215 lines
6.8 KiB
Go
215 lines
6.8 KiB
Go
// Copyright 2023 The go-ethereum Authors
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// This file is part of the go-ethereum library.
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//
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// The go-ethereum library is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Lesser General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// The go-ethereum library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU Lesser General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public License
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// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
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package types
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import (
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"crypto/sha256"
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"encoding/json"
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"fmt"
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"math/bits"
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"github.com/ethereum/go-ethereum/beacon/params"
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"github.com/ethereum/go-ethereum/common"
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"github.com/ethereum/go-ethereum/common/hexutil"
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bls "github.com/protolambda/bls12-381-util"
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)
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// SerializedSyncCommitteeSize is the size of the sync committee plus the
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// aggregate public key.
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const SerializedSyncCommitteeSize = (params.SyncCommitteeSize + 1) * params.BLSPubkeySize
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// SerializedSyncCommittee is the serialized version of a sync committee
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// plus the aggregate public key.
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type SerializedSyncCommittee [SerializedSyncCommitteeSize]byte
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// jsonSyncCommittee is the JSON representation of a sync committee.
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//
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// See data structure definition here:
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// https://github.com/ethereum/consensus-specs/blob/dev/specs/altair/beacon-chain.md#syncaggregate
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type jsonSyncCommittee struct {
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Pubkeys []hexutil.Bytes `json:"pubkeys"`
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Aggregate hexutil.Bytes `json:"aggregate_pubkey"`
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}
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// MarshalJSON implements json.Marshaler.
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func (s *SerializedSyncCommittee) MarshalJSON() ([]byte, error) {
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sc := jsonSyncCommittee{Pubkeys: make([]hexutil.Bytes, params.SyncCommitteeSize)}
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for i := range sc.Pubkeys {
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sc.Pubkeys[i] = make(hexutil.Bytes, params.BLSPubkeySize)
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copy(sc.Pubkeys[i][:], s[i*params.BLSPubkeySize:(i+1)*params.BLSPubkeySize])
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}
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sc.Aggregate = make(hexutil.Bytes, params.BLSPubkeySize)
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copy(sc.Aggregate[:], s[params.SyncCommitteeSize*params.BLSPubkeySize:])
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return json.Marshal(&sc)
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}
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// UnmarshalJSON implements json.Marshaler.
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func (s *SerializedSyncCommittee) UnmarshalJSON(input []byte) error {
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var sc jsonSyncCommittee
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if err := json.Unmarshal(input, &sc); err != nil {
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return err
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}
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if len(sc.Pubkeys) != params.SyncCommitteeSize {
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return fmt.Errorf("invalid number of pubkeys %d", len(sc.Pubkeys))
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}
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for i, key := range sc.Pubkeys {
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if len(key) != params.BLSPubkeySize {
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return fmt.Errorf("pubkey %d has invalid size %d", i, len(key))
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}
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copy(s[i*params.BLSPubkeySize:], key[:])
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}
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if len(sc.Aggregate) != params.BLSPubkeySize {
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return fmt.Errorf("invalid aggregate pubkey size %d", len(sc.Aggregate))
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}
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copy(s[params.SyncCommitteeSize*params.BLSPubkeySize:], sc.Aggregate[:])
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return nil
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}
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// Root calculates the root hash of the binary tree representation of a sync
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// committee provided in serialized format.
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//
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// TODO(zsfelfoldi): Get rid of this when SSZ encoding lands.
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func (s *SerializedSyncCommittee) Root() common.Hash {
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var (
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hasher = sha256.New()
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padding [64 - params.BLSPubkeySize]byte
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data [params.SyncCommitteeSize]common.Hash
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l = params.SyncCommitteeSize
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)
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for i := range data {
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hasher.Reset()
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hasher.Write(s[i*params.BLSPubkeySize : (i+1)*params.BLSPubkeySize])
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hasher.Write(padding[:])
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hasher.Sum(data[i][:0])
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}
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for l > 1 {
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for i := 0; i < l/2; i++ {
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hasher.Reset()
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hasher.Write(data[i*2][:])
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hasher.Write(data[i*2+1][:])
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hasher.Sum(data[i][:0])
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}
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l /= 2
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}
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hasher.Reset()
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hasher.Write(s[SerializedSyncCommitteeSize-params.BLSPubkeySize : SerializedSyncCommitteeSize])
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hasher.Write(padding[:])
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hasher.Sum(data[1][:0])
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hasher.Reset()
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hasher.Write(data[0][:])
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hasher.Write(data[1][:])
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hasher.Sum(data[0][:0])
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return data[0]
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}
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// Deserialize splits open the pubkeys into proper BLS key types.
