diff --git a/lnwallet/channel.go b/lnwallet/channel.go index 81930aad5..8dba07973 100644 --- a/lnwallet/channel.go +++ b/lnwallet/channel.go @@ -4151,6 +4151,27 @@ func (lc *LightningChannel) SignNextCommitment() (*NewCommitState, error) { }, nil } +// resignMusigCommit is used to resign a commitment transaction for taproot +// channels when we need to retransmit a signature after a channel reestablish +// message. Taproot channels use musig2, which means we must use fresh nonces +// each time. After we receive the channel reestablish message, we learn the +// nonce we need to use for the remote party. As a result, we need to generate +// the partial signature again with the new nonce. +func (lc *LightningChannel) resignMusigCommit(commitTx *wire.MsgTx, +) (lnwire.OptPartialSigWithNonceTLV, error) { + + remoteSession := lc.musigSessions.RemoteSession + musig, err := remoteSession.SignCommit(commitTx) + if err != nil { + var none lnwire.OptPartialSigWithNonceTLV + return none, err + } + + partialSig := lnwire.MaybePartialSigWithNonce(musig.ToWireSig()) + + return partialSig, nil +} + // ProcessChanSyncMsg processes a ChannelReestablish message sent by the remote // connection upon re establishment of our connection with them. This method // will return a single message if we are currently out of sync, otherwise a @@ -4428,12 +4449,23 @@ func (lc *LightningChannel) ProcessChanSyncMsg( commitUpdates = append(commitUpdates, logUpdate.UpdateMsg) } + // If this is a taproot channel, then we need to regenerate the + // musig2 signature for the remote party, using their fresh + // nonce. + if lc.channelState.ChanType.IsTaproot() { + partialSig, err := lc.resignMusigCommit( + commitDiff.Commitment.CommitTx, + ) + if err != nil { + return nil, nil, nil, err + } + + commitDiff.CommitSig.PartialSig = partialSig + } + // With the batch of updates accumulated, we'll now re-send the // original CommitSig message required to re-sync their remote // commitment chain with our local version of their chain. - // - // TODO(roasbeef): need to re-sign commitment states w/ - // fresh nonce commitUpdates = append(commitUpdates, commitDiff.CommitSig) // NOTE: If a revocation is not owed, then updates is empty.