/*
* Copyright 2015 Ross Nicoll.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.bitcoinj.examples;
import java.io.IOException;
import java.math.BigInteger;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;
import java.util.EnumSet;
import static com.google.common.base.Preconditions.checkNotNull;
import org.bitcoinj.core.Coin;
import org.bitcoinj.core.ECKey;
import org.bitcoinj.core.NetworkParameters;
import org.bitcoinj.core.ScriptException;
import org.bitcoinj.core.Transaction;
import org.bitcoinj.core.TransactionInput;
import org.bitcoinj.core.TransactionOutput;
import org.bitcoinj.core.Utils;
import org.bitcoinj.crypto.TransactionSignature;
import org.bitcoinj.params.MainNetParams;
import org.bitcoinj.script.Script;
import org.bitcoinj.script.ScriptBuilder;
import org.bitcoinj.script.ScriptChunk;
import static org.bitcoinj.script.ScriptOpCodes.getOpCodeName;
import org.bitcoinj.signers.LocalTransactionSigner;
import org.bitcoinj.signers.TransactionSigner.ProposedTransaction;
import org.bitcoinj.wallet.KeyBag;
import org.bitcoinj.wallet.RedeemData;
/**
* Test case generator for transactions with low-S and high-S signatures, to
* test the LOW_S script validation flag.
*
* @author Ross Nicoll
*/
public class GenerateLowSTests {
public static final BigInteger HIGH_S_DIFFERENCE = new BigInteger("FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFEBAAEDCE6AF48A03BBFD25E8CD0364141", 16);
public static void main(final String[] argv) throws NoSuchAlgorithmException, IOException {
final NetworkParameters params = new MainNetParams();
final LocalTransactionSigner signer = new LocalTransactionSigner();
final SecureRandom secureRandom = SecureRandom.getInstanceStrong();
final ECKey key = new ECKey(secureRandom);
final KeyBag bag = new KeyBag() {
@Override
public ECKey findKeyFromPubHash(byte[] pubkeyHash) {
return key;
}
@Override
public ECKey findKeyFromPubKey(byte[] pubkey) {
return key;
}
@Override
public RedeemData findRedeemDataFromScriptHash(byte[] scriptHash) {
return null;
}
};
// Generate a fictional output transaction we take values from, and
// an input transaction for the test case
final Transaction outputTransaction = new Transaction(params);
final Transaction inputTransaction = new Transaction(params);
final TransactionOutput output = new TransactionOutput(params, inputTransaction, Coin.ZERO, key.toAddress(params));
inputTransaction.addOutput(output);
outputTransaction.addInput(output);
outputTransaction.addOutput(Coin.ZERO, new ECKey(secureRandom).toAddress(params));
addOutputs(outputTransaction, bag);
// Sign the transaction
final ProposedTransaction proposedTransaction = new ProposedTransaction(outputTransaction);
signer.signInputs(proposedTransaction, bag);
final TransactionInput input = proposedTransaction.partialTx.getInput(0);
input.verify(output);
input.getScriptSig().correctlySpends(outputTransaction, 0, output.getScriptPubKey(),
EnumSet.of(Script.VerifyFlag.DERSIG, Script.VerifyFlag.P2SH));
final Script scriptSig = input.getScriptSig();
final TransactionSignature signature = TransactionSignature.decodeFromBitcoin(scriptSig.getChunks().get(0).data, true, false);
// First output a conventional low-S transaction with the LOW_S flag, for the tx_valid.json set
System.out.println("[\"A transaction with a low-S signature.\"],");
System.out.println("[[[\""
+ inputTransaction.getHashAsString() + "\", "
+ output.getIndex() + ", \""
+ scriptToString(output.getScriptPubKey()) + "\"]],\n"
+ "\"" + Utils.HEX.encode(proposedTransaction.partialTx.unsafeBitcoinSerialize()) + "\", \""
+ Script.VerifyFlag.P2SH.name() + "," + Script.VerifyFlag.LOW_S.name() + "\"],");
final BigInteger highS = HIGH_S_DIFFERENCE.subtract(signature.s);
final TransactionSignature highSig = new TransactionSignature(signature.r, highS);
input.setScriptSig(new ScriptBuilder().data(highSig.encodeToBitcoin()).data(scriptSig.getChunks().get(1).data).build());
input.getScriptSig().correctlySpends(outputTransaction, 0, output.getScriptPubKey(),
EnumSet.of(Script.VerifyFlag.P2SH));
// A high-S transaction without the LOW_S flag, for the tx_valid.json set
System.out.println("[\"A transaction with a high-S signature.\"],");
System.out.println("[[[\""
+ inputTransaction.getHashAsString() + "\", "
+ output.getIndex() + ", \""
+ scriptToString(output.getScriptPubKey()) + "\"]],\n"
+ "\"" + Utils.HEX.encode(proposedTransaction.partialTx.unsafeBitcoinSerialize()) + "\", \""
+ Script.VerifyFlag.P2SH.name() + "\"],");
// Lastly a conventional high-S transaction with the LOW_S flag, for the tx_invalid.json set
System.out.println("[\"A transaction with a high-S signature.\"],");
System.out.println("[[[\""
+ inputTransaction.getHashAsString() + "\", "
+ output.getIndex() + ", \""
+ scriptToString(output.getScriptPubKey()) + "\"]],\n"
+ "\"" + Utils.HEX.encode(proposedTransaction.partialTx.unsafeBitcoinSerialize()) + "\", \""
+ Script.VerifyFlag.P2SH.name() + "," + Script.VerifyFlag.LOW_S.name() + "\"],");
}
private static void addOutputs(final Transaction outputTransaction, final KeyBag bag) throws ScriptException {
int numInputs = outputTransaction.getInputs().size();
for (int i = 0; i < numInputs; i++) {
TransactionInput txIn = outputTransaction.getInput(i);
Script scriptPubKey = txIn.getConnectedOutput().getScriptPubKey();
RedeemData redeemData = txIn.getConnectedRedeemData(bag);
checkNotNull(redeemData, "Transaction exists in wallet that we cannot redeem: %s", txIn.getOutpoint().getHash());
txIn.setScriptSig(scriptPubKey.createEmptyInputScript(redeemData.keys.get(0), redeemData.redeemScript));
}
}
/**
* Convert a script to a string format that suits the style expected in
* tx_valid.json and tx_invalid.json.
*/
private static String scriptToString(Script scriptPubKey) {
final StringBuilder buf = new StringBuilder();
for (ScriptChunk chunk: scriptPubKey.getChunks()) {
if (buf.length() > 0) {
buf.append(" ");
}
if (chunk.isOpCode()) {
buf.append(getOpCodeName(chunk.opcode));
} else if (chunk.data != null) {
// Data chunk
buf.append("0x")
.append(Integer.toString(chunk.opcode, 16)).append(" 0x")
.append(Utils.HEX.encode(chunk.data));
} else {
buf.append(chunk.toString());
}
}
return buf.toString();
}
}