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+ − /* rijndael.js Rijndael Reference Implementation
+ − Copyright (c) 2001 Fritz Schneider
+ −
+ − This software is provided as-is, without express or implied warranty.
+ − Permission to use, copy, modify, distribute or sell this software, with or
+ − without fee, for any purpose and by any individual or organization, is hereby
+ − granted, provided that the above copyright notice and this paragraph appear
+ − in all copies. Distribution as a part of an application or binary must
+ − include the above copyright notice in the documentation and/or other materials
+ − provided with the application or distribution.
+ −
+ −
+ − As the above disclaimer notes, you are free to use this code however you
+ − want. However, I would request that you send me an email
+ − (fritz /at/ cs /dot/ ucsd /dot/ edu) to say hi if you find this code useful
+ − or instructional. Seeing that people are using the code acts as
+ − encouragement for me to continue development. If you *really* want to thank
+ − me you can buy the book I wrote with Thomas Powell, _JavaScript:
+ − _The_Complete_Reference_ :)
+ −
+ − This code is an UNOPTIMIZED REFERENCE implementation of Rijndael.
+ − If there is sufficient interest I can write an optimized (word-based,
+ − table-driven) version, although you might want to consider using a
+ − compiled language if speed is critical to your application. As it stands,
+ − one run of the monte carlo test (10,000 encryptions) can take up to
+ − several minutes, depending upon your processor. You shouldn't expect more
+ − than a few kilobytes per second in throughput.
+ −
+ − Also note that there is very little error checking in these functions.
+ − Doing proper error checking is always a good idea, but the ideal
+ − implementation (using the instanceof operator and exceptions) requires
+ − IE5+/NS6+, and I've chosen to implement this code so that it is compatible
+ − with IE4/NS4.
+ −
+ − And finally, because JavaScript doesn't have an explicit byte/char data
+ − type (although JavaScript 2.0 most likely will), when I refer to "byte"
+ − in this code I generally mean "32 bit integer with value in the interval
+ − [0,255]" which I treat as a byte.
+ −
+ − See http://www-cse.ucsd.edu/~fritz/rijndael.html for more documentation
+ − of the (very simple) API provided by this code.
+ −
+ − Fritz Schneider
+ − fritz at cs.ucsd.edu
+ −
+ − */
+ −
+ − // Rijndael parameters -- Valid values are 128, 192, or 256
+ −
+ − var keySizeInBits = ( typeof AES_BITS == 'number' ) ? AES_BITS : 128;
+ − var blockSizeInBits = ( typeof AES_BLOCKSIZE == 'number' ) ? AES_BLOCKSIZE : 128;
+ −
+ − /////// You shouldn't have to modify anything below this line except for
+ − /////// the function getRandomBytes().
+ − //
+ − // Note: in the following code the two dimensional arrays are indexed as
+ − // you would probably expect, as array[row][column]. The state arrays
+ − // are 2d arrays of the form state[4][Nb].
