Add payload attestation helper functions (#14258)

* Add `IndexedPayloadAttestation` container

* Add `GetPayloadAttestingIndices` and its unit test

* Add `GetIndexedPayloadAttestation` and its unit test

* Add `is_valid_indexed_payload_attestation` and its unit test

* Create a smaller set of validators for faster unit test

* Pass context to `GetPayloadTimelinessCommittee`

* Iterate `ValidatorsReadOnly` instead of copying all validators

beacon-chain/core/helpers/BUILD.bazel

@@ -26,6 +26,7 @@ go_library(
         "//beacon-chain/state:go_default_library",
         "//config/fieldparams:go_default_library",
         "//config/params:go_default_library",
+        "//consensus-types/epbs:go_default_library",
         "//consensus-types/interfaces:go_default_library",
         "//consensus-types/primitives:go_default_library",
         "//container/slice:go_default_library",
@@ -77,6 +78,7 @@ go_test(
         "//beacon-chain/state/state-native:go_default_library",
         "//config/fieldparams:go_default_library",
         "//config/params:go_default_library",
+        "//consensus-types/epbs:go_default_library",
         "//consensus-types/primitives:go_default_library",
         "//container/slice:go_default_library",
         "//crypto/hash:go_default_library",

beacon-chain/core/helpers/payload_attestation.go

@@ -2,11 +2,16 @@ package helpers
 
 import (
 	"context"
+	"slices"
 
