cryptojs.aes.js

/*!
* Crypto-JS v2.5.4	AES.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;

	// Precomputed SBOX
	var SBOX = [0x63, 0x7c, 0x77, 0x7b, 0xf2, 0x6b, 0x6f, 0xc5,
            0x30, 0x01, 0x67, 0x2b, 0xfe, 0xd7, 0xab, 0x76,
            0xca, 0x82, 0xc9, 0x7d, 0xfa, 0x59, 0x47, 0xf0,
            0xad, 0xd4, 0xa2, 0xaf, 0x9c, 0xa4, 0x72, 0xc0,
            0xb7, 0xfd, 0x93, 0x26, 0x36, 0x3f, 0xf7, 0xcc,
            0x34, 0xa5, 0xe5, 0xf1, 0x71, 0xd8, 0x31, 0x15,
            0x04, 0xc7, 0x23, 0xc3, 0x18, 0x96, 0x05, 0x9a,
            0x07, 0x12, 0x80, 0xe2, 0xeb, 0x27, 0xb2, 0x75,
            0x09, 0x83, 0x2c, 0x1a, 0x1b, 0x6e, 0x5a, 0xa0,
            0x52, 0x3b, 0xd6, 0xb3, 0x29, 0xe3, 0x2f, 0x84,
            0x53, 0xd1, 0x00, 0xed, 0x20, 0xfc, 0xb1, 0x5b,
            0x6a, 0xcb, 0xbe, 0x39, 0x4a, 0x4c, 0x58, 0xcf,
            0xd0, 0xef, 0xaa, 0xfb, 0x43, 0x4d, 0x33, 0x85,
            0x45, 0xf9, 0x02, 0x7f, 0x50, 0x3c, 0x9f, 0xa8,
            0x51, 0xa3, 0x40, 0x8f, 0x92, 0x9d, 0x38, 0xf5,
            0xbc, 0xb6, 0xda, 0x21, 0x10, 0xff, 0xf3, 0xd2,
            0xcd, 0x0c, 0x13, 0xec, 0x5f, 0x97, 0x44, 0x17,
            0xc4, 0xa7, 0x7e, 0x3d, 0x64, 0x5d, 0x19, 0x73,
            0x60, 0x81, 0x4f, 0xdc, 0x22, 0x2a, 0x90, 0x88,
            0x46, 0xee, 0xb8, 0x14, 0xde, 0x5e, 0x0b, 0xdb,
            0xe0, 0x32, 0x3a, 0x0a, 0x49, 0x06, 0x24, 0x5c,
            0xc2, 0xd3, 0xac, 0x62, 0x91, 0x95, 0xe4, 0x79,
            0xe7, 0xc8, 0x37, 0x6d, 0x8d, 0xd5, 0x4e, 0xa9,
            0x6c, 0x56, 0xf4, 0xea, 0x65, 0x7a, 0xae, 0x08,
            0xba, 0x78, 0x25, 0x2e, 0x1c, 0xa6, 0xb4, 0xc6,
            0xe8, 0xdd, 0x74, 0x1f, 0x4b, 0xbd, 0x8b, 0x8a,
            0x70, 0x3e, 0xb5, 0x66, 0x48, 0x03, 0xf6, 0x0e,
            0x61, 0x35, 0x57, 0xb9, 0x86, 0xc1, 0x1d, 0x9e,
            0xe1, 0xf8, 0x98, 0x11, 0x69, 0xd9, 0x8e, 0x94,
            0x9b, 0x1e, 0x87, 0xe9, 0xce, 0x55, 0x28, 0xdf,
            0x8c, 0xa1, 0x89, 0x0d, 0xbf, 0xe6, 0x42, 0x68,
            0x41, 0x99, 0x2d, 0x0f, 0xb0, 0x54, 0xbb, 0x16];

	// Compute inverse SBOX lookup table
	for (var INVSBOX = [], i = 0; i < 256; i++) INVSBOX[SBOX[i]] = i;

	// Compute multiplication in GF(2^8) lookup tables
	var MULT2 = [],
		MULT3 = [],
		MULT9 = [],
		MULTB = [],
		MULTD = [],
		MULTE = [];

	function xtime(a, b) {
		for (var result = 0, i = 0; i < 8; i++) {
			if (b & 1) result ^= a;
			var hiBitSet = a & 0x80;
			a = (a << 1) & 0xFF;
			if (hiBitSet) a ^= 0x1b;
			b >>>= 1;
		}
		return result;
	}

	for (var i = 0; i < 256; i++) {
		MULT2[i] = xtime(i, 2);
		MULT3[i] = xtime(i, 3);
		MULT9[i] = xtime(i, 9);
		MULTB[i] = xtime(i, 0xB);
		MULTD[i] = xtime(i, 0xD);
		MULTE[i] = xtime(i, 0xE);
	}

