hmac.js

;(function (root, factory) {
	if (typeof exports === "object") {
		// CommonJS
		module.exports = exports = factory(require("./core"));
	}
	else if (typeof define === "function" && define.amd) {
		// AMD
		define(["./core"], 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 C_enc = C.enc;
	    var Utf8 = C_enc.Utf8;
	    var C_algo = C.algo;

	    /**
	     * HMAC algorithm.
	     */
	    var HMAC = C_algo.HMAC = Base.extend({
	        /**
	         * Initializes a newly created HMAC.
	         *
	         * @param {Hasher} hasher The hash algorithm to use.
	         * @param {WordArray|string} key The secret key.
	         *
	         * @example
	         *
	         *     var hmacHasher = CryptoJS.algo.HMAC.create(CryptoJS.algo.SHA256, key);
	         */
	        init: function (hasher, key) {
	            // Init hasher
	            hasher = this._hasher = new hasher.init();

	            // Convert string to WordArray, else assume WordArray already
	            if (typeof key == 'string') {
	                key = Utf8.parse(key);
	            }

	            // Shortcuts
	            var hasherBlockSize = hasher.blockSize;
	            var hasherBlockSizeBytes = hasherBlockSize * 4;

	            // Allow arbitrary length keys
	            if (key.sigBytes > hasherBlockSizeBytes) {
	                key = hasher.finalize(key);
	            }

	            // Clamp excess bits
	            key.clamp();

	            // Clone key for inner and outer pads
	            var oKey = this._oKey = key.clone();
	            var iKey = this._iKey = key.clone();

	            // Shortcuts
	            var oKeyWords = oKey.words;
	            var iKeyWords = iKey.words;

	            // XOR keys with pad constants
	            for (var i = 0; i < hasherBlockSize; i++) {
	                oKeyWords[i] ^= 0x5c5c5c5c;
	                iKeyWords[i] ^= 0x36363636;
	            }
	            oKey.sigBytes = iKey.sigBytes = hasherBlockSizeBytes;

	            // Set initial values
	            this.reset();
	        },

	        /**
	         * Resets this HMAC to its initial state.
	         *
	         * @example
	         *
	         *     hmacHasher.reset();
	         */
	        reset: function () {
	            // Shortcut
	            var hasher = this._hasher;

	            // Reset
	            hasher.reset();
	            hasher.update(this._iKey);
	        },

	        /**
	         * Updates this HMAC with a message.
	         *
	         * @param {WordArray|string} messageUpdate The message to append.
	         *
	         * @return {HMAC} This HMAC instance.
	         *
	         * @example
	         *
	         *     hmacHasher.update('message');
	         *     hmacHasher.update(wordArray);
	         */
	        update: function (messageUpdate) {
	            this._hasher.update(messageUpdate);

	            // Chainable
	            return this;
	        },

	        /**
	         * Finalizes the HMAC computation.
	         * Note that the finalize operation is effectively a destructive, read-once operation.
	         *
	         * @param {WordArray|string} messageUpdate (Optional) A final message update.
	         *
	         * @return {WordArray} The HMAC.
	         *
	         * @example
	         *
	         *     var hmac = hmacHasher.finalize();
	         *     var hmac = hmacHasher.finalize('message');
	         *     var hmac = hmacHasher.finalize(wordArray);
	         */
	        finalize: function (messageUpdate) {
	            // Shortcut
	            var hasher = this._hasher;

	            // Compute HMAC
	            var innerHash = hasher.finalize(messageUpdate);
	            hasher.reset();
	            var hmac = hasher.finalize(this._oKey.clone().concat(innerHash));

	            return hmac;
	        }
	    });
	}());


}));