+ −
+ −
+ − // The number of rounds for the cipher, indexed by [Nk][Nb]
+ − var roundsArray = [ ,,,,[,,,,10,, 12,, 14],,
+ − [,,,,12,, 12,, 14],,
+ − [,,,,14,, 14,, 14] ];
+ −
+ − // The number of bytes to shift by in shiftRow, indexed by [Nb][row]
+ − var shiftOffsets = [ ,,,,[,1, 2, 3],,[,1, 2, 3],,[,1, 3, 4] ];
+ −
+ − // The round constants used in subkey expansion
+ − var Rcon = [
+ − 0x01, 0x02, 0x04, 0x08, 0x10, 0x20,
+ − 0x40, 0x80, 0x1b, 0x36, 0x6c, 0xd8,
+ − 0xab, 0x4d, 0x9a, 0x2f, 0x5e, 0xbc,
+ − 0x63, 0xc6, 0x97, 0x35, 0x6a, 0xd4,
+ − 0xb3, 0x7d, 0xfa, 0xef, 0xc5, 0x91 ];
+ −
+ − // Precomputed lookup table for the SBox
+ − var SBox = [
+ − 99, 124, 119, 123, 242, 107, 111, 197, 48, 1, 103, 43, 254, 215, 171,
+ − 118, 202, 130, 201, 125, 250, 89, 71, 240, 173, 212, 162, 175, 156, 164,
+ − 114, 192, 183, 253, 147, 38, 54, 63, 247, 204, 52, 165, 229, 241, 113,
+ − 216, 49, 21, 4, 199, 35, 195, 24, 150, 5, 154, 7, 18, 128, 226,
+ − 235, 39, 178, 117, 9, 131, 44, 26, 27, 110, 90, 160, 82, 59, 214,
+ − 179, 41, 227, 47, 132, 83, 209, 0, 237, 32, 252, 177, 91, 106, 203,
+ − 190, 57, 74, 76, 88, 207, 208, 239, 170, 251, 67, 77, 51, 133, 69,
+ − 249, 2, 127, 80, 60, 159, 168, 81, 163, 64, 143, 146, 157, 56, 245,
+ − 188, 182, 218, 33, 16, 255, 243, 210, 205, 12, 19, 236, 95, 151, 68,
+ − 23, 196, 167, 126, 61, 100, 93, 25, 115, 96, 129, 79, 220, 34, 42,
+ − 144, 136, 70, 238, 184, 20, 222, 94, 11, 219, 224, 50, 58, 10, 73,
+ − 6, 36, 92, 194, 211, 172, 98, 145, 149, 228, 121, 231, 200, 55, 109,
+ − 141, 213, 78, 169, 108, 86, 244, 234, 101, 122, 174, 8, 186, 120, 37,
+ − 46, 28, 166, 180, 198, 232, 221, 116, 31, 75, 189, 139, 138, 112, 62,
+ − 181, 102, 72, 3, 246, 14, 97, 53, 87, 185, 134, 193, 29, 158, 225,
+ − 248, 152, 17, 105, 217, 142, 148, 155, 30, 135, 233, 206, 85, 40, 223,
+ − 140, 161, 137, 13, 191, 230, 66, 104, 65, 153, 45, 15, 176, 84, 187,
+ − 22 ];
+ −
+ − // Precomputed lookup table for the inverse SBox
+ − var SBoxInverse = [
+ − 82, 9, 106, 213, 48, 54, 165, 56, 191, 64, 163, 158, 129, 243, 215,
+ − 251, 124, 227, 57, 130, 155, 47, 255, 135, 52, 142, 67, 68, 196, 222,
+ − 233, 203, 84, 123, 148, 50, 166, 194, 35, 61, 238, 76, 149, 11, 66,
+ − 250, 195, 78, 8, 46, 161, 102, 40, 217, 36, 178, 118, 91, 162, 73,
+ − 109, 139, 209, 37, 114, 248, 246, 100, 134, 104, 152, 22, 212, 164, 92,
+ − 204, 93, 101, 182, 146, 108, 112, 72, 80, 253, 237, 185, 218, 94, 21,
+ − 70, 87, 167, 141, 157, 132, 144, 216, 171, 0, 140, 188, 211, 10, 247,
+ − 228, 88, 5, 184, 179, 69, 6, 208, 44, 30, 143, 202, 63, 15, 2,
+ − 193, 175, 189, 3, 1, 19, 138, 107, 58, 145, 17, 65, 79, 103, 220,
+ − 234, 151, 242, 207, 206, 240, 180, 230, 115, 150, 172, 116, 34, 231, 173,
+ − 53, 133, 226, 249, 55, 232, 28, 117, 223, 110, 71, 241, 26, 113, 29,
+ − 41, 197, 137, 111, 183, 98, 14, 170, 24, 190, 27, 252, 86, 62, 75,
+ − 198, 210, 121, 32, 154, 219, 192, 254, 120, 205, 90, 244, 31, 221, 168,
+ − 51, 136, 7, 199, 49, 177, 18, 16, 89, 39, 128, 236, 95, 96, 81,
+ − 127, 169, 25, 181, 74, 13, 45, 229, 122, 159, 147, 201, 156, 239, 160,
+ − 224, 59, 77, 174, 42, 245, 176, 200, 235, 187, 60, 131, 83, 153, 97,
+ − 23, 43, 4, 126, 186, 119, 214, 38, 225, 105, 20, 99, 85, 33, 12,
+ − 125 ];
+ −
+ − function str_split(string, chunklen)
+ − {
+ − if(!chunklen) chunklen = 1;
+ − ret = new Array();
+ − for ( i = 0; i < string.length; i+=chunklen )
+ − {
+ − ret[ret.length] = string.slice(i, i+chunklen);
+ − }
+ − return ret;
+ − }
+ −
+ − // This method circularly shifts the array left by the number of elements
+ − // given in its parameter. It returns the resulting array and is used for
+ − // the ShiftRow step. Note that shift() and push() could be used for a more
+ − // elegant solution, but they require IE5.5+, so I chose to do it manually.
