Beispiel #1
0
// receiverHtlcSpendTimeout constructs a valid witness allowing the sender of
// an HTLC to recover the pending funds after an absolute timeout in the
// scenario that the receiver of the HTLC broadcasts their version of the
// commitment transaction.
func receiverHtlcSpendTimeout(commitScript []byte, outputAmt btcutil.Amount,
	senderKey *btcec.PrivateKey, sweepTx *wire.MsgTx,
	absoluteTimeout uint32) (wire.TxWitness, error) {

	// The HTLC output has an absolute time period before we are permitted
	// to recover the pending funds. Therefore we need to set the locktime
	// on this sweeping transaction in order to pass Script verification.
	sweepTx.LockTime = absoluteTimeout

	hashCache := txscript.NewTxSigHashes(sweepTx)
	sweepSig, err := txscript.RawTxInWitnessSignature(
		sweepTx, hashCache, 0, int64(outputAmt), commitScript,
		txscript.SigHashAll, senderKey)
	if err != nil {
		return nil, err
	}

	witnessStack := wire.TxWitness(make([][]byte, 4))
	witnessStack[0] = sweepSig
	witnessStack[1] = []byte{0}
	witnessStack[2] = []byte{0}
	witnessStack[3] = commitScript

	return witnessStack, nil
}
Beispiel #2
0
// htlcSpendTimeout constructs a valid witness allowing the sender of an HTLC
// to recover the pending funds after an absolute, then relative locktime
// period.
func senderHtlcSpendTimeout(commitScript []byte, outputAmt btcutil.Amount,
	senderKey *btcec.PrivateKey, sweepTx *wire.MsgTx,
	absoluteTimeout, relativeTimeout uint32) (wire.TxWitness, error) {

	// Since the HTLC output has an absolute timeout before we're permitted
	// to sweep the output, we need to set the locktime of this sweepign
	// transaction to that aboslute value in order to pass Script
	// verification.
	sweepTx.LockTime = absoluteTimeout

	// Additionally, we're required to wait a relative period of time
	// before we can sweep the output in order to allow the other party to
	// contest our claim of validity to this version of the commitment
	// transaction.
	sweepTx.TxIn[0].Sequence = lockTimeToSequence(false, relativeTimeout)

	// Finally, OP_CSV requires that the version of the transaction
	// spending a pkscript with OP_CSV within it *must* be >= 2.
	sweepTx.Version = 2

	hashCache := txscript.NewTxSigHashes(sweepTx)
	sweepSig, err := txscript.RawTxInWitnessSignature(
		sweepTx, hashCache, 0, int64(outputAmt), commitScript,
		txscript.SigHashAll, senderKey)
	if err != nil {
		return nil, err
	}

	// We place a zero as the first item of the evaluated witness stack in
	// order to force Script execution to the HTLC timeout clause.
	witnessStack := wire.TxWitness(make([][]byte, 3))
	witnessStack[0] = sweepSig
	witnessStack[1] = []byte{0}
	witnessStack[2] = commitScript

	return witnessStack, nil
}