 	var newJustifiedBlockSigned block.SignedBeaconBlock
@@ -159,7 +159,7 @@ func (s *Service) shouldUpdateCurrentJustified(ctx context.Context, newJustified
 	}
 
 	newJustifiedBlock := newJustifiedBlockSigned.Block()
-	jSlot, err := core.StartSlot(s.justifiedCheckpt.Epoch)
+	jSlot, err := slots.EpochStart(s.justifiedCheckpt.Epoch)
 	if err != nil {
 		return false, err
 	}
@@ -212,7 +212,7 @@ func (s *Service) updateJustified(ctx context.Context, state state.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,
@@ -348,7 +348,7 @@ func (s *Service) finalizedImpliesNewJustified(ctx context.Context, state state.
 		}
 
 		// Update justified if store justified is not in chain with finalized check point.
-		finalizedSlot, err := core.StartSlot(s.finalizedCheckpt.Epoch)
+		finalizedSlot, err := slots.EpochStart(s.finalizedCheckpt.Epoch)
 		if err != nil {
 			return err
 		}
@@ -377,7 +377,7 @@ func (s *Service) fillInForkChoiceMissingBlocks(ctx context.Context, blk block.B
 	parentRoot := bytesutil.ToBytes32(blk.ParentRoot())
 	slot := blk.Slot()
 	// Fork choice only matters from last finalized slot.
-	fSlot, err := core.StartSlot(s.finalizedCheckpt.Epoch)
+	fSlot, err := slots.EpochStart(s.finalizedCheckpt.Epoch)
 	if err != nil {
 		return err
 	}

beacon-chain/blockchain/process_block_test.go

@@ -957,6 +957,14 @@ 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) {

beacon-chain/blockchain/receive_attestation.go

@@ -7,7 +7,6 @@ import (
 	"time"
 
 	"github.com/pkg/errors"
-	"github.com/prysmaticlabs/prysm/beacon-chain/core"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/feed"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/helpers"
 	"github.com/prysmaticlabs/prysm/beacon-chain/state"
@@ -51,11 +50,11 @@ func (s *Service) ReceiveAttestationNoPubsub(ctx context.Context, att *ethpb.Att
 
 // AttestationTargetState returns the pre state of attestation.
 func (s *Service) AttestationTargetState(ctx context.Context, target *ethpb.Checkpoint) (state.BeaconState, error) {
-	ss, err := core.StartSlot(target.Epoch)
+	ss, err := slots.EpochStart(target.Epoch)
 	if err != nil {
 		return nil, err
 	}
-	if err := core.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, target)
@@ -63,7 +62,7 @@ func (s *Service) AttestationTargetState(ctx context.Context, target *ethpb.Chec
 
 // 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 := core.StartSlot(a.Data.Target.Epoch)
+	targetSlot, err := slots.EpochStart(a.Data.Target.Epoch)
 	if err != nil {
 		return err
 	}
@@ -88,7 +87,7 @@ func (s *Service) VerifyFinalizedConsistency(ctx context.Context, root []byte) e
 	}
 
 	f := s.FinalizedCheckpt()
-	ss, err := core.StartSlot(f.Epoch)
+	ss, err := slots.EpochStart(f.Epoch)
 	if err != nil {
 		return err
 	}
@@ -147,7 +146,7 @@ func (s *Service) processAttestations(ctx context.Context) {
 		// This delays consideration in the fork choice until their slot is in the past.
 		// https://github.com/ethereum/consensus-specs/blob/dev/specs/phase0/fork-choice.md#validate_on_attestation
 		nextSlot := a.Data.Slot + 1
-		if err := core.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
 		}
 

beacon-chain/blockchain/receive_attestation_test.go

@@ -6,7 +6,6 @@ import (
 	"time"
 
 	types "github.com/prysmaticlabs/eth2-types"
-	"github.com/prysmaticlabs/prysm/beacon-chain/core"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/helpers"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/transition"
 	testDB "github.com/prysmaticlabs/prysm/beacon-chain/db/testing"
@@ -20,6 +19,7 @@ import (
 	"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"
 )
 
@@ -35,7 +35,7 @@ func TestAttestationCheckPtState_FarFutureSlot(t *testing.T) {
 	chainService := setupBeaconChain(t, beaconDB)
 	chainService.genesisTime = time.Now()
 
-	e := types.Epoch(core.MaxSlotBuffer/uint64(params.BeaconConfig().SlotsPerEpoch) + 1)
+	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)
 }

beacon-chain/blockchain/receive_block.go

@@ -5,12 +5,12 @@ import (
 
 	"github.com/pkg/errors"
 	types "github.com/prysmaticlabs/eth2-types"
-	"github.com/prysmaticlabs/prysm/beacon-chain/core"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/feed"
 	statefeed "github.com/prysmaticlabs/prysm/beacon-chain/core/feed/state"
 	"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"
 )
 
@@ -142,7 +142,7 @@ func (s *Service) handlePostBlockOperations(b block.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 := core.SlotToEpoch(s.CurrentSlot())
+	currentEpoch := slots.ToEpoch(s.CurrentSlot())
 	// Prevent `sinceFinality` going underflow.
 	var sinceFinality types.Epoch
 	if currentEpoch > s.finalizedCheckpt.Epoch {

beacon-chain/blockchain/service.go

@@ -11,9 +11,9 @@ 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"
 	"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"
@@ -82,6 +82,7 @@ type Config struct {
 	ForkChoiceStore         f.ForkChoicer
 	AttService              *attestations.Service
 	StateGen                *stategen.State
+	SlasherAttestationsFeed *event.Feed
 	WeakSubjectivityCheckpt *ethpb.Checkpoint
 }
 
@@ -174,7 +175,7 @@ func (s *Service) Start() {
 		s.prevFinalizedCheckpt = ethpb.CopyCheckpoint(finalizedCheckpoint)
 		s.resumeForkChoice(justifiedCheckpoint, finalizedCheckpoint)
 
-		ss, err := core.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)
 		}
@@ -411,7 +412,7 @@ func (s *Service) initializeChainInfo(ctx context.Context) error {
 		if err != nil {
 			return errors.Wrap(err, "could not retrieve head block")
 		}
-		headEpoch := core.SlotToEpoch(headBlock.Block().Slot())
+		headEpoch := slots.ToEpoch(headBlock.Block().Slot())
 		var epochsSinceFinality types.Epoch
 		if headEpoch > finalized.Epoch {
 			epochsSinceFinality = headEpoch - finalized.Epoch

beacon-chain/blockchain/service_test.go

@@ -10,7 +10,6 @@ import (
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/prysmaticlabs/prysm/async/event"
 	"github.com/prysmaticlabs/prysm/beacon-chain/cache/depositcache"
-	"github.com/prysmaticlabs/prysm/beacon-chain/core"
 	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"
@@ -33,6 +32,7 @@ import (
 	"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"
 )
@@ -281,7 +281,7 @@ 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: core.SlotToEpoch(finalizedSlot), Root: headRoot[:]}))
+	require.NoError(t, beaconDB.SaveFinalizedCheckpoint(ctx, &ethpb.Checkpoint{Epoch: slots.ToEpoch(finalizedSlot), Root: headRoot[:]}))
 	c := &Service{cfg: &Config{BeaconDB: beaconDB, StateGen: stategen.New(beaconDB)}}
 	require.NoError(t, c.initializeChainInfo(ctx))
 	headBlk, err := c.HeadBlock(ctx)
@@ -375,7 +375,7 @@ 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: core.SlotToEpoch(finalizedBlock.Block.Slot),
+		Epoch: slots.ToEpoch(finalizedBlock.Block.Slot),
 		Root:  finalizedRoot[:],
 	}))
 

beacon-chain/blockchain/testing/BUILD.bazel

@@ -7,6 +7,7 @@ go_library(
     importpath = "github.com/prysmaticlabs/prysm/beacon-chain/blockchain/testing",
     visibility = [
         "//beacon-chain:__subpackages__",
+        "//testing:__subpackages__",
         "//testing/fuzz:__pkg__",
     ],
     deps = [

beacon-chain/blockchain/weak_subjectivity_checks.go

@@ -4,10 +4,10 @@ import (
 	"context"
 	"fmt"
 
-	"github.com/prysmaticlabs/prysm/beacon-chain/core"
 	"github.com/prysmaticlabs/prysm/beacon-chain/db/filters"
 	"github.com/prysmaticlabs/prysm/config/params"
 	"github.com/prysmaticlabs/prysm/encoding/bytesutil"
+	"github.com/prysmaticlabs/prysm/time/slots"
 )
 
 // VerifyWeakSubjectivityRoot verifies the weak subjectivity root in the service struct.
@@ -38,7 +38,7 @@ func (s *Service) VerifyWeakSubjectivityRoot(ctx context.Context) error {
 		return fmt.Errorf("node does not have root in DB: %#x", r)
 	}
 
-	startSlot, err := core.StartSlot(s.cfg.WeakSubjectivityCheckpt.Epoch)
+	startSlot, err := slots.EpochStart(s.cfg.WeakSubjectivityCheckpt.Epoch)
 	if err != nil {
 		return err
 	}

beacon-chain/cache/committees.go

@@ -10,9 +10,6 @@ import (
 // a Committee struct.
 var ErrNotCommittee = errors.New("object is not a committee struct")
 
-// ErrNonCommitteeKey will be returned when the committee key does not exist in cache.
-var ErrNonCommitteeKey = errors.New("committee key does not exist")
-
 // Committees defines the shuffled committees seed.
 type Committees struct {
 	CommitteeCount  uint64

beacon-chain/core/altair/BUILD.bazel

@@ -21,12 +21,12 @@ go_library(
         "//validator/client:__pkg__",
     ],
     deps = [
-        "//beacon-chain/core:go_default_library",
         "//beacon-chain/core/blocks:go_default_library",
         "//beacon-chain/core/epoch:go_default_library",
         "//beacon-chain/core/epoch/precompute:go_default_library",
         "//beacon-chain/core/helpers:go_default_library",
         "//beacon-chain/core/signing:go_default_library",
+        "//beacon-chain/core/time:go_default_library",
         "//beacon-chain/p2p/types:go_default_library",
         "//beacon-chain/state:go_default_library",
         "//beacon-chain/state/v2:go_default_library",
@@ -38,6 +38,7 @@ go_library(
         "//proto/prysm/v1alpha1:go_default_library",
         "//proto/prysm/v1alpha1/attestation:go_default_library",
         "//proto/prysm/v1alpha1/block:go_default_library",
+        "//time/slots: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",
@@ -61,11 +62,11 @@ go_test(
     ],
     embed = [":go_default_library"],
     deps = [
-        "//beacon-chain/core:go_default_library",
         "//beacon-chain/core/epoch:go_default_library",
         "//beacon-chain/core/epoch/precompute:go_default_library",
         "//beacon-chain/core/helpers:go_default_library",
         "//beacon-chain/core/signing:go_default_library",
+        "//beacon-chain/core/time:go_default_library",
         "//beacon-chain/p2p/types:go_default_library",
         "//beacon-chain/state:go_default_library",
         "//beacon-chain/state/v2:go_default_library",
@@ -81,6 +82,7 @@ go_test(
         "//testing/require:go_default_library",
         "//testing/util:go_default_library",
         "//time:go_default_library",
+        "//time/slots:go_default_library",
         "@com_github_google_gofuzz//:go_default_library",
         "@com_github_prysmaticlabs_eth2_types//:go_default_library",
         "@com_github_prysmaticlabs_go_bitfield//:go_default_library",

beacon-chain/core/altair/attestation.go

@@ -7,9 +7,9 @@ import (
 
 	"github.com/pkg/errors"
 	types "github.com/prysmaticlabs/eth2-types"
-	"github.com/prysmaticlabs/prysm/beacon-chain/core"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/blocks"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/helpers"
+	"github.com/prysmaticlabs/prysm/beacon-chain/core/time"
 	"github.com/prysmaticlabs/prysm/beacon-chain/state"
 	"github.com/prysmaticlabs/prysm/config/params"
 	ethpb "github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1"
@@ -105,7 +105,7 @@ func SetParticipationAndRewardProposer(
 	indices []uint64,
 	participatedFlags map[uint8]bool, totalBalance uint64) (state.BeaconState, error) {
 	var epochParticipation []byte
-	currentEpoch := core.CurrentEpoch(beaconState)
+	currentEpoch := time.CurrentEpoch(beaconState)
 	var err error
 	if targetEpoch == currentEpoch {
 		epochParticipation, err = beaconState.CurrentEpochParticipation()
@@ -240,7 +240,7 @@ func RewardProposer(ctx context.Context, beaconState state.BeaconState, proposer
 //
 //    return participation_flag_indices
 func AttestationParticipationFlagIndices(beaconState state.BeaconStateAltair, data *ethpb.AttestationData, delay types.Slot) (map[uint8]bool, error) {
-	currEpoch := core.CurrentEpoch(beaconState)
+	currEpoch := time.CurrentEpoch(beaconState)
 	var justifiedCheckpt *ethpb.Checkpoint
 	if data.Target.Epoch == currEpoch {
 		justifiedCheckpt = beaconState.CurrentJustifiedCheckpoint()

beacon-chain/core/altair/attestation_test.go

@@ -8,10 +8,10 @@ import (
 	fuzz "github.com/google/gofuzz"
 	types "github.com/prysmaticlabs/eth2-types"
 	"github.com/prysmaticlabs/go-bitfield"
-	"github.com/prysmaticlabs/prysm/beacon-chain/core"
 	"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/time"
 	"github.com/prysmaticlabs/prysm/beacon-chain/state"
 	stateAltair "github.com/prysmaticlabs/prysm/beacon-chain/state/v2"
 	"github.com/prysmaticlabs/prysm/config/params"
@@ -75,8 +75,8 @@ func TestProcessAttestations_NeitherCurrentNorPrevEpoch(t *testing.T) {
 	want := fmt.Sprintf(
 		"expected target epoch (%d) to be the previous epoch (%d) or the current epoch (%d)",
 		att.Data.Target.Epoch,
-		core.PrevEpoch(beaconState),
-		core.CurrentEpoch(beaconState),
+		time.PrevEpoch(beaconState),
+		time.CurrentEpoch(beaconState),
 	)
 	wsb, err := wrapper.WrappedAltairSignedBeaconBlock(b)
 	require.NoError(t, err)
@@ -111,7 +111,7 @@ func TestProcessAttestations_CurrentEpochFFGDataMismatches(t *testing.T) {
 	require.NoError(t, err)
 	_, err = altair.ProcessAttestationsNoVerifySignature(context.Background(), beaconState, wsb)
 	require.ErrorContains(t, want, err)
-	b.Block.Body.Attestations[0].Data.Source.Epoch = core.CurrentEpoch(beaconState)
+	b.Block.Body.Attestations[0].Data.Source.Epoch = time.CurrentEpoch(beaconState)
 	b.Block.Body.Attestations[0].Data.Source.Root = []byte{}
 	wsb, err = wrapper.WrappedAltairSignedBeaconBlock(b)
 	require.NoError(t, err)
@@ -152,8 +152,8 @@ func TestProcessAttestations_PrevEpochFFGDataMismatches(t *testing.T) {
 	require.NoError(t, err)
 	_, err = altair.ProcessAttestationsNoVerifySignature(context.Background(), beaconState, wsb)
 	require.ErrorContains(t, want, err)
-	b.Block.Body.Attestations[0].Data.Source.Epoch = core.PrevEpoch(beaconState)
-	b.Block.Body.Attestations[0].Data.Target.Epoch = core.PrevEpoch(beaconState)
+	b.Block.Body.Attestations[0].Data.Source.Epoch = time.PrevEpoch(beaconState)
+	b.Block.Body.Attestations[0].Data.Target.Epoch = time.PrevEpoch(beaconState)
 	b.Block.Body.Attestations[0].Data.Source.Root = []byte{}
 	wsb, err = wrapper.WrappedAltairSignedBeaconBlock(b)
 	require.NoError(t, err)
@@ -471,7 +471,7 @@ func TestSetParticipationAndRewardProposer(t *testing.T) {
 			beaconState, _ := util.DeterministicGenesisStateAltair(t, params.BeaconConfig().MaxValidatorsPerCommittee)
 			require.NoError(t, beaconState.SetSlot(params.BeaconConfig().SlotsPerEpoch))
 
-			currentEpoch := core.CurrentEpoch(beaconState)
+			currentEpoch := time.CurrentEpoch(beaconState)
 			if test.epoch == currentEpoch {
 				require.NoError(t, beaconState.SetCurrentParticipationBits(test.epochParticipation))
 			} else {

beacon-chain/core/altair/block.go

@@ -5,7 +5,6 @@ import (
 	"errors"
 
 	types "github.com/prysmaticlabs/eth2-types"
-	"github.com/prysmaticlabs/prysm/beacon-chain/core"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/helpers"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/signing"
 	p2pType "github.com/prysmaticlabs/prysm/beacon-chain/p2p/types"
@@ -14,6 +13,7 @@ import (
 	"github.com/prysmaticlabs/prysm/crypto/bls"
 	"github.com/prysmaticlabs/prysm/encoding/bytesutil"
 	ethpb "github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1"
+	"github.com/prysmaticlabs/prysm/time/slots"
 )
 
 // ProcessSyncAggregate verifies sync committee aggregate signature signing over the previous slot block root.
@@ -101,8 +101,8 @@ func FilterSyncCommitteeVotes(s state.BeaconStateAltair, sync *ethpb.SyncAggrega
 
 // VerifySyncCommitteeSig verifies sync committee signature `syncSig` is valid with respect to public keys `syncKeys`.
 func VerifySyncCommitteeSig(s state.BeaconStateAltair, syncKeys []bls.PublicKey, syncSig []byte) error {
-	ps := core.PrevSlot(s.Slot())
-	d, err := signing.Domain(s.Fork(), core.SlotToEpoch(ps), params.BeaconConfig().DomainSyncCommittee, s.GenesisValidatorRoot())
+	ps := slots.PrevSlot(s.Slot())
+	d, err := signing.Domain(s.Fork(), slots.ToEpoch(ps), params.BeaconConfig().DomainSyncCommittee, s.GenesisValidatorRoot())
 	if err != nil {
 		return err
 	}

beacon-chain/core/altair/block_test.go

@@ -7,10 +7,10 @@ import (
 
 	types "github.com/prysmaticlabs/eth2-types"
 	"github.com/prysmaticlabs/go-bitfield"
-	"github.com/prysmaticlabs/prysm/beacon-chain/core"
 	"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/time"
 	p2pType "github.com/prysmaticlabs/prysm/beacon-chain/p2p/types"
 	"github.com/prysmaticlabs/prysm/config/params"
 	"github.com/prysmaticlabs/prysm/crypto/bls"
@@ -18,6 +18,7 @@ import (
 	ethpb "github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1"
 	"github.com/prysmaticlabs/prysm/testing/require"
 	"github.com/prysmaticlabs/prysm/testing/util"
+	"github.com/prysmaticlabs/prysm/time/slots"
 )
 
 func TestProcessSyncCommittee_PerfectParticipation(t *testing.T) {
@@ -33,13 +34,13 @@ func TestProcessSyncCommittee_PerfectParticipation(t *testing.T) {
 	}
 	indices, err := altair.NextSyncCommitteeIndices(context.Background(), beaconState)
 	require.NoError(t, err)
-	ps := core.PrevSlot(beaconState.Slot())
+	ps := slots.PrevSlot(beaconState.Slot())
 	pbr, err := helpers.BlockRootAtSlot(beaconState, ps)
 	require.NoError(t, err)
 	sigs := make([]bls.Signature, len(indices))
 	for i, indice := range indices {
 		b := p2pType.SSZBytes(pbr)
-		sb, err := signing.ComputeDomainAndSign(beaconState, core.CurrentEpoch(beaconState), &b, params.BeaconConfig().DomainSyncCommittee, privKeys[indice])
+		sb, err := signing.ComputeDomainAndSign(beaconState, time.CurrentEpoch(beaconState), &b, params.BeaconConfig().DomainSyncCommittee, privKeys[indice])
 		require.NoError(t, err)
 		sig, err := bls.SignatureFromBytes(sb)
 		require.NoError(t, err)
@@ -107,13 +108,13 @@ func TestProcessSyncCommittee_MixParticipation_BadSignature(t *testing.T) {
 	}
 	indices, err := altair.NextSyncCommitteeIndices(context.Background(), beaconState)
 	require.NoError(t, err)
-	ps := core.PrevSlot(beaconState.Slot())
+	ps := slots.PrevSlot(beaconState.Slot())
 	pbr, err := helpers.BlockRootAtSlot(beaconState, ps)
 	require.NoError(t, err)
 	sigs := make([]bls.Signature, len(indices))
 	for i, indice := range indices {
 		b := p2pType.SSZBytes(pbr)
-		sb, err := signing.ComputeDomainAndSign(beaconState, core.CurrentEpoch(beaconState), &b, params.BeaconConfig().DomainSyncCommittee, privKeys[indice])
+		sb, err := signing.ComputeDomainAndSign(beaconState, time.CurrentEpoch(beaconState), &b, params.BeaconConfig().DomainSyncCommittee, privKeys[indice])
 		require.NoError(t, err)
 		sig, err := bls.SignatureFromBytes(sb)
 		require.NoError(t, err)
@@ -142,14 +143,14 @@ func TestProcessSyncCommittee_MixParticipation_GoodSignature(t *testing.T) {
 	}
 	indices, err := altair.NextSyncCommitteeIndices(context.Background(), beaconState)
 	require.NoError(t, err)
-	ps := core.PrevSlot(beaconState.Slot())
+	ps := slots.PrevSlot(beaconState.Slot())
 	pbr, err := helpers.BlockRootAtSlot(beaconState, ps)
 	require.NoError(t, err)
 	sigs := make([]bls.Signature, 0, len(indices))
 	for i, indice := range indices {
 		if syncBits.BitAt(uint64(i)) {
 			b := p2pType.SSZBytes(pbr)
-			sb, err := signing.ComputeDomainAndSign(beaconState, core.CurrentEpoch(beaconState), &b, params.BeaconConfig().DomainSyncCommittee, privKeys[indice])
+			sb, err := signing.ComputeDomainAndSign(beaconState, time.CurrentEpoch(beaconState), &b, params.BeaconConfig().DomainSyncCommittee, privKeys[indice])
 			require.NoError(t, err)
 			sig, err := bls.SignatureFromBytes(sb)
 			require.NoError(t, err)
@@ -215,14 +216,14 @@ func Test_VerifySyncCommitteeSig(t *testing.T) {
 	}
 	indices, err := altair.NextSyncCommitteeIndices(context.Background(), beaconState)
 	require.NoError(t, err)
-	ps := core.PrevSlot(beaconState.Slot())
+	ps := slots.PrevSlot(beaconState.Slot())
 	pbr, err := helpers.BlockRootAtSlot(beaconState, ps)
 	require.NoError(t, err)
 	sigs := make([]bls.Signature, len(indices))
 	pks := make([]bls.PublicKey, len(indices))
 	for i, indice := range indices {
 		b := p2pType.SSZBytes(pbr)
-		sb, err := signing.ComputeDomainAndSign(beaconState, core.CurrentEpoch(beaconState), &b, params.BeaconConfig().DomainSyncCommittee, privKeys[indice])
+		sb, err := signing.ComputeDomainAndSign(beaconState, time.CurrentEpoch(beaconState), &b, params.BeaconConfig().DomainSyncCommittee, privKeys[indice])
 		require.NoError(t, err)
 		sig, err := bls.SignatureFromBytes(sb)
 		require.NoError(t, err)

beacon-chain/core/altair/epoch_precompute.go

@@ -4,9 +4,9 @@ import (
 	"context"
 