 	"github.com/pkg/errors"
+	"github.com/prysmaticlabs/prysm/v5/beacon-chain/core/signing"
 	"github.com/prysmaticlabs/prysm/v5/beacon-chain/state"
 	fieldparams "github.com/prysmaticlabs/prysm/v5/config/fieldparams"
+	"github.com/prysmaticlabs/prysm/v5/config/params"
+	"github.com/prysmaticlabs/prysm/v5/consensus-types/epbs"
 	"github.com/prysmaticlabs/prysm/v5/consensus-types/primitives"
+	"github.com/prysmaticlabs/prysm/v5/crypto/bls"
 	"github.com/prysmaticlabs/prysm/v5/math"
 	eth "github.com/prysmaticlabs/prysm/v5/proto/prysm/v1alpha1"
 	"github.com/prysmaticlabs/prysm/v5/runtime/version"
@@ -97,3 +102,150 @@ func PtcAllocation(totalActive uint64) (committeesPerSlot, membersPerCommittee u
 	membersPerCommittee = fieldparams.PTCSize / committeesPerSlot
 	return
 }
+
+// GetPayloadAttestingIndices returns the set of attester indices corresponding to the given PayloadAttestation.
+//
+// Spec pseudocode definition:
+//
+//	def get_payload_attesting_indices(state: BeaconState, slot: Slot,
+//		payload_attestation: PayloadAttestation) -> Set[ValidatorIndex]:
+//	"""
+//	Return the set of attesting indices corresponding to ``payload_attestation``.
+//	"""
+//	ptc = get_ptc(state, slot)
+//	return set(index for i, index in enumerate(ptc) if payload_attestation.aggregation_bits[i])
+func GetPayloadAttestingIndices(ctx context.Context, state state.ReadOnlyBeaconState, slot primitives.Slot, att *eth.PayloadAttestation) (indices []primitives.ValidatorIndex, err error) {
+	if state.Version() < version.EPBS {
+		return nil, errPreEPBSState
+	}
+
+	ptc, err := GetPayloadTimelinessCommittee(ctx, state, slot)
+	if err != nil {
+		return nil, err
+	}
+
+	for i, validatorIndex := range ptc {
+		if att.AggregationBits.BitAt(uint64(i)) {
+			indices = append(indices, validatorIndex)
+		}
+	}
+
+	return
+}
+
+// GetIndexedPayloadAttestation replaces a PayloadAttestation's AggregationBits with sorted AttestingIndices and returns an IndexedPayloadAttestation.
+//
+// Spec pseudocode definition:
+//
+//	def get_indexed_payload_attestation(state: BeaconState, slot: Slot,
+//		payload_attestation: PayloadAttestation) -> IndexedPayloadAttestation:
+//	"""
+//	Return the indexed payload attestation corresponding to ``payload_attestation``.
+//	"""
+//	attesting_indices = get_payload_attesting_indices(state, slot, payload_attestation)
+//
+//	return IndexedPayloadAttestation(
+//	attesting_indices=sorted(attesting_indices),
+//	data=payload_attestation.data,
+//	signature=payload_attestation.signature,
+//	)
+func GetIndexedPayloadAttestation(ctx context.Context, state state.ReadOnlyBeaconState, slot primitives.Slot, att *eth.PayloadAttestation) (*epbs.IndexedPayloadAttestation, error) {
+	if state.Version() < version.EPBS {
+		return nil, errPreEPBSState
+	}
+
+	attestingIndices, err := GetPayloadAttestingIndices(ctx, state, slot, att)
+	if err != nil {
+		return nil, err
+	}
+
+	slices.Sort(attestingIndices)
+
+	return &epbs.IndexedPayloadAttestation{
+		AttestingIndices: attestingIndices,
+		Data:             att.Data,
+		Signature:        att.Signature,
+	}, nil
+}
+
+// IsValidIndexedPayloadAttestation validates the given IndexedPayloadAttestation.
+//
+// Spec pseudocode definition:
+//
+//	def is_valid_indexed_payload_attestation(
+//		state: BeaconState,
+//		indexed_payload_attestation: IndexedPayloadAttestation) -> bool:
+//	"""
+//	Check if ``indexed_payload_attestation`` is not empty, has sorted and unique indices and has
+//	a valid aggregate signature.
+//	"""
+//	# Verify the data is valid
+//	if indexed_payload_attestation.data.payload_status >= PAYLOAD_INVALID_STATUS:
+//		return False
+//
+//	# Verify indices are sorted and unique
+//	indices = indexed_payload_attestation.attesting_indices
+//	if len(indices) == 0 or not indices == sorted(set(indices)):
+//		return False
+//
+//	# Verify aggregate signature
+//	pubkeys = [state.validators[i].pubkey for i in indices]
+//	domain = get_domain(state, DOMAIN_PTC_ATTESTER, None)
+//	signing_root = compute_signing_root(indexed_payload_attestation.data, domain)
+//	return bls.FastAggregateVerify(pubkeys, signing_root, indexed_payload_attestation.signature)
+func IsValidIndexedPayloadAttestation(state state.ReadOnlyBeaconState, att *epbs.IndexedPayloadAttestation) (bool, error) {
+	if state.Version() < version.EPBS {
+		return false, errPreEPBSState
+	}
+
+	// Verify the data is valid.
+	if att.Data.PayloadStatus >= primitives.PAYLOAD_INVALID_STATUS {
+		return false, nil
+	}
+
+	// Verify indices are sorted and unique.
+	indices := att.AttestingIndices
+	slices.Sort(indices)
+	if len(indices) == 0 || !slices.Equal(att.AttestingIndices, indices) {
+		return false, nil
+	}
+
+	// Verify aggregate signature.
+	publicKeys := make([]bls.PublicKey, len(indices))
+	for i, index := range indices {
+		validator, err := state.ValidatorAtIndexReadOnly(index)
+		if err != nil {
+			return false, err
+		}
+
+		publicKeyBytes := validator.PublicKey()
+		publicKey, err := bls.PublicKeyFromBytes(publicKeyBytes[:])
+		if err != nil {
+			return false, err
+		}
+
+		publicKeys[i] = publicKey
+	}
+
+	domain, err := signing.Domain(
+		state.Fork(),
+		slots.ToEpoch(state.Slot()),
+		params.BeaconConfig().DomainPTCAttester,
+		state.GenesisValidatorsRoot(),
+	)
+	if err != nil {
+		return false, err
+	}
+
+	signingRoot, err := signing.ComputeSigningRoot(att.Data, domain)
+	if err != nil {
+		return false, err
+	}
+
+	signature, err := bls.SignatureFromBytes(att.Signature)
+	if err != nil {
+		return false, err
+	}
+
+	return signature.FastAggregateVerify(publicKeys, signingRoot), nil
+}

beacon-chain/core/helpers/payload_attestation_test.go

@@ -2,18 +2,25 @@ package helpers_test
 
 import (
 	"context"
+	"slices"
 	"strconv"
 	"testing"
 
