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// Copyright 2018 The dexon-consensus-core Authors
// This file is part of the dexon-consensus-core library.
//
// The dexon-consensus-core 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-core 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-core library. If not, see
// <http://www.gnu.org/licenses/>.
package core
import (
"fmt"
"github.com/dexon-foundation/dexon-consensus-core/common"
"github.com/dexon-foundation/dexon-consensus-core/core/types"
"github.com/dexon-foundation/dexon-consensus-core/crypto"
"github.com/dexon-foundation/dexon-consensus-core/crypto/dkg"
)
// Errors for dkg module.
var (
ErrNotDKGParticipant = fmt.Errorf(
"not a DKG participant")
ErrNotQualifyDKGParticipant = fmt.Errorf(
"not a qualified DKG participant")
ErrIDShareNotFound = fmt.Errorf(
"private share not found for specific ID")
ErrNotReachThreshold = fmt.Errorf(
"threshold not reach")
ErrIncorrectPrivateShareSignature = fmt.Errorf(
"incorrect private share signature")
ErrIncorrectPartialSignatureSignature = fmt.Errorf(
"incorrect partialSignature signature")
ErrIncorrectPartialSignature = fmt.Errorf(
"incorrect partialSignature")
ErrNotEnoughtPartialSignatures = fmt.Errorf(
"not enough of partial signatures")
)
type dkgComplaintReceiver interface {
// ProposeDKGComplaint proposes a DKGComplaint.
ProposeDKGComplaint(complaint *types.DKGComplaint)
// ProposeDKGMasterPublicKey propose a DKGMasterPublicKey.
ProposeDKGMasterPublicKey(mpk *types.DKGMasterPublicKey)
// ProposeDKGPrivateShare propose a DKGPrivateShare.
ProposeDKGPrivateShare(to types.ValidatorID, prv *types.DKGPrivateShare)
}
type dkgProtocol struct {
ID types.ValidatorID
recv dkgComplaintReceiver
round uint64
threshold int
sigToPub SigToPubFn
idMap map[types.ValidatorID]dkg.ID
mpkMap map[types.ValidatorID]*dkg.PublicKeyShares
masterPrivateShare *dkg.PrivateKeyShares
prvShares *dkg.PrivateKeyShares
}
type dkgShareSecret struct {
privateKey *dkg.PrivateKey
}
type dkgGroupPublicKey struct {
round uint64
qualifyIDs dkg.IDs
idMap map[types.ValidatorID]dkg.ID
publicKeys map[types.ValidatorID]*dkg.PublicKey
groupPublicKey *dkg.PublicKey
threshold int
sigToPub SigToPubFn
}
type tsigProtocol struct {
groupPublicKey *dkgGroupPublicKey
sigs map[dkg.ID]dkg.PartialSignature
threshold int
}
func newDKGID(ID types.ValidatorID) dkg.ID {
return dkg.NewID(ID.Hash[:])
}
func newDKGProtocol(
ID types.ValidatorID,
recv dkgComplaintReceiver,
round uint64,
threshold int,
sigToPub SigToPubFn) *dkgProtocol {
prvShare, pubShare := dkg.NewPrivateKeyShares(threshold)
recv.ProposeDKGMasterPublicKey(&types.DKGMasterPublicKey{
ProposerID: ID,
Round: round,
DKGID: newDKGID(ID),
PublicKeyShares: *pubShare,
})
return &dkgProtocol{
ID: ID,
recv: recv,
round: round,
threshold: threshold,
sigToPub: sigToPub,
idMap: make(map[types.ValidatorID]dkg.ID),
mpkMap: make(map[types.ValidatorID]*dkg.PublicKeyShares),
masterPrivateShare: prvShare,
prvShares: dkg.NewEmptyPrivateKeyShares(),
}
}
func (d *dkgProtocol) processMasterPublicKeys(
mpks []*types.DKGMasterPublicKey) error {
d.idMap = make(map[types.ValidatorID]dkg.ID, len(mpks))
d.mpkMap = make(map[types.ValidatorID]*dkg.PublicKeyShares, len(mpks))
ids := make(dkg.IDs, len(mpks))
for i := range mpks {
vID := mpks[i].ProposerID
d.idMap[vID] = mpks[i].DKGID
d.mpkMap[vID] = &mpks[i].PublicKeyShares
ids[i] = mpks[i].DKGID
}
d.masterPrivateShare.SetParticipants(ids)
for _, mpk := range mpks {
share, ok := d.masterPrivateShare.Share(mpk.DKGID)
if !ok {
return ErrIDShareNotFound
}
d.recv.ProposeDKGPrivateShare(mpk.ProposerID, &types.DKGPrivateShare{
ProposerID: d.ID,
Round: d.round,
PrivateShare: *share,
})
}
return nil
}
func (d *dkgProtocol) sanityCheck(prvShare *types.DKGPrivateShare) error {
if _, exist := d.idMap[prvShare.ProposerID]; !exist {
return ErrNotDKGParticipant
}
ok, err := verifyDKGPrivateShareSignature(prvShare, d.sigToPub)
if err != nil {
return err
}
if !ok {
return ErrIncorrectPrivateShareSignature
}
return nil
}
func (d *dkgProtocol) processPrivateShare(
prvShare *types.DKGPrivateShare) error {
if d.round != prvShare.Round {
return nil
}
self, exist := d.idMap[d.ID]
// This validator is not a DKG participant, ignore the private share.