 	"github.com/pkg/errors"
-	"github.com/prysmaticlabs/prysm/beacon-chain/core"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/epoch/precompute"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/helpers"
+	"github.com/prysmaticlabs/prysm/beacon-chain/core/time"
 	"github.com/prysmaticlabs/prysm/beacon-chain/state"
 	"github.com/prysmaticlabs/prysm/config/params"
 	"github.com/prysmaticlabs/prysm/math"
@@ -19,8 +19,8 @@ func InitializePrecomputeValidators(ctx context.Context, beaconState state.Beaco
 	defer span.End()
 	vals := make([]*precompute.Validator, beaconState.NumValidators())
 	bal := &precompute.Balance{}
-	prevEpoch := core.PrevEpoch(beaconState)
-	currentEpoch := core.CurrentEpoch(beaconState)
+	prevEpoch := time.PrevEpoch(beaconState)
+	currentEpoch := time.CurrentEpoch(beaconState)
 	inactivityScores, err := beaconState.InactivityScores()
 	if err != nil {
 		return nil, nil, err
@@ -74,7 +74,7 @@ func ProcessInactivityScores(
 	defer span.End()
 
 	cfg := params.BeaconConfig()
-	if core.CurrentEpoch(beaconState) == cfg.GenesisEpoch {
+	if time.CurrentEpoch(beaconState) == cfg.GenesisEpoch {
 		return beaconState, vals, nil
 	}
 
@@ -85,7 +85,7 @@ func ProcessInactivityScores(
 
 	bias := cfg.InactivityScoreBias
 	recoveryRate := cfg.InactivityScoreRecoveryRate
-	prevEpoch := core.PrevEpoch(beaconState)
+	prevEpoch := time.PrevEpoch(beaconState)
 	finalizedEpoch := beaconState.FinalizedCheckpointEpoch()
 	for i, v := range vals {
 		if !precompute.EligibleForRewards(v) {
@@ -98,7 +98,10 @@ func ProcessInactivityScores(
 				v.InactivityScore -= 1
 			}
 		} else {
-			v.InactivityScore += bias
+			v.InactivityScore, err = math.Add64(v.InactivityScore, bias)
+			if err != nil {
+				return nil, nil, err
+			}
 		}
 
 		if !helpers.IsInInactivityLeak(prevEpoch, finalizedEpoch) {
@@ -179,7 +182,7 @@ func ProcessRewardsAndPenaltiesPrecompute(
 ) (state.BeaconStateAltair, error) {
 	// Don't process rewards and penalties in genesis epoch.
 	cfg := params.BeaconConfig()
-	if core.CurrentEpoch(beaconState) == cfg.GenesisEpoch {
+	if time.CurrentEpoch(beaconState) == cfg.GenesisEpoch {
 		return beaconState, nil
 	}
 
@@ -200,7 +203,10 @@ func ProcessRewardsAndPenaltiesPrecompute(
 
 		// Compute the post balance of the validator after accounting for the
 		// attester and proposer rewards and penalties.
-		balances[i] = helpers.IncreaseBalanceWithVal(balances[i], attsRewards[i])
+		balances[i], err = helpers.IncreaseBalanceWithVal(balances[i], attsRewards[i])
+		if err != nil {
+			return nil, err
+		}
 		balances[i] = helpers.DecreaseBalanceWithVal(balances[i], attsPenalties[i])
 
 		vals[i].AfterEpochTransitionBalance = balances[i]
@@ -221,7 +227,7 @@ func AttestationsDelta(beaconState state.BeaconStateAltair, bal *precompute.Bala
 	penalties = make([]uint64, numOfVals)
 
 	cfg := params.BeaconConfig()
-	prevEpoch := core.PrevEpoch(beaconState)
+	prevEpoch := time.PrevEpoch(beaconState)
 	finalizedEpoch := beaconState.FinalizedCheckpointEpoch()
 	increment := cfg.EffectiveBalanceIncrement
 	factor := cfg.BaseRewardFactor
@@ -230,7 +236,10 @@ func AttestationsDelta(beaconState state.BeaconStateAltair, bal *precompute.Bala
 	inactivityDenominator := cfg.InactivityScoreBias * cfg.InactivityPenaltyQuotientAltair
 
 	for i, v := range vals {
-		rewards[i], penalties[i] = attestationDelta(bal, v, baseRewardMultiplier, inactivityDenominator, leak)
+		rewards[i], penalties[i], err = attestationDelta(bal, v, baseRewardMultiplier, inactivityDenominator, leak)
+		if err != nil {
+			return nil, nil, err
+		}
 	}
 
 	return rewards, penalties, nil
@@ -240,11 +249,11 @@ func attestationDelta(
 	bal *precompute.Balance,
 	val *precompute.Validator,
 	baseRewardMultiplier, inactivityDenominator uint64,
-	inactivityLeak bool) (reward, penalty uint64) {
+	inactivityLeak bool) (reward, penalty uint64, err error) {
 	eligible := val.IsActivePrevEpoch || (val.IsSlashed && !val.IsWithdrawableCurrentEpoch)
 	// Per spec `ActiveCurrentEpoch` can't be 0 to process attestation delta.
 	if !eligible || bal.ActiveCurrentEpoch == 0 {
-		return 0, 0
+		return 0, 0, nil
 	}
 
 	cfg := params.BeaconConfig()
@@ -289,9 +298,12 @@ func attestationDelta(
 	// Process finality delay penalty
 	// Apply an additional penalty to validators that did not vote on the correct target or slashed
 	if !val.IsPrevEpochTargetAttester || val.IsSlashed {
-		n := effectiveBalance * val.InactivityScore
+		n, err := math.Mul64(effectiveBalance, val.InactivityScore)
+		if err != nil {
+			return 0, 0, err
+		}
 		penalty += n / inactivityDenominator
 	}
 
-	return reward, penalty
+	return reward, penalty, nil
 }

beacon-chain/core/altair/epoch_spec.go

@@ -3,8 +3,8 @@ package altair
 import (
 	"context"
 
-	"github.com/prysmaticlabs/prysm/beacon-chain/core"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/helpers"
+	"github.com/prysmaticlabs/prysm/beacon-chain/core/time"
 	"github.com/prysmaticlabs/prysm/beacon-chain/state"
 	"github.com/prysmaticlabs/prysm/config/params"
 	log "github.com/sirupsen/logrus"
@@ -19,7 +19,7 @@ import (
 //        state.current_sync_committee = state.next_sync_committee
 //        state.next_sync_committee = get_next_sync_committee(state)
 func ProcessSyncCommitteeUpdates(ctx context.Context, beaconState state.BeaconStateAltair) (state.BeaconStateAltair, error) {
-	nextEpoch := core.NextEpoch(beaconState)
+	nextEpoch := time.NextEpoch(beaconState)
 	if nextEpoch%params.BeaconConfig().EpochsPerSyncCommitteePeriod == 0 {
 		nextSyncCommittee, err := beaconState.NextSyncCommittee()
 		if err != nil {

beacon-chain/core/altair/epoch_spec_test.go

@@ -3,13 +3,14 @@ package altair_test
 import (
 	"context"
 	"fmt"
+	"math"
 	"testing"
 
 	types "github.com/prysmaticlabs/eth2-types"
-	"github.com/prysmaticlabs/prysm/beacon-chain/core"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/altair"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/epoch"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/helpers"
+	"github.com/prysmaticlabs/prysm/beacon-chain/core/time"
 	stateAltair "github.com/prysmaticlabs/prysm/beacon-chain/state/v2"
 	"github.com/prysmaticlabs/prysm/config/params"
 	"github.com/prysmaticlabs/prysm/encoding/bytesutil"
@@ -58,7 +59,7 @@ func TestProcessSyncCommitteeUpdates_CanRotate(t *testing.T) {
 	require.DeepEqual(t, next, c)
 
 	// Test boundary condition.
-	slot := params.BeaconConfig().SlotsPerEpoch * types.Slot(core.CurrentEpoch(s)+params.BeaconConfig().EpochsPerSyncCommitteePeriod)
+	slot := params.BeaconConfig().SlotsPerEpoch * types.Slot(time.CurrentEpoch(s)+params.BeaconConfig().EpochsPerSyncCommitteePeriod)
 	require.NoError(t, s.SetSlot(slot))
 	boundaryCommittee, err := altair.NextSyncCommittee(context.Background(), s)
 	require.NoError(t, err)
@@ -181,3 +182,16 @@ func TestProcessSlashings_SlashedLess(t *testing.T) {
 		})
 	}
 }
+
+func TestProcessSlashings_BadValue(t *testing.T) {
+	base := &ethpb.BeaconStateAltair{
+		Slot:       0,
+		Validators: []*ethpb.Validator{{Slashed: true}},
+		Balances:   []uint64{params.BeaconConfig().MaxEffectiveBalance},
+		Slashings:  []uint64{math.MaxUint64, 1e9},
+	}
+	s, err := stateAltair.InitializeFromProto(base)
+	require.NoError(t, err)
+	_, err = epoch.ProcessSlashings(s, params.BeaconConfig().ProportionalSlashingMultiplierAltair)
+	require.ErrorContains(t, "addition overflows", err)
+}

beacon-chain/core/altair/sync_committee.go

@@ -7,8 +7,8 @@ import (
 
 	"github.com/pkg/errors"
 	types "github.com/prysmaticlabs/eth2-types"
-	"github.com/prysmaticlabs/prysm/beacon-chain/core"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/helpers"
+	coreTime "github.com/prysmaticlabs/prysm/beacon-chain/core/time"
 	"github.com/prysmaticlabs/prysm/beacon-chain/state"
 	"github.com/prysmaticlabs/prysm/config/params"
 	"github.com/prysmaticlabs/prysm/crypto/bls"
@@ -16,6 +16,7 @@ import (
 	"github.com/prysmaticlabs/prysm/encoding/bytesutil"
 	"github.com/prysmaticlabs/prysm/math"
 	ethpb "github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1"
+	"github.com/prysmaticlabs/prysm/time/slots"
 )
 
 const maxRandomByte = uint64(1<<8 - 1)
@@ -97,7 +98,7 @@ func NextSyncCommittee(ctx context.Context, s state.BeaconStateAltair) (*ethpb.S
 //        i += 1
 //    return sync_committee_indices
 func NextSyncCommitteeIndices(ctx context.Context, s state.BeaconStateAltair) ([]types.ValidatorIndex, error) {
-	epoch := core.NextEpoch(s)
+	epoch := coreTime.NextEpoch(s)
 	indices, err := helpers.ActiveValidatorIndices(ctx, s, epoch)
 	if err != nil {
 		return nil, err
@@ -185,15 +186,15 @@ func IsSyncCommitteeAggregator(sig []byte) (bool, error) {
 
 // ValidateSyncMessageTime validates sync message to ensure that the provided slot is valid.
 func ValidateSyncMessageTime(slot types.Slot, genesisTime time.Time, clockDisparity time.Duration) error {
-	if err := core.ValidateSlotClock(slot, uint64(genesisTime.Unix())); err != nil {
+	if err := slots.ValidateClock(slot, uint64(genesisTime.Unix())); err != nil {
 		return err
 	}
-	messageTime, err := core.SlotToTime(uint64(genesisTime.Unix()), slot)
+	messageTime, err := slots.ToTime(uint64(genesisTime.Unix()), slot)
 	if err != nil {
 		return err
 	}
-	currentSlot := core.SlotsSince(genesisTime)
-	slotStartTime, err := core.SlotToTime(uint64(genesisTime.Unix()), currentSlot)
+	currentSlot := slots.Since(genesisTime)
+	slotStartTime, err := slots.ToTime(uint64(genesisTime.Unix()), currentSlot)
 	if err != nil {
 		return err
 	}
@@ -214,8 +215,8 @@ func ValidateSyncMessageTime(slot types.Slot, genesisTime time.Time, clockDispar
 		return fmt.Errorf(
 			"sync message slot %d not within allowable range of %d to %d (current slot)",
 			slot,
-			lowerBound.Unix(),
-			upperBound.Unix(),
+			uint64(lowerBound.Unix()-genesisTime.Unix())/params.BeaconConfig().SecondsPerSlot,
+			uint64(upperBound.Unix()-genesisTime.Unix())/params.BeaconConfig().SecondsPerSlot,
 		)
 	}
 	return nil

beacon-chain/core/altair/upgrade.go

@@ -3,8 +3,8 @@ package altair
 import (
 	"context"
 
-	"github.com/prysmaticlabs/prysm/beacon-chain/core"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/helpers"
+	"github.com/prysmaticlabs/prysm/beacon-chain/core/time"
 	"github.com/prysmaticlabs/prysm/beacon-chain/state"
 	statealtair "github.com/prysmaticlabs/prysm/beacon-chain/state/v2"
 	"github.com/prysmaticlabs/prysm/config/params"
@@ -63,7 +63,7 @@ import (
 //    post.next_sync_committee = get_next_sync_committee(post)
 //    return post
 func UpgradeToAltair(ctx context.Context, state state.BeaconState) (state.BeaconStateAltair, error) {
-	epoch := core.CurrentEpoch(state)
+	epoch := time.CurrentEpoch(state)
 
 	numValidators := state.NumValidators()
 	s := &ethpb.BeaconStateAltair{

beacon-chain/core/altair/upgrade_test.go

@@ -6,9 +6,9 @@ import (
 
 	types "github.com/prysmaticlabs/eth2-types"
 	"github.com/prysmaticlabs/go-bitfield"
-	"github.com/prysmaticlabs/prysm/beacon-chain/core"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/altair"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/helpers"
+	"github.com/prysmaticlabs/prysm/beacon-chain/core/time"
 	"github.com/prysmaticlabs/prysm/beacon-chain/state"
 	stateAltair "github.com/prysmaticlabs/prysm/beacon-chain/state/v2"
 	"github.com/prysmaticlabs/prysm/config/params"
@@ -109,7 +109,7 @@ func TestUpgradeToAltair(t *testing.T) {
 	require.DeepSSZEqual(t, &ethpb.Fork{
 		PreviousVersion: st.Fork().CurrentVersion,
 		CurrentVersion:  params.BeaconConfig().AltairForkVersion,
-		Epoch:           core.CurrentEpoch(st),
+		Epoch:           time.CurrentEpoch(st),
 	}, f)
 	csc, err := aState.CurrentSyncCommittee()
 	require.NoError(t, err)

beacon-chain/core/blocks/BUILD.bazel

@@ -21,12 +21,12 @@ go_library(
         "//testing/fuzz:__pkg__",
         "//testing/spectest:__subpackages__",
         "//testing/util:__pkg__",
-        "//validator/accounts:__pkg__",
+        "//validator:__subpackages__",
     ],
     deps = [
-        "//beacon-chain/core:go_default_library",
         "//beacon-chain/core/helpers:go_default_library",
         "//beacon-chain/core/signing:go_default_library",
+        "//beacon-chain/core/time:go_default_library",
         "//beacon-chain/core/validators:go_default_library",
         "//beacon-chain/state:go_default_library",
         "//config/params:go_default_library",
@@ -43,6 +43,7 @@ go_library(
         "//proto/prysm/v1alpha1/block:go_default_library",
         "//proto/prysm/v1alpha1/slashings:go_default_library",
         "//runtime/version:go_default_library",
+        "//time/slots: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",
@@ -74,9 +75,9 @@ go_test(
     embed = [":go_default_library"],
     shard_count = 2,
     deps = [
-        "//beacon-chain/core:go_default_library",
         "//beacon-chain/core/helpers:go_default_library",
         "//beacon-chain/core/signing:go_default_library",
+        "//beacon-chain/core/time:go_default_library",
         "//beacon-chain/core/validators:go_default_library",
         "//beacon-chain/p2p/types:go_default_library",
         "//beacon-chain/state:go_default_library",
@@ -93,6 +94,7 @@ go_test(
         "//testing/assert:go_default_library",
         "//testing/require:go_default_library",
         "//testing/util:go_default_library",
+        "//time/slots:go_default_library",
         "@com_github_google_gofuzz//:go_default_library",
         "@com_github_prysmaticlabs_eth2_types//:go_default_library",
         "@com_github_prysmaticlabs_go_bitfield//:go_default_library",

beacon-chain/core/blocks/attestation.go

@@ -6,9 +6,9 @@ import (
 
 	"github.com/pkg/errors"
 	types "github.com/prysmaticlabs/eth2-types"
-	"github.com/prysmaticlabs/prysm/beacon-chain/core"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/helpers"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/signing"
+	"github.com/prysmaticlabs/prysm/beacon-chain/core/time"
 	"github.com/prysmaticlabs/prysm/beacon-chain/state"
 	"github.com/prysmaticlabs/prysm/config/params"
 	"github.com/prysmaticlabs/prysm/crypto/bls"
@@ -52,8 +52,8 @@ func VerifyAttestationNoVerifySignature(
 	if err := helpers.ValidateNilAttestation(att); err != nil {
 		return err
 	}
-	currEpoch := core.CurrentEpoch(beaconState)
-	prevEpoch := core.PrevEpoch(beaconState)
+	currEpoch := time.CurrentEpoch(beaconState)
+	prevEpoch := time.PrevEpoch(beaconState)
 	data := att.Data
 	if data.Target.Epoch != prevEpoch && data.Target.Epoch != currEpoch {
 		return fmt.Errorf(
@@ -137,7 +137,7 @@ func ProcessAttestationNoVerifySignature(
 		return nil, err
 	}
 
-	currEpoch := core.CurrentEpoch(beaconState)
+	currEpoch := time.CurrentEpoch(beaconState)
 	data := att.Data
 	s := att.Data.Slot
 	proposerIndex, err := helpers.BeaconProposerIndex(ctx, beaconState)

beacon-chain/core/blocks/attester_slashing.go

@@ -6,7 +6,6 @@ import (
 
 	"github.com/pkg/errors"
 	types "github.com/prysmaticlabs/eth2-types"
-	"github.com/prysmaticlabs/prysm/beacon-chain/core"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/helpers"
 	"github.com/prysmaticlabs/prysm/beacon-chain/state"
 	"github.com/prysmaticlabs/prysm/config/params"
@@ -15,6 +14,7 @@ import (
 	"github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1/attestation"
 	"github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1/slashings"
 	"github.com/prysmaticlabs/prysm/runtime/version"
+	"github.com/prysmaticlabs/prysm/time/slots"
 )
 
 // ProcessAttesterSlashings is one of the operations performed
@@ -50,7 +50,7 @@ func ProcessAttesterSlashings(
 		sort.SliceStable(slashableIndices, func(i, j int) bool {
 			return slashableIndices[i] < slashableIndices[j]
 		})
-		currentEpoch := core.SlotToEpoch(beaconState.Slot())
+		currentEpoch := slots.ToEpoch(beaconState.Slot())
 		var err error
 		var slashedAny bool
 		var val state.ReadOnlyValidator

beacon-chain/core/blocks/exit.go

@@ -6,13 +6,13 @@ import (
 
 	"github.com/pkg/errors"
 	types "github.com/prysmaticlabs/eth2-types"
-	"github.com/prysmaticlabs/prysm/beacon-chain/core"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/helpers"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/signing"
 	v "github.com/prysmaticlabs/prysm/beacon-chain/core/validators"
 	"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"
 )
 
 // ValidatorAlreadyExitedMsg defines a message saying that a validator has already exited.
@@ -135,7 +135,7 @@ func VerifyExitAndSignature(
 //    # Initiate exit
 //    initiate_validator_exit(state, voluntary_exit.validator_index)
 func verifyExitConditions(validator state.ReadOnlyValidator, currentSlot types.Slot, exit *ethpb.VoluntaryExit) error {
-	currentEpoch := core.SlotToEpoch(currentSlot)
+	currentEpoch := slots.ToEpoch(currentSlot)
 	// Verify the validator is active.
 	if !helpers.IsActiveValidatorUsingTrie(validator, currentEpoch) {
 		return errors.New("non-active validator cannot exit")

beacon-chain/core/blocks/exit_test.go

@@ -5,10 +5,10 @@ import (
 	"testing"
 
 	types "github.com/prysmaticlabs/eth2-types"
-	"github.com/prysmaticlabs/prysm/beacon-chain/core"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/blocks"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/helpers"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/signing"
+	"github.com/prysmaticlabs/prysm/beacon-chain/core/time"
 	v1 "github.com/prysmaticlabs/prysm/beacon-chain/state/v1"
 	"github.com/prysmaticlabs/prysm/config/params"
 	"github.com/prysmaticlabs/prysm/crypto/bls"
@@ -113,7 +113,7 @@ func TestProcessVoluntaryExits_AppliesCorrectStatus(t *testing.T) {
 	require.NoError(t, err)
 	val.PublicKey = priv.PublicKey().Marshal()
 	require.NoError(t, state.UpdateValidatorAtIndex(0, val))
-	exits[0].Signature, err = signing.ComputeDomainAndSign(state, core.CurrentEpoch(state), exits[0].Exit, params.BeaconConfig().DomainVoluntaryExit, priv)
+	exits[0].Signature, err = signing.ComputeDomainAndSign(state, time.CurrentEpoch(state), exits[0].Exit, params.BeaconConfig().DomainVoluntaryExit, priv)
 	require.NoError(t, err)
 
 	b := util.NewBeaconBlock()

beacon-chain/core/blocks/header_test.go

@@ -5,10 +5,10 @@ import (
 	"io/ioutil"
 	"testing"
 
-	"github.com/prysmaticlabs/prysm/beacon-chain/core"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/blocks"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/helpers"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/signing"
+	"github.com/prysmaticlabs/prysm/beacon-chain/core/time"
 	p2ptypes "github.com/prysmaticlabs/prysm/beacon-chain/p2p/types"
 	"github.com/prysmaticlabs/prysm/config/params"
 	"github.com/prysmaticlabs/prysm/crypto/bls"
@@ -48,7 +48,7 @@ func TestProcessBlockHeader_ImproperBlockSlot(t *testing.T) {
 	latestBlockSignedRoot, err := state.LatestBlockHeader().HashTreeRoot()
 	require.NoError(t, err)
 
-	currentEpoch := core.CurrentEpoch(state)
+	currentEpoch := time.CurrentEpoch(state)
 	priv, err := bls.RandKey()
 	require.NoError(t, err)
 	pID, err := helpers.BeaconProposerIndex(context.Background(), state)
@@ -120,7 +120,7 @@ func TestProcessBlockHeader_DifferentSlots(t *testing.T) {
 
 	lbhsr, err := state.LatestBlockHeader().HashTreeRoot()
 	require.NoError(t, err)
-	currentEpoch := core.CurrentEpoch(state)
+	currentEpoch := time.CurrentEpoch(state)
 
 	priv, err := bls.RandKey()
 	require.NoError(t, err)
@@ -159,7 +159,7 @@ func TestProcessBlockHeader_PreviousBlockRootNotSignedRoot(t *testing.T) {
 	bh := state.LatestBlockHeader()
 	bh.Slot = 9
 	require.NoError(t, state.SetLatestBlockHeader(bh))
-	currentEpoch := core.CurrentEpoch(state)
+	currentEpoch := time.CurrentEpoch(state)
 	priv, err := bls.RandKey()
 	require.NoError(t, err)
 	sszBytes := p2ptypes.SSZBytes("hello")
@@ -200,7 +200,7 @@ func TestProcessBlockHeader_SlashedProposer(t *testing.T) {
 	require.NoError(t, state.SetLatestBlockHeader(bh))
 	parentRoot, err := state.LatestBlockHeader().HashTreeRoot()
 	require.NoError(t, err)
-	currentEpoch := core.CurrentEpoch(state)
+	currentEpoch := time.CurrentEpoch(state)
 	priv, err := bls.RandKey()
 	require.NoError(t, err)
 	sszBytes := p2ptypes.SSZBytes("hello")
@@ -244,7 +244,7 @@ func TestProcessBlockHeader_OK(t *testing.T) {
 	latestBlockSignedRoot, err := state.LatestBlockHeader().HashTreeRoot()
 	require.NoError(t, err)
 