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func (s *SerializedSyncCommittee) Deserialize() (*SyncCommittee, error) {
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sc := new(SyncCommittee)
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for i := 0; i <= params.SyncCommitteeSize; i++ {
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key := new(bls.Pubkey)
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var bytes [params.BLSPubkeySize]byte
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copy(bytes[:], s[i*params.BLSPubkeySize:(i+1)*params.BLSPubkeySize])
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if err := key.Deserialize(&bytes); err != nil {
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return nil, err
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}
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if i < params.SyncCommitteeSize {
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sc.keys[i] = key
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} else {
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sc.aggregate = key
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}
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}
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return sc, nil
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}
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// SyncCommittee is a set of sync committee signer pubkeys and the aggregate key.
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//
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// See data structure definition here:
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// https://github.com/ethereum/consensus-specs/blob/dev/specs/altair/beacon-chain.md#syncaggregate
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type SyncCommittee struct {
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keys [params.SyncCommitteeSize]*bls.Pubkey
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aggregate *bls.Pubkey
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}
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// VerifySignature returns true if the given sync aggregate is a valid signature
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// or the given hash.
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func (sc *SyncCommittee) VerifySignature(signingRoot common.Hash, signature *SyncAggregate) bool {
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var (
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sig bls.Signature
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keys = make([]*bls.Pubkey, 0, params.SyncCommitteeSize)
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)
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if err := sig.Deserialize(&signature.Signature); err != nil {
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return false
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}
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for i, key := range sc.keys {
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if signature.Signers[i/8]&(byte(1)<<(i%8)) != 0 {
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keys = append(keys, key)
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}
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}
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return bls.FastAggregateVerify(keys, signingRoot[:], &sig)
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}
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// SyncAggregate represents an aggregated BLS signature with Signers referring
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// to a subset of the corresponding sync committee.
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//
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// See data structure definition here:
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// https://github.com/ethereum/consensus-specs/blob/dev/specs/altair/beacon-chain.md#syncaggregate
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type SyncAggregate struct {
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Signers [params.SyncCommitteeBitmaskSize]byte
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Signature [params.BLSSignatureSize]byte
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}
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type jsonSyncAggregate struct {
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Signers hexutil.Bytes `json:"sync_committee_bits"`
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Signature hexutil.Bytes `json:"sync_committee_signature"`
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}
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// MarshalJSON implements json.Marshaler.
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func (s *SyncAggregate) MarshalJSON() ([]byte, error) {
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return json.Marshal(&jsonSyncAggregate{
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Signers: s.Signers[:],
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Signature: s.Signature[:],
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})
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}
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// UnmarshalJSON implements json.Marshaler.
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func (s *SyncAggregate) UnmarshalJSON(input []byte) error {
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var sc jsonSyncAggregate
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if err := json.Unmarshal(input, &sc); err != nil {
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return err
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}
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if len(sc.Signers) != params.SyncCommitteeBitmaskSize {
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return fmt.Errorf("invalid signature bitmask size %d", len(sc.Signers))
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}
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if len(sc.Signature) != params.BLSSignatureSize {
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return fmt.Errorf("invalid signature size %d", len(sc.Signature))
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}
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copy(s.Signers[:], sc.Signers)
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copy(s.Signature[:], sc.Signature)
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return nil
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}
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// SignerCount returns the number of signers in the aggregate signature.
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func (s *SyncAggregate) SignerCount() int {
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var count int
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for _, v := range s.Signers {
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count += bits.OnesCount8(v)
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}
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return count
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}
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