// // Copyright Coinbase, Inc. All Rights Reserved. // // SPDX-License-Identifier: Apache-2.0 // package gennaro import ( "fmt" "source.quilibrium.com/quilibrium/monorepo/nekryptology/internal" v1 "source.quilibrium.com/quilibrium/monorepo/nekryptology/pkg/sharing/v1" ) type Round2Bcast = []*v1.ShareVerifier // Round2 computes the second round for Gennaro DKG // Algorithm 3 - Gennaro DKG Round 2 // bcast contains all Round1 broadcast from other participants to this participant // p2p contains all Round1 P2P send message from other participants to this participant func (dp *Participant) Round2(bcast map[uint32]Round1Bcast, p2p map[uint32]*Round1P2PSendPacket) (Round2Bcast, error) { // Check participant is not empty if dp == nil || dp.curve == nil { return nil, internal.ErrNilArguments } // Check participant has the correct dkg round number if dp.round != 2 { return nil, internal.ErrInvalidRound } // Check the input is valid if bcast == nil || p2p == nil || len(bcast) == 0 || len(p2p) == 0 { return nil, internal.ErrNilArguments } // 1. set sk = x_{ii} sk := dp.pedersenResult.SecretShares[dp.id-1].Value // 2. for j in 1,...,n for id := range bcast { // 3. if i = j continue if id == dp.id { continue } // Ensure a valid p2p entry exists if p2p[id] == nil { return nil, fmt.Errorf("missing p2p packet for id=%v", id) } // 4. If PedersenVerify(E, Q, x_ji, r_ji, {X_ji,...,X_jt}) = false, abort xji := p2p[id].SecretShare rji := p2p[id].BlindingShare bvs := bcast[id] if ok, err := dp.pedersen.Verify(xji, rji, bvs); !ok { if err != nil { return nil, err } else { return nil, fmt.Errorf("invalid share for participant id=%v", id) } } // Store other participants' shares xji for usage in round 3 dp.otherParticipantShares[id].Share = p2p[id].SecretShare // 5. sk = (sk+xji) mod q // NOTE: we use the EcScalar class to add instead of // just using big.Int Add and Mod // because Ed25519 will fail with the big.Int Add and Mod // and Ed25519 uses different little endian vs big endian // in big.Int t1 := sk.BigInt() t2 := xji.Value.BigInt() r := dp.scalar.Add(t1, t2) sk = sk.Field().NewElement(r) } // Update internal state dp.round = 3 // 7. Store ski as participant i's secret key share dp.skShare = sk // 6. EchoBroadcast {R_1,...,R_t} to all other participants. return dp.pedersenResult.Verifiers, nil }