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round_1.go
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round_1.go
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// Copyright © 2022 AMIS Technologies
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package refresh
import (
"errors"
"math/big"
"github.com/getamis/alice/crypto/birkhoffinterpolation"
commitment "github.com/getamis/alice/crypto/commitment"
ecpointgrouplaw "github.com/getamis/alice/crypto/ecpointgrouplaw"
pt "github.com/getamis/alice/crypto/ecpointgrouplaw"
"github.com/getamis/alice/crypto/homo/paillier"
"github.com/getamis/alice/crypto/polynomial"
"github.com/getamis/alice/crypto/tss"
"github.com/getamis/alice/crypto/tss/ecdsa/cggmp"
"github.com/getamis/alice/crypto/utils"
paillierzkproof "github.com/getamis/alice/crypto/zkproof/paillier"
"github.com/getamis/alice/types"
"github.com/getamis/sirius/log"
)
const (
BYTELENGTHKAPPA = 32
)
var (
ErrNotEnoughRanks = errors.New("not enough ranks")
)
type round1Handler struct {
ssid []byte
oldShare *big.Int
partialPubKey map[string]*ecpointgrouplaw.ECPoint
paillierKey *paillier.Paillier
pubKey *ecpointgrouplaw.ECPoint
threshold uint32
ownBK *birkhoffinterpolation.BkParameter
y *big.Int
tau *big.Int // Schnorr commitment of y
poly *polynomial.Polynomial
feldCommitment *commitment.FeldmanCommitmenter
rho []byte
u []byte // salt
ped *paillier.PederssenParameter
pedParZkproof *paillierzkproof.RingPederssenParameterMessage
V *commitment.HashCommitmenter
ai map[string]*big.Int // Schnorr commitment of shares
bks map[string]*birkhoffinterpolation.BkParameter
peerManager types.PeerManager
peerNum uint32
peers map[string]*peer
}
func newRound1Handler(oldShare *big.Int, pubKey *ecpointgrouplaw.ECPoint, peerManager types.PeerManager, threshold uint32, partialPubKey map[string]*ecpointgrouplaw.ECPoint, bks map[string]*birkhoffinterpolation.BkParameter, keySize int, ssid []byte) (*round1Handler, error) {
numPeers := peerManager.NumPeers()
// curve := pubKey.GetCurve()
// Generate 4*kappa long safe primes p, q with N = p*q
paillierKey, err := paillier.NewPaillierSafePrime(keySize)
if err != nil {
return nil, err
}
// Set pederssen parameter from paillierKey: Sample r in Z_N^ast, lambda = Z_phi(N), t = r^2 and s = t^lambda mod N
ped, err := paillierKey.NewPedersenParameterByPaillier()
if err != nil {
return nil, err
}
p := &round1Handler{
ssid: ssid,
oldShare: oldShare,
paillierKey: paillierKey,
pubKey: pubKey,
threshold: threshold,
bks: bks,
ownBK: bks[peerManager.SelfID()],
partialPubKey: partialPubKey,
peerNum: numPeers,
peers: buildPeers(peerManager),
peerManager: peerManager,
}
curve := pubKey.GetCurve()
// Sample y in F_q and Set Y = y*G. And compute Schnorr commitment.
y, err := utils.RandomInt(curve.Params().N)
if err != nil {
return nil, err
}
Y := pt.ScalarBaseMult(curve, y)
msgY, err := Y.ToEcPointMessage()
if err != nil {
return nil, err
}
tau, err := utils.RandomInt(curve.Params().N)
if err != nil {
return nil, err
}
B := pt.ScalarBaseMult(curve, tau)
msgB, err := B.ToEcPointMessage()
if err != nil {
return nil, err
}
// Generate polynomial commitment f(x) with f(0) mod q.