	// Precomputed RCon lookup
	var RCON = [0x00, 0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1b, 0x36];

	// Inner state
	var state = [[], [], [], []],
		keylength,
		nrounds,
		keyschedule;

	var AES = C.AES = {

		/**
		* Public API
		*/

		encrypt: function (message, password, options) {

			options = options || {};

			// Determine mode
			var mode = options.mode || new C.mode.OFB;

			// Allow mode to override options
			if (mode.fixOptions) mode.fixOptions(options);

			var 

			// Convert to bytes if message is a string
		m = (
			message.constructor == String ?
			UTF8.stringToBytes(message) :
			message
		),

			// Generate random IV
		iv = options.iv || util.randomBytes(AES._blocksize * 4),

			// Generate key
		k = (
			password.constructor == String ?
			// Derive key from pass-phrase
			C.PBKDF2(password, iv, 32, { asBytes: true }) :
			// else, assume byte array representing cryptographic key
			password
		);

			// Encrypt
			AES._init(k);
			mode.encrypt(AES, m, iv);

			// Return ciphertext
			m = options.iv ? m : iv.concat(m);
			return (options && options.asBytes) ? m : util.bytesToBase64(m);

		},

		decrypt: function (ciphertext, password, options) {

			options = options || {};

			// Determine mode
			var mode = options.mode || new C.mode.OFB;

			// Allow mode to override options
			if (mode.fixOptions) mode.fixOptions(options);

			var 

			// Convert to bytes if ciphertext is a string
		c = (
			ciphertext.constructor == String ?
			util.base64ToBytes(ciphertext) :
			ciphertext
		),

			// Separate IV and message
		iv = options.iv || c.splice(0, AES._blocksize * 4),

			// Generate key
		k = (
			password.constructor == String ?
			// Derive key from pass-phrase
			C.PBKDF2(password, iv, 32, { asBytes: true }) :
			// else, assume byte array representing cryptographic key
			password
		);

			// Decrypt
			AES._init(k);
			mode.decrypt(AES, c, iv);

			// Return plaintext
			return (options && options.asBytes) ? c : UTF8.bytesToString(c);

		},


		/**
		* Package private methods and properties
		*/

		_blocksize: 4,

		_encryptblock: function (m, offset) {

			// Set input
			for (var row = 0; row < AES._blocksize; row++) {
				for (var col = 0; col < 4; col++)
					state[row][col] = m[offset + col * 4 + row];
			}

			// Add round key
			for (var row = 0; row < 4; row++) {
				for (var col = 0; col < 4; col++)
					state[row][col] ^= keyschedule[col][row];
			}

			for (var round = 1; round < nrounds; round++) {

				// Sub bytes
				for (var row = 0; row < 4; row++) {
					for (var col = 0; col < 4; col++)
						state[row][col] = SBOX[state[row][col]];
				}

				// Shift rows
				state[1].push(state[1].shift());
				state[2].push(state[2].shift());
				state[2].push(state[2].shift());
				state[3].unshift(state[3].pop());

				// Mix columns
				for (var col = 0; col < 4; col++) {

					var s0 = state[0][col],
				s1 = state[1][col],
				s2 = state[2][col],
				s3 = state[3][col];

					state[0][col] = MULT2[s0] ^ MULT3[s1] ^ s2 ^ s3;
					state[1][col] = s0 ^ MULT2[s1] ^ MULT3[s2] ^ s3;
					state[2][col] = s0 ^ s1 ^ MULT2[s2] ^ MULT3[s3];
					state[3][col] = MULT3[s0] ^ s1 ^ s2 ^ MULT2[s3];

				}

				// Add round key
				for (var row = 0; row < 4; row++) {
					for (var col = 0; col < 4; col++)
						state[row][col] ^= keyschedule[round * 4 + col][row];
				}

			}

			// Sub bytes
			for (var row = 0; row < 4; row++) {
				for (var col = 0; col < 4; col++)
					state[row][col] = SBOX[state[row][col]];
			}

			// Shift rows
			state[1].push(state[1].shift());
			state[2].push(state[2].shift());
			state[2].push(state[2].shift());
			state[3].unshift(state[3].pop());

