TransactionWitness.java

package org.bitcoinj.core;

import org.bitcoinj.crypto.TransactionSignature;

import javax.annotation.Nullable;

public class TransactionWitness {
    static TransactionWitness empty = new TransactionWitness(0);

    public static TransactionWitness getEmpty() {
        return empty;
    }

    byte[][] pushes;

    public TransactionWitness(int pushCount) {
        pushes = new byte[pushCount][];
    }

    public byte[] getPush(int i) {
        return pushes[i];
    }

    public int getPushCount() {
        return pushes.length;
    }

    public void setPush(int i, byte[] value) {
        pushes[i] = value;
    }

    /**
     * Create a witness that can redeem a pay-to-witness-pubkey-hash output.
     */
    public static TransactionWitness createWitness(@Nullable final TransactionSignature signature, final ECKey pubKey) {
        final byte[] sigBytes = signature != null ? signature.encodeToBitcoin() : new byte[]{};
        final byte[] pubKeyBytes = pubKey.getPubKey();
        final TransactionWitness witness = new TransactionWitness(2);
        witness.setPush(0, sigBytes);
        witness.setPush(1, pubKeyBytes);
        return witness;
    }
}