/**
* Returns a copy of the given scriptSig with the signature inserted in the given position.
*
* <p>This function assumes that any missing sigs have OP_0 placeholders. If given scriptSig
* already has all the signatures in place, IllegalArgumentException will be thrown.
*
* @param targetIndex where to insert the signature
* @param sigsPrefixCount how many items to copy verbatim (e.g. initial OP_0 for multisig)
* @param sigsSuffixCount how many items to copy verbatim at end (e.g. redeemScript for P2SH)
*/
public static Script updateScriptWithSignature(
Script scriptSig,
byte[] signature,
int targetIndex,
int sigsPrefixCount,
int sigsSuffixCount) {
ScriptBuilder builder = new ScriptBuilder();
List<ScriptChunk> inputChunks = scriptSig.getChunks();
int totalChunks = inputChunks.size();
// Check if we have a place to insert, otherwise just return given scriptSig unchanged.
// We assume here that OP_0 placeholders always go after the sigs, so
// to find if we have sigs missing, we can just check the chunk in latest sig position
boolean hasMissingSigs = inputChunks.get(totalChunks - sigsSuffixCount - 1).equalsOpCode(OP_0);
checkArgument(hasMissingSigs, "ScriptSig is already filled with signatures");
// copy the prefix
for (ScriptChunk chunk : inputChunks.subList(0, sigsPrefixCount)) builder.addChunk(chunk);
// copy the sigs
int pos = 0;
boolean inserted = false;
for (ScriptChunk chunk : inputChunks.subList(sigsPrefixCount, totalChunks - sigsSuffixCount)) {
if (pos == targetIndex) {
inserted = true;
builder.data(signature);
pos++;
}
if (!chunk.equalsOpCode(OP_0)) {
builder.addChunk(chunk);
pos++;
}
}
// add OP_0's if needed, since we skipped them in the previous loop
while (pos < totalChunks - sigsPrefixCount - sigsSuffixCount) {
if (pos == targetIndex) {
inserted = true;
builder.data(signature);
} else {
builder.addChunk(new ScriptChunk(OP_0, null));
}
pos++;
}
// copy the suffix
for (ScriptChunk chunk : inputChunks.subList(totalChunks - sigsSuffixCount, totalChunks))
builder.addChunk(chunk);
checkState(inserted);
return builder.build();
}
@Test
public void testCreateMultiSigInputScript() throws AddressFormatException {
// Setup transaction and signatures
ECKey key1 =
new DumpedPrivateKey(params, "cVLwRLTvz3BxDAWkvS3yzT9pUcTCup7kQnfT2smRjvmmm1wAP6QT")
.getKey();
ECKey key2 =
new DumpedPrivateKey(params, "cTine92s8GLpVqvebi8rYce3FrUYq78ZGQffBYCS1HmDPJdSTxUo")
.getKey();
ECKey key3 =
new DumpedPrivateKey(params, "cVHwXSPRZmL9adctwBwmn4oTZdZMbaCsR5XF6VznqMgcvt1FDDxg")
.getKey();
Script multisigScript =
ScriptBuilder.createMultiSigOutputScript(2, Arrays.asList(key1, key2, key3));
byte[] bytes =
Hex.decode(
"01000000013df681ff83b43b6585fa32dd0e12b0b502e6481e04ee52ff0fdaf55a16a4ef61000000006b483045022100a84acca7906c13c5895a1314c165d33621cdcf8696145080895cbf301119b7cf0220730ff511106aa0e0a8570ff00ee57d7a6f24e30f592a10cae1deffac9e13b990012102b8d567bcd6328fd48a429f9cf4b315b859a58fd28c5088ef3cb1d98125fc4e8dffffffff02364f1c00000000001976a91439a02793b418de8ec748dd75382656453dc99bcb88ac40420f000000000017a9145780b80be32e117f675d6e0ada13ba799bf248e98700000000");
Transaction transaction = new Transaction(params, bytes);
TransactionOutput output = transaction.getOutput(1);
Transaction spendTx = new Transaction(params);
Address address = new Address(params, "n3CFiCmBXVt5d3HXKQ15EFZyhPz4yj5F3H");
Script outputScript = ScriptBuilder.createOutputScript(address);
spendTx.addOutput(output.getValue(), outputScript);
spendTx.addInput(output);
Sha256Hash sighash = spendTx.hashForSignature(0, multisigScript, SigHash.ALL, false);
ECKey.ECDSASignature party1Signature = key1.sign(sighash);
ECKey.ECDSASignature party2Signature = key2.sign(sighash);
TransactionSignature party1TransactionSignature =
new TransactionSignature(party1Signature, SigHash.ALL, false);
TransactionSignature party2TransactionSignature =
new TransactionSignature(party2Signature, SigHash.ALL, false);
// Create p2sh multisig input script
Script inputScript =
ScriptBuilder.createP2SHMultiSigInputScript(
ImmutableList.of(party1TransactionSignature, party2TransactionSignature),
multisigScript.getProgram());
// Assert that the input script contains 4 chunks
assertTrue(inputScript.getChunks().size() == 4);
// Assert that the input script created contains the original multisig
// script as the last chunk
ScriptChunk scriptChunk = inputScript.getChunks().get(inputScript.getChunks().size() - 1);
Assert.assertArrayEquals(scriptChunk.data, multisigScript.getProgram());
// Create regular multisig input script
inputScript =
ScriptBuilder.createMultiSigInputScript(
ImmutableList.of(party1TransactionSignature, party2TransactionSignature));
// Assert that the input script only contains 3 chunks
assertTrue(inputScript.getChunks().size() == 3);
// Assert that the input script created does not end with the original
// multisig script
scriptChunk = inputScript.getChunks().get(inputScript.getChunks().size() - 1);
Assert.assertThat(scriptChunk.data, IsNot.not(IsEqual.equalTo(multisigScript.getProgram())));
}
/** Creates a fresh ScriptBuilder with the given program as the starting point. */
public ScriptBuilder(Script template) {
chunks = new ArrayList<ScriptChunk>(template.getChunks());
}