static byte[] addChecksum(byte[] input) {
int inputLength = input.length;
byte[] checksummed = new byte[inputLength + 4];
System.arraycopy(input, 0, checksummed, 0, inputLength);
byte[] checksum = Sha256Hash.hashTwice(input);
System.arraycopy(checksum, 0, checksummed, inputLength, 4);
return checksummed;
}
/**
* Returns private key bytes, padded with zeros to 33 bytes.
*
* @throws java.lang.IllegalStateException if the private key bytes are missing.
*/
public byte[] getPrivKeyBytes33() {
byte[] bytes33 = new byte[33];
byte[] priv = getPrivKeyBytes();
System.arraycopy(priv, 0, bytes33, 33 - priv.length, priv.length);
return bytes33;
}