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signature.go
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signature.go
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// Copyright 2023 The klaytn Authors
// This file is part of the klaytn library.
//
// The klaytn library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The klaytn library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the klaytn library. If not, see <http://www.gnu.org/licenses/>.
package blst
import (
"crypto/rand"
"fmt"
"sync"
"github.com/klaytn/klaytn/crypto/bls/types"
"github.com/pkg/errors"
)
type signature struct {
// Pointer to underlying blst struct, hence the name 'p'
p *blstSignature
}
func SignatureFromBytes(b []byte) (types.Signature, error) {
if len(b) != types.SignatureLength {
return nil, types.ErrSignatureLength(len(b))
}
if s, ok := signatureCache.Get(cacheKey(b)); ok {
return s.(*signature).Copy(), nil
}
p := new(blstSignature).Uncompress(b)
// Do not check for infinity since an aggregated signature could be infinite.
if p == nil || !p.SigValidate(false) {
return nil, types.ErrSignatureUnmarshal
}
s := &signature{p: p}
signatureCache.Add(cacheKey(b), s.Copy())
return s, nil
}
func MultipleSignaturesFromBytes(bs [][]byte) ([]types.Signature, error) {
if len(bs) == 0 {
return nil, nil
}
for _, b := range bs {
if len(b) != types.SignatureLength {
return nil, types.ErrSignatureLength(len(b))
}
}
// Separate cached and uncached element
sigs := make([]types.Signature, len(bs))
var batchIndices []int
var batchBytes [][]byte
for i, b := range bs {
if sig, ok := signatureCache.Get(cacheKey(b)); ok {
sigs[i] = sig.(*signature).Copy()
} else {
batchIndices = append(batchIndices, i)
batchBytes = append(batchBytes, b)
}
}
// Compute on uncached elements
batchPs := new(blstSignature).BatchUncompress(batchBytes)
if batchPs == nil || len(batchPs) != len(batchBytes) {
return nil, types.ErrSignatureUnmarshal
}
// Merge cached and uncached elements
for i, outIdx := range batchIndices {
p := batchPs[i]
b := batchBytes[i]
// Do not check for infinity since an aggregated signature could be infinite.
if p == nil || !p.SigValidate(false) {
return nil, types.ErrSignatureUnmarshal
}
sig := &signature{p: p}
signatureCache.Add(cacheKey(b), sig.Copy())
sigs[outIdx] = sig
}
return sigs, nil
}
// AggregateSignatures assumes that given signatures has passed the SigValidate() check
// i.e. they are on the right subgroup.
//
// Signature objects are expected to be returned by Sign(), SignatureFromBytes()
// and AggregateSignaturesFromBytes(), and they all should be valid.
// Therefore AggregateSignatures skips the validatity check.
func AggregateSignatures(sigs []types.Signature) (types.Signature, error) {
if len(sigs) == 0 {
return nil, types.ErrEmptyArray
}
ps := make([]*blstSignature, len(sigs))
for i, sig := range sigs {
ps[i] = sig.(*signature).p
}
agg := new(blstAggregateSignature)
groupcheck := false // alreaay checked in *SignatureFromBytes()
if !agg.Aggregate(ps, groupcheck) {
return nil, types.ErrSignatureAggregate
}
return &signature{p: agg.ToAffine()}, nil
}
func AggregateSignaturesFromBytes(bs [][]byte) (types.Signature, error) {
pks, err := MultipleSignaturesFromBytes(bs)
if err != nil {
return nil, err
}
return AggregateSignatures(pks)
}
func (s *signature) Marshal() []byte {
return s.p.Compress()
}
func (s *signature) Copy() types.Signature {
np := *s.p
return &signature{p: &np}
}
func Sign(sk types.SecretKey, msg []byte) types.Signature {
sig := new(blstSignature).Sign(
sk.(*secretKey).p, msg, types.DomainSeparationTag)
return &signature{p: sig}
}
func Verify(sig types.Signature, msg []byte, pk types.PublicKey) bool {
sigGroupCheck := false // alreaay checked in *SignatureFromBytes()
pkValidate := false // alreaay checked in *PublicKeyFromBytes()
return sig.(*signature).p.Verify(
sigGroupCheck, pk.(*publicKey).p, pkValidate, msg, types.DomainSeparationTag)
}
func FastAggregateVerify(sig types.Signature, msg []byte, pks []types.PublicKey) bool {
pubPs := make([]*blstPublicKey, len(pks))
for i := 0; i < len(pks); i++ {
pubPs[i] = pks[i].(*publicKey).p
}
sigGroupCheck := false // alreaay checked in *SignatureFromBytes()
return sig.(*signature).p.FastAggregateVerify(
sigGroupCheck, pubPs, msg, types.DomainSeparationTag)
}
func VerifySignature(sigb []byte, msg [32]byte, pk types.PublicKey) (bool, error) {
sig, err := SignatureFromBytes(sigb)
if err != nil {
return false, err
}
sigGroupCheck := false // alreaay checked in SignatureFromBytes()
pkValidate := false // alreaay checked in *PublicKeyFromBytes()
ok := sig.(*signature).p.Verify(
sigGroupCheck, pk.(*publicKey).p, pkValidate, msg[:], types.DomainSeparationTag)
return ok, nil
}
// https://ethresear.ch/t/fast-verification-of-multiple-bls-signatures/5407
func VerifyMultipleSignatures(sigbs [][]byte, msgs [][32]byte, pks []types.PublicKey) (bool, error) {
if len(sigbs) == 0 {
return false, nil
}
if len(sigbs) != len(msgs) || len(msgs) != len(pks) {
return false, errors.Errorf("Unmatched sigs, msgs, pubkeys lengths: %d, %d, %d", len(sigbs), len(msgs), len(pks))
}
count := len(sigbs)
// Benefit from cache
sigs, err := MultipleSignaturesFromBytes(sigbs)
if err != nil {
return false, err
}
// Convert to blst pointers
var (
sigPs = make([]*blstSignature, count)
pkPs = make([]*blstPublicKey, count)
msgPs = make([]blstMessage, count)
)
for i := 0; i < len(sigs); i++ {
sigPs[i] = sigs[i].(*signature).p
pkPs[i] = pks[i].(*publicKey).p
msgPs[i] = msgs[i][:]
}
// Supply random source
var randErr error
randLock := new(sync.Mutex)
randFunc := func(outScalar *blstScalar) {
var r [blstScalarBytes]byte
randLock.Lock()
_, err := rand.Read(r[:])
randLock.Unlock()
if err != nil {
randErr = err
}
outScalar.FromBEndian(r[:])
}
dummy := new(blstSignature)
sigGroupCheck := false // alreaay checked in MultipleSignaturesFromBytes()
pkValidate := false // alreaay checked in *PublicKeyFromBytes()
ok := dummy.MultipleAggregateVerify(
sigPs, sigGroupCheck, pkPs, pkValidate, msgPs, types.DomainSeparationTag, randFunc, blstRandBits)
if randErr != nil {
return false, fmt.Errorf("verify aborted: %s", randErr.Error())
} else {
return ok, nil
}
}