-	currentEpoch := core.CurrentEpoch(state)
+	currentEpoch := time.CurrentEpoch(state)
 	priv, err := bls.RandKey()
 	require.NoError(t, err)
 	pID, err := helpers.BeaconProposerIndex(context.Background(), state)
@@ -303,7 +303,7 @@ func TestBlockSignatureSet_OK(t *testing.T) {
 	latestBlockSignedRoot, err := state.LatestBlockHeader().HashTreeRoot()
 	require.NoError(t, err)
 
-	currentEpoch := core.CurrentEpoch(state)
+	currentEpoch := time.CurrentEpoch(state)
 	priv, err := bls.RandKey()
 	require.NoError(t, err)
 	pID, err := helpers.BeaconProposerIndex(context.Background(), state)

beacon-chain/core/blocks/proposer_slashing.go

@@ -6,13 +6,14 @@ import (
 
 	"github.com/pkg/errors"
 	types "github.com/prysmaticlabs/eth2-types"
-	"github.com/prysmaticlabs/prysm/beacon-chain/core"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/helpers"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/signing"
+	"github.com/prysmaticlabs/prysm/beacon-chain/core/time"
 	"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/runtime/version"
+	"github.com/prysmaticlabs/prysm/time/slots"
 	"google.golang.org/protobuf/proto"
 )
 
@@ -72,7 +73,7 @@ func ProcessProposerSlashings(
 
 // VerifyProposerSlashing verifies that the data provided from slashing is valid.
 func VerifyProposerSlashing(
-	beaconState state.BeaconState,
+	beaconState state.ReadOnlyBeaconState,
 	slashing *ethpb.ProposerSlashing,
 ) error {
 	if slashing.Header_1 == nil || slashing.Header_1.Header == nil || slashing.Header_2 == nil || slashing.Header_2.Header == nil {
@@ -93,12 +94,12 @@ func VerifyProposerSlashing(
 	if err != nil {
 		return err
 	}
-	if !helpers.IsSlashableValidatorUsingTrie(proposer, core.CurrentEpoch(beaconState)) {
+	if !helpers.IsSlashableValidatorUsingTrie(proposer, time.CurrentEpoch(beaconState)) {
 		return fmt.Errorf("validator with key %#x is not slashable", proposer.PublicKey())
 	}
 	headers := []*ethpb.SignedBeaconBlockHeader{slashing.Header_1, slashing.Header_2}
 	for _, header := range headers {
-		if err := signing.ComputeDomainVerifySigningRoot(beaconState, pIdx, core.SlotToEpoch(hSlot),
+		if err := signing.ComputeDomainVerifySigningRoot(beaconState, pIdx, slots.ToEpoch(hSlot),
 			header.Header, params.BeaconConfig().DomainBeaconProposer, header.Signature); err != nil {
 			return errors.Wrap(err, "could not verify beacon block header")
 		}

beacon-chain/core/blocks/proposer_slashing_test.go

@@ -6,7 +6,6 @@ import (
 	"testing"
 
 	types "github.com/prysmaticlabs/eth2-types"
-	"github.com/prysmaticlabs/prysm/beacon-chain/core"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/blocks"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/signing"
 	v "github.com/prysmaticlabs/prysm/beacon-chain/core/validators"
@@ -19,6 +18,7 @@ import (
 	"github.com/prysmaticlabs/prysm/testing/assert"
 	"github.com/prysmaticlabs/prysm/testing/require"
 	"github.com/prysmaticlabs/prysm/testing/util"
+	"github.com/prysmaticlabs/prysm/time/slots"
 )
 
 func TestProcessProposerSlashings_UnmatchedHeaderSlots(t *testing.T) {
@@ -329,7 +329,7 @@ func TestVerifyProposerSlashing(t *testing.T) {
 		t.Run(tt.name, func(t *testing.T) {
 
 			sk := sks[tt.args.slashing.Header_1.Header.ProposerIndex]
-			d, err := signing.Domain(tt.args.beaconState.Fork(), core.SlotToEpoch(tt.args.slashing.Header_1.Header.Slot), params.BeaconConfig().DomainBeaconProposer, tt.args.beaconState.GenesisValidatorRoot())
+			d, err := signing.Domain(tt.args.beaconState.Fork(), slots.ToEpoch(tt.args.slashing.Header_1.Header.Slot), params.BeaconConfig().DomainBeaconProposer, tt.args.beaconState.GenesisValidatorRoot())
 			require.NoError(t, err)
 			if tt.args.slashing.Header_1.Signature == nil {
 				sr, err := signing.ComputeSigningRoot(tt.args.slashing.Header_1.Header, d)

beacon-chain/core/blocks/randao.go

@@ -4,12 +4,12 @@ import (
 	"context"
 
 	"github.com/pkg/errors"
-	"github.com/prysmaticlabs/prysm/beacon-chain/core"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/helpers"
 	"github.com/prysmaticlabs/prysm/beacon-chain/state"
 	"github.com/prysmaticlabs/prysm/config/params"
 	"github.com/prysmaticlabs/prysm/crypto/hash"
 	"github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1/block"
+	"github.com/prysmaticlabs/prysm/time/slots"
 )
 
 // ProcessRandao checks the block proposer's
@@ -63,7 +63,7 @@ func ProcessRandaoNoVerify(
 	beaconState state.BeaconState,
 	randaoReveal []byte,
 ) (state.BeaconState, error) {
-	currentEpoch := core.SlotToEpoch(beaconState.Slot())
+	currentEpoch := slots.ToEpoch(beaconState.Slot())
 	// If block randao passed verification, we XOR the state's latest randao mix with the block's
 	// randao and update the state's corresponding latest randao mix value.
 	latestMixesLength := params.BeaconConfig().EpochsPerHistoricalVector

beacon-chain/core/blocks/randao_test.go

@@ -6,10 +6,10 @@ import (
 	"testing"
 
 	types "github.com/prysmaticlabs/eth2-types"
-	"github.com/prysmaticlabs/prysm/beacon-chain/core"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/blocks"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/helpers"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/signing"
+	"github.com/prysmaticlabs/prysm/beacon-chain/core/time"
 	"github.com/prysmaticlabs/prysm/config/params"
 	ethpb "github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1"
 	"github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1/wrapper"
@@ -47,7 +47,7 @@ func TestProcessRandao_IncorrectProposerFailsVerification(t *testing.T) {
 func TestProcessRandao_SignatureVerifiesAndUpdatesLatestStateMixes(t *testing.T) {
 	beaconState, privKeys := util.DeterministicGenesisState(t, 100)
 
-	epoch := core.CurrentEpoch(beaconState)
+	epoch := time.CurrentEpoch(beaconState)
 	epochSignature, err := util.RandaoReveal(beaconState, epoch, privKeys)
 	require.NoError(t, err)
 
@@ -64,7 +64,7 @@ func TestProcessRandao_SignatureVerifiesAndUpdatesLatestStateMixes(t *testing.T)
 		wrapper.WrappedPhase0SignedBeaconBlock(b),
 	)
 	require.NoError(t, err, "Unexpected error processing block randao")
-	currentEpoch := core.CurrentEpoch(beaconState)
+	currentEpoch := time.CurrentEpoch(beaconState)
 	mix := newState.RandaoMixes()[currentEpoch%params.BeaconConfig().EpochsPerHistoricalVector]
 	assert.DeepNotEqual(t, params.BeaconConfig().ZeroHash[:], mix, "Expected empty signature to be overwritten by randao reveal")
 }
@@ -72,7 +72,7 @@ func TestProcessRandao_SignatureVerifiesAndUpdatesLatestStateMixes(t *testing.T)
 func TestRandaoSignatureSet_OK(t *testing.T) {
 	beaconState, privKeys := util.DeterministicGenesisState(t, 100)
 
-	epoch := core.CurrentEpoch(beaconState)
+	epoch := time.CurrentEpoch(beaconState)
 	epochSignature, err := util.RandaoReveal(beaconState, epoch, privKeys)
 	require.NoError(t, err)
 

beacon-chain/core/blocks/signature.go

@@ -6,7 +6,6 @@ import (
 
 	"github.com/pkg/errors"
 	types "github.com/prysmaticlabs/eth2-types"
-	"github.com/prysmaticlabs/prysm/beacon-chain/core"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/helpers"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/signing"
 	"github.com/prysmaticlabs/prysm/beacon-chain/state"
@@ -16,6 +15,7 @@ import (
 	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"
 )
 
 // retrieves the signature set from the raw data, public key,signature and domain provided.
@@ -67,7 +67,7 @@ func VerifyBlockSignature(beaconState state.ReadOnlyBeaconState,
 	proposerIndex types.ValidatorIndex,
 	sig []byte,
 	rootFunc func() ([32]byte, error)) error {
-	currentEpoch := core.SlotToEpoch(beaconState.Slot())
+	currentEpoch := slots.ToEpoch(beaconState.Slot())
 	domain, err := signing.Domain(beaconState.Fork(), currentEpoch, params.BeaconConfig().DomainBeaconProposer, beaconState.GenesisValidatorRoot())
 	if err != nil {
 		return err
@@ -82,7 +82,7 @@ func VerifyBlockSignature(beaconState state.ReadOnlyBeaconState,
 
 // VerifyBlockHeaderSignature verifies the proposer signature of a beacon block header.
 func VerifyBlockHeaderSignature(beaconState state.BeaconState, header *ethpb.SignedBeaconBlockHeader) error {
-	currentEpoch := core.SlotToEpoch(beaconState.Slot())
+	currentEpoch := slots.ToEpoch(beaconState.Slot())
 	domain, err := signing.Domain(beaconState.Fork(), currentEpoch, params.BeaconConfig().DomainBeaconProposer, beaconState.GenesisValidatorRoot())
 	if err != nil {
 		return err
@@ -99,7 +99,7 @@ func VerifyBlockHeaderSignature(beaconState state.BeaconState, header *ethpb.Sig
 // from the above method by not using fork data from the state and instead retrieving it
 // via the respective epoch.
 func VerifyBlockSignatureUsingCurrentFork(beaconState state.ReadOnlyBeaconState, blk block.SignedBeaconBlock) error {
-	currentEpoch := core.SlotToEpoch(blk.Block().Slot())
+	currentEpoch := slots.ToEpoch(blk.Block().Slot())
 	fork, err := forks.Fork(currentEpoch)
 	if err != nil {
 		return err
@@ -121,7 +121,7 @@ func BlockSignatureSet(beaconState state.ReadOnlyBeaconState,
 	proposerIndex types.ValidatorIndex,
 	sig []byte,
 	rootFunc func() ([32]byte, error)) (*bls.SignatureSet, error) {
-	currentEpoch := core.SlotToEpoch(beaconState.Slot())
+	currentEpoch := slots.ToEpoch(beaconState.Slot())
 	domain, err := signing.Domain(beaconState.Fork(), currentEpoch, params.BeaconConfig().DomainBeaconProposer, beaconState.GenesisValidatorRoot())
 	if err != nil {
 		return nil, err
@@ -160,7 +160,7 @@ func randaoSigningData(ctx context.Context, beaconState state.ReadOnlyBeaconStat
 	}
 	proposerPub := beaconState.PubkeyAtIndex(proposerIdx)
 
-	currentEpoch := core.SlotToEpoch(beaconState.Slot())
+	currentEpoch := slots.ToEpoch(beaconState.Slot())
 	buf := make([]byte, 32)
 	binary.LittleEndian.PutUint64(buf, uint64(currentEpoch))
 
@@ -238,7 +238,7 @@ func AttestationSignatureSet(ctx context.Context, beaconState state.ReadOnlyBeac
 	var preForkAtts []*ethpb.Attestation
 	var postForkAtts []*ethpb.Attestation
 	for _, a := range atts {
-		if core.SlotToEpoch(a.Data.Slot) < fork.Epoch {
+		if slots.ToEpoch(a.Data.Slot) < fork.Epoch {
 			preForkAtts = append(preForkAtts, a)
 		} else {
 			postForkAtts = append(postForkAtts, a)

beacon-chain/core/epoch/BUILD.bazel

@@ -9,8 +9,8 @@ go_library(
         "//testing/spectest:__subpackages__",
     ],
     deps = [
-        "//beacon-chain/core:go_default_library",
         "//beacon-chain/core/helpers:go_default_library",
+        "//beacon-chain/core/time:go_default_library",
         "//beacon-chain/core/validators:go_default_library",
         "//beacon-chain/state:go_default_library",
         "//config/features:go_default_library",
@@ -32,8 +32,8 @@ go_test(
     ],
     embed = [":go_default_library"],
     deps = [
-        "//beacon-chain/core:go_default_library",
         "//beacon-chain/core/helpers:go_default_library",
+        "//beacon-chain/core/time:go_default_library",
         "//beacon-chain/state:go_default_library",
         "//beacon-chain/state/v1:go_default_library",
         "//config/params:go_default_library",

beacon-chain/core/epoch/epoch_processing.go

@@ -11,8 +11,8 @@ import (
 
 	"github.com/pkg/errors"
 	types "github.com/prysmaticlabs/eth2-types"
-	"github.com/prysmaticlabs/prysm/beacon-chain/core"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/helpers"
+	"github.com/prysmaticlabs/prysm/beacon-chain/core/time"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/validators"
 	"github.com/prysmaticlabs/prysm/beacon-chain/state"
 	"github.com/prysmaticlabs/prysm/config/features"
@@ -88,11 +88,11 @@ func AttestingBalance(ctx context.Context, state state.ReadOnlyBeaconState, atts
 //        validator = state.validators[index]
 //        validator.activation_epoch = compute_activation_exit_epoch(get_current_epoch(state))
 func ProcessRegistryUpdates(ctx context.Context, state state.BeaconState) (state.BeaconState, error) {
-	currentEpoch := core.CurrentEpoch(state)
+	currentEpoch := time.CurrentEpoch(state)
 	vals := state.Validators()
 	var err error
 	ejectionBal := params.BeaconConfig().EjectionBalance
-	activationEligibilityEpoch := core.CurrentEpoch(state) + 1
+	activationEligibilityEpoch := time.CurrentEpoch(state) + 1
 	for idx, validator := range vals {
 		// Process the validators for activation eligibility.
 		if helpers.IsEligibleForActivationQueue(validator) {
@@ -167,7 +167,7 @@ func ProcessRegistryUpdates(ctx context.Context, state state.BeaconState) (state
 //            penalty = penalty_numerator // total_balance * increment
 //            decrease_balance(state, ValidatorIndex(index), penalty)
 func ProcessSlashings(state state.BeaconState, slashingMultiplier uint64) (state.BeaconState, error) {
-	currentEpoch := core.CurrentEpoch(state)
+	currentEpoch := time.CurrentEpoch(state)
 	totalBalance, err := helpers.TotalActiveBalance(state)
 	if err != nil {
 		return nil, errors.Wrap(err, "could not get total active balance")
@@ -180,7 +180,10 @@ func ProcessSlashings(state state.BeaconState, slashingMultiplier uint64) (state
 	slashings := state.Slashings()
 	totalSlashing := uint64(0)
 	for _, slashing := range slashings {
-		totalSlashing += slashing
+		totalSlashing, err = math.Add64(totalSlashing, slashing)
+		if err != nil {
+			return nil, err
+		}
 	}
 
 	// a callback is used here to apply the following actions  to all validators
@@ -211,7 +214,7 @@ func ProcessSlashings(state state.BeaconState, slashingMultiplier uint64) (state
 //    if next_epoch % EPOCHS_PER_ETH1_VOTING_PERIOD == 0:
 //        state.eth1_data_votes = []
 func ProcessEth1DataReset(state state.BeaconState) (state.BeaconState, error) {
-	currentEpoch := core.CurrentEpoch(state)
+	currentEpoch := time.CurrentEpoch(state)
 	nextEpoch := currentEpoch + 1
 
 	// Reset ETH1 data votes.
@@ -309,7 +312,7 @@ func ProcessEffectiveBalanceUpdates(state state.BeaconState) (state.BeaconState,
 //    # Reset slashings
 //    state.slashings[next_epoch % EPOCHS_PER_SLASHINGS_VECTOR] = Gwei(0)
 func ProcessSlashingsReset(state state.BeaconState) (state.BeaconState, error) {
-	currentEpoch := core.CurrentEpoch(state)
+	currentEpoch := time.CurrentEpoch(state)
 	nextEpoch := currentEpoch + 1
 
 	// Set total slashed balances.
@@ -339,7 +342,7 @@ func ProcessSlashingsReset(state state.BeaconState) (state.BeaconState, error) {
 //    # Set randao mix
 //    state.randao_mixes[next_epoch % EPOCHS_PER_HISTORICAL_VECTOR] = get_randao_mix(state, current_epoch)
 func ProcessRandaoMixesReset(state state.BeaconState) (state.BeaconState, error) {
-	currentEpoch := core.CurrentEpoch(state)
+	currentEpoch := time.CurrentEpoch(state)
 	nextEpoch := currentEpoch + 1
 
 	// Set RANDAO mix.
@@ -372,7 +375,7 @@ func ProcessRandaoMixesReset(state state.BeaconState) (state.BeaconState, error)
 //        historical_batch = HistoricalBatch(block_roots=state.block_roots, state_roots=state.state_roots)
 //        state.historical_roots.append(hash_tree_root(historical_batch))
 func ProcessHistoricalRootsUpdate(state state.BeaconState) (state.BeaconState, error) {
-	currentEpoch := core.CurrentEpoch(state)
+	currentEpoch := time.CurrentEpoch(state)
 	nextEpoch := currentEpoch + 1
 
 	// Set historical root accumulator.

beacon-chain/core/epoch/epoch_processing_test.go

@@ -3,13 +3,14 @@ package epoch_test
 import (
 	"context"
 	"fmt"
+	"math"
 	"testing"
 
 	types "github.com/prysmaticlabs/eth2-types"
 	"github.com/prysmaticlabs/go-bitfield"
-	"github.com/prysmaticlabs/prysm/beacon-chain/core"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/epoch"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/helpers"
+	"github.com/prysmaticlabs/prysm/beacon-chain/core/time"
 	"github.com/prysmaticlabs/prysm/beacon-chain/state"
 	v1 "github.com/prysmaticlabs/prysm/beacon-chain/state/v1"
 	"github.com/prysmaticlabs/prysm/config/params"
@@ -242,7 +243,7 @@ func TestProcessSlashings_SlashedLess(t *testing.T) {
 
 func TestProcessFinalUpdates_CanProcess(t *testing.T) {
 	s := buildState(t, params.BeaconConfig().SlotsPerHistoricalRoot-1, uint64(params.BeaconConfig().SlotsPerEpoch))
-	ce := core.CurrentEpoch(s)
+	ce := time.CurrentEpoch(s)
 	ne := ce + 1
 	require.NoError(t, s.SetEth1DataVotes([]*ethpb.Eth1Data{}))
 	balances := s.Balances()
@@ -316,7 +317,7 @@ func TestProcessRegistryUpdates_EligibleToActivate(t *testing.T) {
 	}
 	beaconState, err := v1.InitializeFromProto(base)
 	require.NoError(t, err)
-	currentEpoch := core.CurrentEpoch(beaconState)
+	currentEpoch := time.CurrentEpoch(beaconState)
 	newState, err := epoch.ProcessRegistryUpdates(context.Background(), beaconState)
 	require.NoError(t, err)
 	for i, validator := range newState.Validators() {
@@ -440,3 +441,16 @@ func buildState(t testing.TB, slot types.Slot, validatorCount uint64) state.Beac
 	}
 	return s
 }
+
+func TestProcessSlashings_BadValue(t *testing.T) {
+	base := &ethpb.BeaconState{
+		Slot:       0,
+		Validators: []*ethpb.Validator{{Slashed: true}},
+		Balances:   []uint64{params.BeaconConfig().MaxEffectiveBalance},
+		Slashings:  []uint64{math.MaxUint64, 1e9},
+	}
+	s, err := v1.InitializeFromProto(base)
+	require.NoError(t, err)
+	_, err = epoch.ProcessSlashings(s, params.BeaconConfig().ProportionalSlashingMultiplier)
+	require.ErrorContains(t, "addition overflows", err)
+}

beacon-chain/core/epoch/precompute/BUILD.bazel

@@ -16,14 +16,15 @@ go_library(
         "//testing/spectest:__subpackages__",
     ],
     deps = [
-        "//beacon-chain/core:go_default_library",
         "//beacon-chain/core/helpers:go_default_library",
+        "//beacon-chain/core/time:go_default_library",
         "//beacon-chain/state:go_default_library",
         "//config/params:go_default_library",
         "//math:go_default_library",
         "//monitoring/tracing:go_default_library",
         "//proto/prysm/v1alpha1:go_default_library",
         "//proto/prysm/v1alpha1/attestation:go_default_library",
+        "//time/slots:go_default_library",
         "@com_github_pkg_errors//:go_default_library",
         "@com_github_prysmaticlabs_eth2_types//:go_default_library",
         "@io_opencensus_go//trace:go_default_library",
@@ -41,9 +42,9 @@ go_test(
     ],
     embed = [":go_default_library"],
     deps = [
-        "//beacon-chain/core:go_default_library",
         "//beacon-chain/core/epoch:go_default_library",
         "//beacon-chain/core/helpers:go_default_library",
+        "//beacon-chain/core/time:go_default_library",
         "//beacon-chain/state:go_default_library",
         "//beacon-chain/state/v1:go_default_library",
         "//config/params:go_default_library",

beacon-chain/core/epoch/precompute/attestation.go

@@ -6,8 +6,8 @@ import (
 
 	"github.com/pkg/errors"
 	types "github.com/prysmaticlabs/eth2-types"
-	"github.com/prysmaticlabs/prysm/beacon-chain/core"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/helpers"
+	"github.com/prysmaticlabs/prysm/beacon-chain/core/time"
 	"github.com/prysmaticlabs/prysm/beacon-chain/state"
 	"github.com/prysmaticlabs/prysm/config/params"
 	"github.com/prysmaticlabs/prysm/monitoring/tracing"
@@ -71,7 +71,7 @@ func ProcessAttestations(
 
 // AttestedCurrentEpoch returns true if attestation `a` attested once in current epoch and/or epoch boundary block.
 func AttestedCurrentEpoch(s state.ReadOnlyBeaconState, a *ethpb.PendingAttestation) (bool, bool, error) {
-	currentEpoch := core.CurrentEpoch(s)
+	currentEpoch := time.CurrentEpoch(s)
 	var votedCurrentEpoch, votedTarget bool
 	// Did validator vote current epoch.
 	if a.Data.Target.Epoch == currentEpoch {
@@ -89,7 +89,7 @@ func AttestedCurrentEpoch(s state.ReadOnlyBeaconState, a *ethpb.PendingAttestati
 
 // AttestedPrevEpoch returns true if attestation `a` attested once in previous epoch and epoch boundary block and/or the same head.
 func AttestedPrevEpoch(s state.ReadOnlyBeaconState, a *ethpb.PendingAttestation) (bool, bool, bool, error) {
-	prevEpoch := core.PrevEpoch(s)
+	prevEpoch := time.PrevEpoch(s)
 	var votedPrevEpoch, votedTarget, votedHead bool
 	// Did validator vote previous epoch.
 	if a.Data.Target.Epoch == prevEpoch {

beacon-chain/core/epoch/precompute/justification_finalization.go

@@ -2,10 +2,11 @@ package precompute
 
 import (
 	"github.com/pkg/errors"
-	"github.com/prysmaticlabs/prysm/beacon-chain/core"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/helpers"
+	"github.com/prysmaticlabs/prysm/beacon-chain/core/time"
 	"github.com/prysmaticlabs/prysm/beacon-chain/state"
 	ethpb "github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1"
+	"github.com/prysmaticlabs/prysm/time/slots"
 )
 