 	"github.com/prysmaticlabs/go-bitfield"
 	"github.com/prysmaticlabs/prysm/v5/beacon-chain/core/helpers"
+	"github.com/prysmaticlabs/prysm/v5/beacon-chain/core/signing"
 	state_native "github.com/prysmaticlabs/prysm/v5/beacon-chain/state/state-native"
 	fieldparams "github.com/prysmaticlabs/prysm/v5/config/fieldparams"
 	"github.com/prysmaticlabs/prysm/v5/config/params"
+	"github.com/prysmaticlabs/prysm/v5/consensus-types/epbs"
+	"github.com/prysmaticlabs/prysm/v5/consensus-types/primitives"
+	"github.com/prysmaticlabs/prysm/v5/crypto/bls"
+	"github.com/prysmaticlabs/prysm/v5/crypto/rand"
 	"github.com/prysmaticlabs/prysm/v5/math"
 	eth "github.com/prysmaticlabs/prysm/v5/proto/prysm/v1alpha1"
 	ethpb "github.com/prysmaticlabs/prysm/v5/proto/prysm/v1alpha1"
 	"github.com/prysmaticlabs/prysm/v5/testing/require"
+	"github.com/prysmaticlabs/prysm/v5/testing/util"
 	"github.com/prysmaticlabs/prysm/v5/testing/util/random"
 	"github.com/prysmaticlabs/prysm/v5/time/slots"
 )
@@ -115,3 +122,242 @@ func Test_PtcAllocation(t *testing.T) {
 		}
 	}
 }
+
+func TestGetPayloadAttestingIndices(t *testing.T) {
+	helpers.ClearCache()
+
+	// Create 10 committees. Total 40960 validators.
+	committeeCount := uint64(10)
+	validatorCount := committeeCount * params.BeaconConfig().TargetCommitteeSize * uint64(params.BeaconConfig().SlotsPerEpoch)
+	validators := make([]*ethpb.Validator, validatorCount)
+
+	for i := 0; i < len(validators); i++ {
+		pubkey := make([]byte, 48)
+		copy(pubkey, strconv.Itoa(i))
+		validators[i] = &ethpb.Validator{
+			PublicKey:             pubkey,
+			WithdrawalCredentials: make([]byte, 32),
+			ExitEpoch:             params.BeaconConfig().FarFutureEpoch,
+		}
+	}
+
+	// Create a beacon state.
+	state, err := state_native.InitializeFromProtoEpbs(&ethpb.BeaconStateEPBS{
+		Validators:  validators,
+		RandaoMixes: make([][]byte, params.BeaconConfig().EpochsPerHistoricalVector),
+	})
+	require.NoError(t, err)
+
+	// Get PTC.
+	ptc, err := helpers.GetPayloadTimelinessCommittee(context.Background(), state, state.Slot())
+	require.NoError(t, err)
+	require.Equal(t, fieldparams.PTCSize, len(ptc))
+
+	// Generate random indices. PTC members at the corresponding indices are considered attested.
+	randGen := rand.NewDeterministicGenerator()
+	attesterCount := randGen.Intn(fieldparams.PTCSize) + 1
+	indices := randGen.Perm(fieldparams.PTCSize)[:attesterCount]
+	slices.Sort(indices)
+	require.Equal(t, attesterCount, len(indices))
+
+	// Create a PayloadAttestation with AggregationBits set true at the indices.
+	aggregationBits := bitfield.NewBitvector512()
+	for _, index := range indices {
+		aggregationBits.SetBitAt(uint64(index), true)
+	}
+
+	payloadAttestation := &eth.PayloadAttestation{
+		AggregationBits: aggregationBits,
+		Data: &eth.PayloadAttestationData{
+			BeaconBlockRoot: make([]byte, 32),
+		},
+		Signature: make([]byte, 96),
+	}
+
+	// Get attesting indices.
+	attesters, err := helpers.GetPayloadAttestingIndices(context.Background(), state, state.Slot(), payloadAttestation)
+	require.NoError(t, err)
+	require.Equal(t, len(indices), len(attesters))
+
+	// Check if each attester equals to the PTC member at the corresponding index.
+	for i, index := range indices {
+		require.Equal(t, attesters[i], ptc[index])
+	}
+}
+
+func TestGetIndexedPayloadAttestation(t *testing.T) {
+	helpers.ClearCache()
+
+	// Create 10 committees. Total 40960 validators.
+	committeeCount := uint64(10)
+	validatorCount := committeeCount * params.BeaconConfig().TargetCommitteeSize * uint64(params.BeaconConfig().SlotsPerEpoch)
+	validators := make([]*ethpb.Validator, validatorCount)
+
+	for i := 0; i < len(validators); i++ {
+		publicKey := make([]byte, 48)
+		copy(publicKey, strconv.Itoa(i))
+		validators[i] = &ethpb.Validator{
+			PublicKey:             publicKey,
+			WithdrawalCredentials: make([]byte, 32),
+			ExitEpoch:             params.BeaconConfig().FarFutureEpoch,
+		}
+	}
+
+	// Create a beacon state.
+	state, err := state_native.InitializeFromProtoEpbs(&ethpb.BeaconStateEPBS{
+		Validators:  validators,
+		RandaoMixes: make([][]byte, params.BeaconConfig().EpochsPerHistoricalVector),
+	})
+	require.NoError(t, err)
+
+	// Get PTC.
+	ptc, err := helpers.GetPayloadTimelinessCommittee(context.Background(), state, state.Slot())
+	require.NoError(t, err)
+	require.Equal(t, fieldparams.PTCSize, len(ptc))
+
+	// Generate random indices. PTC members at the corresponding indices are considered attested.
+	randGen := rand.NewDeterministicGenerator()
+	attesterCount := randGen.Intn(fieldparams.PTCSize) + 1
+	indices := randGen.Perm(fieldparams.PTCSize)[:attesterCount]
+	slices.Sort(indices)
+	require.Equal(t, attesterCount, len(indices))
+