+ −
+ − function cyclicShiftLeft(theArray, positions) {
+ − var temp = theArray.slice(0, positions);
+ − theArray = theArray.slice(positions).concat(temp);
+ − return theArray;
+ − }
+ −
+ − // Cipher parameters ... do not change these
+ − var Nk = keySizeInBits / 32;
+ − var Nb = blockSizeInBits / 32;
+ − var Nr = roundsArray[Nk][Nb];
+ −
+ − // Multiplies the element "poly" of GF(2^8) by x. See the Rijndael spec.
+ −
+ − function xtime(poly) {
+ − poly <<= 1;
+ − return ((poly & 0x100) ? (poly ^ 0x11B) : (poly));
+ − }
+ −
+ − // Multiplies the two elements of GF(2^8) together and returns the result.
+ − // See the Rijndael spec, but should be straightforward: for each power of
+ − // the indeterminant that has a 1 coefficient in x, add y times that power
+ − // to the result. x and y should be bytes representing elements of GF(2^8)
+ −
+ − function mult_GF256(x, y) {
+ − var bit, result = 0;
+ −
+ − for (bit = 1; bit < 256; bit *= 2, y = xtime(y)) {
+ − if (x & bit)
+ − result ^= y;
+ − }
+ − return result;
+ − }
+ −
+ − // Performs the substitution step of the cipher. State is the 2d array of
+ − // state information (see spec) and direction is string indicating whether
+ − // we are performing the forward substitution ("encrypt") or inverse
+ − // substitution (anything else)
+ −
+ − function byteSub(state, direction) {
+ − var S;
+ − if (direction == "encrypt") // Point S to the SBox we're using
+ − S = SBox;
+ − else
+ − S = SBoxInverse;
+ − for (var i = 0; i < 4; i++) // Substitute for every byte in state
+ − for (var j = 0; j < Nb; j++)
+ − state[i][j] = S[state[i][j]];
+ − }
+ −
+ − // Performs the row shifting step of the cipher.
+ −
+ − function shiftRow(state, direction) {
+ − for (var i=1; i<4; i++) // Row 0 never shifts
+ − if (direction == "encrypt")
+ − state[i] = cyclicShiftLeft(state[i], shiftOffsets[Nb][i]);
+ − else
+ − state[i] = cyclicShiftLeft(state[i], Nb - shiftOffsets[Nb][i]);
+ −
+ − }
+ −
+ − // Performs the column mixing step of the cipher. Most of these steps can
+ − // be combined into table lookups on 32bit values (at least for encryption)
+ − // to greatly increase the speed.
+ −
+ − function mixColumn(state, direction) {
+ − var b = []; // Result of matrix multiplications
+ − for (var j = 0; j < Nb; j++) { // Go through each column...
+ − for (var i = 0; i < 4; i++) { // and for each row in the column...
+ − if (direction == "encrypt")
+ − b[i] = mult_GF256(state[i][j], 2) ^ // perform mixing
+ − mult_GF256(state[(i+1)%4][j], 3) ^
+ − state[(i+2)%4][j] ^
+ − state[(i+3)%4][j];
+ − else
+ − b[i] = mult_GF256(state[i][j], 0xE) ^
+ − mult_GF256(state[(i+1)%4][j], 0xB) ^
+ − mult_GF256(state[(i+2)%4][j], 0xD) ^
+ − mult_GF256(state[(i+3)%4][j], 9);
+ − }
+ − for (var i = 0; i < 4; i++) // Place result back into column
+ − state[i][j] = b[i];
+ − }
+ − }
+ −
+ − // Adds the current round key to the state information. Straightforward.