 // ProcessJustificationAndFinalizationPreCompute processes justification and finalization during
@@ -25,7 +26,7 @@ import (
 //    current_target_balance = get_attesting_balance(state, current_attestations)
 //    weigh_justification_and_finalization(state, total_active_balance, previous_target_balance, current_target_balance)
 func ProcessJustificationAndFinalizationPreCompute(state state.BeaconState, pBal *Balance) (state.BeaconState, error) {
-	canProcessSlot, err := core.StartSlot(2 /*epoch*/)
+	canProcessSlot, err := slots.EpochStart(2 /*epoch*/)
 	if err != nil {
 		return nil, err
 	}
@@ -78,8 +79,8 @@ func ProcessJustificationAndFinalizationPreCompute(state state.BeaconState, pBal
 //        state.finalized_checkpoint = old_current_justified_checkpoint
 func weighJustificationAndFinalization(state state.BeaconState,
 	totalActiveBalance, prevEpochTargetBalance, currEpochTargetBalance uint64) (state.BeaconState, error) {
-	prevEpoch := core.PrevEpoch(state)
-	currentEpoch := core.CurrentEpoch(state)
+	prevEpoch := time.PrevEpoch(state)
+	currentEpoch := time.CurrentEpoch(state)
 	oldPrevJustifiedCheckpoint := state.PreviousJustifiedCheckpoint()
 	oldCurrJustifiedCheckpoint := state.CurrentJustifiedCheckpoint()
 

beacon-chain/core/epoch/precompute/new.go

@@ -7,8 +7,8 @@ import (
 	"context"
 
 	"github.com/pkg/errors"
-	"github.com/prysmaticlabs/prysm/beacon-chain/core"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/helpers"
+	"github.com/prysmaticlabs/prysm/beacon-chain/core/time"
 	"github.com/prysmaticlabs/prysm/beacon-chain/state"
 	"github.com/prysmaticlabs/prysm/config/params"
 	"go.opencensus.io/trace"
@@ -24,8 +24,8 @@ func New(ctx context.Context, s state.BeaconState) ([]*Validator, *Balance, erro
 	pValidators := make([]*Validator, s.NumValidators())
 	pBal := &Balance{}
 
-	currentEpoch := core.CurrentEpoch(s)
-	prevEpoch := core.PrevEpoch(s)
+	currentEpoch := time.CurrentEpoch(s)
+	prevEpoch := time.PrevEpoch(s)
 
 	if err := s.ReadFromEveryValidator(func(idx int, val state.ReadOnlyValidator) error {
 		// Was validator withdrawable or slashed

beacon-chain/core/epoch/precompute/reward_penalty.go

@@ -3,8 +3,8 @@ package precompute
 import (
 	"github.com/pkg/errors"
 	types "github.com/prysmaticlabs/eth2-types"
-	"github.com/prysmaticlabs/prysm/beacon-chain/core"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/helpers"
+	"github.com/prysmaticlabs/prysm/beacon-chain/core/time"
 	"github.com/prysmaticlabs/prysm/beacon-chain/state"
 	"github.com/prysmaticlabs/prysm/config/params"
 	"github.com/prysmaticlabs/prysm/math"
@@ -23,7 +23,7 @@ func ProcessRewardsAndPenaltiesPrecompute(
 	proRewardsFunc proposerRewardsFunc,
 ) (state.BeaconState, error) {
 	// Can't process rewards and penalties in genesis epoch.
-	if core.CurrentEpoch(state) == 0 {
+	if time.CurrentEpoch(state) == 0 {
 		return state, nil
 	}
 
@@ -47,7 +47,10 @@ func ProcessRewardsAndPenaltiesPrecompute(
 
 		// Compute the post balance of the validator after accounting for the
 		// attester and proposer rewards and penalties.
-		validatorBals[i] = helpers.IncreaseBalanceWithVal(validatorBals[i], attsRewards[i]+proposerRewards[i])
+		validatorBals[i], err = helpers.IncreaseBalanceWithVal(validatorBals[i], attsRewards[i]+proposerRewards[i])
+		if err != nil {
+			return nil, err
+		}
 		validatorBals[i] = helpers.DecreaseBalanceWithVal(validatorBals[i], attsPenalties[i])
 
 		vp[i].AfterEpochTransitionBalance = validatorBals[i]
@@ -66,7 +69,7 @@ func AttestationsDelta(state state.ReadOnlyBeaconState, pBal *Balance, vp []*Val
 	numOfVals := state.NumValidators()
 	rewards := make([]uint64, numOfVals)
 	penalties := make([]uint64, numOfVals)
-	prevEpoch := core.PrevEpoch(state)
+	prevEpoch := time.PrevEpoch(state)
 	finalizedEpoch := state.FinalizedCheckpointEpoch()
 
 	sqrtActiveCurrentEpoch := math.IntegerSquareRoot(pBal.ActiveCurrentEpoch)

beacon-chain/core/epoch/precompute/reward_penalty_test.go

@@ -7,9 +7,9 @@ import (
 	"github.com/pkg/errors"
 	types "github.com/prysmaticlabs/eth2-types"
 	"github.com/prysmaticlabs/go-bitfield"
-	"github.com/prysmaticlabs/prysm/beacon-chain/core"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/epoch"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/helpers"
+	"github.com/prysmaticlabs/prysm/beacon-chain/core/time"
 	"github.com/prysmaticlabs/prysm/beacon-chain/state"
 	v1 "github.com/prysmaticlabs/prysm/beacon-chain/state/v1"
 	"github.com/prysmaticlabs/prysm/config/params"
@@ -246,7 +246,7 @@ func TestProcessRewardsAndPenaltiesPrecompute_SlashedInactivePenalty(t *testing.
 	rewards, penalties, err := AttestationsDelta(beaconState, bp, vp)
 	require.NoError(t, err)
 
-	finalityDelay := core.PrevEpoch(beaconState) - beaconState.FinalizedCheckpointEpoch()
+	finalityDelay := time.PrevEpoch(beaconState) - beaconState.FinalizedCheckpointEpoch()
 	for _, i := range slashedAttestedIndices {
 		base, err := baseReward(beaconState, i)
 		require.NoError(t, err, "Could not get base reward")

beacon-chain/core/epoch/precompute/slashing.go

@@ -2,8 +2,8 @@ package precompute
 
 import (
 	types "github.com/prysmaticlabs/eth2-types"
-	"github.com/prysmaticlabs/prysm/beacon-chain/core"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/helpers"
+	"github.com/prysmaticlabs/prysm/beacon-chain/core/time"
 	"github.com/prysmaticlabs/prysm/beacon-chain/state"
 	"github.com/prysmaticlabs/prysm/config/params"
 	"github.com/prysmaticlabs/prysm/math"
@@ -13,7 +13,7 @@ import (
 // ProcessSlashingsPrecompute processes the slashed validators during epoch processing.
 // This is an optimized version by passing in precomputed total epoch balances.
 func ProcessSlashingsPrecompute(s state.BeaconState, pBal *Balance) error {
-	currentEpoch := core.CurrentEpoch(s)
+	currentEpoch := time.CurrentEpoch(s)
 	exitLength := params.BeaconConfig().EpochsPerSlashingsVector
 
 	// Compute the sum of state slashings

beacon-chain/core/feed/BUILD.bazel

@@ -6,6 +6,6 @@ go_library(
     importpath = "github.com/prysmaticlabs/prysm/beacon-chain/core/feed",
     visibility = [
         "//beacon-chain:__subpackages__",
-        "//shared:__subpackages__",
+        "//testing/slasher/simulator:__subpackages__",
     ],
 )

beacon-chain/core/feed/state/BUILD.bazel

@@ -7,7 +7,10 @@ go_library(
         "notifier.go",
     ],
     importpath = "github.com/prysmaticlabs/prysm/beacon-chain/core/feed/state",
-    visibility = ["//beacon-chain:__subpackages__"],
+    visibility = [
+        "//beacon-chain:__subpackages__",
+        "//testing/slasher/simulator:__subpackages__",
+    ],
     deps = [
         "//async/event:go_default_library",
         "//proto/prysm/v1alpha1/block:go_default_library",

beacon-chain/core/helpers/BUILD.bazel

@@ -18,17 +18,18 @@ go_library(
     visibility = [
         "//beacon-chain:__subpackages__",
         "//contracts/deposit:__pkg__",
+        "//crypto/keystore:__pkg__",
         "//fuzz:__pkg__",
         "//network/forks:__pkg__",
+        "//proto/prysm/v1alpha1:__subpackages__",
         "//proto/prysm/v1alpha1/attestation:__pkg__",
         "//runtime/interop:__pkg__",
-        "//shared/attestationutil:__pkg__",
-        "//shared/keystore:__pkg__",
         "//slasher:__subpackages__",
         "//testing/altair:__pkg__",
         "//testing/benchmark/benchmark_files:__subpackages__",
         "//testing/endtoend/evaluators:__pkg__",
         "//testing/fuzz:__pkg__",
+        "//testing/slasher/simulator:__pkg__",
         "//testing/spectest:__subpackages__",
         "//testing/util:__pkg__",
         "//tools:__subpackages__",
@@ -36,7 +37,7 @@ go_library(
     ],
     deps = [
         "//beacon-chain/cache:go_default_library",
-        "//beacon-chain/core:go_default_library",
+        "//beacon-chain/core/time:go_default_library",
         "//beacon-chain/state:go_default_library",
         "//config/params:go_default_library",
         "//container/slice:go_default_library",
@@ -48,6 +49,7 @@ go_library(
         "//proto/prysm/v1alpha1:go_default_library",
         "//proto/prysm/v1alpha1/block:go_default_library",
         "//time:go_default_library",
+        "//time/slots: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",
@@ -75,7 +77,7 @@ go_test(
     shard_count = 2,
     deps = [
         "//beacon-chain/cache:go_default_library",
-        "//beacon-chain/core:go_default_library",
+        "//beacon-chain/core/time:go_default_library",
         "//beacon-chain/state:go_default_library",
         "//beacon-chain/state/v1:go_default_library",
         "//beacon-chain/state/v2:go_default_library",
@@ -90,6 +92,7 @@ go_test(
         "//testing/require:go_default_library",
         "//testing/util:go_default_library",
         "//time:go_default_library",
+        "//time/slots:go_default_library",
         "@com_github_prysmaticlabs_eth2_types//:go_default_library",
         "@com_github_prysmaticlabs_go_bitfield//:go_default_library",
     ],

beacon-chain/core/helpers/attestation.go

@@ -7,12 +7,12 @@ import (
 	"time"
 
 	types "github.com/prysmaticlabs/eth2-types"
-	"github.com/prysmaticlabs/prysm/beacon-chain/core"
 	"github.com/prysmaticlabs/prysm/config/params"
 	"github.com/prysmaticlabs/prysm/crypto/bls"
 	"github.com/prysmaticlabs/prysm/crypto/hash"
 	ethpb "github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1"
 	prysmTime "github.com/prysmaticlabs/prysm/time"
+	"github.com/prysmaticlabs/prysm/time/slots"
 )
 
 // ValidateNilAttestation checks if any composite field of input attestation is nil.
@@ -40,7 +40,7 @@ func ValidateNilAttestation(attestation *ethpb.Attestation) error {
 // ValidateSlotTargetEpoch checks if attestation data's epoch matches target checkpoint's epoch.
 // It is recommended to run `ValidateNilAttestation` first to ensure `data.Target` can't be nil.
 func ValidateSlotTargetEpoch(data *ethpb.AttestationData) error {
-	if core.SlotToEpoch(data.Slot) != data.Target.Epoch {
+	if slots.ToEpoch(data.Slot) != data.Target.Epoch {
 		return fmt.Errorf("slot %d does not match target epoch %d", data.Slot, data.Target.Epoch)
 	}
 	return nil
@@ -121,7 +121,7 @@ func ComputeSubnetForAttestation(activeValCount uint64, att *ethpb.Attestation)
 //
 //    return uint64((committees_since_epoch_start + committee_index) % ATTESTATION_SUBNET_COUNT)
 func ComputeSubnetFromCommitteeAndSlot(activeValCount uint64, comIdx types.CommitteeIndex, attSlot types.Slot) uint64 {
-	slotSinceStart := core.SlotsSinceEpochStarts(attSlot)
+	slotSinceStart := slots.SinceEpochStarts(attSlot)
 	comCount := SlotCommitteeCount(activeValCount)
 	commsSinceStart := uint64(slotSinceStart.Mul(comCount))
 	computedSubnet := (commsSinceStart + uint64(comIdx)) % params.BeaconNetworkConfig().AttestationSubnetCount
@@ -142,14 +142,14 @@ func ComputeSubnetFromCommitteeAndSlot(activeValCount uint64, comIdx types.Commi
 //   valid_attestation_slot = 101
 // In the attestation must be within the range of 95 to 102 in the example above.
 func ValidateAttestationTime(attSlot types.Slot, genesisTime time.Time, clockDisparity time.Duration) error {
-	if err := core.ValidateSlotClock(attSlot, uint64(genesisTime.Unix())); err != nil {
+	if err := slots.ValidateClock(attSlot, uint64(genesisTime.Unix())); err != nil {
 		return err
 	}
-	attTime, err := core.SlotToTime(uint64(genesisTime.Unix()), attSlot)
+	attTime, err := slots.ToTime(uint64(genesisTime.Unix()), attSlot)
 	if err != nil {
 		return err
 	}
-	currentSlot := core.SlotsSince(genesisTime)
+	currentSlot := slots.Since(genesisTime)
 
 	// When receiving an attestation, it can be from the future.
 	// so the upper bounds is set to now + clockDisparity(SECONDS_PER_SLOT * 2).
@@ -163,7 +163,7 @@ func ValidateAttestationTime(attSlot types.Slot, genesisTime time.Time, clockDis
 	if currentSlot > params.BeaconNetworkConfig().AttestationPropagationSlotRange {
 		lowerBoundsSlot = currentSlot - params.BeaconNetworkConfig().AttestationPropagationSlotRange
 	}
-	lowerTime, err := core.SlotToTime(uint64(genesisTime.Unix()), lowerBoundsSlot)
+	lowerTime, err := slots.ToTime(uint64(genesisTime.Unix()), lowerBoundsSlot)
 	if err != nil {
 		return err
 	}
@@ -187,7 +187,7 @@ func VerifyCheckpointEpoch(c *ethpb.Checkpoint, genesis time.Time) bool {
 	now := uint64(prysmTime.Now().Unix())
 	genesisTime := uint64(genesis.Unix())
 	currentSlot := types.Slot((now - genesisTime) / params.BeaconConfig().SecondsPerSlot)
-	currentEpoch := core.SlotToEpoch(currentSlot)
+	currentEpoch := slots.ToEpoch(currentSlot)
 
 	var prevEpoch types.Epoch
 	if currentEpoch > 1 {

beacon-chain/core/helpers/attestation_test.go

@@ -7,7 +7,6 @@ import (
 	"time"
 
 	types "github.com/prysmaticlabs/eth2-types"
-	"github.com/prysmaticlabs/prysm/beacon-chain/core"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/helpers"
 	v1 "github.com/prysmaticlabs/prysm/beacon-chain/state/v1"
 	"github.com/prysmaticlabs/prysm/config/params"
@@ -18,6 +17,7 @@ import (
 	"github.com/prysmaticlabs/prysm/testing/require"
 	"github.com/prysmaticlabs/prysm/testing/util"
 	prysmTime "github.com/prysmaticlabs/prysm/time"
+	"github.com/prysmaticlabs/prysm/time/slots"
 )
 
 func TestAttestation_IsAggregator(t *testing.T) {
@@ -118,7 +118,7 @@ func TestAttestation_ComputeSubnetForAttestation(t *testing.T) {
 		},
 		Signature: []byte{'B'},
 	}
-	valCount, err := helpers.ActiveValidatorCount(context.Background(), state, core.SlotToEpoch(att.Data.Slot))
+	valCount, err := helpers.ActiveValidatorCount(context.Background(), state, slots.ToEpoch(att.Data.Slot))
 	require.NoError(t, err)
 	sub := helpers.ComputeSubnetForAttestation(valCount, att)
 	assert.Equal(t, uint64(6), sub, "Did not get correct subnet for attestation")

beacon-chain/core/helpers/beacon_committee.go

@@ -12,7 +12,7 @@ import (
 	types "github.com/prysmaticlabs/eth2-types"
 	"github.com/prysmaticlabs/go-bitfield"
 	"github.com/prysmaticlabs/prysm/beacon-chain/cache"
-	"github.com/prysmaticlabs/prysm/beacon-chain/core"
+	"github.com/prysmaticlabs/prysm/beacon-chain/core/time"
 	"github.com/prysmaticlabs/prysm/beacon-chain/state"
 	"github.com/prysmaticlabs/prysm/config/params"
 	"github.com/prysmaticlabs/prysm/container/slice"
@@ -20,6 +20,7 @@ import (
 	"github.com/prysmaticlabs/prysm/encoding/bytesutil"
 	"github.com/prysmaticlabs/prysm/math"
 	ethpb "github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1"
+	"github.com/prysmaticlabs/prysm/time/slots"
 )
 
 var (
@@ -73,7 +74,7 @@ func SlotCommitteeCount(activeValidatorCount uint64) uint64 {
 //        count=committees_per_slot * SLOTS_PER_EPOCH,
 //    )
 func BeaconCommitteeFromState(ctx context.Context, state state.ReadOnlyBeaconState, slot types.Slot, committeeIndex types.CommitteeIndex) ([]types.ValidatorIndex, error) {
-	epoch := core.SlotToEpoch(slot)
+	epoch := slots.ToEpoch(slot)
 	seed, err := Seed(state, epoch, params.BeaconConfig().DomainBeaconAttester)
 	if err != nil {
 		return nil, errors.Wrap(err, "could not get seed")
@@ -157,7 +158,7 @@ func CommitteeAssignments(
 	state state.BeaconState,
 	epoch types.Epoch,
 ) (map[types.ValidatorIndex]*CommitteeAssignmentContainer, map[types.ValidatorIndex][]types.Slot, error) {
-	nextEpoch := core.NextEpoch(state)
+	nextEpoch := time.NextEpoch(state)
 	if epoch > nextEpoch {
 		return nil, nil, fmt.Errorf(
 			"epoch %d can't be greater than next epoch %d",
@@ -169,7 +170,7 @@ func CommitteeAssignments(
 	// We determine the slots in which proposers are supposed to act.
 	// Some validators may need to propose multiple times per epoch, so
 	// we use a map of proposer idx -> []slot to keep track of this possibility.
-	startSlot, err := core.StartSlot(epoch)
+	startSlot, err := slots.EpochStart(epoch)
 	if err != nil {
 		return nil, nil, err
 	}
@@ -318,18 +319,15 @@ func UpdateCommitteeCache(state state.ReadOnlyBeaconState, epoch types.Epoch) er
 
 // UpdateProposerIndicesInCache updates proposer indices entry of the committee cache.
 func UpdateProposerIndicesInCache(ctx context.Context, state state.ReadOnlyBeaconState) error {
-	// The cache uses the state root at the (current epoch - 2)'s slot as key. (e.g. for epoch 2, the key is root at slot 31)
+	// The cache uses the state root at the (current epoch - 1)'s slot as key. (e.g. for epoch 2, the key is root at slot 63)
 	// Which is the reason why we skip genesis epoch.
-	if core.CurrentEpoch(state) <= params.BeaconConfig().GenesisEpoch+params.BeaconConfig().MinSeedLookahead {
+	if time.CurrentEpoch(state) <= params.BeaconConfig().GenesisEpoch+params.BeaconConfig().MinSeedLookahead {
 		return nil
 	}
 
-	// Use state root from (current_epoch - 1 - lookahead))
-	wantedEpoch := core.CurrentEpoch(state) - 1
-	if wantedEpoch >= params.BeaconConfig().MinSeedLookahead {
-		wantedEpoch -= params.BeaconConfig().MinSeedLookahead
-	}
-	s, err := core.EndSlot(wantedEpoch)
+	// Use state root from (current_epoch - 1))
+	wantedEpoch := time.PrevEpoch(state)
+	s, err := slots.EpochEnd(wantedEpoch)
 	if err != nil {
 		return err
 	}
@@ -350,7 +348,7 @@ func UpdateProposerIndicesInCache(ctx context.Context, state state.ReadOnlyBeaco
 		return nil
 	}
 
-	indices, err := ActiveValidatorIndices(ctx, state, core.CurrentEpoch(state))
+	indices, err := ActiveValidatorIndices(ctx, state, time.CurrentEpoch(state))
 	if err != nil {
 		return err
 	}
@@ -418,12 +416,12 @@ func precomputeProposerIndices(state state.ReadOnlyBeaconState, activeIndices []
 	hashFunc := hash.CustomSHA256Hasher()
 	proposerIndices := make([]types.ValidatorIndex, params.BeaconConfig().SlotsPerEpoch)
 
-	e := core.CurrentEpoch(state)
+	e := time.CurrentEpoch(state)
 	seed, err := Seed(state, e, params.BeaconConfig().DomainBeaconProposer)
 	if err != nil {
 		return nil, errors.Wrap(err, "could not generate seed")
 	}
-	slot, err := core.StartSlot(e)
+	slot, err := slots.EpochStart(e)
 	if err != nil {
 		return nil, err
 	}

beacon-chain/core/helpers/beacon_committee_test.go

@@ -8,7 +8,7 @@ import (
 
 	types "github.com/prysmaticlabs/eth2-types"
 	"github.com/prysmaticlabs/go-bitfield"
-	"github.com/prysmaticlabs/prysm/beacon-chain/core"
+	"github.com/prysmaticlabs/prysm/beacon-chain/core/time"
 	v1 "github.com/prysmaticlabs/prysm/beacon-chain/state/v1"
 	"github.com/prysmaticlabs/prysm/config/params"
 	"github.com/prysmaticlabs/prysm/container/slice"
@@ -17,6 +17,7 @@ import (
 	ethpb "github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1"
 	"github.com/prysmaticlabs/prysm/testing/assert"
 	"github.com/prysmaticlabs/prysm/testing/require"
+	"github.com/prysmaticlabs/prysm/time/slots"
 )
 
 func TestComputeCommittee_WithoutCache(t *testing.T) {
@@ -44,7 +45,7 @@ func TestComputeCommittee_WithoutCache(t *testing.T) {
 	})
 	require.NoError(t, err)
 
-	epoch := core.CurrentEpoch(state)
+	epoch := time.CurrentEpoch(state)
 	indices, err := ActiveValidatorIndices(context.Background(), state, epoch)
 	require.NoError(t, err)
 	seed, err := Seed(state, epoch, params.BeaconConfig().DomainBeaconAttester)
@@ -190,7 +191,7 @@ func TestCommitteeAssignments_CanRetrieve(t *testing.T) {
 	for i, tt := range tests {
 		t.Run(fmt.Sprintf("%d", i), func(t *testing.T) {
 			ClearCache()
-			validatorIndexToCommittee, proposerIndexToSlots, err := CommitteeAssignments(context.Background(), state, core.SlotToEpoch(tt.slot))
+			validatorIndexToCommittee, proposerIndexToSlots, err := CommitteeAssignments(context.Background(), state, slots.ToEpoch(tt.slot))
 			require.NoError(t, err, "Failed to determine CommitteeAssignments")
 			cac := validatorIndexToCommittee[tt.index]
 			assert.Equal(t, tt.committeeIndex, cac.CommitteeIndex, "Unexpected committeeIndex for validator index %d", tt.index)
@@ -225,11 +226,11 @@ func TestCommitteeAssignments_CannotRetrieveFuture(t *testing.T) {
 		RandaoMixes: make([][]byte, params.BeaconConfig().EpochsPerHistoricalVector),
 	})
 	require.NoError(t, err)
-	_, proposerIndxs, err := CommitteeAssignments(context.Background(), state, core.CurrentEpoch(state))
+	_, proposerIndxs, err := CommitteeAssignments(context.Background(), state, time.CurrentEpoch(state))
 	require.NoError(t, err)
 	require.NotEqual(t, 0, len(proposerIndxs), "wanted non-zero proposer index set")
 