+	// Create a PayloadAttestation with AggregationBits set true at the indices.
+	aggregationBits := bitfield.NewBitvector512()
+	for _, index := range indices {
+		aggregationBits.SetBitAt(uint64(index), true)
+	}
+
+	payloadAttestation := &eth.PayloadAttestation{
+		AggregationBits: aggregationBits,
+		Data: &eth.PayloadAttestationData{
+			BeaconBlockRoot: make([]byte, 32),
+		},
+		Signature: make([]byte, 96),
+	}
+
+	// Get attesting indices.
+	ctx := context.Background()
+	attesters, err := helpers.GetPayloadAttestingIndices(ctx, state, state.Slot(), payloadAttestation)
+	require.NoError(t, err)
+	require.Equal(t, len(indices), len(attesters))
+
+	// Get an IndexedPayloadAttestation.
+	indexedPayloadAttestation, err := helpers.GetIndexedPayloadAttestation(ctx, state, state.Slot(), payloadAttestation)
+	require.NoError(t, err)
+	require.Equal(t, len(indices), len(indexedPayloadAttestation.AttestingIndices))
+	require.DeepEqual(t, payloadAttestation.Data, indexedPayloadAttestation.Data)
+	require.DeepEqual(t, payloadAttestation.Signature, indexedPayloadAttestation.Signature)
+
+	// Check if the attesting indices are the same.
+	slices.Sort(attesters) // GetIndexedPayloadAttestation sorts attesting indices.
+	require.DeepEqual(t, attesters, indexedPayloadAttestation.AttestingIndices)
+}
+
+func TestIsValidIndexedPayloadAttestation(t *testing.T) {
+	helpers.ClearCache()
+
+	// Create validators.
+	validatorCount := uint64(350)
+	validators := make([]*ethpb.Validator, validatorCount)
+	_, secretKeys, err := util.DeterministicDepositsAndKeys(validatorCount)
+	require.NoError(t, err)
+
+	for i := 0; i < len(validators); i++ {
+		validators[i] = &ethpb.Validator{
+			PublicKey:             secretKeys[i].PublicKey().Marshal(),
+			WithdrawalCredentials: make([]byte, 32),
+			ExitEpoch:             params.BeaconConfig().FarFutureEpoch,
+		}
+	}
+
+	// Create a beacon state.
+	state, err := state_native.InitializeFromProtoEpbs(&ethpb.BeaconStateEPBS{
+		Validators: validators,
+		Fork: &ethpb.Fork{
+			Epoch:           0,
+			CurrentVersion:  params.BeaconConfig().GenesisForkVersion,
+			PreviousVersion: params.BeaconConfig().GenesisForkVersion,
+		},
+		RandaoMixes: make([][]byte, params.BeaconConfig().EpochsPerHistoricalVector),
+	})
+	require.NoError(t, err)
+
+	// Define test cases.
+	tests := []struct {
+		attestation *epbs.IndexedPayloadAttestation
+	}{
+		{
+			attestation: &epbs.IndexedPayloadAttestation{
+				AttestingIndices: []primitives.ValidatorIndex{1},
+				Data: &eth.PayloadAttestationData{
+					BeaconBlockRoot: make([]byte, fieldparams.RootLength),
+				},
+				Signature: make([]byte, fieldparams.BLSSignatureLength),
+			},
+		},
+		{
+			attestation: &epbs.IndexedPayloadAttestation{
+				AttestingIndices: []primitives.ValidatorIndex{13, 19},
+				Data: &eth.PayloadAttestationData{
+					BeaconBlockRoot: make([]byte, fieldparams.RootLength),
+				},
+				Signature: make([]byte, fieldparams.BLSSignatureLength),
+			},
+		},
+		{
+			attestation: &epbs.IndexedPayloadAttestation{
+				AttestingIndices: []primitives.ValidatorIndex{123, 234, 345},
+				Data: &eth.PayloadAttestationData{
+					BeaconBlockRoot: make([]byte, fieldparams.RootLength),
+				},
+				Signature: make([]byte, fieldparams.BLSSignatureLength),
+			},
+		},
+		{
+			attestation: &epbs.IndexedPayloadAttestation{
+				AttestingIndices: []primitives.ValidatorIndex{38, 46, 54, 62, 70, 78, 86, 194},
+				Data: &eth.PayloadAttestationData{
+					BeaconBlockRoot: make([]byte, fieldparams.RootLength),
+				},
+				Signature: make([]byte, fieldparams.BLSSignatureLength),
+			},
+		},
+		{
+			attestation: &epbs.IndexedPayloadAttestation{
+				AttestingIndices: []primitives.ValidatorIndex{5},
+				Data: &eth.PayloadAttestationData{
+					BeaconBlockRoot: make([]byte, fieldparams.RootLength),
+				},
+				Signature: make([]byte, fieldparams.BLSSignatureLength),
+			},
+		},
+	}
+
+	// Run test cases.
+	for _, test := range tests {
+		signatures := make([]bls.Signature, len(test.attestation.AttestingIndices))
+		for i, index := range test.attestation.AttestingIndices {
+			signedBytes, err := signing.ComputeDomainAndSign(
+				state,
+				slots.ToEpoch(test.attestation.Data.Slot),
+				test.attestation.Data,
+				params.BeaconConfig().DomainPTCAttester,
+				secretKeys[index],
+			)
+			require.NoError(t, err)
+
+			signature, err := bls.SignatureFromBytes(signedBytes)
+			require.NoError(t, err)
+
+			signatures[i] = signature
+		}
+
+		aggregatedSignature := bls.AggregateSignatures(signatures)
+		test.attestation.Signature = aggregatedSignature.Marshal()
+
+		isValid, err := helpers.IsValidIndexedPayloadAttestation(state, test.attestation)
+		require.NoError(t, err)
+		require.Equal(t, true, isValid)
+	}
+}

