// Signs the first input of the transaction which must spend the multisig contract.
private void signMultisigInput(
Transaction tx, Transaction.SigHash hashType, boolean anyoneCanPay) {
TransactionSignature signature =
tx.calculateSignature(0, serverKey, multisigScript, hashType, anyoneCanPay);
byte[] mySig = signature.encodeToBitcoin();
Script scriptSig =
ScriptBuilder.createMultiSigInputScriptBytes(ImmutableList.of(bestValueSignature, mySig));
tx.getInput(0).setScriptSig(scriptSig);
}
/**
* Called when the client provides the refund transaction. The refund transaction must have one
* input from the multisig contract (that we don't have yet) and one output that the client
* creates to themselves. This object will later be modified when we start getting paid.
*
* @param refundTx The refund transaction, this object will be mutated when payment is
* incremented.
* @param clientMultiSigPubKey The client's pubkey which is required for the multisig output
* @return Our signature that makes the refund transaction valid
* @throws VerificationException If the transaction isnt valid or did not meet the requirements of
* a refund transaction.
*/
public synchronized byte[] provideRefundTransaction(
Transaction refundTx, byte[] clientMultiSigPubKey) throws VerificationException {
checkNotNull(refundTx);
checkNotNull(clientMultiSigPubKey);
checkState(state == State.WAITING_FOR_REFUND_TRANSACTION);
log.info("Provided with refund transaction: {}", refundTx);
// Do a few very basic syntax sanity checks.
refundTx.verify();
// Verify that the refund transaction has a single input (that we can fill to sign the multisig
// output).
if (refundTx.getInputs().size() != 1)
throw new VerificationException("Refund transaction does not have exactly one input");
// Verify that the refund transaction has a time lock on it and a sequence number of zero.
if (refundTx.getInput(0).getSequenceNumber() != 0)
throw new VerificationException("Refund transaction's input's sequence number is non-0");
if (refundTx.getLockTime() < minExpireTime)
throw new VerificationException("Refund transaction has a lock time too soon");
// Verify the transaction has one output (we don't care about its contents, its up to the
// client)
// Note that because we sign with SIGHASH_NONE|SIGHASH_ANYOENCANPAY the client can later add
// more outputs and
// inputs, but we will need only one output later to create the paying transactions
if (refundTx.getOutputs().size() != 1)
throw new VerificationException("Refund transaction does not have exactly one output");
refundTransactionUnlockTimeSecs = refundTx.getLockTime();
// Sign the refund tx with the scriptPubKey and return the signature. We don't have the spending
// transaction
// so do the steps individually.
clientKey = ECKey.fromPublicOnly(clientMultiSigPubKey);
Script multisigPubKey =
ScriptBuilder.createMultiSigOutputScript(2, ImmutableList.of(clientKey, serverKey));
// We are really only signing the fact that the transaction has a proper lock time and don't
// care about anything
// else, so we sign SIGHASH_NONE and SIGHASH_ANYONECANPAY.
TransactionSignature sig =
refundTx.calculateSignature(0, serverKey, multisigPubKey, Transaction.SigHash.NONE, true);
log.info("Signed refund transaction.");
this.clientOutput = refundTx.getOutput(0);
state = State.WAITING_FOR_MULTISIG_CONTRACT;
return sig.encodeToBitcoin();
}