+ −
+ − function addRoundKey(state, roundKey) {
+ − for (var j = 0; j < Nb; j++) { // Step through columns...
+ − state[0][j] ^= (roundKey[j] & 0xFF); // and XOR
+ − state[1][j] ^= ((roundKey[j]>>8) & 0xFF);
+ − state[2][j] ^= ((roundKey[j]>>16) & 0xFF);
+ − state[3][j] ^= ((roundKey[j]>>24) & 0xFF);
+ − }
+ − }
+ −
+ − // This function creates the expanded key from the input (128/192/256-bit)
+ − // key. The parameter key is an array of bytes holding the value of the key.
+ − // The returned value is an array whose elements are the 32-bit words that
+ − // make up the expanded key.
+ −
+ − function keyExpansion(key) {
+ − var expandedKey = new Array();
+ − var temp;
+ −
+ − // in case the key size or parameters were changed...
+ − Nk = keySizeInBits / 32;
+ − Nb = blockSizeInBits / 32;
+ − Nr = roundsArray[Nk][Nb];
+ −
+ − for (var j=0; j < Nk; j++) // Fill in input key first
+ − expandedKey[j] =
+ − (key[4*j]) | (key[4*j+1]<<8) | (key[4*j+2]<<16) | (key[4*j+3]<<24);
+ −
+ − // Now walk down the rest of the array filling in expanded key bytes as
+ − // per Rijndael's spec
+ − for (j = Nk; j < Nb * (Nr + 1); j++) { // For each word of expanded key
+ − temp = expandedKey[j - 1];
+ − if (j % Nk == 0)
+ − temp = ( (SBox[(temp>>8) & 0xFF]) |
+ − (SBox[(temp>>16) & 0xFF]<<8) |
+ − (SBox[(temp>>24) & 0xFF]<<16) |
+ − (SBox[temp & 0xFF]<<24) ) ^ Rcon[Math.floor(j / Nk) - 1];
+ − else if (Nk > 6 && j % Nk == 4)
+ − temp = (SBox[(temp>>24) & 0xFF]<<24) |
+ − (SBox[(temp>>16) & 0xFF]<<16) |
+ − (SBox[(temp>>8) & 0xFF]<<8) |
+ − (SBox[temp & 0xFF]);
+ − expandedKey[j] = expandedKey[j-Nk] ^ temp;
+ − }
+ − return expandedKey;
+ − }
+ −
+ − // Rijndael's round functions...
+ −
+ − function Round(state, roundKey) {
+ − byteSub(state, "encrypt");
+ − shiftRow(state, "encrypt");
+ − mixColumn(state, "encrypt");
+ − addRoundKey(state, roundKey);
+ − }
+ −
+ − function InverseRound(state, roundKey) {
+ − addRoundKey(state, roundKey);
+ − mixColumn(state, "decrypt");
+ − shiftRow(state, "decrypt");
+ − byteSub(state, "decrypt");
+ − }
+ −
+ − function FinalRound(state, roundKey) {
+ − byteSub(state, "encrypt");
+ − shiftRow(state, "encrypt");
+ − addRoundKey(state, roundKey);
+ − }
+ −
+ − function InverseFinalRound(state, roundKey){
+ − addRoundKey(state, roundKey);
+ − shiftRow(state, "decrypt");
+ − byteSub(state, "decrypt");
+ − }
+ −
+ − // encrypt is the basic encryption function. It takes parameters
+ − // block, an array of bytes representing a plaintext block, and expandedKey,
+ − // an array of words representing the expanded key previously returned by
+ − // keyExpansion(). The ciphertext block is returned as an array of bytes.
+ −
+ − function encrypt(block, expandedKey) {
+ − var i;
+ − if (!block || block.length*8 != blockSizeInBits)
+ − return;
+ − if (!expandedKey)
+ − return;
+ −
+ − block = packBytes(block);
+ − addRoundKey(block, expandedKey);
+ − for (i=1; i<Nr; i++)
+ − Round(block, expandedKey.slice(Nb*i, Nb*(i+1)));
+ − FinalRound(block, expandedKey.slice(Nb*Nr));
+ − return unpackBytes(block);
+ − }
+ −
+ − // decrypt is the basic decryption function. It takes parameters
+ − // block, an array of bytes representing a ciphertext block, and expandedKey,
+ − // an array of words representing the expanded key previously returned by
+ − // keyExpansion(). The decrypted block is returned as an array of bytes.
