mirror of
https://gitlab.com/pulsechaincom/prysm-pulse.git
synced 2024-12-25 12:57:18 +00:00
162 lines
5.3 KiB
Go
162 lines
5.3 KiB
Go
package helpers
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import (
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"encoding/binary"
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"github.com/gogo/protobuf/proto"
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"github.com/pkg/errors"
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ethpb "github.com/prysmaticlabs/ethereumapis/eth/v1alpha1"
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"github.com/prysmaticlabs/go-ssz"
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pb "github.com/prysmaticlabs/prysm/proto/beacon/p2p/v1"
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"github.com/prysmaticlabs/prysm/shared/bls"
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"github.com/prysmaticlabs/prysm/shared/hashutil"
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"github.com/prysmaticlabs/prysm/shared/params"
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)
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var (
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// ErrAttestationAggregationBitsOverlap is returned when two attestations aggregation
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// bits overlap with each other.
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ErrAttestationAggregationBitsOverlap = errors.New("overlapping aggregation bits")
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)
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// AggregateAttestations such that the minimal number of attestations are returned.
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// Note: this is currently a naive implementation to the order of O(n^2).
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func AggregateAttestations(atts []*ethpb.Attestation) ([]*ethpb.Attestation, error) {
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if len(atts) <= 1 {
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return atts, nil
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}
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// Naive aggregation. O(n^2) time.
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for i, a := range atts {
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if i >= len(atts) {
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break
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}
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for j := i + 1; j < len(atts); j++ {
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b := atts[j]
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if !a.AggregationBits.Overlaps(b.AggregationBits) {
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var err error
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a, err = AggregateAttestation(a, b)
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if err != nil {
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return nil, err
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}
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// Delete b
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atts = append(atts[:j], atts[j+1:]...)
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j--
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atts[i] = a
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}
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}
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}
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// Naive deduplication of identical aggregations. O(n^2) time.
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for i, a := range atts {
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for j := i + 1; j < len(atts); j++ {
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b := atts[j]
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if a.AggregationBits.Contains(b.AggregationBits) {
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// If b is fully contained in a, then b can be removed.
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atts = append(atts[:j], atts[j+1:]...)
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j--
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} else if b.AggregationBits.Contains(a.AggregationBits) {
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// if a is fully contained in b, then a can be removed.
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atts = append(atts[:i], atts[i+1:]...)
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i--
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break // Stop the inner loop, advance a.
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}
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}
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}
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return atts, nil
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}
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// BLS aggregate signature aliases for testing / benchmark substitution. These methods are
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// significantly more expensive than the inner logic of AggregateAttestations so they must be
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// substituted for benchmarks which analyze AggregateAttestations.
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var aggregateSignatures = bls.AggregateSignatures
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var signatureFromBytes = bls.SignatureFromBytes
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// AggregateAttestation aggregates attestations a1 and a2 together.
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func AggregateAttestation(a1 *ethpb.Attestation, a2 *ethpb.Attestation) (*ethpb.Attestation, error) {
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if a1.AggregationBits.Overlaps(a2.AggregationBits) {
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return nil, ErrAttestationAggregationBitsOverlap
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}
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baseAtt := proto.Clone(a1).(*ethpb.Attestation)
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newAtt := proto.Clone(a2).(*ethpb.Attestation)
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if newAtt.AggregationBits.Count() > baseAtt.AggregationBits.Count() {
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baseAtt, newAtt = newAtt, baseAtt
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}
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if baseAtt.AggregationBits.Contains(newAtt.AggregationBits) {
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return baseAtt, nil
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}
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newBits := baseAtt.AggregationBits.Or(newAtt.AggregationBits)
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newSig, err := signatureFromBytes(newAtt.Signature)
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if err != nil {
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return nil, err
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}
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baseSig, err := signatureFromBytes(baseAtt.Signature)
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if err != nil {
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return nil, err
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}
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aggregatedSig := aggregateSignatures([]*bls.Signature{baseSig, newSig})
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baseAtt.Signature = aggregatedSig.Marshal()
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baseAtt.AggregationBits = newBits
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return baseAtt, nil
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}
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// SlotSignature returns the signed signature of the hash tree root of input slot.
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//
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// Spec pseudocode definition:
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// def slot_signature(state: BeaconState, slot: Slot, privkey: int) -> BLSSignature:
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// domain = get_domain(state, DOMAIN_BEACON_ATTESTER, compute_epoch_at_slot(slot))
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// return bls_sign(privkey, hash_tree_root(slot), domain)
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func SlotSignature(state *pb.BeaconState, slot uint64, privKey *bls.SecretKey) (*bls.Signature, error) {
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d := Domain(state.Fork, CurrentEpoch(state), params.BeaconConfig().DomainBeaconAttester)
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s, err := ssz.HashTreeRoot(slot)
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if err != nil {
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return nil, err
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}
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return privKey.Sign(s[:], d), nil
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}
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// IsAggregator returns true if the signature is from the input validator.
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//
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// Spec pseudocode definition:
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// def is_aggregator(state: BeaconState, slot: Slot, index: CommitteeIndex, slot_signature: BLSSignature) -> bool:
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// committee = get_beacon_committee(state, slot, index)
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// modulo = max(1, len(committee) // TARGET_AGGREGATORS_PER_COMMITTEE)
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// return bytes_to_int(hash(slot_signature)[0:8]) % modulo == 0
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func IsAggregator(state *pb.BeaconState, slot uint64, index uint64, slotSig *bls.Signature) (bool, error) {
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committee, err := BeaconCommittee(state, slot, index)
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if err != nil {
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return false, err
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}
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modulo := uint64(1)
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if len(committee)/int(params.BeaconConfig().TargetAggregatorsPerCommittee) > 1 {
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modulo = uint64(len(committee)) / params.BeaconConfig().TargetAggregatorsPerCommittee
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}
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b := hashutil.Hash(slotSig.Marshal())
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return binary.LittleEndian.Uint64(b[:8])%modulo == 0, nil
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}
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// AggregateSignature returns the aggregated signature of the input attestations.
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//
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// Spec pseudocode definition:
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// def get_aggregate_signature(attestations: Sequence[Attestation]) -> BLSSignature:
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// signatures = [attestation.signature for attestation in attestations]
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// return bls_aggregate_signatures(signatures)
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func AggregateSignature(attestations []*ethpb.Attestation) (*bls.Signature, error) {
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sigs := make([]*bls.Signature, len(attestations))
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var err error
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for i := 0; i < len(sigs); i++ {
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sigs[i], err = signatureFromBytes(attestations[i].Signature)
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if err != nil {
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return nil, err
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}
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}
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return aggregateSignatures(sigs), nil
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}
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