/*
CryptoJS v3.1.2
code.google.com/p/crypto-js
(c) 2009-2013 by Jeff Mott. All rights reserved.
code.google.com/p/crypto-js/wiki/License
*/
(function () {

    // Shortcuts

    var C = CryptoJS;

    var C_lib = C.lib;

    var Base = C_lib.Base;

    var WordArray = C_lib.WordArray;

    var C_algo = C.algo;

    var SHA1 = C_algo.SHA1;

    var HMAC = C_algo.HMAC;



    /**

     * Password-Based Key Derivation Function 2 algorithm.

     */

    var PBKDF2 = C_algo.PBKDF2 = Base.extend({

        /**

         * Configuration options.

         *

         * @property {number} keySize The key size in words to generate. Default: 4 (128 bits)

         * @property {Hasher} hasher The hasher to use. Default: SHA1

         * @property {number} iterations The number of iterations to perform. Default: 1

         */

        cfg: Base.extend({

            keySize: 128/32,

            hasher: SHA1,

            iterations: 1

        }),



        /**

         * Initializes a newly created key derivation function.

         *

         * @param {Object} cfg (Optional) The configuration options to use for the derivation.

         *

         * @example

         *

         *     var kdf = CryptoJS.algo.PBKDF2.create();

         *     var kdf = CryptoJS.algo.PBKDF2.create({ keySize: 8 });

         *     var kdf = CryptoJS.algo.PBKDF2.create({ keySize: 8, iterations: 1000 });

         */

        init: function (cfg) {

            this.cfg = this.cfg.extend(cfg);

        },



        /**

         * Computes the Password-Based Key Derivation Function 2.

         *

         * @param {WordArray|string} password The password.

         * @param {WordArray|string} salt A salt.

         *

         * @return {WordArray} The derived key.

         *

         * @example

         *

         *     var key = kdf.compute(password, salt);

         */

        compute: function (password, salt) {

            // Shortcut

            var cfg = this.cfg;



            // Init HMAC

            var hmac = HMAC.create(cfg.hasher, password);



            // Initial values

            var derivedKey = WordArray.create();

            var blockIndex = WordArray.create([0x00000001]);



            // Shortcuts

            var derivedKeyWords = derivedKey.words;

            var blockIndexWords = blockIndex.words;

            var keySize = cfg.keySize;

            var iterations = cfg.iterations;



            // Generate key

            while (derivedKeyWords.length < keySize) {

                var block = hmac.update(salt).finalize(blockIndex);

                hmac.reset();



                // Shortcuts

                var blockWords = block.words;

                var blockWordsLength = blockWords.length;



                // Iterations

                var intermediate = block;

                for (var i = 1; i < iterations; i++) {

                    intermediate = hmac.finalize(intermediate);

                    hmac.reset();



                    // Shortcut

                    var intermediateWords = intermediate.words;



                    // XOR intermediate with block

                    for (var j = 0; j < blockWordsLength; j++) {

                        blockWords[j] ^= intermediateWords[j];

                    }

                }



                derivedKey.concat(block);

                blockIndexWords[0]++;

            }

            derivedKey.sigBytes = keySize * 4;



            return derivedKey;

        }

    });



    /**

     * Computes the Password-Based Key Derivation Function 2.

     *

     * @param {WordArray|string} password The password.

     * @param {WordArray|string} salt A salt.

     * @param {Object} cfg (Optional) The configuration options to use for this computation.

     *

     * @return {WordArray} The derived key.

     *

     * @static

     *

     * @example

     *

     *     var key = CryptoJS.PBKDF2(password, salt);

     *     var key = CryptoJS.PBKDF2(password, salt, { keySize: 8 });

     *     var key = CryptoJS.PBKDF2(password, salt, { keySize: 8, iterations: 1000 });

     */

    C.PBKDF2 = function (password, salt, cfg) {

        return PBKDF2.create(cfg).compute(password, salt);

    };

}());