+ −
+ − function decrypt(block, expandedKey) {
+ − var i;
+ − if (!block || block.length*8 != blockSizeInBits)
+ − return;
+ − if (!expandedKey)
+ − return;
+ −
+ − block = packBytes(block);
+ − InverseFinalRound(block, expandedKey.slice(Nb*Nr));
+ − for (i = Nr - 1; i>0; i--)
+ − InverseRound(block, expandedKey.slice(Nb*i, Nb*(i+1)));
+ − addRoundKey(block, expandedKey);
+ − return unpackBytes(block);
+ − }
+ −
+ − // This method takes a byte array (byteArray) and converts it to a string by
+ − // applying String.fromCharCode() to each value and concatenating the result.
+ − // The resulting string is returned. Note that this function SKIPS zero bytes
+ − // under the assumption that they are padding added in formatPlaintext().
+ − // Obviously, do not invoke this method on raw data that can contain zero
+ − // bytes. It is really only appropriate for printable ASCII/Latin-1
+ − // values. Roll your own function for more robust functionality :)
+ −
+ − function byteArrayToString(byteArray) {
+ − var result = "";
+ − for(var i=0; i<byteArray.length; i++)
+ − if (byteArray[i] != 0)
+ − result += String.fromCharCode(byteArray[i]);
+ − return result;
+ − }
+ −
+ − // This function takes an array of bytes (byteArray) and converts them
+ − // to a hexadecimal string. Array element 0 is found at the beginning of
+ − // the resulting string, high nibble first. Consecutive elements follow
+ − // similarly, for example [16, 255] --> "10ff". The function returns a
+ − // string.
+ −
+ − function byteArrayToHex(byteArray) {
+ − var result = "";
+ − if (!byteArray)
+ − return;
+ − for (var i=0; i<byteArray.length; i++)
+ − result += ((byteArray[i]<16) ? "0" : "") + byteArray[i].toString(16);
+ −
+ − return result;
+ − }
+ −
+ − // This function converts a string containing hexadecimal digits to an
+ − // array of bytes. The resulting byte array is filled in the order the
+ − // values occur in the string, for example "10FF" --> [16, 255]. This
+ − // function returns an array.
+ −
+ − function hexToByteArray(hexString) {
+ − /*
+ − var byteArray = [];
+ − if (hexString.length % 2) // must have even length
+ − return;
+ − if (hexString.indexOf("0x") == 0 || hexString.indexOf("0X") == 0)
+ − hexString = hexString.substring(2);
+ − for (var i = 0; i<hexString.length; i += 2)
+ − byteArray[Math.floor(i/2)] = parseInt(hexString.slice(i, i+2), 16);
+ − return byteArray;
+ − */
+ − var bytes = new Array();
+ − hexString = str_split(hexString, 2);
+ − //alert(hexString.toString());
+ − //return false;
+ − for( var i in hexString )
+ − {
+ − bytes[bytes.length] = parseInt(hexString[i], 16);
+ − }
+ − //alert(bytes.toString());
+ − return bytes;
+ − }
+ −
+ − // This function packs an array of bytes into the four row form defined by
+ − // Rijndael. It assumes the length of the array of bytes is divisible by
+ − // four. Bytes are filled in according to the Rijndael spec (starting with
+ − // column 0, row 0 to 3). This function returns a 2d array.
+ −
+ − function packBytes(octets) {
+ − var state = new Array();
+ − if (!octets || octets.length % 4)
+ − return;
+ −
+ − state[0] = new Array(); state[1] = new Array();
+ − state[2] = new Array(); state[3] = new Array();
+ − for (var j=0; j<octets.length; j+= 4) {
+ − state[0][j/4] = octets[j];
+ − state[1][j/4] = octets[j+1];
+ − state[2][j/4] = octets[j+2];
+ − state[3][j/4] = octets[j+3];
+ − }
+ − return state;
+ − }
+ −
+ − // This function unpacks an array of bytes from the four row format preferred
+ − // by Rijndael into a single 1d array of bytes. It assumes the input "packed"
+ − // is a packed array. Bytes are filled in according to the Rijndael spec.
