fh-wfm-user/lib/mbaas/hash.js

A user module for WFM

var crypto = require('crypto');
var semver = require('semver');

var SALT_LENGTH = 64;
var HASH_ITERATIONS = 10000;
var HASH_LENGTH = 256;
var CIPHER = 'sha1';
var SEPARATOR = ':';

function genSalt() {
  return crypto.randomBytes(SALT_LENGTH).toString('hex');
}

/**
 * Wrapper around node.js' pbkdf2 implementation.
 *
 * The PBKDF2 algorithm applies a hashing function to a password and salt a large number of times
 * in order to generate a secure hash that requires high computational power to brute-force against.
 *
 * In node versions <0.12 the only supported hashing function is sha1, and the cipher parameter is ignored.
 */
function pbkdf2(pwd, salt, iterations, length, cipher, cb) {
  if (semver.satisfies(process.version, '>=0.12.0')) {
    crypto.pbkdf2(pwd, salt, iterations, length, cipher, cb);
  } else {
    crypto.pbkdf2(pwd, salt, iterations, length, cb);
  }
}

/**
 * @callback saltAndHashCallback
 * @param {Error}
 * @param {String} responseMessage
 */

/**
 * Generates a random salt and hashes the given password, supplying it to a node-style callback.
 * The hashed password follows the format {cipher}:{iterations}:{hash}:{salt}, in which:
 *
 * cipher: The algorithm used to form the hashed password
 * iterations: The number of iterations of the algorithm run by {@link https://nodejs.org/api/crypto.html#crypto_crypto_pbkdf2_password_salt_iterations_keylen_digest_callback | pbkdf2}
 * hash: The hashed password
 * salt: The random salt for that hash
 * @param  {String}   pwd Password to be encrypted
 * @param  {saltAndHashCallback} cb Node-style callback
 */
exports.saltAndHash = function(pwd, cb) {
  var salt = genSalt();
  pbkdf2(pwd, salt, HASH_ITERATIONS, HASH_LENGTH, CIPHER, function(err, hashed) {
    if (err) {
      return cb(err);
    }

    var finalHash = [CIPHER, HASH_ITERATIONS, hashed.toString('hex'), salt].join(SEPARATOR);
    cb(null, finalHash);
  });
};

/**
 * @callback verifyCallback
 * @param {Error}
 * @param {Boolean} Whether the password corresponds to the supplied hashed string
 */

/**
 * Verifies a given password against a hashed version of it.
 * The hashed string should follow the same format as in {@link saltAndHash}
 *
 * In node <0.12 the cipher information is ignored and the default sha1 is used,
 * so hashes using other algorithms will not match.
 *
 * @param  {String}   pwd Password to be verified
 * @param  {String}   hashed Hash generated by {@link exports.saltAndHash}
 * @param  {verifyCallback} cb Node-style callback
 */
exports.verify = function(pwd, hashed, cb) {
  var split = hashed.split(SEPARATOR);
  if (!split || split.length !== 4) {
    return cb(new Error('Hash string should be in {cipher}:{iterations}:{hash}:{salt} format'));
  }
  var cipher = split[0];
  var iterations = Number(split[1]);
  var hash = split[2];
  var salt = split[3];

  pbkdf2(pwd, salt, iterations, HASH_LENGTH, cipher, function(err, verify) {
    // available on node 6.0+
    if (crypto.timingSafeEqual) {
      var hashBuf;
      try {
        hashBuf = Buffer.from(hash, 'hex');
      } catch (e) {
        // invalid hex string
        return cb(err);
      }
      return cb(err, crypto.timingSafeEqual(hashBuf, verify));
    }
    cb(err, hash === verify.toString('hex'));
  });
};

exports.separator = SEPARATOR;