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signature.go
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signature.go
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package bls
import (
"errors"
"fmt"
"math/big"
bn256 "github.com/umbracle/go-eth-bn256"
)
// Signature represents bls signature which is point on the curve
type Signature struct {
g1 *bn256.G1
}
// Verify checks the BLS signature of the message against the public key of its signer
func (s *Signature) Verify(pub *PublicKey, message, domain []byte) bool {
point, err := hashToPoint(message, domain)
if err != nil {
return false
}
return bn256.PairingCheck([]*bn256.G1{s.g1, point}, []*bn256.G2{negG2Point, pub.g2})
}
// VerifyAggregated checks the BLS signature of the message against the aggregated public keys of its signers
func (s *Signature) VerifyAggregated(publicKeys []*PublicKey, msg, domain []byte) bool {
return s.Verify(PublicKeys(publicKeys).Aggregate(), msg, domain)
}
// Marshal the signature to bytes.
func (s *Signature) Marshal() ([]byte, error) {
return s.g1.Marshal(), nil
}
// ToBigInt marshalls signature (which is point) to 2 big ints - one for each coordinate
func (s Signature) ToBigInt() ([2]*big.Int, error) {
sig, err := s.Marshal()
if err != nil {
return [2]*big.Int{}, err
}
return [2]*big.Int{
new(big.Int).SetBytes(sig[0:32]),
new(big.Int).SetBytes(sig[32:64]),
}, nil
}
// UnmarshalSignature reads the signature from the given byte array
func UnmarshalSignature(raw []byte) (*Signature, error) {
if len(raw) == 0 {
return nil, errors.New("cannot unmarshal signature from empty slice")
}
g1 := new(bn256.G1)
if _, err := g1.Unmarshal(raw); err != nil {
return nil, err
}
// check if it is the point at infinity
if g1.IsInfinity() {
return nil, errInfinityPoint
}
// check if not part of the subgroup
if !g1.InCorrectSubgroup() {
return nil, fmt.Errorf("incorrect subgroup")
}
return &Signature{g1: g1}, nil
}
// Signatures is a slice of signatures
type Signatures []*Signature
// Aggregate aggregates all signatures into one
func (sigs Signatures) Aggregate() *Signature {
g1 := new(bn256.G1)
for _, sig := range sigs {
g1.Add(g1, sig.g1)
}
return &Signature{g1: g1}
}