if !exist {
return nil
}
if err := d.sanityCheck(prvShare); err != nil {
return err
}
mpk := d.mpkMap[prvShare.ProposerID]
ok, err := mpk.VerifyPrvShare(self, &prvShare.PrivateShare)
if err != nil {
return err
}
if !ok {
complaint := &types.DKGComplaint{
ProposerID: d.ID,
Round: d.round,
PrivateShare: *prvShare,
}
d.recv.ProposeDKGComplaint(complaint)
} else {
sender := d.idMap[prvShare.ProposerID]
if err := d.prvShares.AddShare(sender, &prvShare.PrivateShare); err != nil {
return err
}
}
return nil
}
func (d *dkgProtocol) recoverShareSecret(qualifyIDs dkg.IDs) (
*dkgShareSecret, error) {
if len(qualifyIDs) <= d.threshold {
return nil, ErrNotReachThreshold
}
prvKey, err := d.prvShares.RecoverPrivateKey(qualifyIDs)
if err != nil {
return nil, err
}
return &dkgShareSecret{
privateKey: prvKey,
}, nil
}
func (ss *dkgShareSecret) sign(hash common.Hash) dkg.PartialSignature {
// DKG sign will always success.
sig, _ := ss.privateKey.Sign(hash)
return dkg.PartialSignature(sig)
}
func newDKGGroupPublicKey(
round uint64,
mpks []*types.DKGMasterPublicKey, complaints []*types.DKGComplaint,
threshold int, sigToPub SigToPubFn) (
*dkgGroupPublicKey, error) {
// Calculate qualify members.
complaintsByID := map[types.ValidatorID]int{}
for _, complaint := range complaints {
complaintsByID[complaint.PrivateShare.ProposerID]++
}
disqualifyIDs := map[types.ValidatorID]struct{}{}
for vID, num := range complaintsByID {
if num > threshold {
disqualifyIDs[vID] = struct{}{}
}
}
qualifyIDs := make(dkg.IDs, 0, len(mpks)-len(disqualifyIDs))
mpkMap := make(map[dkg.ID]*types.DKGMasterPublicKey, cap(qualifyIDs))
idMap := make(map[types.ValidatorID]dkg.ID)
for _, mpk := range mpks {
if _, exist := disqualifyIDs[mpk.ProposerID]; exist {
continue
}
mpkMap[mpk.DKGID] = mpk
idMap[mpk.ProposerID] = mpk.DKGID
qualifyIDs = append(qualifyIDs, mpk.DKGID)
}
// Recover qualify members' public key.
pubKeys := make(map[types.ValidatorID]*dkg.PublicKey, len(qualifyIDs))
for _, recvID := range qualifyIDs {
pubShares := dkg.NewEmptyPublicKeyShares()
for _, id := range qualifyIDs {
pubShare, err := mpkMap[id].PublicKeyShares.Share(recvID)
if err != nil {
return nil, err
}
if err := pubShares.AddShare(id, pubShare); err != nil {
return nil, err
}
}
pubKey, err := pubShares.RecoverPublicKey(qualifyIDs)
if err != nil {
return nil, err
}
pubKeys[mpkMap[recvID].ProposerID] = pubKey
}
// Recover Group Public Key.
pubShares := make([]*dkg.PublicKeyShares, 0, len(qualifyIDs))
for _, id := range qualifyIDs {
pubShares = append(pubShares, &mpkMap[id].PublicKeyShares)
}
groupPK := dkg.RecoverGroupPublicKey(pubShares)
return &dkgGroupPublicKey{
round: round,
qualifyIDs: qualifyIDs,
idMap: idMap,
publicKeys: pubKeys,
threshold: threshold,
groupPublicKey: groupPK,
sigToPub: sigToPub,
}, nil
}
func (gpk *dkgGroupPublicKey) verifySignature(
hash common.Hash, sig crypto.Signature) bool {
return gpk.groupPublicKey.VerifySignature(hash, sig)
}
func newTSigProtocol(gpk *dkgGroupPublicKey) *tsigProtocol {
return &tsigProtocol{
groupPublicKey: gpk,
sigs: make(map[dkg.ID]dkg.PartialSignature, gpk.threshold+1),
}
}
func (tsig *tsigProtocol) sanityCheck(psig *types.DKGPartialSignature) error {
_, exist := tsig.groupPublicKey.publicKeys[psig.ProposerID]
if !exist {
return ErrNotQualifyDKGParticipant
}
ok, err := verifyDKGPartialSignatureSignature(
psig, tsig.groupPublicKey.sigToPub)
if err != nil {
return err
}
if !ok {
return ErrIncorrectPartialSignatureSignature
}
return nil
}
func (tsig *tsigProtocol) processPartialSignature(
hash common.Hash, psig *types.DKGPartialSignature) error {
if psig.Round != tsig.groupPublicKey.round {
return nil
}
id, exist := tsig.groupPublicKey.idMap[psig.ProposerID]
if !exist {
return ErrNotQualifyDKGParticipant
}
if err := tsig.sanityCheck(psig); err != nil {
return err
}
pubKey := tsig.groupPublicKey.publicKeys[psig.ProposerID]
if !pubKey.VerifySignature(hash, crypto.Signature(psig.PartialSignature)) {
return ErrIncorrectPartialSignature
}
tsig.sigs[id] = psig.PartialSignature
return nil
}
func (tsig *tsigProtocol) signature() (crypto.Signature, error) {
if len(tsig.sigs) <= tsig.groupPublicKey.threshold {
return nil, ErrNotEnoughtPartialSignatures
}
ids := make(dkg.IDs, 0, len(tsig.sigs))
psigs := make([]dkg.PartialSignature, 0, len(tsig.sigs))
for id, psig := range tsig.sigs {
ids = append(ids, id)
psigs = append(psigs, psig)
}
return dkg.RecoverSignature(psigs, ids)
}
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