text: var Crypto = require('./crypto-js/crypto');
  
  /**
   * Cross-browser compatibility version of Array.isArray.
   */
  exports.isArray = Array.isArray || function(o) {
      return Object.prototype.toString.call(o) === '[object Array]';
  }
  
  /**
   * Create a byte array representing a number with the given length
   */
  exports.numToBytes = function(num, bytes) {
      if (bytes === undefined) bytes = 8;
      if (bytes === 0) return [];
      return [num % 256].concat(module.exports.numToBytes(Math.floor(num / 256), bytes - 1));
  }
  
  /**
   * Convert a byte array to the number that it represents
   */
  exports.bytesToNum = function(bytes) {
      if (bytes.length === 0) return 0;
      return bytes[0] + 256 * module.exports.bytesToNum(bytes.slice(1));
  }
  
  /**
   * Turn an integer into a "var_int".
   *
   * "var_int" is a variable length integer used by Bitcoin's binary format.
   *
   * Returns a byte array.
   */
  exports.numToVarInt = function(num) {
      if (num < 253) return [num];
      if (num < 65536) return [253].concat(exports.numToBytes(num, 2));
      if (num < 4294967296) return [254].concat(exports.numToBytes(num, 4));
      return [253].concat(exports.numToBytes(num, 8));
  }
  
  exports.bytesToWords = function (bytes) {
      var words = [];
      for (var i = 0, b = 0; i < bytes.length; i++, b += 8) {
          words[b >>> 5] |= bytes[i] << (24 - b % 32);
      }
      return words;
  }
  
  exports.wordsToBytes = function (words) {
      var bytes = [];
      for (var b = 0; b < words.length * 32; b += 8) {
          bytes.push((words[b >>> 5] >>> (24 - b % 32)) & 0xFF);
      }
      return bytes;
  },
  
  /**
   * Calculate RIPEMD160(SHA256(data)).
   *
   * Takes an arbitrary byte array as inputs and returns the hash as a byte
   * array.
   */
  exports.sha256ripe160 = function (data) {
      return Crypto.RIPEMD160(Crypto.SHA256(data, {asBytes: true}), {asBytes: true});
  }
  
  exports.error = function(msg) {
      throw new Error(msg);
  }
  