evpkdf.js

;(function (root, factory, undef) {
	if (typeof exports === "object") {
		// CommonJS
		module.exports = exports = factory(require("./core"), require("./sha1"), require("./hmac"));
	}
	else if (typeof define === "function" && define.amd) {
		// AMD
		define(["./core", "./sha1", "./hmac"], factory);
	}
	else {
		// Global (browser)
		factory(root.CryptoJS);
	}
}(this, function (CryptoJS) {

	(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 MD5 = C_algo.MD5;

	    /**
	     * This key derivation function is meant to conform with EVP_BytesToKey.
	     * www.openssl.org/docs/crypto/EVP_BytesToKey.html
	     */
	    var EvpKDF = C_algo.EvpKDF = Base.extend({
	        /**
	         * Configuration options.
	         *
	         * @property {number} keySize The key size in words to generate. Default: 4 (128 bits)
	         * @property {Hasher} hasher The hash algorithm to use. Default: MD5
	         * @property {number} iterations The number of iterations to perform. Default: 1
	         */
	        cfg: Base.extend({
	            keySize: 128/32,
	            hasher: MD5,
	            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.EvpKDF.create();
	         *     var kdf = CryptoJS.algo.EvpKDF.create({ keySize: 8 });
	         *     var kdf = CryptoJS.algo.EvpKDF.create({ keySize: 8, iterations: 1000 });
	         */
	        init: function (cfg) {
	            this.cfg = this.cfg.extend(cfg);
	        },

	        /**
	         * Derives a key from a password.
	         *
	         * @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) {
	            var block;

	            // Shortcut
	            var cfg = this.cfg;

	            // Init hasher
	            var hasher = cfg.hasher.create();

	            // Initial values
	            var derivedKey = WordArray.create();

	            // Shortcuts
	            var derivedKeyWords = derivedKey.words;
	            var keySize = cfg.keySize;
	            var iterations = cfg.iterations;

	            // Generate key
	            while (derivedKeyWords.length < keySize) {
	                if (block) {
	                    hasher.update(block);
	                }
	                block = hasher.update(password).finalize(salt);
	                hasher.reset();

	                // Iterations
	                for (var i = 1; i < iterations; i++) {
	                    block = hasher.finalize(block);
	                    hasher.reset();
	                }

	                derivedKey.concat(block);
	            }
	            derivedKey.sigBytes = keySize * 4;

	            return derivedKey;
	        }
	    });

	    /**
	     * Derives a key from a password.
	     *
	     * @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.EvpKDF(password, salt);
	     *     var key = CryptoJS.EvpKDF(password, salt, { keySize: 8 });
	     *     var key = CryptoJS.EvpKDF(password, salt, { keySize: 8, iterations: 1000 });
	     */
	    C.EvpKDF = function (password, salt, cfg) {
	        return EvpKDF.create(cfg).compute(password, salt);
	    };
	}());


	return CryptoJS.EvpKDF;

}));