-	_, proposerIndxs, err = CommitteeAssignments(context.Background(), state, core.CurrentEpoch(state)+1)
+	_, proposerIndxs, err = CommitteeAssignments(context.Background(), state, time.CurrentEpoch(state)+1)
 	require.NoError(t, err)
 	require.Equal(t, 0, len(proposerIndxs), "wanted empty proposer index set")
 }
@@ -261,9 +262,9 @@ func TestCommitteeAssignments_EverySlotHasMin1Proposer(t *testing.T) {
 		}
 	}
 	assert.Equal(t, uint64(params.BeaconConfig().SlotsPerEpoch), uint64(len(slotsWithProposers)), "Unexpected slots")
-	startSlot, err := core.StartSlot(epoch)
+	startSlot, err := slots.EpochStart(epoch)
 	require.NoError(t, err)
-	endSlot, err := core.StartSlot(epoch + 1)
+	endSlot, err := slots.EpochStart(epoch + 1)
 	require.NoError(t, err)
 	for i := startSlot; i < endSlot; i++ {
 		hasProposer := slotsWithProposers[i]
@@ -385,7 +386,7 @@ func TestUpdateCommitteeCache_CanUpdate(t *testing.T) {
 		RandaoMixes: make([][]byte, params.BeaconConfig().EpochsPerHistoricalVector),
 	})
 	require.NoError(t, err)
-	require.NoError(t, UpdateCommitteeCache(state, core.CurrentEpoch(state)))
+	require.NoError(t, UpdateCommitteeCache(state, time.CurrentEpoch(state)))
 
 	epoch := types.Epoch(1)
 	idx := types.CommitteeIndex(1)
@@ -410,7 +411,7 @@ func BenchmarkComputeCommittee300000_WithPreCache(b *testing.B) {
 	})
 	require.NoError(b, err)
 
-	epoch := core.CurrentEpoch(state)
+	epoch := time.CurrentEpoch(state)
 	indices, err := ActiveValidatorIndices(context.Background(), state, epoch)
 	require.NoError(b, err)
 	seed, err := Seed(state, epoch, params.BeaconConfig().DomainBeaconAttester)
@@ -444,7 +445,7 @@ func BenchmarkComputeCommittee3000000_WithPreCache(b *testing.B) {
 	})
 	require.NoError(b, err)
 
-	epoch := core.CurrentEpoch(state)
+	epoch := time.CurrentEpoch(state)
 	indices, err := ActiveValidatorIndices(context.Background(), state, epoch)
 	require.NoError(b, err)
 	seed, err := Seed(state, epoch, params.BeaconConfig().DomainBeaconAttester)
@@ -478,7 +479,7 @@ func BenchmarkComputeCommittee128000_WithOutPreCache(b *testing.B) {
 	})
 	require.NoError(b, err)
 
-	epoch := core.CurrentEpoch(state)
+	epoch := time.CurrentEpoch(state)
 	indices, err := ActiveValidatorIndices(context.Background(), state, epoch)
 	require.NoError(b, err)
 	seed, err := Seed(state, epoch, params.BeaconConfig().DomainBeaconAttester)
@@ -513,7 +514,7 @@ func BenchmarkComputeCommittee1000000_WithOutCache(b *testing.B) {
 	})
 	require.NoError(b, err)
 
-	epoch := core.CurrentEpoch(state)
+	epoch := time.CurrentEpoch(state)
 	indices, err := ActiveValidatorIndices(context.Background(), state, epoch)
 	require.NoError(b, err)
 	seed, err := Seed(state, epoch, params.BeaconConfig().DomainBeaconAttester)
@@ -548,7 +549,7 @@ func BenchmarkComputeCommittee4000000_WithOutCache(b *testing.B) {
 	})
 	require.NoError(b, err)
 
-	epoch := core.CurrentEpoch(state)
+	epoch := time.CurrentEpoch(state)
 	indices, err := ActiveValidatorIndices(context.Background(), state, epoch)
 	require.NoError(b, err)
 	seed, err := Seed(state, epoch, params.BeaconConfig().DomainBeaconAttester)

beacon-chain/core/helpers/block.go

@@ -5,10 +5,10 @@ import (
 
 	"github.com/pkg/errors"
 	types "github.com/prysmaticlabs/eth2-types"
-	"github.com/prysmaticlabs/prysm/beacon-chain/core"
 	"github.com/prysmaticlabs/prysm/beacon-chain/state"
 	"github.com/prysmaticlabs/prysm/config/params"
 	"github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1/block"
+	"github.com/prysmaticlabs/prysm/time/slots"
 )
 
 // VerifyNilBeaconBlock checks if any composite field of input signed beacon block is nil.
@@ -65,7 +65,7 @@ func StateRootAtSlot(state state.ReadOnlyBeaconState, slot types.Slot) ([]byte,
 //    """
 //    return get_block_root_at_slot(state, compute_start_slot_at_epoch(epoch))
 func BlockRoot(state state.ReadOnlyBeaconState, epoch types.Epoch) ([]byte, error) {
-	s, err := core.StartSlot(epoch)
+	s, err := slots.EpochStart(epoch)
 	if err != nil {
 		return nil, err
 	}

beacon-chain/core/helpers/rewards_penalties.go

@@ -5,9 +5,10 @@ import (
 
 	types "github.com/prysmaticlabs/eth2-types"
 	"github.com/prysmaticlabs/prysm/beacon-chain/cache"
-	"github.com/prysmaticlabs/prysm/beacon-chain/core"
 	"github.com/prysmaticlabs/prysm/beacon-chain/state"
 	"github.com/prysmaticlabs/prysm/config/params"
+	mathutil "github.com/prysmaticlabs/prysm/math"
+	"github.com/prysmaticlabs/prysm/time/slots"
 )
 
 var balanceCache = cache.NewEffectiveBalanceCache()
@@ -65,7 +66,7 @@ func TotalActiveBalance(s state.ReadOnlyBeaconState) (uint64, error) {
 	}
 
 	total := uint64(0)
-	epoch := core.SlotToEpoch(s.Slot())
+	epoch := slots.ToEpoch(s.Slot())
 	if err := s.ReadFromEveryValidator(func(idx int, val state.ReadOnlyValidator) error {
 		if IsActiveValidatorUsingTrie(val, epoch) {
 			total += val.EffectiveBalance()
@@ -95,7 +96,11 @@ func IncreaseBalance(state state.BeaconState, idx types.ValidatorIndex, delta ui
 	if err != nil {
 		return err
 	}
-	return state.UpdateBalancesAtIndex(idx, IncreaseBalanceWithVal(balAtIdx, delta))
+	newBal, err := IncreaseBalanceWithVal(balAtIdx, delta)
+	if err != nil {
+		return err
+	}
+	return state.UpdateBalancesAtIndex(idx, newBal)
 }
 
 // IncreaseBalanceWithVal increases validator with the given 'index' balance by 'delta' in Gwei.
@@ -108,8 +113,8 @@ func IncreaseBalance(state state.BeaconState, idx types.ValidatorIndex, delta ui
 //    Increase the validator balance at index ``index`` by ``delta``.
 //    """
 //    state.balances[index] += delta
-func IncreaseBalanceWithVal(currBalance, delta uint64) uint64 {
-	return currBalance + delta
+func IncreaseBalanceWithVal(currBalance, delta uint64) (uint64, error) {
+	return mathutil.Add64(currBalance, delta)
 }
 
 // DecreaseBalance decreases validator with the given 'index' balance by 'delta' in Gwei.

beacon-chain/core/helpers/rewards_penalties_test.go

@@ -1,10 +1,11 @@
 package helpers
 
 import (
+	"math"
 	"testing"
 
 	types "github.com/prysmaticlabs/eth2-types"
-	"github.com/prysmaticlabs/prysm/beacon-chain/core"
+	"github.com/prysmaticlabs/prysm/beacon-chain/core/time"
 	v1 "github.com/prysmaticlabs/prysm/beacon-chain/state/v1"
 	"github.com/prysmaticlabs/prysm/config/features"
 	"github.com/prysmaticlabs/prysm/config/params"
@@ -157,24 +158,24 @@ func TestFinalityDelay(t *testing.T) {
 	finalizedEpoch := types.Epoch(0)
 	// Set values for each test case
 	setVal := func() {
-		prevEpoch = core.PrevEpoch(beaconState)
+		prevEpoch = time.PrevEpoch(beaconState)
 		finalizedEpoch = beaconState.FinalizedCheckpointEpoch()
 	}
 	setVal()
 	d := FinalityDelay(prevEpoch, finalizedEpoch)
-	w := core.PrevEpoch(beaconState) - beaconState.FinalizedCheckpointEpoch()
+	w := time.PrevEpoch(beaconState) - beaconState.FinalizedCheckpointEpoch()
 	assert.Equal(t, w, d, "Did not get wanted finality delay")
 
 	require.NoError(t, beaconState.SetFinalizedCheckpoint(&ethpb.Checkpoint{Epoch: 4}))
 	setVal()
 	d = FinalityDelay(prevEpoch, finalizedEpoch)
-	w = core.PrevEpoch(beaconState) - beaconState.FinalizedCheckpointEpoch()
+	w = time.PrevEpoch(beaconState) - beaconState.FinalizedCheckpointEpoch()
 	assert.Equal(t, w, d, "Did not get wanted finality delay")
 
 	require.NoError(t, beaconState.SetFinalizedCheckpoint(&ethpb.Checkpoint{Epoch: 5}))
 	setVal()
 	d = FinalityDelay(prevEpoch, finalizedEpoch)
-	w = core.PrevEpoch(beaconState) - beaconState.FinalizedCheckpointEpoch()
+	w = time.PrevEpoch(beaconState) - beaconState.FinalizedCheckpointEpoch()
 	assert.Equal(t, w, d, "Did not get wanted finality delay")
 }
 
@@ -187,7 +188,7 @@ func TestIsInInactivityLeak(t *testing.T) {
 	finalizedEpoch := types.Epoch(0)
 	// Set values for each test case
 	setVal := func() {
-		prevEpoch = core.PrevEpoch(beaconState)
+		prevEpoch = time.PrevEpoch(beaconState)
 		finalizedEpoch = beaconState.FinalizedCheckpointEpoch()
 	}
 	setVal()
@@ -238,3 +239,23 @@ func buildState(slot types.Slot, validatorCount uint64) *ethpb.BeaconState {
 		CurrentJustifiedCheckpoint:  &ethpb.Checkpoint{Root: make([]byte, 32)},
 	}
 }
+
+func TestIncreaseBadBalance_NotOK(t *testing.T) {
+	tests := []struct {
+		i  types.ValidatorIndex
+		b  []uint64
+		nb uint64
+	}{
+		{i: 0, b: []uint64{math.MaxUint64, math.MaxUint64, math.MaxUint64}, nb: 1},
+		{i: 2, b: []uint64{math.MaxUint64, math.MaxUint64, math.MaxUint64}, nb: 33 * 1e9},
+	}
+	for _, test := range tests {
+		state, err := v1.InitializeFromProto(&ethpb.BeaconState{
+			Validators: []*ethpb.Validator{
+				{EffectiveBalance: 4}, {EffectiveBalance: 4}, {EffectiveBalance: 4}},
+			Balances: test.b,
+		})
+		require.NoError(t, err)
+		require.ErrorContains(t, "addition overflows", IncreaseBalance(state, test.i, test.nb))
+	}
+}

beacon-chain/core/helpers/sync_committee.go

@@ -8,10 +8,11 @@ import (
 	"github.com/pkg/errors"
 	types "github.com/prysmaticlabs/eth2-types"
 	"github.com/prysmaticlabs/prysm/beacon-chain/cache"
-	"github.com/prysmaticlabs/prysm/beacon-chain/core"
+	"github.com/prysmaticlabs/prysm/beacon-chain/core/time"
 	"github.com/prysmaticlabs/prysm/beacon-chain/state"
 	"github.com/prysmaticlabs/prysm/config/params"
 	"github.com/prysmaticlabs/prysm/encoding/bytesutil"
+	"github.com/prysmaticlabs/prysm/time/slots"
 	log "github.com/sirupsen/logrus"
 )
 
@@ -154,7 +155,7 @@ func UpdateSyncCommitteeCache(st state.BeaconStateAltair) error {
 	if nextSlot%params.BeaconConfig().SlotsPerEpoch != 0 {
 		return errors.New("not at the end of the epoch to update cache")
 	}
-	if core.SlotToEpoch(nextSlot)%params.BeaconConfig().EpochsPerSyncCommitteePeriod != 0 {
+	if slots.ToEpoch(nextSlot)%params.BeaconConfig().EpochsPerSyncCommitteePeriod != 0 {
 		return errors.New("not at sync committee period boundary to update cache")
 	}
 
@@ -191,11 +192,11 @@ func syncPeriodBoundaryRoot(st state.ReadOnlyBeaconState) ([]byte, error) {
 		return params.BeaconConfig().ZeroHash[:], nil
 	}
 
-	startEpoch, err := core.SyncCommitteePeriodStartEpoch(core.CurrentEpoch(st))
+	startEpoch, err := slots.SyncCommitteePeriodStartEpoch(time.CurrentEpoch(st))
 	if err != nil {
 		return nil, err
 	}
-	startEpochSlot, err := core.StartSlot(startEpoch)
+	startEpochSlot, err := slots.EpochStart(startEpoch)
 	if err != nil {
 		return nil, err
 	}

beacon-chain/core/helpers/validators.go

@@ -9,12 +9,13 @@ import (
 	"github.com/prometheus/client_golang/prometheus/promauto"
 	types "github.com/prysmaticlabs/eth2-types"
 	"github.com/prysmaticlabs/prysm/beacon-chain/cache"
-	"github.com/prysmaticlabs/prysm/beacon-chain/core"
+	"github.com/prysmaticlabs/prysm/beacon-chain/core/time"
 	"github.com/prysmaticlabs/prysm/beacon-chain/state"
 	"github.com/prysmaticlabs/prysm/config/params"
 	"github.com/prysmaticlabs/prysm/crypto/hash"
 	"github.com/prysmaticlabs/prysm/encoding/bytesutil"
 	ethpb "github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1"
+	"github.com/prysmaticlabs/prysm/time/slots"
 	log "github.com/sirupsen/logrus"
 )
 
@@ -224,15 +225,12 @@ func ValidatorChurnLimit(activeValidatorCount uint64) (uint64, error) {
 //    indices = get_active_validator_indices(state, epoch)
 //    return compute_proposer_index(state, indices, seed)
 func BeaconProposerIndex(ctx context.Context, state state.ReadOnlyBeaconState) (types.ValidatorIndex, error) {
-	e := core.CurrentEpoch(state)
+	e := time.CurrentEpoch(state)
 	// The cache uses the state root of the previous epoch - minimum_seed_lookahead last slot as key. (e.g. Starting epoch 1, slot 32, the key would be block root at slot 31)
 	// For simplicity, the node will skip caching of genesis epoch.
 	if e > params.BeaconConfig().GenesisEpoch+params.BeaconConfig().MinSeedLookahead {
-		wantedEpoch := core.PrevEpoch(state)
-		if wantedEpoch >= params.BeaconConfig().MinSeedLookahead {
-			wantedEpoch -= params.BeaconConfig().MinSeedLookahead
-		}
-		s, err := core.EndSlot(wantedEpoch)
+		wantedEpoch := time.PrevEpoch(state)
+		s, err := slots.EpochEnd(wantedEpoch)
 		if err != nil {
 			return 0, err
 		}

beacon-chain/core/helpers/validators_test.go

@@ -7,7 +7,7 @@ import (
 
 	types "github.com/prysmaticlabs/eth2-types"
 	"github.com/prysmaticlabs/prysm/beacon-chain/cache"
-	"github.com/prysmaticlabs/prysm/beacon-chain/core"
+	"github.com/prysmaticlabs/prysm/beacon-chain/core/time"
 	v1 "github.com/prysmaticlabs/prysm/beacon-chain/state/v1"
 	"github.com/prysmaticlabs/prysm/config/params"
 	"github.com/prysmaticlabs/prysm/crypto/hash"
@@ -376,7 +376,7 @@ func TestActiveValidatorCount_Genesis(t *testing.T) {
 	seed, err := Seed(beaconState, 0, params.BeaconConfig().DomainBeaconAttester)
 	require.NoError(t, err)
 	require.NoError(t, committeeCache.AddCommitteeShuffledList(&cache.Committees{Seed: seed, ShuffledIndices: []types.ValidatorIndex{1, 2, 3}}))
-	validatorCount, err := ActiveValidatorCount(context.Background(), beaconState, core.CurrentEpoch(beaconState))
+	validatorCount, err := ActiveValidatorCount(context.Background(), beaconState, time.CurrentEpoch(beaconState))
 	require.NoError(t, err)
 	assert.Equal(t, uint64(c), validatorCount, "Did not get the correct validator count")
 }
@@ -407,7 +407,7 @@ func TestChurnLimit_OK(t *testing.T) {
 			RandaoMixes: make([][]byte, params.BeaconConfig().EpochsPerHistoricalVector),
 		})
 		require.NoError(t, err)
-		validatorCount, err := ActiveValidatorCount(context.Background(), beaconState, core.CurrentEpoch(beaconState))
+		validatorCount, err := ActiveValidatorCount(context.Background(), beaconState, time.CurrentEpoch(beaconState))
 		require.NoError(t, err)
 		resultChurn, err := ValidatorChurnLimit(validatorCount)
 		require.NoError(t, err)

beacon-chain/core/helpers/weak_subjectivity.go

@@ -10,11 +10,12 @@ import (
 	"strings"
 
 	types "github.com/prysmaticlabs/eth2-types"
-	"github.com/prysmaticlabs/prysm/beacon-chain/core"
+	"github.com/prysmaticlabs/prysm/beacon-chain/core/time"
 	"github.com/prysmaticlabs/prysm/beacon-chain/state"
 	"github.com/prysmaticlabs/prysm/config/params"
 	"github.com/prysmaticlabs/prysm/math"
 	eth "github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1"
+	"github.com/prysmaticlabs/prysm/time/slots"
 )
 
 // ComputeWeakSubjectivityPeriod returns weak subjectivity period for the active validator count and finalized epoch.
@@ -58,7 +59,7 @@ func ComputeWeakSubjectivityPeriod(ctx context.Context, st state.ReadOnlyBeaconS
 	wsp := uint64(params.BeaconConfig().MinValidatorWithdrawabilityDelay)
 
 	// Cardinality of active validator set.
-	N, err := ActiveValidatorCount(ctx, st, core.CurrentEpoch(st))
+	N, err := ActiveValidatorCount(ctx, st, time.CurrentEpoch(st))
 	if err != nil {
 		return 0, fmt.Errorf("cannot obtain active valiadtor count: %w", err)
 	}
@@ -132,9 +133,9 @@ func IsWithinWeakSubjectivityPeriod(
 		return false, fmt.Errorf("state (%#x) and checkpoint (%#x) roots do not match",
 			wsState.LatestBlockHeader().StateRoot, wsCheckpoint.StateRoot)
 	}
-	if core.SlotToEpoch(wsState.Slot()) != wsCheckpoint.Epoch {
+	if slots.ToEpoch(wsState.Slot()) != wsCheckpoint.Epoch {
 		return false, fmt.Errorf("state (%v) and checkpoint (%v) epochs do not match",
-			core.SlotToEpoch(wsState.Slot()), wsCheckpoint.Epoch)
+			slots.ToEpoch(wsState.Slot()), wsCheckpoint.Epoch)
 	}
 
 	// Compare given epoch to state epoch + weak subjectivity period.
@@ -142,7 +143,7 @@ func IsWithinWeakSubjectivityPeriod(
 	if err != nil {
 		return false, fmt.Errorf("cannot compute weak subjectivity period: %w", err)
 	}
-	wsStateEpoch := core.SlotToEpoch(wsState.Slot())
+	wsStateEpoch := slots.ToEpoch(wsState.Slot())
 
 	return currentEpoch <= wsStateEpoch+wsPeriod, nil
 }

beacon-chain/core/signing/BUILD.bazel

@@ -28,8 +28,8 @@ go_test(
     ],
     embed = [":go_default_library"],
     deps = [
-        "//beacon-chain/core:go_default_library",
         "//beacon-chain/core/helpers:go_default_library",
+        "//beacon-chain/core/time:go_default_library",
         "//beacon-chain/state:go_default_library",
         "//config/params:go_default_library",
         "//crypto/bls:go_default_library",

beacon-chain/core/signing/signing_root.go

@@ -64,7 +64,7 @@ func signingData(rootFunc func() ([32]byte, error), domain []byte) ([32]byte, er
 }
 
 // ComputeDomainVerifySigningRoot computes domain and verifies signing root of an object given the beacon state, validator index and signature.
-func ComputeDomainVerifySigningRoot(st state.BeaconState, index types.ValidatorIndex, epoch types.Epoch, obj fssz.HashRoot, domain [4]byte, sig []byte) error {
+func ComputeDomainVerifySigningRoot(st state.ReadOnlyBeaconState, index types.ValidatorIndex, epoch types.Epoch, obj fssz.HashRoot, domain [4]byte, sig []byte) error {
 	v, err := st.ValidatorAtIndex(index)
 	if err != nil {
 		return err

beacon-chain/core/signing/signing_root_test.go

@@ -6,9 +6,9 @@ import (
 	"testing"
 
 	fuzz "github.com/google/gofuzz"
-	"github.com/prysmaticlabs/prysm/beacon-chain/core"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/helpers"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/signing"
+	"github.com/prysmaticlabs/prysm/beacon-chain/core/time"
 	"github.com/prysmaticlabs/prysm/beacon-chain/state"
 	"github.com/prysmaticlabs/prysm/config/params"
 	"github.com/prysmaticlabs/prysm/crypto/bls"
@@ -86,7 +86,7 @@ func TestSigningRoot_ComputeDomainAndSign(t *testing.T) {
 			require.NoError(t, err)
 			block := tt.genBlock(t, beaconState, privKeys)
 			got, err := signing.ComputeDomainAndSign(
-				beaconState, core.CurrentEpoch(beaconState), block, tt.domainType, privKeys[idx])
+				beaconState, time.CurrentEpoch(beaconState), block, tt.domainType, privKeys[idx])
 			require.NoError(t, err)
 			require.DeepEqual(t, tt.want, got, "Incorrect signature")
 		})

