Bug: Failing correct web3 extensions

web3-ethereumjs-tx-fail.js

/**
 * @author Thomas Haller <[email protected]>
 * @abstract showcases an issue creating a web3 transaction with RSV if R or S has a leading zeros
 * Those leading zeros are optimized away by ethereumjs-tx but are required later by the RLP Logic.
 * This code sample is designed to be easy adoptable to be picked up for an automatic test. 
 * it was tested with [email protected].
 * Since beta.51 ethereumjs-tx is referenced by web3.
 *
 * @see https://github.com/ethereumjs/ethereumjs-tx/issues/140
 */


const Web3 = require('web3')
const Tx = require('ethereumjs-tx');


const web3_options = {
    transactionConfirmationBlocks: 1,
    defaultGasPrice: 1000000000
}

const rpcAddress = 'http://127.0.0.1:9545/';
var web3 = new Web3(rpcAddress, null, web3_options);

const txRaw = {
     nonce: '0x00',
     gasPrice: 1000000000,
     gas: 21000,
     to: '0x92d8099b5b4dd10234ec8f1f03e691aeea2f6527',
     value: 1000
   };

const tx = new Tx(txRaw);

const address = "0x0774fe042Bc23D01599B5A92b97B3125a4Cb20EE";

// a valid signature for this transaction: 
const r = "707f45cea1c62ded74d5a7ee2e40bebc4adf79f2cffc94e73527c5903b98cddb";
const s = "00c3749242f56c7c06a842e516d43e97bd35e1127708a76277e998ea1257f6ed";
const v = "1b";

tx.r = "0x" + r;
tx.s = "0x" + s;
tx.v = "0x" + v;

var serializedTx = toHex(tx.serialize());

var recoveredAddress;

try {
    recoveredAddress = web3.eth.accounts.recoverTransaction(serializedTx)
    console.assert(recoveredAddress == address, "Unexpected: recovery was success, but address is wrong:" + recoveredAddress)
    console.log("hoorray - recover success - bug is fixed in web3 library: " + recoveredAddress);
    return;

} catch(error) {
    console.log("BUG is still here: RLP is wrong.");
}

//i am fixing the problem here by manipulating the serialized RLP string.
//i replace the problematic 31 byte long string with a 32 byte string 
//and taking care about the RLP values as well.

// 9f is the size header in the case the leading zero has been optimized away
// a0 is the size header in the case where the leading zero is kept.

var searchString = "9f" + s.slice(2, 64);
var replaceString = "a0" + s;

console.log("searchString:" + searchString);
console.log("replaceString:" + replaceString);

serializedTx = serializedTx.replace(searchString, replaceString);

console.log("Repaired Transaction: " + serializedTx);

//now we have repaired the transaction and can prove that it is valid

try {
    recoveredAddress = web3.eth.accounts.recoverTransaction(serializedTx)
    console.assert(recoveredAddress == address, "Unexpected: recovery was success, but address is wrong:" + recoveredAddress)
    console.log("recover success with repeaired transaction: " + recoveredAddress);

} catch(error) {
    console.error("UNEXPECTED ERROR:", error);
}

function toHex(nonHex, prefix = true) {
    let temp = nonHex.toString('hex');
    if (prefix) {
      temp = `0x${temp}`;
    }
    return temp;
};