poly, err := polynomial.RandomPolynomial(curve.Params().N, p.threshold-1)
if err != nil {
return nil, err
}
poly.SetConstant(big.NewInt(0))
// Build polynomial commitmenter with Xi
feldmanCommitmenter, err := commitment.NewFeldmanCommitmenter(curve, poly)
if err != nil {
return nil, err
}
// Generate psi^hat := prm zk proof
pedPar, err := paillierzkproof.NewRingPederssenParameterMessage(cggmp.ComputeZKSsid(ssid, p.ownBK), ped.GetEulerValue(), ped.PedersenOpenParameter.GetN(), ped.PedersenOpenParameter.GetS(), ped.PedersenOpenParameter.GetT(), ped.Getlambda(), paillierzkproof.MINIMALCHALLENGE)
if err != nil {
return nil, err
}
Ai := make(map[string]*big.Int)
msgAi := make(map[string]*pt.EcPointMessage)
for _, peerId := range peerManager.PeerIDs() {
temp, err := utils.RandomInt(curve.Params().N)
if err != nil {
return nil, err
}
Ai[peerId] = temp
tempPoint := pt.ScalarBaseMult(curve, temp)
MsgTempPoint, err := tempPoint.ToEcPointMessage()
if err != nil {
return nil, err
}
msgAi[peerId] = MsgTempPoint
}
// Sample rho, u in {0,1}^kappa
rhoi, err := utils.GenRandomBytes(BYTELENGTHKAPPA)
if err != nil {
return nil, err
}
ui, err := utils.GenRandomBytes(BYTELENGTHKAPPA)
if err != nil {
return nil, err
}
// Compute Vi = H(ssid, i, X, A, Y, B, N, s, t, psi^hat, rho, u)
inputData := &HashMsg{
PointCommitment: feldmanCommitmenter.GetCommitmentMessage(),
Y: msgY,
PedPar: pedPar,
Rho: rhoi,
U: ui,
Ssid: ssid,
Bk: []byte(p.ownBK.String()),
A: msgAi,
B: msgB,
}
p.V, err = commitment.NewProtoHashCommitmenter(inputData)
if err != nil {
return nil, err
}
p.feldCommitment = feldmanCommitmenter
p.y = y
p.poly = poly
p.rho = rhoi
p.u = ui
p.paillierKey = paillierKey
p.ped = ped
p.pedParZkproof = pedPar
p.tau = tau
p.ai = Ai
return p, nil
}
func (p *round1Handler) MessageType() types.MessageType {
return types.MessageType(Type_Round1)
}
func (p *round1Handler) GetRequiredMessageCount() uint32 {
return p.peerNum
}
func (p *round1Handler) IsHandled(logger log.Logger, id string) bool {
peer, ok := p.peers[id]
if !ok {
logger.Warn("Peer not found")
return false
}
return peer.Messages[p.MessageType()] != nil
}
func (p *round1Handler) HandleMessage(logger log.Logger, message types.Message) error {
msg := getMessage(message)
id := msg.GetId()
peer, ok := p.peers[id]
if !ok {
logger.Warn("Peer not found")
return tss.ErrPeerNotFound
}
return peer.AddMessage(msg)
}
func (p *round1Handler) Finalize(logger log.Logger) (types.Handler, error) {
cggmp.Broadcast(p.peerManager, &Message{
Type: Type_Round2,
Id: p.peerManager.SelfID(),
Body: &Message_Round2{
Round2: &Round2Msg{
Decommitment: p.V.GetDecommitmentMessage(),
},
},
})
return newRound2Handler(p), nil
}
func (p *round1Handler) getRound1Message() *Message {
return &Message{
Type: Type_Round1,
Id: p.peerManager.SelfID(),
Body: &Message_Round1{
Round1: &Round1Msg{
Commitment: p.V.GetCommitmentMessage(),
},
},
}
}
func getMessage(messsage types.Message) *Message {
return messsage.(*Message)
}
func buildPeers(peerManager types.PeerManager) map[string]*peer {
peers := make(map[string]*peer, peerManager.NumPeers())
for _, id := range peerManager.PeerIDs() {
peers[id] = newPeer(id)
}
return peers
}