beacon-chain/core/slot_epoch.go

@@ -1,238 +0,0 @@
-package core
-
-import (
-	"fmt"
-	"math"
-	"time"
-
-	math2 "github.com/ethereum/go-ethereum/common/math"
-	"github.com/pkg/errors"
-	types "github.com/prysmaticlabs/eth2-types"
-	"github.com/prysmaticlabs/prysm/beacon-chain/state"
-	"github.com/prysmaticlabs/prysm/config/params"
-	"github.com/prysmaticlabs/prysm/runtime/version"
-	prysmTime "github.com/prysmaticlabs/prysm/time"
-)
-
-// MaxSlotBuffer specifies the max buffer given to slots from
-// incoming objects. (24 mins with mainnet spec)
-const MaxSlotBuffer = uint64(1 << 7)
-
-// SlotToEpoch returns the epoch number of the input slot.
-//
-// Spec pseudocode definition:
-//  def compute_epoch_at_slot(slot: Slot) -> Epoch:
-//    """
-//    Return the epoch number at ``slot``.
-//    """
-//    return Epoch(slot // SLOTS_PER_EPOCH)
-func SlotToEpoch(slot types.Slot) types.Epoch {
-	return types.Epoch(slot.DivSlot(params.BeaconConfig().SlotsPerEpoch))
-}
-
-// CurrentEpoch returns the current epoch number calculated from
-// the slot number stored in beacon state.
-//
-// Spec pseudocode definition:
-//  def get_current_epoch(state: BeaconState) -> Epoch:
-//    """
-//    Return the current epoch.
-//    """
-//    return compute_epoch_at_slot(state.slot)
-func CurrentEpoch(state state.ReadOnlyBeaconState) types.Epoch {
-	return SlotToEpoch(state.Slot())
-}
-
-// PrevEpoch returns the previous epoch number calculated from
-// the slot number stored in beacon state. It also checks for
-// underflow condition.
-//
-// Spec pseudocode definition:
-//  def get_previous_epoch(state: BeaconState) -> Epoch:
-//    """`
-//    Return the previous epoch (unless the current epoch is ``GENESIS_EPOCH``).
-//    """
-//    current_epoch = get_current_epoch(state)
-//    return GENESIS_EPOCH if current_epoch == GENESIS_EPOCH else Epoch(current_epoch - 1)
-func PrevEpoch(state state.ReadOnlyBeaconState) types.Epoch {
-	currentEpoch := CurrentEpoch(state)
-	if currentEpoch == 0 {
-		return 0
-	}
-	return currentEpoch - 1
-}
-
-// NextEpoch returns the next epoch number calculated from
-// the slot number stored in beacon state.
-func NextEpoch(state state.ReadOnlyBeaconState) types.Epoch {
-	return SlotToEpoch(state.Slot()) + 1
-}
-
-// AltairCompatible returns if the input state `s` is altair compatible and input epoch `e` is higher equal than fork epoch.
-func AltairCompatible(s state.BeaconState, e types.Epoch) bool {
-	return s.Version() == version.Altair && e >= params.BeaconConfig().AltairForkEpoch
-}
-
-// StartSlot returns the first slot number of the
-// current epoch.
-//
-// Spec pseudocode definition:
-//  def compute_start_slot_at_epoch(epoch: Epoch) -> Slot:
-//    """
-//    Return the start slot of ``epoch``.
-//    """
-//    return Slot(epoch * SLOTS_PER_EPOCH)
-func StartSlot(epoch types.Epoch) (types.Slot, error) {
-	slot, err := params.BeaconConfig().SlotsPerEpoch.SafeMul(uint64(epoch))
-	if err != nil {
-		return slot, errors.Errorf("start slot calculation overflows: %v", err)
-	}
-	return slot, nil
-}
-
-// EndSlot returns the last slot number of the
-// current epoch.
-func EndSlot(epoch types.Epoch) (types.Slot, error) {
-	if epoch == math.MaxUint64 {
-		return 0, errors.New("start slot calculation overflows")
-	}
-	slot, err := StartSlot(epoch + 1)
-	if err != nil {
-		return 0, err
-	}
-	return slot - 1, nil
-}
-
-// IsEpochStart returns true if the given slot number is an epoch starting slot
-// number.
-func IsEpochStart(slot types.Slot) bool {
-	return slot%params.BeaconConfig().SlotsPerEpoch == 0
-}
-
-// IsEpochEnd returns true if the given slot number is an epoch ending slot
-// number.
-func IsEpochEnd(slot types.Slot) bool {
-	return IsEpochStart(slot + 1)
-}
-
-// SlotsSinceEpochStarts returns number of slots since the start of the epoch.
-func SlotsSinceEpochStarts(slot types.Slot) types.Slot {
-	return slot % params.BeaconConfig().SlotsPerEpoch
-}
-
-// VerifySlotTime validates the input slot is not from the future.
-func VerifySlotTime(genesisTime uint64, slot types.Slot, timeTolerance time.Duration) error {
-	slotTime, err := SlotToTime(genesisTime, slot)
-	if err != nil {
-		return err
-	}
-
-	// Defensive check to ensure unreasonable slots are rejected
-	// straight away.
-	if err := ValidateSlotClock(slot, genesisTime); err != nil {
-		return err
-	}
-
-	currentTime := prysmTime.Now()
-	diff := slotTime.Sub(currentTime)
-
-	if diff > timeTolerance {
-		return fmt.Errorf("could not process slot from the future, slot time %s > current time %s", slotTime, currentTime)
-	}
-	return nil
-}
-
-// SlotToTime takes the given slot and genesis time to determine the start time of the slot.
-func SlotToTime(genesisTimeSec uint64, slot types.Slot) (time.Time, error) {
-	timeSinceGenesis, err := slot.SafeMul(params.BeaconConfig().SecondsPerSlot)
-	if err != nil {
-		return time.Unix(0, 0), fmt.Errorf("slot (%d) is in the far distant future: %w", slot, err)
-	}
-	sTime, err := timeSinceGenesis.SafeAdd(genesisTimeSec)
-	if err != nil {
-		return time.Unix(0, 0), fmt.Errorf("slot (%d) is in the far distant future: %w", slot, err)
-	}
-	return time.Unix(int64(sTime), 0), nil
-}
-
-// SlotsSince computes the number of time slots that have occurred since the given timestamp.
-func SlotsSince(time time.Time) types.Slot {
-	return CurrentSlot(uint64(time.Unix()))
-}
-
-// CurrentSlot returns the current slot as determined by the local clock and
-// provided genesis time.
-func CurrentSlot(genesisTimeSec uint64) types.Slot {
-	now := prysmTime.Now().Unix()
-	genesis := int64(genesisTimeSec)
-	if now < genesis {
-		return 0
-	}
-	return types.Slot(uint64(now-genesis) / params.BeaconConfig().SecondsPerSlot)
-}
-
-// ValidateSlotClock validates a provided slot against the local
-// clock to ensure slots that are unreasonable are returned with
-// an error.
-func ValidateSlotClock(slot types.Slot, genesisTimeSec uint64) error {
-	maxPossibleSlot := CurrentSlot(genesisTimeSec).Add(MaxSlotBuffer)
-	// Defensive check to ensure that we only process slots up to a hard limit
-	// from our local clock.
-	if slot > maxPossibleSlot {
-		return fmt.Errorf("slot %d > %d which exceeds max allowed value relative to the local clock", slot, maxPossibleSlot)
-	}
-	return nil
-}
-
-// RoundUpToNearestEpoch rounds up the provided slot value to the nearest epoch.
-func RoundUpToNearestEpoch(slot types.Slot) types.Slot {
-	if slot%params.BeaconConfig().SlotsPerEpoch != 0 {
-		slot -= slot % params.BeaconConfig().SlotsPerEpoch
-		slot += params.BeaconConfig().SlotsPerEpoch
-	}
-	return slot
-}
-
-// VotingPeriodStartTime returns the current voting period's start time
-// depending on the provided genesis and current slot.
-func VotingPeriodStartTime(genesis uint64, slot types.Slot) uint64 {
-	slots := params.BeaconConfig().SlotsPerEpoch.Mul(uint64(params.BeaconConfig().EpochsPerEth1VotingPeriod))
-	startTime := uint64((slot - slot.ModSlot(slots)).Mul(params.BeaconConfig().SecondsPerSlot))
-	return genesis + startTime
-}
-
-// PrevSlot returns previous slot, with an exception in slot 0 to prevent underflow.
-func PrevSlot(slot types.Slot) types.Slot {
-	if slot > 0 {
-		return slot.Sub(1)
-	}
-	return 0
-}
-
-// SyncCommitteePeriod returns the sync committee period of input epoch `e`.
-//
-// Spec code:
-// def compute_sync_committee_period(epoch: Epoch) -> uint64:
-//    return epoch // EPOCHS_PER_SYNC_COMMITTEE_PERIOD
-func SyncCommitteePeriod(e types.Epoch) uint64 {
-	return uint64(e / params.BeaconConfig().EpochsPerSyncCommitteePeriod)
-}
-
-// SyncCommitteePeriodStartEpoch returns the start epoch of a sync committee period.
-func SyncCommitteePeriodStartEpoch(e types.Epoch) (types.Epoch, error) {
-	// Overflow is impossible here because of division of `EPOCHS_PER_SYNC_COMMITTEE_PERIOD`.
-	startEpoch, overflow := math2.SafeMul(SyncCommitteePeriod(e), uint64(params.BeaconConfig().EpochsPerSyncCommitteePeriod))
-	if overflow {
-		return 0, errors.New("start epoch calculation overflow")
-	}
-	return types.Epoch(startEpoch), nil
-}
-
-// CanUpgradeToAltair returns true if the input `slot` can upgrade to Altair.
-// Spec code:
-// If state.slot % SLOTS_PER_EPOCH == 0 and compute_epoch_at_slot(state.slot) == ALTAIR_FORK_EPOCH
-func CanUpgradeToAltair(slot types.Slot) bool {
-	epochStart := IsEpochStart(slot)
-	altairEpoch := SlotToEpoch(slot) == params.BeaconConfig().AltairForkEpoch
-	return epochStart && altairEpoch
-}

beacon-chain/core/time/BUILD.bazel

@@ -3,33 +3,13 @@ load("@prysm//tools/go:def.bzl", "go_library", "go_test")
 go_library(
     name = "go_default_library",
     srcs = ["slot_epoch.go"],
-    importpath = "github.com/prysmaticlabs/prysm/beacon-chain/core",
-    visibility = [
-        "//beacon-chain:__subpackages__",
-        "//contracts/deposit:__pkg__",
-        "//fuzz:__pkg__",
-        "//network/forks:__pkg__",
-        "//proto/prysm/v1alpha1/attestation:__pkg__",
-        "//runtime/interop:__pkg__",
-        "//shared/attestationutil:__pkg__",
-        "//shared/keystore:__pkg__",
-        "//slasher:__subpackages__",
-        "//testing/altair:__pkg__",
-        "//testing/benchmark/benchmark_files:__subpackages__",
-        "//testing/endtoend/evaluators:__pkg__",
-        "//testing/fuzz:__pkg__",
-        "//testing/spectest:__subpackages__",
-        "//testing/util:__pkg__",
-        "//tools:__subpackages__",
-        "//validator:__subpackages__",
-    ],
+    importpath = "github.com/prysmaticlabs/prysm/beacon-chain/core/time",
+    visibility = ["//visibility:public"],
     deps = [
         "//beacon-chain/state:go_default_library",
         "//config/params:go_default_library",
         "//runtime/version:go_default_library",
-        "//time:go_default_library",
-        "@com_github_ethereum_go_ethereum//common/math:go_default_library",
-        "@com_github_pkg_errors//:go_default_library",
+        "//time/slots:go_default_library",
         "@com_github_prysmaticlabs_eth2_types//:go_default_library",
     ],
 )
@@ -45,6 +25,7 @@ go_test(
         "//testing/assert:go_default_library",
         "//testing/require:go_default_library",
         "//time:go_default_library",
+        "//time/slots:go_default_library",
         "@com_github_prysmaticlabs_eth2_types//:go_default_library",
     ],
 )

beacon-chain/core/time/slot_epoch.go

@@ -0,0 +1,61 @@
+package time
+
+import (
+	types "github.com/prysmaticlabs/eth2-types"
+	"github.com/prysmaticlabs/prysm/beacon-chain/state"
+	"github.com/prysmaticlabs/prysm/config/params"
+	"github.com/prysmaticlabs/prysm/runtime/version"
+	"github.com/prysmaticlabs/prysm/time/slots"
+)
+
+// CurrentEpoch returns the current epoch number calculated from
+// the slot number stored in beacon state.
+//
+// Spec pseudocode definition:
+//  def get_current_epoch(state: BeaconState) -> Epoch:
+//    """
+//    Return the current epoch.
+//    """
+//    return compute_epoch_at_slot(state.slot)
+func CurrentEpoch(state state.ReadOnlyBeaconState) types.Epoch {
+	return slots.ToEpoch(state.Slot())
+}
+
+// PrevEpoch returns the previous epoch number calculated from
+// the slot number stored in beacon state. It also checks for
+// underflow condition.
+//
+// Spec pseudocode definition:
+//  def get_previous_epoch(state: BeaconState) -> Epoch:
+//    """`
+//    Return the previous epoch (unless the current epoch is ``GENESIS_EPOCH``).
+//    """
+//    current_epoch = get_current_epoch(state)
+//    return GENESIS_EPOCH if current_epoch == GENESIS_EPOCH else Epoch(current_epoch - 1)
+func PrevEpoch(state state.ReadOnlyBeaconState) types.Epoch {
+	currentEpoch := CurrentEpoch(state)
+	if currentEpoch == 0 {
+		return 0
+	}
+	return currentEpoch - 1
+}
+
+// NextEpoch returns the next epoch number calculated from
+// the slot number stored in beacon state.
+func NextEpoch(state state.ReadOnlyBeaconState) types.Epoch {
+	return slots.ToEpoch(state.Slot()) + 1
+}
+
+// AltairCompatible returns if the input state `s` is altair compatible and input epoch `e` is higher equal than fork epoch.
+func AltairCompatible(s state.BeaconState, e types.Epoch) bool {
+	return s.Version() == version.Altair && e >= params.BeaconConfig().AltairForkEpoch
+}
+
+// CanUpgradeToAltair returns true if the input `slot` can upgrade to Altair.
+// Spec code:
+// If state.slot % SLOTS_PER_EPOCH == 0 and compute_epoch_at_slot(state.slot) == ALTAIR_FORK_EPOCH
+func CanUpgradeToAltair(slot types.Slot) bool {
+	epochStart := slots.IsEpochStart(slot)
+	altairEpoch := slots.ToEpoch(slot) == params.BeaconConfig().AltairForkEpoch
+	return epochStart && altairEpoch
+}

beacon-chain/core/time/slot_epoch_test.go

@@ -1,4 +1,4 @@
-package core
+package time
 
 import (
 	"math"
@@ -12,6 +12,7 @@ import (
 	"github.com/prysmaticlabs/prysm/testing/assert"
 	"github.com/prysmaticlabs/prysm/testing/require"
 	prysmTime "github.com/prysmaticlabs/prysm/time"
+	"github.com/prysmaticlabs/prysm/time/slots"
 )
 
 func TestSlotToEpoch_OK(t *testing.T) {
@@ -26,7 +27,7 @@ func TestSlotToEpoch_OK(t *testing.T) {
 		{slot: 200, epoch: 6},
 	}
 	for _, tt := range tests {
-		assert.Equal(t, tt.epoch, SlotToEpoch(tt.slot), "SlotToEpoch(%d)", tt.slot)
+		assert.Equal(t, tt.epoch, slots.ToEpoch(tt.slot), "ToEpoch(%d)", tt.slot)
 	}
 }
 
@@ -96,10 +97,10 @@ func TestEpochStartSlot_OK(t *testing.T) {
 		{epoch: 1 << 60, startSlot: 1 << 63, error: true},
 	}
 	for _, tt := range tests {
-		ss, err := StartSlot(tt.epoch)
+		ss, err := slots.EpochStart(tt.epoch)
 		if !tt.error {
 			require.NoError(t, err)
-			assert.Equal(t, tt.startSlot, ss, "StartSlot(%d)", tt.epoch)
+			assert.Equal(t, tt.startSlot, ss, "EpochStart(%d)", tt.epoch)
 		} else {
 			require.ErrorContains(t, "start slot calculation overflow", err)
 		}
@@ -120,10 +121,10 @@ func TestEpochEndSlot_OK(t *testing.T) {
 		{epoch: math.MaxUint64, startSlot: 0, error: true},
 	}
 	for _, tt := range tests {
-		ss, err := EndSlot(tt.epoch)
+		ss, err := slots.EpochEnd(tt.epoch)
 		if !tt.error {
 			require.NoError(t, err)
-			assert.Equal(t, tt.startSlot, ss, "StartSlot(%d)", tt.epoch)
+			assert.Equal(t, tt.startSlot, ss, "EpochStart(%d)", tt.epoch)
 		} else {
 			require.ErrorContains(t, "start slot calculation overflow", err)
 		}
@@ -156,7 +157,7 @@ func TestIsEpochStart(t *testing.T) {
 	}
 
 	for _, tt := range tests {
-		assert.Equal(t, tt.result, IsEpochStart(tt.slot), "IsEpochStart(%d)", tt.slot)
+		assert.Equal(t, tt.result, slots.IsEpochStart(tt.slot), "IsEpochStart(%d)", tt.slot)
 	}
 }
 
@@ -182,7 +183,7 @@ func TestIsEpochEnd(t *testing.T) {
 	}
 
 	for _, tt := range tests {
-		assert.Equal(t, tt.result, IsEpochEnd(tt.slot), "IsEpochEnd(%d)", tt.slot)
+		assert.Equal(t, tt.result, slots.IsEpochEnd(tt.slot), "IsEpochEnd(%d)", tt.slot)
 	}
 }
 
@@ -198,7 +199,7 @@ func TestSlotsSinceEpochStarts(t *testing.T) {
 		{slots: 10*params.BeaconConfig().SlotsPerEpoch + 2, wantedSlots: 2},
 	}
 	for _, tt := range tests {
-		assert.Equal(t, tt.wantedSlots, SlotsSinceEpochStarts(tt.slots))
+		assert.Equal(t, tt.wantedSlots, slots.SinceEpochStarts(tt.slots))
 	}
 }
 
@@ -212,7 +213,7 @@ func TestRoundUpToNearestEpoch_OK(t *testing.T) {
 		{startSlot: 10*params.BeaconConfig().SlotsPerEpoch - (params.BeaconConfig().SlotsPerEpoch - 1), roundedUpSlot: 10 * params.BeaconConfig().SlotsPerEpoch},
 	}
 	for _, tt := range tests {
-		assert.Equal(t, tt.roundedUpSlot, RoundUpToNearestEpoch(tt.startSlot), "RoundUpToNearestEpoch(%d)", tt.startSlot)
+		assert.Equal(t, tt.roundedUpSlot, slots.RoundUpToNearestEpoch(tt.startSlot), "RoundUpToNearestEpoch(%d)", tt.startSlot)
 	}
 }
 
@@ -262,7 +263,7 @@ func TestSlotToTime(t *testing.T) {
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
-			got, err := SlotToTime(tt.args.genesisTimeSec, tt.args.slot)
+			got, err := slots.ToTime(tt.args.genesisTimeSec, tt.args.slot)
 			if tt.wantedErr != "" {
 				assert.ErrorContains(t, tt.wantedErr, err)
 			} else {
@@ -310,7 +311,7 @@ func TestVerifySlotTime(t *testing.T) {
 			name: "max future slot",
 			args: args{
 				genesisTime: prysmTime.Now().Add(-1 * 5 * time.Duration(params.BeaconConfig().SecondsPerSlot) * time.Second).Unix(),
-				slot:        types.Slot(MaxSlotBuffer + 6),
+				slot:        types.Slot(slots.MaxSlotBuffer + 6),
 			},
 			wantedErr: "exceeds max allowed value relative to the local clock",
 		},
@@ -327,7 +328,7 @@ func TestVerifySlotTime(t *testing.T) {
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
-			err := VerifySlotTime(uint64(tt.args.genesisTime), tt.args.slot, tt.args.timeTolerance)
+			err := slots.VerifyTime(uint64(tt.args.genesisTime), tt.args.slot, tt.args.timeTolerance)
 			if tt.wantedErr != "" {
 				assert.ErrorContains(t, tt.wantedErr, err)
 			} else {
@@ -338,12 +339,12 @@ func TestVerifySlotTime(t *testing.T) {
 }
 
 func TestValidateSlotClock_HandlesBadSlot(t *testing.T) {
-	genTime := prysmTime.Now().Add(-1 * time.Duration(MaxSlotBuffer) * time.Duration(params.BeaconConfig().SecondsPerSlot) * time.Second).Unix()
+	genTime := prysmTime.Now().Add(-1 * time.Duration(slots.MaxSlotBuffer) * time.Duration(params.BeaconConfig().SecondsPerSlot) * time.Second).Unix()
 
-	assert.NoError(t, ValidateSlotClock(types.Slot(MaxSlotBuffer), uint64(genTime)), "unexpected error validating slot")
-	assert.NoError(t, ValidateSlotClock(types.Slot(2*MaxSlotBuffer), uint64(genTime)), "unexpected error validating slot")
-	assert.ErrorContains(t, "which exceeds max allowed value relative to the local clock", ValidateSlotClock(types.Slot(2*MaxSlotBuffer+1), uint64(genTime)), "no error from bad slot")
-	assert.ErrorContains(t, "which exceeds max allowed value relative to the local clock", ValidateSlotClock(1<<63, uint64(genTime)), "no error from bad slot")
+	assert.NoError(t, slots.ValidateClock(types.Slot(slots.MaxSlotBuffer), uint64(genTime)), "unexpected error validating slot")
+	assert.NoError(t, slots.ValidateClock(types.Slot(2*slots.MaxSlotBuffer), uint64(genTime)), "unexpected error validating slot")
+	assert.ErrorContains(t, "which exceeds max allowed value relative to the local clock", slots.ValidateClock(types.Slot(2*slots.MaxSlotBuffer+1), uint64(genTime)), "no error from bad slot")
+	assert.ErrorContains(t, "which exceeds max allowed value relative to the local clock", slots.ValidateClock(1<<63, uint64(genTime)), "no error from bad slot")
 }
 
 func TestPrevSlot(t *testing.T) {
@@ -375,7 +376,7 @@ func TestPrevSlot(t *testing.T) {
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
-			if got := PrevSlot(tt.slot); got != tt.want {
+			if got := slots.PrevSlot(tt.slot); got != tt.want {
 				t.Errorf("PrevSlot() = %v, want %v", got, tt.want)
 			}
 		})
@@ -393,7 +394,7 @@ func TestSyncCommitteePeriod(t *testing.T) {
 		{epoch: 1000, wanted: 1000 / uint64(params.BeaconConfig().EpochsPerSyncCommitteePeriod)},
 	}
 	for _, test := range tests {
-		require.Equal(t, test.wanted, SyncCommitteePeriod(test.epoch))
+		require.Equal(t, test.wanted, slots.SyncCommitteePeriod(test.epoch))
 	}
 }
 
@@ -408,7 +409,7 @@ func TestSyncCommitteePeriodStartEpoch(t *testing.T) {
 		{epoch: params.BeaconConfig().EpochsPerSyncCommitteePeriod*params.BeaconConfig().EpochsPerSyncCommitteePeriod + 1, wanted: params.BeaconConfig().EpochsPerSyncCommitteePeriod * params.BeaconConfig().EpochsPerSyncCommitteePeriod},
 	}
 	for _, test := range tests {
-		e, err := SyncCommitteePeriodStartEpoch(test.epoch)
+		e, err := slots.SyncCommitteePeriodStartEpoch(test.epoch)
 		require.NoError(t, err)
 		require.Equal(t, test.wanted, e)
 	}

beacon-chain/core/transition/BUILD.bazel

@@ -26,12 +26,12 @@ go_library(
     ],
     deps = [
         "//beacon-chain/cache:go_default_library",
-        "//beacon-chain/core:go_default_library",
         "//beacon-chain/core/altair:go_default_library",
         "//beacon-chain/core/blocks:go_default_library",
         "//beacon-chain/core/epoch:go_default_library",
         "//beacon-chain/core/epoch/precompute:go_default_library",
         "//beacon-chain/core/helpers:go_default_library",
+        "//beacon-chain/core/time:go_default_library",
         "//beacon-chain/core/transition/interop:go_default_library",
         "//beacon-chain/core/validators:go_default_library",
         "//beacon-chain/state:go_default_library",
@@ -46,6 +46,7 @@ go_library(
         "//proto/prysm/v1alpha1:go_default_library",
         "//proto/prysm/v1alpha1/block:go_default_library",
         "//runtime/version:go_default_library",
+        "//time/slots: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",
@@ -75,11 +76,11 @@ go_test(
     embed = [":go_default_library"],
     shard_count = 3,
     deps = [
-        "//beacon-chain/core:go_default_library",
         "//beacon-chain/core/altair:go_default_library",
         "//beacon-chain/core/blocks:go_default_library",
         "//beacon-chain/core/helpers:go_default_library",
         "//beacon-chain/core/signing:go_default_library",
+        "//beacon-chain/core/time:go_default_library",
         "//beacon-chain/p2p/types:go_default_library",
         "//beacon-chain/state:go_default_library",
         "//beacon-chain/state/v1:go_default_library",

beacon-chain/core/transition/altair_transition_no_verify_sig_test.go

@@ -2,13 +2,14 @@ package transition_test
 
 import (
 	"context"
+	"math"
 	"testing"
 
