// 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 dkg
import (
"encoding/json"
"fmt"
"github.com/Spiderpowa/bls/ffi/go/bls"
"github.com/dexon-foundation/dexon-consensus-core/common"
"github.com/dexon-foundation/dexon-consensus-core/crypto"
)
var (
// ErrDuplicatedShare is reported when adding an private key share of same id.
ErrDuplicatedShare = fmt.Errorf("invalid share")
// ErrNoIDToRecover is reported when no id is provided for recovering private
// key.
ErrNoIDToRecover = fmt.Errorf("no id to recover private key")
// ErrShareNotFound is reported when the private key share of id is not found
// when recovering private key.
ErrShareNotFound = fmt.Errorf("share not found")
)
var publicKeyLength int
func init() {
bls.Init(curve)
pubKey := &bls.PublicKey{}
publicKeyLength = len(pubKey.Serialize())
}
// PrivateKey represents a private key structure implments
// Crypto.PrivateKey interface.
type PrivateKey struct {
privateKey bls.SecretKey
publicKey PublicKey
}
// MarshalJSON implements json.Marshaller.
func (prv *PrivateKey) MarshalJSON() ([]byte, error) {
return json.Marshal(&prv.privateKey)
}
// UnmarshalJSON implements json.Unmarshaller.
func (prv *PrivateKey) UnmarshalJSON(data []byte) error {
return json.Unmarshal(data, &prv.privateKey)
}
// ID is the id for DKG protocol.
type ID = bls.ID
// IDs is an array of ID.
type IDs []ID
// PublicKey represents a public key structure implements
// Crypto.PublicKey interface.
type PublicKey struct {
publicKey bls.PublicKey
}
// PrivateKeyShares represents a private key shares for DKG protocol.
type PrivateKeyShares struct {
shares []PrivateKey
shareIndex map[ID]int
masterPrivateKey []bls.SecretKey
}
// PublicKeyShares represents a public key shares for DKG protocol.
type PublicKeyShares struct {
shares []PublicKey
shareIndex map[ID]int
masterPublicKey []bls.PublicKey
}
// MarshalJSON implements json.Marshaller.
func (pubs *PublicKeyShares) MarshalJSON() ([]byte, error) {
type Alias PublicKeyShares
data := &struct {
MasterPublicKeys []*bls.PublicKey `json:"master_public_keys"`
}{
make([]*bls.PublicKey, len(pubs.masterPublicKey)),
}
for i := range pubs.masterPublicKey {
data.MasterPublicKeys[i] = &pubs.masterPublicKey[i]
}
return json.Marshal(data)
}
// UnmarshalJSON implements json.Unmarshaller.
func (pubs *PublicKeyShares) UnmarshalJSON(data []byte) error {
type Alias PublicKeyShares
aux := &struct {
MasterPublicKeys []*bls.PublicKey `json:"master_public_keys"`
}{}
if err := json.Unmarshal(data, &aux); err != nil {
return err
}
mpk := make([]bls.PublicKey, len(aux.MasterPublicKeys))
for i, pk := range aux.MasterPublicKeys {
mpk[i] = *pk
}
pubs.masterPublicKey = mpk
return nil
}
// NewID creates a ew ID structure.
func NewID(id []byte) ID {
var blsID bls.ID
blsID.SetLittleEndian(id)
return blsID
}
// NewPrivateKey creates a new PrivateKey structure.
func NewPrivateKey() *PrivateKey {
var key bls.SecretKey
key.SetByCSPRNG()
return &PrivateKey{
privateKey: key,
publicKey: *newPublicKey(&key),
}
}
// NewPrivateKeyShares creates a DKG private key shares of threshold t.
func NewPrivateKeyShares(t int) (*PrivateKeyShares, *PublicKeyShares) {
var prv bls.SecretKey
prv.SetByCSPRNG()
msk := prv.GetMasterSecretKey(t)
mpk := bls.GetMasterPublicKey(msk)
return &PrivateKeyShares{
masterPrivateKey: msk,
shareIndex: make(map[ID]int),
}, &PublicKeyShares{
shareIndex: make(map[ID]int),
masterPublicKey: mpk,
}
}
// NewEmptyPrivateKeyShares creates an empty private key shares.
func NewEmptyPrivateKeyShares() *PrivateKeyShares {
return &PrivateKeyShares{
shareIndex: make(map[ID]int),
}
}
// SetParticipants sets the DKG participants.
func (prvs *PrivateKeyShares) SetParticipants(IDs IDs) {
prvs.shares = make([]PrivateKey, len(IDs))
prvs.shareIndex = make(map[ID]int, len(IDs))
for idx, ID := range IDs {
prvs.shares[idx].privateKey.Set(prvs.masterPrivateKey, &ID)
prvs.shareIndex[ID] = idx
}
}
// AddShare adds a share.
func (prvs *PrivateKeyShares) AddShare(ID ID, share *PrivateKey) error {
if idx, exist := prvs.shareIndex[ID]; exist {
if !share.privateKey.IsEqual(&prvs.shares[idx].privateKey) {
return ErrDuplicatedShare
}
return nil
}
prvs.shareIndex[ID] = len(prvs.shares)
prvs.shares = append(prvs.shares, *share)
return nil
}
// RecoverPrivateKey recovers private key from the shares.
func (prvs *PrivateKeyShares) RecoverPrivateKey(qualifyIDs IDs) (
*PrivateKey, error) {
var prv PrivateKey
if len(qualifyIDs) == 0 {
return nil, ErrNoIDToRecover
}
for i, ID := range qualifyIDs {
idx, exist := prvs.shareIndex[ID]
if !exist {
return nil, ErrShareNotFound
}
if i == 0 {
prv.privateKey = prvs.shares[idx].privateKey
continue
}
prv.privateKey.Add(&prvs.shares[idx].privateKey)
}
return &prv, nil
}
// RecoverPublicKey recovers public key from the shares.
