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// Copyright 2018 The dexon-consensus Authors
// This file is part of the dexon-consensus library.
//
// The dexon-consensus 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 dexon-consensus 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 dexon-consensus library. If not, see
// <http://www.gnu.org/licenses/>.
package dkg
import (
"encoding/binary"
"fmt"
"math/rand"
"github.com/dexon-foundation/bls/ffi/go/bls"
"github.com/dexon-foundation/dexon-consensus/core/crypto"
)
// PartialSignature is a partial signature in DKG+TSIG protocol.
type PartialSignature crypto.Signature
var (
// ErrEmptySignature is reported if the signature is empty.
ErrEmptySignature = fmt.Errorf("invalid empty signature")
)
// RecoverSignature recovers TSIG signature.
func RecoverSignature(sigs []PartialSignature, signerIDs IDs) (
crypto.Signature, error) {
blsSigs := make([]bls.Sign, len(sigs))
for i, sig := range sigs {
if len(sig.Signature) == 0 {
return crypto.Signature{}, ErrEmptySignature
}
if err := blsSigs[i].Deserialize([]byte(sig.Signature)); err != nil {
return crypto.Signature{}, err
}
}
var recoverSig bls.Sign
if err := recoverSig.Recover(blsSigs, []bls.ID(signerIDs)); err != nil {
return crypto.Signature{}, err
}
return crypto.Signature{
Type: cryptoType,
Signature: recoverSig.Serialize()}, nil
}
// RecoverGroupPublicKey recovers group public key.
func RecoverGroupPublicKey(pubShares []*PublicKeyShares) *PublicKey {
var pub *PublicKey
for _, pubShare := range pubShares {
pk0 := pubShare.masterPublicKey[0]
if pub == nil {
pub = &PublicKey{
publicKey: pk0,
}
} else {
pub.publicKey.Add(&pk0)
}
}
return pub
}
// NewRandomPrivateKeyShares constructs a private key shares randomly.
func NewRandomPrivateKeyShares() *PrivateKeyShares {
// Generate IDs.
rndIDs := make(IDs, 0, 10)
for i := range rndIDs {
id := make([]byte, 8)
binary.LittleEndian.PutUint64(id, rand.Uint64())
rndIDs[i] = NewID(id)
}
prvShares := NewEmptyPrivateKeyShares()
prvShares.SetParticipants(rndIDs)
for _, id := range rndIDs {
if err := prvShares.AddShare(id, NewPrivateKey()); err != nil {
panic(err)
}
}
return prvShares
}
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