text: /*
  Copyright (c) 2013-2016 Matteo Collina, http://matteocollina.com
  
  Permission is hereby granted, free of charge, to any person
  obtaining a copy of this software and associated documentation
  files (the "Software"), to deal in the Software without
  restriction, including without limitation the rights to use,
  copy, modify, merge, publish, distribute, sublicense, and/or sell
  copies of the Software, and to permit persons to whom the
  Software is furnished to do so, subject to the following
  conditions:
  
  The above copyright notice and this permission notice shall be
  included in all copies or substantial portions of the Software.
  
  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
  OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
  HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
  WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
  OTHER DEALINGS IN THE SOFTWARE.
  */
  "use strict";
  
  var crypto = require("crypto");
  var fastfall = require("fastfall");
  
  // we can support a digest if we are not in node v0.10
  var supportsDigest = process.version.indexOf('v0.10') !== 0
  
  /**
   * Creates a new password hasher
   *
   * options:
   *  - `saltLength`, the length of the random salt
   *  - `iterations`, number of pbkdf2 iterations
   *  - `keyLength`, the length of the generated keys
   *  - `digest`, the digest algorithm, default 'sha1'
   */
  module.exports = function build(options) {
    options = options || {};
  
    var saltLength = options.saltLength || 64;
    var iterations = options.iterations || 10000;
    var keyLength = options.keyLength || 128;
    var digest = options.digest || 'sha1'
    var genHash = supportsDigest ? genHashWithDigest : genHashWithoutDigest
  
    if (digest !== 'sha1' && !supportsDigest) {
      throw new Error('v0.10 does not support setting a digest')
    }
  
    var passNeeded = fastfall([
      genPass,
      genSalt,
      genHash
    ])
  
    var saltNeeded = fastfall([
      genSalt,
      genHash
    ])
  
    /**
     * Hash a password, using a hash and the pbkd2
     * crypto module.
     *
     * Options:
     *  - `password`, the password to hash.
     *  - `salt`, the salt to use, as a base64 string.
     *
     *  If the `password` is left undefined, a new
     *  10-bytes password will be generated, and converted
     *  to base64.
     *
     *  If the `salt` is left undefined, a new salt is generated.
     *
     *  The callback will be called with the following arguments:
     *   - the error, if something went wrong.
     *   - the password.
     *   - the salt, encoded in base64.
     *   - the hash, encoded in base64.
     *
     * @param {Object} opts The options (optional)
     * @param {Function} callback
     */
    function hasher(opts, callback) {
      if (typeof opts.password !== 'string') {
        passNeeded(opts, callback);
      } else if (typeof opts.salt !== 'string') {
        saltNeeded(opts, callback);
      } else {
        opts.salt = new Buffer(opts.salt, 'base64');
        genHash(opts, callback);
      }
    };
  
    /**
     * Generates a new password
     *
     * @api private
     * @param {Object} opts The options (where the new password will be stored)
     * @param {Function} cb The callback
     */
    function genPass(opts, cb) {
      // generate a 10-bytes password
      crypto.randomBytes(10, function(err, buffer) {
        if (buffer) {
          opts.password = buffer.toString("base64");
        }
        cb(err, opts);
      });
    }
  
    /**
     * Generates a new salt
     *
     * @api private
     * @param {Object} opts The options (where the new password will be stored)
     * @param {Function} cb The callback
     */
    function genSalt(opts, cb) {
      crypto.randomBytes(saltLength, function(err, buf) {
        opts.salt = buf;
        cb(err, opts);
      });
    }
  
    /**
     * Generates a new hash using the password and the salt
     *
     *  The callback will be called with the following arguments:
     *   - the error, if something when wrong.
     *   - the password.
     *   - the salt, encoded in base64.
     *   - the hash, encoded in base64.
     *
     * @api private
     * @param {Object} opts The options used to generate the hash (password & salt)
     * @param {Function} cb The callback
     */
    function genHashWithDigest(opts, cb) {
      crypto.pbkdf2(opts.password, opts.salt, iterations, keyLength, digest, function(err, hash) {
        if (typeof hash === 'string') {
          hash = new Buffer(hash, 'binary');
        }
  
        cb(err, opts.password, opts.salt.toString("base64"), hash.toString("base64"));
      });
    }
  
    /**
     * Generates a new hash using the password and the salt
     *
     *  The callback will be called with the following arguments:
     *   - the error, if something when wrong.
     *   - the password.
     *   - the salt, encoded in base64.
     *   - the hash, encoded in base64.
     *
     * @api private
     * @param {Object} opts The options used to generate the hash (password & salt)
     * @param {Function} cb The callback
     */
    function genHashWithoutDigest(opts, cb) {
      crypto.pbkdf2(opts.password, opts.salt, iterations, keyLength, function(err, hash) {
        if (typeof hash === 'string') {
          hash = new Buffer(hash, 'binary');
        }
  
        cb(err, opts.password, opts.salt.toString("base64"), hash.toString("base64"));
      });
    }
  
    return hasher;
  }
  