func (prvs *PrivateKeyShares) RecoverPublicKey(qualifyIDs IDs) (
*PublicKey, error) {
var pub PublicKey
if len(qualifyIDs) == 0 {
return nil, ErrNoIDToRecover
}
for i, ID := range qualifyIDs {
idx, exist := prvs.shareIndex[ID]
if !exist {
return nil, ErrShareNotFound
}
if i == 0 {
pub.publicKey = *prvs.shares[idx].privateKey.GetPublicKey()
continue
}
pub.publicKey.Add(prvs.shares[idx].privateKey.GetPublicKey())
}
return &pub, nil
}
// Share returns the share for the ID.
func (prvs *PrivateKeyShares) Share(ID ID) (*PrivateKey, bool) {
idx, exist := prvs.shareIndex[ID]
if !exist {
return nil, false
}
return &prvs.shares[idx], true
}
// NewEmptyPublicKeyShares creates an empty public key shares.
func NewEmptyPublicKeyShares() *PublicKeyShares {
return &PublicKeyShares{
shareIndex: make(map[ID]int),
}
}
// Share returns the share for the ID.
func (pubs *PublicKeyShares) Share(ID ID) (*PublicKey, error) {
idx, exist := pubs.shareIndex[ID]
if exist {
return &pubs.shares[idx], nil
}
var pk PublicKey
if err := pk.publicKey.Set(pubs.masterPublicKey, &ID); err != nil {
return nil, err
}
pubs.AddShare(ID, &pk)
return &pk, nil
}
// AddShare adds a share.
func (pubs *PublicKeyShares) AddShare(ID ID, share *PublicKey) error {
if idx, exist := pubs.shareIndex[ID]; exist {
if !share.publicKey.IsEqual(&pubs.shares[idx].publicKey) {
return ErrDuplicatedShare
}
return nil
}
pubs.shareIndex[ID] = len(pubs.shares)
pubs.shares = append(pubs.shares, *share)
return nil
}
// VerifyPrvShare verifies if the private key shares is valid.
func (pubs *PublicKeyShares) VerifyPrvShare(ID ID, share *PrivateKey) (
bool, error) {
var pk bls.PublicKey
if err := pk.Set(pubs.masterPublicKey, &ID); err != nil {
return false, err
}
return pk.IsEqual(share.privateKey.GetPublicKey()), nil
}
// VerifyPubShare verifies if the public key shares is valid.
func (pubs *PublicKeyShares) VerifyPubShare(ID ID, share *PublicKey) (
bool, error) {
var pk bls.PublicKey
if err := pk.Set(pubs.masterPublicKey, &ID); err != nil {
return false, err
}
return pk.IsEqual(&share.publicKey), nil
}
// RecoverPublicKey recovers private key from the shares.
func (pubs *PublicKeyShares) RecoverPublicKey(qualifyIDs IDs) (
*PublicKey, error) {
var pub PublicKey
if len(qualifyIDs) == 0 {
return nil, ErrNoIDToRecover
}
for i, ID := range qualifyIDs {
idx, exist := pubs.shareIndex[ID]
if !exist {
return nil, ErrShareNotFound
}
if i == 0 {
pub.publicKey = pubs.shares[idx].publicKey
continue
}
pub.publicKey.Add(&pubs.shares[idx].publicKey)
}
return &pub, nil
}
// MasterKeyBytes returns []byte representation of master public key.
func (pubs *PublicKeyShares) MasterKeyBytes() []byte {
bytes := make([]byte, 0, len(pubs.masterPublicKey)*publicKeyLength)
for _, pk := range pubs.masterPublicKey {
bytes = append(bytes, pk.Serialize()...)
}
return bytes
}
// newPublicKey creates a new PublicKey structure.
func newPublicKey(prvKey *bls.SecretKey) *PublicKey {
return &PublicKey{
publicKey: *prvKey.GetPublicKey(),
}
}
// PublicKey returns the public key associate this private key.
func (prv *PrivateKey) PublicKey() crypto.PublicKey {
return prv.publicKey
}
// Sign calculates a signature.
func (prv *PrivateKey) Sign(hash common.Hash) (crypto.Signature, error) {
msg := string(hash[:])
sign := prv.privateKey.Sign(msg)
return crypto.Signature(sign.Serialize()), nil
}
// Bytes returns []byte representation of private key.
func (prv *PrivateKey) Bytes() []byte {
return prv.privateKey.GetLittleEndian()
}
// SetBytes sets the private key data to []byte.
func (prv *PrivateKey) SetBytes(bytes []byte) error {
var key bls.SecretKey
if err := key.SetLittleEndian(bytes); err != nil {
return err
}
prv.privateKey = key
prv.publicKey = *newPublicKey(&prv.privateKey)
return nil
}
// String returns string representation of privat key.
func (prv *PrivateKey) String() string {
return prv.privateKey.GetHexString()
}
// VerifySignature checks that the given public key created signature over hash.
func (pub PublicKey) VerifySignature(
hash common.Hash, signature crypto.Signature) bool {
if len(signature) == 0 {
return false
}
var sig bls.Sign
if err := sig.Deserialize(signature[:]); err != nil {
fmt.Println(err)
return false
}
msg := string(hash[:])
return sig.Verify(&pub.publicKey, msg)
}
// Bytes returns []byte representation of public key.
func (pub PublicKey) Bytes() []byte {
var bytes []byte
pub.publicKey.Deserialize(bytes)
return bytes
}