 	"github.com/prysmaticlabs/go-bitfield"
-	"github.com/prysmaticlabs/prysm/beacon-chain/core"
 	"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/time"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/transition"
 	p2pType "github.com/prysmaticlabs/prysm/beacon-chain/p2p/types"
 	"github.com/prysmaticlabs/prysm/beacon-chain/state"
@@ -44,7 +45,7 @@ func TestExecuteAltairStateTransitionNoVerify_FullProcess(t *testing.T) {
 	require.NoError(t, beaconState.SetEth1DataVotes([]*ethpb.Eth1Data{eth1Data}))
 
 	require.NoError(t, beaconState.SetSlot(beaconState.Slot()+1))
-	epoch := core.CurrentEpoch(beaconState)
+	epoch := time.CurrentEpoch(beaconState)
 	randaoReveal, err := util.RandaoReveal(beaconState, epoch, privKeys)
 	require.NoError(t, err)
 	require.NoError(t, beaconState.SetSlot(beaconState.Slot()-1))
@@ -77,7 +78,7 @@ func TestExecuteAltairStateTransitionNoVerify_FullProcess(t *testing.T) {
 	syncSigs := make([]bls.Signature, len(indices))
 	for i, indice := range indices {
 		b := p2pType.SSZBytes(pbr[:])
-		sb, err := signing.ComputeDomainAndSign(beaconState, core.CurrentEpoch(beaconState), &b, params.BeaconConfig().DomainSyncCommittee, privKeys[indice])
+		sb, err := signing.ComputeDomainAndSign(beaconState, time.CurrentEpoch(beaconState), &b, params.BeaconConfig().DomainSyncCommittee, privKeys[indice])
 		require.NoError(t, err)
 		sig, err := bls.SignatureFromBytes(sb)
 		require.NoError(t, err)
@@ -131,7 +132,7 @@ func TestExecuteAltairStateTransitionNoVerifySignature_CouldNotVerifyStateRoot(t
 	require.NoError(t, beaconState.SetEth1DataVotes([]*ethpb.Eth1Data{eth1Data}))
 
 	require.NoError(t, beaconState.SetSlot(beaconState.Slot()+1))
-	epoch := core.CurrentEpoch(beaconState)
+	epoch := time.CurrentEpoch(beaconState)
 	randaoReveal, err := util.RandaoReveal(beaconState, epoch, privKeys)
 	require.NoError(t, err)
 	require.NoError(t, beaconState.SetSlot(beaconState.Slot()-1))
@@ -164,7 +165,7 @@ func TestExecuteAltairStateTransitionNoVerifySignature_CouldNotVerifyStateRoot(t
 	syncSigs := make([]bls.Signature, len(indices))
 	for i, indice := range indices {
 		b := p2pType.SSZBytes(pbr[:])
-		sb, err := signing.ComputeDomainAndSign(beaconState, core.CurrentEpoch(beaconState), &b, params.BeaconConfig().DomainSyncCommittee, privKeys[indice])
+		sb, err := signing.ComputeDomainAndSign(beaconState, time.CurrentEpoch(beaconState), &b, params.BeaconConfig().DomainSyncCommittee, privKeys[indice])
 		require.NoError(t, err)
 		sig, err := bls.SignatureFromBytes(sb)
 		require.NoError(t, err)
@@ -207,6 +208,24 @@ func TestExecuteStateTransitionNoVerifyAnySig_PassesProcessingConditions(t *test
 	require.Equal(t, true, verified, "Could not verify signature set")
 }
 
+func TestProcessEpoch_BadBalanceAltair(t *testing.T) {
+	s, _ := util.DeterministicGenesisStateAltair(t, 100)
+	assert.NoError(t, s.SetSlot(63))
+	assert.NoError(t, s.UpdateBalancesAtIndex(0, math.MaxUint64))
+	participation := byte(0)
+	participation = altair.AddValidatorFlag(participation, params.BeaconConfig().TimelyHeadFlagIndex)
+	participation = altair.AddValidatorFlag(participation, params.BeaconConfig().TimelySourceFlagIndex)
+	participation = altair.AddValidatorFlag(participation, params.BeaconConfig().TimelyTargetFlagIndex)
+
+	epochParticipation, err := s.CurrentEpochParticipation()
+	assert.NoError(t, err)
+	epochParticipation[0] = participation
+	assert.NoError(t, s.SetCurrentParticipationBits(epochParticipation))
+	assert.NoError(t, s.SetPreviousParticipationBits(epochParticipation))
+	_, err = altair.ProcessEpoch(context.Background(), s)
+	assert.ErrorContains(t, "addition overflows", err)
+}
+
 func createFullAltairBlockWithOperations(t *testing.T) (state.BeaconStateAltair,
 	*ethpb.SignedBeaconBlockAltair) {
 	beaconState, privKeys := util.DeterministicGenesisStateAltair(t, 32)

beacon-chain/core/transition/benchmarks_test.go

@@ -4,8 +4,8 @@ import (
 	"context"
 	"testing"
 
-	"github.com/prysmaticlabs/prysm/beacon-chain/core"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/helpers"
+	"github.com/prysmaticlabs/prysm/beacon-chain/core/time"
 	coreState "github.com/prysmaticlabs/prysm/beacon-chain/core/transition"
 	"github.com/prysmaticlabs/prysm/beacon-chain/state"
 	v1 "github.com/prysmaticlabs/prysm/beacon-chain/state/v1"
@@ -47,7 +47,7 @@ func BenchmarkExecuteStateTransition_WithCache(b *testing.B) {
 	// some attestations in block are from previous epoch
 	currentSlot := beaconState.Slot()
 	require.NoError(b, beaconState.SetSlot(beaconState.Slot()-params.BeaconConfig().SlotsPerEpoch))
-	require.NoError(b, helpers.UpdateCommitteeCache(beaconState, core.CurrentEpoch(beaconState)))
+	require.NoError(b, helpers.UpdateCommitteeCache(beaconState, time.CurrentEpoch(beaconState)))
 	require.NoError(b, beaconState.SetSlot(currentSlot))
 	// Run the state transition once to populate the cache.
 	_, err = coreState.ExecuteStateTransition(context.Background(), beaconState, wrapper.WrappedPhase0SignedBeaconBlock(block))
@@ -69,7 +69,7 @@ func BenchmarkProcessEpoch_2FullEpochs(b *testing.B) {
 	// some attestations in block are from previous epoch
 	currentSlot := beaconState.Slot()
 	require.NoError(b, beaconState.SetSlot(beaconState.Slot()-params.BeaconConfig().SlotsPerEpoch))
-	require.NoError(b, helpers.UpdateCommitteeCache(beaconState, core.CurrentEpoch(beaconState)))
+	require.NoError(b, helpers.UpdateCommitteeCache(beaconState, time.CurrentEpoch(beaconState)))
 	require.NoError(b, beaconState.SetSlot(currentSlot))
 
 	b.ResetTimer()

beacon-chain/core/transition/transition.go

@@ -11,17 +11,18 @@ import (
 	"github.com/pkg/errors"
 	types "github.com/prysmaticlabs/eth2-types"
 	"github.com/prysmaticlabs/prysm/beacon-chain/cache"
-	"github.com/prysmaticlabs/prysm/beacon-chain/core"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/altair"
 	e "github.com/prysmaticlabs/prysm/beacon-chain/core/epoch"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/epoch/precompute"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/helpers"
+	"github.com/prysmaticlabs/prysm/beacon-chain/core/time"
 	"github.com/prysmaticlabs/prysm/beacon-chain/state"
 	"github.com/prysmaticlabs/prysm/config/params"
 	"github.com/prysmaticlabs/prysm/math"
 	"github.com/prysmaticlabs/prysm/monitoring/tracing"
 	"github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1/block"
 	"github.com/prysmaticlabs/prysm/runtime/version"
+	"github.com/prysmaticlabs/prysm/time/slots"
 	"go.opencensus.io/trace"
 )
 
@@ -282,8 +283,8 @@ func ProcessSlots(ctx context.Context, state state.BeaconState, slot types.Slot)
 // Spec code:
 // If state.slot % SLOTS_PER_EPOCH == 0 and compute_epoch_at_slot(state.slot) == ALTAIR_FORK_EPOCH
 func CanUpgradeToAltair(slot types.Slot) bool {
-	epochStart := core.IsEpochStart(slot)
-	altairEpoch := core.SlotToEpoch(slot) == params.BeaconConfig().AltairForkEpoch
+	epochStart := slots.IsEpochStart(slot)
+	altairEpoch := slots.ToEpoch(slot) == params.BeaconConfig().AltairForkEpoch
 	return epochStart && altairEpoch
 }
 
@@ -356,7 +357,7 @@ func CanProcessEpoch(state state.ReadOnlyBeaconState) bool {
 func ProcessEpochPrecompute(ctx context.Context, state state.BeaconState) (state.BeaconState, error) {
 	ctx, span := trace.StartSpan(ctx, "core.state.ProcessEpochPrecompute")
 	defer span.End()
-	span.AddAttributes(trace.Int64Attribute("epoch", int64(core.CurrentEpoch(state))))
+	span.AddAttributes(trace.Int64Attribute("epoch", int64(time.CurrentEpoch(state))))
 
 	if state == nil || state.IsNil() {
 		return nil, errors.New("nil state")

beacon-chain/core/transition/transition_no_verify_sig_test.go

@@ -4,8 +4,8 @@ import (
 	"context"
 	"testing"
 
-	"github.com/prysmaticlabs/prysm/beacon-chain/core"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/helpers"
+	"github.com/prysmaticlabs/prysm/beacon-chain/core/time"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/transition"
 	"github.com/prysmaticlabs/prysm/config/params"
 	"github.com/prysmaticlabs/prysm/encoding/bytesutil"
@@ -34,7 +34,7 @@ func TestExecuteStateTransitionNoVerify_FullProcess(t *testing.T) {
 	require.NoError(t, beaconState.SetEth1DataVotes([]*ethpb.Eth1Data{eth1Data}))
 
 	require.NoError(t, beaconState.SetSlot(beaconState.Slot()+1))
-	epoch := core.CurrentEpoch(beaconState)
+	epoch := time.CurrentEpoch(beaconState)
 	randaoReveal, err := util.RandaoReveal(beaconState, epoch, privKeys)
 	require.NoError(t, err)
 	require.NoError(t, beaconState.SetSlot(beaconState.Slot()-1))
@@ -86,7 +86,7 @@ func TestExecuteStateTransitionNoVerifySignature_CouldNotVerifyStateRoot(t *test
 	require.NoError(t, beaconState.SetEth1DataVotes([]*ethpb.Eth1Data{eth1Data}))
 
 	require.NoError(t, beaconState.SetSlot(beaconState.Slot()+1))
-	epoch := core.CurrentEpoch(beaconState)
+	epoch := time.CurrentEpoch(beaconState)
 	randaoReveal, err := util.RandaoReveal(beaconState, epoch, privKeys)
 	require.NoError(t, err)
 	require.NoError(t, beaconState.SetSlot(beaconState.Slot()-1))

beacon-chain/core/transition/transition_test.go

@@ -7,10 +7,10 @@ import (
 
 	types "github.com/prysmaticlabs/eth2-types"
 	"github.com/prysmaticlabs/go-bitfield"
-	"github.com/prysmaticlabs/prysm/beacon-chain/core"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/blocks"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/helpers"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/signing"
+	"github.com/prysmaticlabs/prysm/beacon-chain/core/time"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/transition"
 	"github.com/prysmaticlabs/prysm/beacon-chain/state"
 	v1 "github.com/prysmaticlabs/prysm/beacon-chain/state/v1"
@@ -68,7 +68,7 @@ func TestExecuteStateTransition_FullProcess(t *testing.T) {
 	require.NoError(t, err)
 
 	require.NoError(t, beaconState.SetSlot(beaconState.Slot()+1))
-	epoch := core.CurrentEpoch(beaconState)
+	epoch := time.CurrentEpoch(beaconState)
 	randaoReveal, err := util.RandaoReveal(beaconState, epoch, privKeys)
 	require.NoError(t, err)
 	require.NoError(t, beaconState.SetSlot(beaconState.Slot()-1))
@@ -214,7 +214,7 @@ func createFullBlockWithOperations(t *testing.T) (state.BeaconState,
 	err = beaconState.SetSlot(slotsPerEpoch.Mul(uint64(params.BeaconConfig().ShardCommitteePeriod)) + params.BeaconConfig().MinAttestationInclusionDelay)
 	require.NoError(t, err)
 
-	currentEpoch := core.CurrentEpoch(beaconState)
+	currentEpoch := time.CurrentEpoch(beaconState)
 	header1 := util.HydrateSignedBeaconHeader(&ethpb.SignedBeaconBlockHeader{
 		Header: &ethpb.BeaconBlockHeader{
 			ProposerIndex: proposerSlashIdx,
@@ -232,7 +232,7 @@ func createFullBlockWithOperations(t *testing.T) (state.BeaconState,
 			StateRoot:     bytesutil.PadTo([]byte("B"), 32),
 		},
 	})
-	header2.Signature, err = signing.ComputeDomainAndSign(beaconState, core.CurrentEpoch(beaconState), header2.Header, params.BeaconConfig().DomainBeaconProposer, privKeys[proposerSlashIdx])
+	header2.Signature, err = signing.ComputeDomainAndSign(beaconState, time.CurrentEpoch(beaconState), header2.Header, params.BeaconConfig().DomainBeaconProposer, privKeys[proposerSlashIdx])
 	require.NoError(t, err)
 
 	proposerSlashings := []*ethpb.ProposerSlashing{
@@ -295,7 +295,7 @@ func createFullBlockWithOperations(t *testing.T) (state.BeaconState,
 	blockAtt := util.HydrateAttestation(&ethpb.Attestation{
 		Data: &ethpb.AttestationData{
 			Slot:   beaconState.Slot(),
-			Target: &ethpb.Checkpoint{Epoch: core.CurrentEpoch(beaconState)},
+			Target: &ethpb.Checkpoint{Epoch: time.CurrentEpoch(beaconState)},
 			Source: &ethpb.Checkpoint{Root: mockRoot[:]}},
 		AggregationBits: aggBits,
 	})

beacon-chain/core/validators/BUILD.bazel

@@ -9,11 +9,12 @@ go_library(
         "//testing/spectest:__subpackages__",
     ],
     deps = [
-        "//beacon-chain/core:go_default_library",
         "//beacon-chain/core/helpers:go_default_library",
+        "//beacon-chain/core/time:go_default_library",
         "//beacon-chain/state:go_default_library",
         "//config/params:go_default_library",
         "//proto/prysm/v1alpha1:go_default_library",
+        "//time/slots:go_default_library",
         "@com_github_pkg_errors//:go_default_library",
         "@com_github_prysmaticlabs_eth2_types//:go_default_library",
     ],
@@ -25,8 +26,8 @@ go_test(
     srcs = ["validator_test.go"],
     embed = [":go_default_library"],
     deps = [
-        "//beacon-chain/core:go_default_library",
         "//beacon-chain/core/helpers:go_default_library",
+        "//beacon-chain/core/time:go_default_library",
         "//beacon-chain/state/v1:go_default_library",
         "//config/params:go_default_library",
         "//proto/prysm/v1alpha1:go_default_library",

beacon-chain/core/validators/validator.go

@@ -9,11 +9,12 @@ import (
 
 	"github.com/pkg/errors"
 	types "github.com/prysmaticlabs/eth2-types"
-	"github.com/prysmaticlabs/prysm/beacon-chain/core"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/helpers"
+	"github.com/prysmaticlabs/prysm/beacon-chain/core/time"
 	"github.com/prysmaticlabs/prysm/beacon-chain/state"
 	"github.com/prysmaticlabs/prysm/config/params"
 	ethpb "github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1"
+	"github.com/prysmaticlabs/prysm/time/slots"
 )
 
 // InitiateValidatorExit takes in validator index and updates
@@ -57,7 +58,7 @@ func InitiateValidatorExit(ctx context.Context, s state.BeaconState, idx types.V
 	if err != nil {
 		return nil, err
 	}
-	exitEpochs = append(exitEpochs, helpers.ActivationExitEpoch(core.CurrentEpoch(s)))
+	exitEpochs = append(exitEpochs, helpers.ActivationExitEpoch(time.CurrentEpoch(s)))
 
 	// Obtain the exit queue epoch as the maximum number in the exit epochs array.
 	exitQueueEpoch := types.Epoch(0)
@@ -78,7 +79,7 @@ func InitiateValidatorExit(ctx context.Context, s state.BeaconState, idx types.V
 	if err != nil {
 		return nil, err
 	}
-	activeValidatorCount, err := helpers.ActiveValidatorCount(ctx, s, core.CurrentEpoch(s))
+	activeValidatorCount, err := helpers.ActiveValidatorCount(ctx, s, time.CurrentEpoch(s))
 	if err != nil {
 		return nil, errors.Wrap(err, "could not get active validator count")
 	}
@@ -134,7 +135,7 @@ func SlashValidator(
 	if err != nil {
 		return nil, errors.Wrapf(err, "could not initiate validator %d exit", slashedIdx)
 	}
-	currentEpoch := core.SlotToEpoch(s.Slot())
+	currentEpoch := slots.ToEpoch(s.Slot())
 	validator, err := s.ValidatorAtIndex(slashedIdx)
 	if err != nil {
 		return nil, err

beacon-chain/core/validators/validator_test.go

@@ -5,8 +5,8 @@ import (
 	"testing"
 
 	types "github.com/prysmaticlabs/eth2-types"
-	"github.com/prysmaticlabs/prysm/beacon-chain/core"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/helpers"
+	"github.com/prysmaticlabs/prysm/beacon-chain/core/time"
 	v1 "github.com/prysmaticlabs/prysm/beacon-chain/state/v1"
 	"github.com/prysmaticlabs/prysm/config/params"
 	ethpb "github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1"
@@ -135,7 +135,7 @@ func TestSlashValidator_OK(t *testing.T) {
 	v, err := state.ValidatorAtIndex(slashedIdx)
 	require.NoError(t, err)
 	assert.Equal(t, true, v.Slashed, "Validator not slashed despite supposed to being slashed")
-	assert.Equal(t, core.CurrentEpoch(state)+params.BeaconConfig().EpochsPerSlashingsVector, v.WithdrawableEpoch, "Withdrawable epoch not the expected value")
+	assert.Equal(t, time.CurrentEpoch(state)+params.BeaconConfig().EpochsPerSlashingsVector, v.WithdrawableEpoch, "Withdrawable epoch not the expected value")
 
 	maxBalance := params.BeaconConfig().MaxEffectiveBalance
 	slashedBalance := state.Slashings()[state.Slot().Mod(uint64(params.BeaconConfig().EpochsPerSlashingsVector))]
@@ -205,7 +205,7 @@ func TestActivatedValidatorIndices(t *testing.T) {
 	for _, tt := range tests {
 		s, err := v1.InitializeFromProto(tt.state)
 		require.NoError(t, err)
-		activatedIndices := ActivatedValidatorIndices(core.CurrentEpoch(s), tt.state.Validators)
+		activatedIndices := ActivatedValidatorIndices(time.CurrentEpoch(s), tt.state.Validators)
 		assert.DeepEqual(t, tt.wanted, activatedIndices)
 	}
 }
@@ -259,7 +259,7 @@ func TestSlashedValidatorIndices(t *testing.T) {
 	for _, tt := range tests {
 		s, err := v1.InitializeFromProto(tt.state)
 		require.NoError(t, err)
-		slashedIndices := SlashedValidatorIndices(core.CurrentEpoch(s), tt.state.Validators)
+		slashedIndices := SlashedValidatorIndices(time.CurrentEpoch(s), tt.state.Validators)
 		assert.DeepEqual(t, tt.wanted, slashedIndices)
 	}
 }
@@ -319,7 +319,7 @@ func TestExitedValidatorIndices(t *testing.T) {
 	for _, tt := range tests {
 		s, err := v1.InitializeFromProto(tt.state)
 		require.NoError(t, err)
-		activeCount, err := helpers.ActiveValidatorCount(context.Background(), s, core.PrevEpoch(s))
+		activeCount, err := helpers.ActiveValidatorCount(context.Background(), s, time.PrevEpoch(s))
 		require.NoError(t, err)
 		exitedIndices, err := ExitedValidatorIndices(0, tt.state.Validators, activeCount)
 		require.NoError(t, err)

beacon-chain/db/BUILD.bazel

@@ -13,6 +13,7 @@ go_library(
         "//beacon-chain:__subpackages__",
         "//cmd/beacon-chain:__subpackages__",
         "//testing/fuzz:__pkg__",
+        "//testing/slasher/simulator:__pkg__",
         "//tools:__subpackages__",
     ],
     deps = [

beacon-chain/db/iface/interface.go

@@ -147,6 +147,10 @@ type SlasherDatabase interface {
 	PruneProposalsAtEpoch(
 		ctx context.Context, maxEpoch types.Epoch,
 	) (numPruned uint, err error)
+	HighestAttestations(
+		ctx context.Context,
+		indices []types.ValidatorIndex,
+	) ([]*ethpb.HighestAttestation, error)
 	DatabasePath() string
 	ClearDB() error
 }

beacon-chain/db/kv/BUILD.bazel

@@ -34,7 +34,6 @@ go_library(
         "//tools:__subpackages__",
     ],
     deps = [
-        "//beacon-chain/core:go_default_library",
         "//beacon-chain/core/blocks:go_default_library",
         "//beacon-chain/core/helpers:go_default_library",
         "//beacon-chain/db/filters:go_default_library",
@@ -54,6 +53,7 @@ go_library(
         "//proto/prysm/v1alpha1/block:go_default_library",
         "//proto/prysm/v1alpha1/wrapper:go_default_library",
         "//runtime/version:go_default_library",
+        "//time/slots:go_default_library",
         "@com_github_dgraph_io_ristretto//:go_default_library",
         "@com_github_ethereum_go_ethereum//common:go_default_library",
         "@com_github_ethereum_go_ethereum//common/hexutil:go_default_library",

beacon-chain/db/kv/blocks.go

@@ -8,7 +8,6 @@ import (
 	"github.com/golang/snappy"
 	"github.com/pkg/errors"
 	types "github.com/prysmaticlabs/eth2-types"
-	"github.com/prysmaticlabs/prysm/beacon-chain/core"
 	"github.com/prysmaticlabs/prysm/beacon-chain/db/filters"
 	"github.com/prysmaticlabs/prysm/config/params"
 	"github.com/prysmaticlabs/prysm/container/slice"
@@ -17,6 +16,7 @@ import (
 	"github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1/block"
 	"github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1/wrapper"
 	"github.com/prysmaticlabs/prysm/runtime/version"
+	"github.com/prysmaticlabs/prysm/time/slots"
 	bolt "go.etcd.io/bbolt"
 	"go.opencensus.io/trace"
 )
@@ -479,11 +479,11 @@ func blockRootsBySlotRange(
 	endEpoch, endEpochOk := endEpochEncoded.(types.Epoch)
 	var err error
 	if startEpochOk && endEpochOk {
-		startSlot, err = core.StartSlot(startEpoch)
+		startSlot, err = slots.EpochStart(startEpoch)
 		if err != nil {
 			return nil, err
 		}
-		endSlot, err = core.StartSlot(endEpoch)
+		endSlot, err = slots.EpochStart(endEpoch)
 		if err != nil {
 			return nil, err
 		}

beacon-chain/db/kv/state.go

@@ -7,7 +7,6 @@ import (
 	"github.com/golang/snappy"
 	"github.com/pkg/errors"
 	types "github.com/prysmaticlabs/eth2-types"
-	"github.com/prysmaticlabs/prysm/beacon-chain/core"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/helpers"
 	"github.com/prysmaticlabs/prysm/beacon-chain/state"
 	"github.com/prysmaticlabs/prysm/beacon-chain/state/genesis"
@@ -19,6 +18,7 @@ import (
 	"github.com/prysmaticlabs/prysm/monitoring/tracing"
 	ethpb "github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1"
 	"github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1/wrapper"
+	"github.com/prysmaticlabs/prysm/time/slots"
 	bolt "go.etcd.io/bbolt"
 	"go.opencensus.io/trace"
 )
@@ -666,7 +666,7 @@ func (s *Store) CleanUpDirtyStates(ctx context.Context, slotsPerArchivedPoint ty
 	if err != nil {
 		return err
 	}
-	finalizedSlot, err := core.StartSlot(f.Epoch)
+	finalizedSlot, err := slots.EpochStart(f.Epoch)
 	if err != nil {
 		return err
 	}

beacon-chain/db/slasherkv/BUILD.bazel

@@ -13,13 +13,13 @@ go_library(
     importpath = "github.com/prysmaticlabs/prysm/beacon-chain/db/slasherkv",
     visibility = ["//beacon-chain:__subpackages__"],
     deps = [
-        "//beacon-chain/core:go_default_library",
         "//beacon-chain/db/iface:go_default_library",
         "//beacon-chain/slasher/types:go_default_library",
         "//config/params:go_default_library",
         "//encoding/bytesutil:go_default_library",
         "//io/file:go_default_library",
         "//proto/prysm/v1alpha1:go_default_library",
+        "//time/slots:go_default_library",
         "@com_github_ferranbt_fastssz//:go_default_library",
         "@com_github_golang_snappy//:go_default_library",
         "@com_github_pkg_errors//:go_default_library",
@@ -43,13 +43,13 @@ go_test(
     ],
     embed = [":go_default_library"],
     deps = [
-        "//beacon-chain/core:go_default_library",
         "//beacon-chain/slasher/types: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",
+        "//time/slots:go_default_library",
         "@com_github_ferranbt_fastssz//:go_default_library",
         "@com_github_prysmaticlabs_eth2_types//:go_default_library",
         "@com_github_sirupsen_logrus//:go_default_library",

beacon-chain/db/slasherkv/pruning.go

@@ -7,7 +7,7 @@ import (
 
 	fssz "github.com/ferranbt/fastssz"
 	types "github.com/prysmaticlabs/eth2-types"
-	"github.com/prysmaticlabs/prysm/beacon-chain/core"
+	"github.com/prysmaticlabs/prysm/time/slots"
 	bolt "go.etcd.io/bbolt"
 )
 
