How to extract the signature of a transaction using bitcoinj

Question

I am trying to extract the signatures from a transaction. What is the best way to do this given a com.google.bitcoin.core.Transaction object I just received from the network?

Answer 1

This works for P2PK, and P2PKH, but multisig will not work.

int index = (the index you want);
List<TransactionInput> inputs = Transaction.getInputs()
TransactionInput input = inputs.get(index);
Script scriptSig = input.getScriptSig();
List<ScriptChunk> signature_and_pubkey = scriptSig.getChunks();
ScriptChunk sig_chunk = signature_and_pubkey.get(0);
bytes[] sig_bytes = sig_chunk.data;

If you want a TransactionSignature object instead of raw bytes:

TransactionSignature ts = TransactionSignature.decodeFromBitcoin(sig_bytes, false)