coinutils-browserify

A fully self-contained client side JavaScript library bundle for creating and using URO/LTC/BTC brain wallets to sign and verify blockchain currency transactions.

Originally designed to be used with the BlockCypher Transactions and Blockchain APIs, but can work with any cryptocurrency transactions workload based on hex string and Buffer formats.

All the cryptography is done using CryptoCoinJS.

Available Functions

/**
   * Takes in a hex string message, decodes it into binary, signs it with ECDSA, 
   * and returns the result as a hex string
   * @param {hex string} shaMsg the message to sign
   * @param {Buffer} privateKey the private key to sign with, normally you would 
   * get this from CoinKey.privateKey (from CryptocoinJS)
   */
  this.signMsg =  function (shaMsg, privateKey) {
    var Buffer = require('buffer').Buffer
    var sigRs = ecdsa.sign(new Buffer(shaMsg, 'hex'), privateKey);
    var byteArr = ecdsa.serializeSig(sigRs);
    return new Buffer(byteArr).toString('hex');
  };
    
  /**
   * Takes in a hex string message and verifies it against the 
   * @param {hex string} shaMsg the message to test the signature against
   * @param {hex string} signature the signature 
   * @param {hex string} 
   */
  this.verifyMsg = function (shaMsg, signature, publicKey) {
    var Buffer = require('buffer').Buffer
    var shaMsgBuf = new Buffer(shaMsg, 'hex');
    var sigBuf = new Buffer(signature, 'hex');
    var pubKeyBuf = new Buffer(publicKey, 'hex');
    return ecdsa.verify(shaMsgBuf, sigBuf, pubKeyBuf);
  };
    
  /**
   * Returns a privateKey as a Buffer which is derived deterministically the 
   * username and password arguments
   */
  this.createBrainPrivateKey = function (username, password) {
    return crypto.createHash('sha256').update(username + password).digest();
  };
    
  /**
   * Converts a Buffer to a hex string for sending across the network
   */    
  this.bufferToHex = function (buf) {
    return buf.toString('hex');
  };
    
  /**
   * Creates a CryptocoinJS CoinKey for the URO network corresponding 
   * to the supplied private key 
   * @param {Buffer} privateKey
   */
  this.createUroCoinKey = function (privateKey) {
    return new CoinKey(privateKey, CoinInfo('URO').versions);
  };
    
  /**
   * Creates a CryptocoinJS CoinKey for the LTC network corresponding 
   * to the supplied private key 
   * @param {Buffer} privateKey
   */
  this.createLtcCoinKey = function (privateKey) {
    return new CoinKey(privateKey, CoinInfo('LTC').versions);
  };
    
  /**
   * Creates a CryptocoinJS CoinKey for the BTC network corresponding 
   * to the supplied private key 
   * @param {Buffer} privateKey
   */
  this.createBtcCoinKey = function (privateKey) {
    return new CoinKey(privateKey, CoinInfo('BTC').versions);
  };

Sample code demonstrating use with BlockCypher V1 API

function checkUserPass(){
    var username = $('#uro-username-input').val();
    if (username.length < 8) {
        alert('Username needs to be 8 characters or more');
        return false;
    }
    var password = $('#uro-password-input').val();
    if (username.length < 8) {
        alert('Password needs to be 10 characters or more');
        return false;
    }    
    Nuro.username = username;
    Nuro.password = password;
    var coinutils = require('coinutils.js');
    Nuro.privateKey = coinutils.createBrainPrivateKey(username, password);
    Nuro.uroCoinKey = coinutils.createUroCoinKey(Nuro.privateKey);
    Nuro.ltcCoinKey = coinutils.createLtcCoinKey(Nuro.privateKey);
    Nuro.btcCoinKey = coinutils.createBtcCoinKey(Nuro.privateKey);

    return true;
}

function checkError(msg) {
    if (msg.errors && msg.errors.length) {
        log("Errors occured!!/n" + msg.errors.join("/n"));
        return true;
    }
}

// 1. Post our simple transaction information to get back the fully built transaction,
//    includes fees when required.
// amount should be in number of coins, e.g. 1.2, or 0.1
function createTx(srcAddr, destAddr, amount) {
    var rootUrl = "https://api.blockcypher.com/v1/uro/main";
    var newTx = {
        "inputs": [{"addresses": [srcAddr]}],
        "outputs": [{"addresses": [destAddr], "value": amount * Nuro.satoshiToCoinMultiplier}]
    };
    $.post(rootUrl+"/txs/new", JSON.stringify(newTx), function(newTx){
        if (!checkError(newTx)) {
            $('#send-status-label').html('Sending funds. Please wait...');
        } else {
            $('#send-status-label').html('Error occured during processing transaction');
        }
        signAndSendTx(newTx);
    });
}

// 2. Sign the hexadecimal strings returned with the fully built transaction and include
//    the source public address.
function signAndSendTx(newTx) {
    var rootUrl = "https://api.blockcypher.com/v1/uro/main";
    if (checkError(newTx)) return;
    var coinutils = require('coinutils.js');
    var publicKey = Nuro.uroCoinKey.publicKey;
    var privateKey = Nuro.uroCoinKey.privateKey;
    newTx.pubkeys = [];

    newTx.signatures = newTx.tosign.map(function(tosign) {
        newTx.pubkeys.push(coinutils.bufferToHex(publicKey));
        return coinutils.signMsg(tosign, privateKey);
    });
    console.log(JSON.stringify(newTx));
    $.post(rootUrl+"/txs/send", JSON.stringify(newTx), function(newTx){
        if (!checkError(newTx)) {
            $('#send-status-label').html('Funds sent sucessfully.');
            alert('Funds sent. The recipent will be able to confirm receipt of the funds after a few minutes');
            resetSendPageStatus();
        } else {
            $('#send-status-label').html('Error occured during processing transaction');
        }
    });
}

/*
Sends a transaction from data entered on the send page
*/
function sendTxFromPageData() {
    var destAddr = $('#recipient-address-input').val();
    var amt = $('#send-amount-input').val();
    createTx(Nuro.uroCoinKey.publicAddress, destAddr, amt);
}

function satoshiToCoinStr(sats) {
    var coins = "";
    if (sats == 0) {
        coins = 0;
    } else {
        coins = sats / Nuro.satoshiToCoinMultiplier;
    }
    return coins + " " + Nuro.currentCoinTicker;
}