			// Add round key
			for (var row = 0; row < 4; row++) {
				for (var col = 0; col < 4; col++)
					state[row][col] ^= keyschedule[nrounds * 4 + col][row];
			}

			// Set output
			for (var row = 0; row < AES._blocksize; row++) {
				for (var col = 0; col < 4; col++)
					m[offset + col * 4 + row] = state[row][col];
			}

		},

		_decryptblock: function (c, offset) {

			// Set input
			for (var row = 0; row < AES._blocksize; row++) {
				for (var col = 0; col < 4; col++)
					state[row][col] = c[offset + col * 4 + row];
			}

			// Add round key
			for (var row = 0; row < 4; row++) {
				for (var col = 0; col < 4; col++)
					state[row][col] ^= keyschedule[nrounds * 4 + col][row];
			}

			for (var round = 1; round < nrounds; round++) {

				// Inv shift rows
				state[1].unshift(state[1].pop());
				state[2].push(state[2].shift());
				state[2].push(state[2].shift());
				state[3].push(state[3].shift());

				// Inv sub bytes
				for (var row = 0; row < 4; row++) {
					for (var col = 0; col < 4; col++)
						state[row][col] = INVSBOX[state[row][col]];
				}

				// Add round key
				for (var row = 0; row < 4; row++) {
					for (var col = 0; col < 4; col++)
						state[row][col] ^= keyschedule[(nrounds - round) * 4 + col][row];
				}

				// Inv mix columns
				for (var col = 0; col < 4; col++) {

					var s0 = state[0][col],
				s1 = state[1][col],
				s2 = state[2][col],
				s3 = state[3][col];

					state[0][col] = MULTE[s0] ^ MULTB[s1] ^ MULTD[s2] ^ MULT9[s3];
					state[1][col] = MULT9[s0] ^ MULTE[s1] ^ MULTB[s2] ^ MULTD[s3];
					state[2][col] = MULTD[s0] ^ MULT9[s1] ^ MULTE[s2] ^ MULTB[s3];
					state[3][col] = MULTB[s0] ^ MULTD[s1] ^ MULT9[s2] ^ MULTE[s3];

				}

			}

			// Inv shift rows
			state[1].unshift(state[1].pop());
			state[2].push(state[2].shift());
			state[2].push(state[2].shift());
			state[3].push(state[3].shift());

			// Inv sub bytes
			for (var row = 0; row < 4; row++) {
				for (var col = 0; col < 4; col++)
					state[row][col] = INVSBOX[state[row][col]];
			}

			// Add round key
			for (var row = 0; row < 4; row++) {
				for (var col = 0; col < 4; col++)
					state[row][col] ^= keyschedule[col][row];
			}

			// Set output
			for (var row = 0; row < AES._blocksize; row++) {
				for (var col = 0; col < 4; col++)
					c[offset + col * 4 + row] = state[row][col];
			}

		},


		/**
		* Private methods
		*/

		_init: function (k) {
			keylength = k.length / 4;
			nrounds = keylength + 6;
			AES._keyexpansion(k);
		},

		// Generate a key schedule
		_keyexpansion: function (k) {

			keyschedule = [];

			for (var row = 0; row < keylength; row++) {
				keyschedule[row] = [
			k[row * 4],
			k[row * 4 + 1],
			k[row * 4 + 2],
			k[row * 4 + 3]
		];
			}

			for (var row = keylength; row < AES._blocksize * (nrounds + 1); row++) {

				var temp = [
			keyschedule[row - 1][0],
			keyschedule[row - 1][1],
			keyschedule[row - 1][2],
			keyschedule[row - 1][3]
		];

				if (row % keylength == 0) {

					// Rot word
					temp.push(temp.shift());

					// Sub word
					temp[0] = SBOX[temp[0]];
					temp[1] = SBOX[temp[1]];
					temp[2] = SBOX[temp[2]];
					temp[3] = SBOX[temp[3]];

					temp[0] ^= RCON[row / keylength];

				} else if (keylength > 6 && row % keylength == 4) {

					// Sub word
					temp[0] = SBOX[temp[0]];
					temp[1] = SBOX[temp[1]];
					temp[2] = SBOX[temp[2]];
					temp[3] = SBOX[temp[3]];

				}

				keyschedule[row] = [
			keyschedule[row - keylength][0] ^ temp[0],
			keyschedule[row - keylength][1] ^ temp[1],
			keyschedule[row - keylength][2] ^ temp[2],
			keyschedule[row - keylength][3] ^ temp[3]
		];

			}

		}

	};

})();