consensus-types/epbs/BUILD.bazel

@@ -0,0 +1,12 @@
+load("@prysm//tools/go:def.bzl", "go_library")
+
+go_library(
+    name = "go_default_library",
+    srcs = ["indexed_payload_attestation.go"],
+    importpath = "github.com/prysmaticlabs/prysm/v5/consensus-types/epbs",
+    visibility = ["//visibility:public"],
+    deps = [
+        "//consensus-types/primitives:go_default_library",
+        "//proto/prysm/v1alpha1:go_default_library",
+    ],
+)

consensus-types/epbs/indexed_payload_attestation.go

@@ -0,0 +1,33 @@
+package epbs
+
+import (
+	"github.com/prysmaticlabs/prysm/v5/consensus-types/primitives"
+	eth "github.com/prysmaticlabs/prysm/v5/proto/prysm/v1alpha1"
+)
+
+type IndexedPayloadAttestation struct {
+	AttestingIndices []primitives.ValidatorIndex
+	Data             *eth.PayloadAttestationData
+	Signature        []byte
+}
+
+func (x *IndexedPayloadAttestation) GetAttestingIndices() []primitives.ValidatorIndex {
+	if x != nil {
+		return x.AttestingIndices
+	}
+	return []primitives.ValidatorIndex(nil)
+}
+
+func (x *IndexedPayloadAttestation) GetData() *eth.PayloadAttestationData {
+	if x != nil {
+		return x.Data
+	}
+	return nil
+}
+
+func (x *IndexedPayloadAttestation) GetSignature() []byte {
+	if x != nil {
+		return x.Signature
+	}
+	return nil
+}