cryptojs.hmac.js

/*!
* Crypto-JS v2.5.4	HMAC.js
* http://code.google.com/p/crypto-js/
* Copyright (c) 2009-2013, Jeff Mott. All rights reserved.
* http://code.google.com/p/crypto-js/wiki/License
*/
(function () {

	// Shortcuts
	var C = Crypto,
		util = C.util,
		charenc = C.charenc,
		UTF8 = charenc.UTF8,
		Binary = charenc.Binary;

	C.HMAC = function (hasher, message, key, options) {

		// Convert to byte arrays
		if (message.constructor == String) message = UTF8.stringToBytes(message);
		if (key.constructor == String) key = UTF8.stringToBytes(key);
		/* else, assume byte arrays already */

		// Allow arbitrary length keys
		if (key.length > hasher._blocksize * 4)
			key = hasher(key, { asBytes: true });

		// XOR keys with pad constants
		var okey = key.slice(0),
			ikey = key.slice(0);
		for (var i = 0; i < hasher._blocksize * 4; i++) {
			okey[i] ^= 0x5C;
			ikey[i] ^= 0x36;
		}

		var hmacbytes = hasher(okey.concat(hasher(ikey.concat(message), { asBytes: true })), { asBytes: true });

		return options && options.asBytes ? hmacbytes :
		options && options.asString ? Binary.bytesToString(hmacbytes) :
		util.bytesToHex(hmacbytes);

	};

})();