@@ -88,7 +88,7 @@ func (s *Store) PruneProposalsAtEpoch(
 	ctx context.Context, maxEpoch types.Epoch,
 ) (numPruned uint, err error) {
 	var endPruneSlot types.Slot
-	endPruneSlot, err = core.EndSlot(maxEpoch)
+	endPruneSlot, err = slots.EpochEnd(maxEpoch)
 	if err != nil {
 		return
 	}

beacon-chain/db/slasherkv/pruning_test.go

@@ -6,10 +6,10 @@ import (
 	"testing"
 
 	types "github.com/prysmaticlabs/eth2-types"
-	"github.com/prysmaticlabs/prysm/beacon-chain/core"
 	slashertypes "github.com/prysmaticlabs/prysm/beacon-chain/slasher/types"
 	"github.com/prysmaticlabs/prysm/config/params"
 	"github.com/prysmaticlabs/prysm/testing/require"
+	"github.com/prysmaticlabs/prysm/time/slots"
 	logTest "github.com/sirupsen/logrus/hooks/test"
 	bolt "go.etcd.io/bbolt"
 )
@@ -29,7 +29,7 @@ func TestStore_PruneProposalsAtEpoch(t *testing.T) {
 		historyLength := types.Epoch(10)
 
 		pruningLimitEpoch := currentEpoch - historyLength
-		lowestStoredSlot, err := core.EndSlot(pruningLimitEpoch)
+		lowestStoredSlot, err := slots.EpochEnd(pruningLimitEpoch)
 		require.NoError(t, err)
 
 		err = beaconDB.db.Update(func(tx *bolt.Tx) error {
@@ -68,9 +68,9 @@ func TestStore_PruneProposalsAtEpoch(t *testing.T) {
 		slotsPerEpoch := params.BeaconConfig().SlotsPerEpoch
 		proposals := make([]*slashertypes.SignedBlockHeaderWrapper, 0, uint64(currentEpoch)*uint64(slotsPerEpoch)*2)
 		for i := types.Epoch(0); i < currentEpoch; i++ {
-			startSlot, err := core.StartSlot(i)
+			startSlot, err := slots.EpochStart(i)
 			require.NoError(t, err)
-			endSlot, err := core.StartSlot(i + 1)
+			endSlot, err := slots.EpochStart(i + 1)
 			require.NoError(t, err)
 			for j := startSlot; j < endSlot; j++ {
 				prop1 := createProposalWrapper(t, j, 0 /* proposer index */, []byte{0})
@@ -89,9 +89,9 @@ func TestStore_PruneProposalsAtEpoch(t *testing.T) {
 		for i := types.Epoch(0); i < pruningLimitEpoch; i++ {
 			err = beaconDB.db.View(func(tx *bolt.Tx) error {
 				bkt := tx.Bucket(proposalRecordsBucket)
-				startSlot, err := core.StartSlot(i)
+				startSlot, err := slots.EpochStart(i)
 				require.NoError(t, err)
-				endSlot, err := core.StartSlot(i + 1)
+				endSlot, err := slots.EpochStart(i + 1)
 				require.NoError(t, err)
 				for j := startSlot; j < endSlot; j++ {
 					prop1Key, err := keyForValidatorProposal(j, 0)
@@ -168,9 +168,9 @@ func TestStore_PruneAttestations_OK(t *testing.T) {
 		slotsPerEpoch := params.BeaconConfig().SlotsPerEpoch
 		attestations := make([]*slashertypes.IndexedAttestationWrapper, 0, uint64(currentEpoch)*uint64(slotsPerEpoch)*2)
 		for i := types.Epoch(0); i < currentEpoch; i++ {
-			startSlot, err := core.StartSlot(i)
+			startSlot, err := slots.EpochStart(i)
 			require.NoError(t, err)
-			endSlot, err := core.StartSlot(i + 1)
+			endSlot, err := slots.EpochStart(i + 1)
 			require.NoError(t, err)
 			for j := startSlot; j < endSlot; j++ {
 				attester1 := uint64(j + 10)
@@ -196,9 +196,9 @@ func TestStore_PruneAttestations_OK(t *testing.T) {
 		for i := types.Epoch(0); i < pruningLimitEpoch; i++ {
 			err = beaconDB.db.View(func(tx *bolt.Tx) error {
 				bkt := tx.Bucket(attestationDataRootsBucket)
-				startSlot, err := core.StartSlot(i)
+				startSlot, err := slots.EpochStart(i)
 				require.NoError(t, err)
-				endSlot, err := core.StartSlot(i + 1)
+				endSlot, err := slots.EpochStart(i + 1)
 				require.NoError(t, err)
 				for j := startSlot; j < endSlot; j++ {
 					attester1 := types.ValidatorIndex(j + 10)

beacon-chain/db/slasherkv/slasher.go

@@ -271,7 +271,11 @@ func (s *Store) SaveSlasherChunks(
 	encodedChunks := make([][]byte, len(chunkKeys))
 	for i := 0; i < len(chunkKeys); i++ {
 		encodedKeys[i] = append(ssz.MarshalUint8(make([]byte, 0), uint8(kind)), chunkKeys[i]...)
-		encodedChunks[i] = encodeSlasherChunk(chunks[i])
+		encodedChunk, err := encodeSlasherChunk(chunks[i])
+		if err != nil {
+			return err
+		}
+		encodedChunks[i] = encodedChunk
 	}
 	return s.db.Update(func(tx *bolt.Tx) error {
 		bkt := tx.Bucket(slasherChunksBucket)
@@ -453,12 +457,15 @@ func keyForValidatorProposal(slot types.Slot, proposerIndex types.ValidatorIndex
 	return append(encSlot, encValidatorIdx...), nil
 }
 
-func encodeSlasherChunk(chunk []uint16) []byte {
+func encodeSlasherChunk(chunk []uint16) ([]byte, error) {
 	val := make([]byte, 0)
 	for i := 0; i < len(chunk); i++ {
 		val = append(val, ssz.MarshalUint16(make([]byte, 0), chunk[i])...)
 	}
-	return snappy.Encode(nil, val)
+	if len(val) == 0 {
+		return nil, errors.New("cannot encode empty chunk")
+	}
+	return snappy.Encode(nil, val), nil
 }
 
 func decodeSlasherChunk(enc []byte) ([]uint16, error) {
@@ -466,6 +473,12 @@ func decodeSlasherChunk(enc []byte) ([]uint16, error) {
 	if err != nil {
 		return nil, err
 	}
+	if len(chunkBytes)%2 != 0 {
+		return nil, fmt.Errorf(
+			"cannot decode slasher chunk with length %d, must be a multiple of 2",
+			len(chunkBytes),
+		)
+	}
 	chunk := make([]uint16, 0)
 	for i := 0; i < len(chunkBytes); i += 2 {
 		distance := ssz.UnmarshallUint16(chunkBytes[i : i+2])

beacon-chain/db/slasherkv/slasher_test.go

@@ -183,6 +183,21 @@ func TestStore_SlasherChunk_SaveRetrieve(t *testing.T) {
 	}
 }
 
+func TestStore_SlasherChunk_PreventsSavingWrongLength(t *testing.T) {
+	ctx := context.Background()
+	beaconDB := setupDB(t)
+	totalChunks := 64
+	chunkKeys := make([][]byte, totalChunks)
+	chunks := make([][]uint16, totalChunks)
+	for i := 0; i < totalChunks; i++ {
+		chunks[i] = []uint16{}
+		chunkKeys[i] = ssz.MarshalUint64(make([]byte, 0), uint64(i))
+	}
+	// We should get an error if saving empty chunks.
+	err := beaconDB.SaveSlasherChunks(ctx, slashertypes.MinSpan, chunkKeys, chunks)
+	require.ErrorContains(t, "cannot encode empty chunk", err)
+}
+
 func TestStore_ExistingBlockProposals(t *testing.T) {
 	ctx := context.Background()
 	beaconDB := setupDB(t)

beacon-chain/db/testing/BUILD.bazel

@@ -7,7 +7,7 @@ go_library(
     importpath = "github.com/prysmaticlabs/prysm/beacon-chain/db/testing",
     visibility = [
         "//beacon-chain:__subpackages__",
-        "//testing/endtoend:__subpackages__",
+        "//testing:__subpackages__",
     ],
     deps = [
         "//beacon-chain/db:go_default_library",

beacon-chain/node/BUILD.bazel

@@ -21,6 +21,7 @@ go_library(
         "//beacon-chain/core/helpers:go_default_library",
         "//beacon-chain/db:go_default_library",
         "//beacon-chain/db/kv:go_default_library",
+        "//beacon-chain/db/slasherkv:go_default_library",
         "//beacon-chain/forkchoice:go_default_library",
         "//beacon-chain/forkchoice/protoarray:go_default_library",
         "//beacon-chain/gateway:go_default_library",
@@ -34,6 +35,7 @@ go_library(
         "//beacon-chain/powchain:go_default_library",
         "//beacon-chain/rpc:go_default_library",
         "//beacon-chain/rpc/apimiddleware:go_default_library",
+        "//beacon-chain/slasher:go_default_library",
         "//beacon-chain/state/stategen:go_default_library",
         "//beacon-chain/sync:go_default_library",
         "//beacon-chain/sync/initial-sync:go_default_library",

beacon-chain/node/node.go

@@ -24,6 +24,7 @@ import (
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/helpers"
 	"github.com/prysmaticlabs/prysm/beacon-chain/db"
 	"github.com/prysmaticlabs/prysm/beacon-chain/db/kv"
+	"github.com/prysmaticlabs/prysm/beacon-chain/db/slasherkv"
 	"github.com/prysmaticlabs/prysm/beacon-chain/forkchoice"
 	"github.com/prysmaticlabs/prysm/beacon-chain/forkchoice/protoarray"
 	"github.com/prysmaticlabs/prysm/beacon-chain/gateway"
@@ -37,6 +38,7 @@ import (
 	"github.com/prysmaticlabs/prysm/beacon-chain/powchain"
 	"github.com/prysmaticlabs/prysm/beacon-chain/rpc"
 	"github.com/prysmaticlabs/prysm/beacon-chain/rpc/apimiddleware"
+	"github.com/prysmaticlabs/prysm/beacon-chain/slasher"
 	"github.com/prysmaticlabs/prysm/beacon-chain/state/stategen"
 	regularsync "github.com/prysmaticlabs/prysm/beacon-chain/sync"
 	initialsync "github.com/prysmaticlabs/prysm/beacon-chain/sync/initial-sync"
@@ -64,24 +66,27 @@ const debugGrpcMaxMsgSize = 1 << 27
 // full PoS node. It handles the lifecycle of the entire system and registers
 // services to a service registry.
 type BeaconNode struct {
-	cliCtx            *cli.Context
-	ctx               context.Context
-	cancel            context.CancelFunc
-	services          *runtime.ServiceRegistry
-	lock              sync.RWMutex
-	stop              chan struct{} // Channel to wait for termination notifications.
-	db                db.Database
-	attestationPool   attestations.Pool
-	exitPool          voluntaryexits.PoolManager
-	slashingsPool     slashings.PoolManager
-	syncCommitteePool synccommittee.Pool
-	depositCache      *depositcache.DepositCache
-	stateFeed         *event.Feed
-	blockFeed         *event.Feed
-	opFeed            *event.Feed
-	forkChoiceStore   forkchoice.ForkChoicer
-	stateGen          *stategen.State
-	collector         *bcnodeCollector
+	cliCtx                  *cli.Context
+	ctx                     context.Context
+	cancel                  context.CancelFunc
+	services                *runtime.ServiceRegistry
+	lock                    sync.RWMutex
+	stop                    chan struct{} // Channel to wait for termination notifications.
+	db                      db.Database
+	slasherDB               db.SlasherDatabase
+	attestationPool         attestations.Pool
+	exitPool                voluntaryexits.PoolManager
+	slashingsPool           slashings.PoolManager
+	syncCommitteePool       synccommittee.Pool
+	depositCache            *depositcache.DepositCache
+	stateFeed               *event.Feed
+	blockFeed               *event.Feed
+	opFeed                  *event.Feed
+	forkChoiceStore         forkchoice.ForkChoicer
+	stateGen                *stategen.State
+	collector               *bcnodeCollector
+	slasherBlockHeadersFeed *event.Feed
+	slasherAttestationsFeed *event.Feed
 }
 
 // New creates a new node instance, sets up configuration options, and registers
@@ -108,18 +113,20 @@ func New(cliCtx *cli.Context) (*BeaconNode, error) {
 
 	ctx, cancel := context.WithCancel(cliCtx.Context)
 	beacon := &BeaconNode{
-		cliCtx:            cliCtx,
-		ctx:               ctx,
-		cancel:            cancel,
-		services:          registry,
-		stop:              make(chan struct{}),
-		stateFeed:         new(event.Feed),
-		blockFeed:         new(event.Feed),
-		opFeed:            new(event.Feed),
-		attestationPool:   attestations.NewPool(),
-		exitPool:          voluntaryexits.NewPool(),
-		slashingsPool:     slashings.NewPool(),
-		syncCommitteePool: synccommittee.NewPool(),
+		cliCtx:                  cliCtx,
+		ctx:                     ctx,
+		cancel:                  cancel,
+		services:                registry,
+		stop:                    make(chan struct{}),
+		stateFeed:               new(event.Feed),
+		blockFeed:               new(event.Feed),
+		opFeed:                  new(event.Feed),
+		attestationPool:         attestations.NewPool(),
+		exitPool:                voluntaryexits.NewPool(),
+		slashingsPool:           slashings.NewPool(),
+		syncCommitteePool:       synccommittee.NewPool(),
+		slasherBlockHeadersFeed: new(event.Feed),
+		slasherAttestationsFeed: new(event.Feed),
 	}
 
 	depositAddress, err := registration.DepositContractAddress()
@@ -130,6 +137,10 @@ func New(cliCtx *cli.Context) (*BeaconNode, error) {
 		return nil, err
 	}
 
+	if err := beacon.startSlasherDB(cliCtx); err != nil {
+		return nil, err
+	}
+
 	beacon.startStateGen()
 
 	if err := beacon.registerP2P(cliCtx); err != nil {
@@ -162,6 +173,10 @@ func New(cliCtx *cli.Context) (*BeaconNode, error) {
 		return nil, err
 	}
 
+	if err := beacon.registerSlasherService(); err != nil {
+		return nil, err
+	}
+
 	if err := beacon.registerRPCService(); err != nil {
 		return nil, err
 	}
@@ -329,11 +344,9 @@ func (b *BeaconNode) startDB(cliCtx *cli.Context, depositAddress string) error {
 			return errors.Wrap(err, "could not load genesis from file")
 		}
 	}
-
 	if err := b.db.EnsureEmbeddedGenesis(b.ctx); err != nil {
 		return err
 	}
-
 	knownContract, err := b.db.DepositContractAddress(b.ctx)
 	if err != nil {
 		return err
@@ -351,7 +364,53 @@ func (b *BeaconNode) startDB(cliCtx *cli.Context, depositAddress string) error {
 			knownContract, addr.Bytes())
 	}
 	log.Infof("Deposit contract: %#x", addr.Bytes())
+	return nil
+}
 
+func (b *BeaconNode) startSlasherDB(cliCtx *cli.Context) error {
+	if !features.Get().EnableSlasher {
+		return nil
+	}
+	baseDir := cliCtx.String(cmd.DataDirFlag.Name)
+	dbPath := filepath.Join(baseDir, kv.BeaconNodeDbDirName)
+	clearDB := cliCtx.Bool(cmd.ClearDB.Name)
+	forceClearDB := cliCtx.Bool(cmd.ForceClearDB.Name)
+
+	log.WithField("database-path", dbPath).Info("Checking DB")
+
+	d, err := slasherkv.NewKVStore(b.ctx, dbPath, &slasherkv.Config{
+		InitialMMapSize: cliCtx.Int(cmd.BoltMMapInitialSizeFlag.Name),
+	})
+	if err != nil {
+		return err
+	}
+	clearDBConfirmed := false
+	if clearDB && !forceClearDB {
+		actionText := "This will delete your beacon chain database stored in your data directory. " +
+			"Your database backups will not be removed - do you want to proceed? (Y/N)"
+		deniedText := "Database will not be deleted. No changes have been made."
+		clearDBConfirmed, err = cmd.ConfirmAction(actionText, deniedText)
+		if err != nil {
+			return err
+		}
+	}
+	if clearDBConfirmed || forceClearDB {
+		log.Warning("Removing database")
+		if err := d.Close(); err != nil {
+			return errors.Wrap(err, "could not close db prior to clearing")
+		}
+		if err := d.ClearDB(); err != nil {
+			return errors.Wrap(err, "could not clear database")
+		}
+		d, err = slasherkv.NewKVStore(b.ctx, dbPath, &slasherkv.Config{
+			InitialMMapSize: cliCtx.Int(cmd.BoltMMapInitialSizeFlag.Name),
+		})
+		if err != nil {
+			return errors.Wrap(err, "could not create new database")
+		}
+	}
+
+	b.slasherDB = d
 	return nil
 }
 
@@ -441,6 +500,7 @@ func (b *BeaconNode) registerBlockchainService() error {
 		ForkChoiceStore:         b.forkChoiceStore,
 		AttService:              attService,
 		StateGen:                b.stateGen,
+		SlasherAttestationsFeed: b.slasherAttestationsFeed,
 		WeakSubjectivityCheckpt: wsCheckpt,
 	})
 	if err != nil {
@@ -500,18 +560,21 @@ func (b *BeaconNode) registerSyncService() error {
 	}
 
 	rs := regularsync.NewService(b.ctx, &regularsync.Config{
-		DB:                b.db,
-		P2P:               b.fetchP2P(),
-		Chain:             chainService,
-		InitialSync:       initSync,
-		StateNotifier:     b,
-		BlockNotifier:     b,
-		OperationNotifier: b,
-		AttPool:           b.attestationPool,
-		ExitPool:          b.exitPool,
-		SlashingPool:      b.slashingsPool,
-		SyncCommsPool:     b.syncCommitteePool,
-		StateGen:          b.stateGen,
+		DB:                      b.db,
+		P2P:                     b.fetchP2P(),
+		Chain:                   chainService,
+		InitialSync:             initSync,
+		StateNotifier:           b,
+		BlockNotifier:           b,
+		AttestationNotifier:     b,
+		OperationNotifier:       b,
+		AttPool:                 b.attestationPool,
+		ExitPool:                b.exitPool,
+		SlashingPool:            b.slashingsPool,
+		SyncCommsPool:           b.syncCommitteePool,
+		StateGen:                b.stateGen,
+		SlasherAttestationsFeed: b.slasherAttestationsFeed,
+		SlasherBlockHeadersFeed: b.slasherBlockHeadersFeed,
 	})
 
 	return b.services.RegisterService(rs)
@@ -533,6 +596,36 @@ func (b *BeaconNode) registerInitialSyncService() error {
 	return b.services.RegisterService(is)
 }
 
+func (b *BeaconNode) registerSlasherService() error {
+	if !features.Get().EnableSlasher {
+		return nil
+	}
+	var chainService *blockchain.Service
+	if err := b.services.FetchService(&chainService); err != nil {
+		return err
+	}
+	var syncService *initialsync.Service
+	if err := b.services.FetchService(&syncService); err != nil {
+		return err
+	}
+
+	slasherSrv, err := slasher.New(b.ctx, &slasher.ServiceConfig{
+		IndexedAttestationsFeed: b.slasherAttestationsFeed,
+		BeaconBlockHeadersFeed:  b.slasherBlockHeadersFeed,
+		Database:                b.slasherDB,
+		StateNotifier:           b,
+		AttestationStateFetcher: chainService,
+		StateGen:                b.stateGen,
+		SlashingPoolInserter:    b.slashingsPool,
+		SyncChecker:             syncService,
+		HeadStateFetcher:        chainService,
+	})
+	if err != nil {
+		return err
+	}
+	return b.services.RegisterService(slasherSrv)
+}
+
 func (b *BeaconNode) registerRPCService() error {
 	var chainService *blockchain.Service
 	if err := b.services.FetchService(&chainService); err != nil {
@@ -549,6 +642,13 @@ func (b *BeaconNode) registerRPCService() error {
 		return err
 	}
 
+	var slasherService *slasher.Service
+	if features.Get().EnableSlasher {
+		if err := b.services.FetchService(&slasherService); err != nil {
+			return err
+		}
+	}
+
 	genesisValidators := b.cliCtx.Uint64(flags.InteropNumValidatorsFlag.Name)
 	genesisStatePath := b.cliCtx.String(flags.InteropGenesisStateFlag.Name)
 	var depositFetcher depositcache.DepositFetcher
@@ -604,6 +704,7 @@ func (b *BeaconNode) registerRPCService() error {
 		AttestationsPool:        b.attestationPool,
 		ExitPool:                b.exitPool,
 		SlashingsPool:           b.slashingsPool,
+		SlashingChecker:         slasherService,
 		SyncCommitteeObjectPool: b.syncCommitteePool,
 		POWChainService:         web3Service,
 		ChainStartFetcher:       chainStartFetcher,

beacon-chain/operations/slashings/BUILD.bazel

@@ -13,12 +13,14 @@ go_library(
     importpath = "github.com/prysmaticlabs/prysm/beacon-chain/operations/slashings",
     visibility = [
         "//beacon-chain:__subpackages__",
+        "//testing/endtoend:__subpackages__",
         "//testing/fuzz:__pkg__",
+        "//testing/slasher/simulator:__pkg__",
     ],
     deps = [
-        "//beacon-chain/core:go_default_library",
         "//beacon-chain/core/blocks:go_default_library",
         "//beacon-chain/core/helpers:go_default_library",
+        "//beacon-chain/core/time:go_default_library",
         "//beacon-chain/state:go_default_library",
         "//config/params:go_default_library",
         "//container/slice:go_default_library",