+ − // This function returns a 1d array of bytes.
+ −
+ − function unpackBytes(packed) {
+ − var result = new Array();
+ − for (var j=0; j<packed[0].length; j++) {
+ − result[result.length] = packed[0][j];
+ − result[result.length] = packed[1][j];
+ − result[result.length] = packed[2][j];
+ − result[result.length] = packed[3][j];
+ − }
+ − return result;
+ − }
+ −
+ − // This function takes a prospective plaintext (string or array of bytes)
+ − // and pads it with zero bytes if its length is not a multiple of the block
+ − // size. If plaintext is a string, it is converted to an array of bytes
+ − // in the process. The type checking can be made much nicer using the
+ − // instanceof operator, but this operator is not available until IE5.0 so I
+ − // chose to use the heuristic below.
+ −
+ − function formatPlaintext(plaintext) {
+ − var bpb = blockSizeInBits / 8; // bytes per block
+ − var i;
+ −
+ − // if primitive string or String instance
+ − if (typeof plaintext == "string" || plaintext.split) {
+ − // alert('AUUGH you idiot it\'s NOT A STRING ITS A '+typeof(plaintext)+'!!!');
+ − // return false;
+ − plaintext = plaintext.split("");
+ − // Unicode issues here (ignoring high byte)
+ − for (i=0; i<plaintext.length; i++)
+ − plaintext[i] = plaintext[i].charCodeAt(0) & 0xFF;
+ − }
+ −
+ − for (i = bpb - (plaintext.length % bpb); i > 0 && i < bpb; i--)
+ − plaintext[plaintext.length] = 0;
+ −
+ − return plaintext;
+ − }
+ −
+ − // Returns an array containing "howMany" random bytes. YOU SHOULD CHANGE THIS
+ − // TO RETURN HIGHER QUALITY RANDOM BYTES IF YOU ARE USING THIS FOR A "REAL"
+ − // APPLICATION.
+ −
+ − function getRandomBytes(howMany) {
+ − var i;
+ − var bytes = new Array();
+ − for (i=0; i<howMany; i++)
+ − bytes[i] = Math.round(Math.random()*255);
+ − return bytes;
+ − }
+ −
+ − // rijndaelEncrypt(plaintext, key, mode)
+ − // Encrypts the plaintext using the given key and in the given mode.
+ − // The parameter "plaintext" can either be a string or an array of bytes.
+ − // The parameter "key" must be an array of key bytes. If you have a hex
+ − // string representing the key, invoke hexToByteArray() on it to convert it
+ − // to an array of bytes. The third parameter "mode" is a string indicating
+ − // the encryption mode to use, either "ECB" or "CBC". If the parameter is
+ − // omitted, ECB is assumed.
+ − //
+ − // An array of bytes representing the cihpertext is returned. To convert
+ − // this array to hex, invoke byteArrayToHex() on it. If you are using this
+ − // "for real" it is a good idea to change the function getRandomBytes() to
+ − // something that returns truly random bits.
+ −
+ − function rijndaelEncrypt(plaintext, key, mode) {
+ − var expandedKey, i, aBlock;
+ − var bpb = blockSizeInBits / 8; // bytes per block
+ − var ct; // ciphertext
+ −
+ − if (typeof plaintext != 'object' || typeof key != 'object')
+ − {
+ − alert( 'Invalid params\nplaintext: '+typeof(plaintext)+'\nkey: '+typeof(key) );
+ − return false;
+ − }
+ − if (key.length*8 == keySizeInBits+8)
+ − key.length = keySizeInBits / 8;
+ − if (key.length*8 != keySizeInBits)
+ − {
+ − alert( 'Key length is bad!\nLength: '+key.length+'\nExpected: '+keySizeInBits / 8 );
+ − return false;
+ − }
+ − if (mode == "CBC")
+ − ct = getRandomBytes(bpb); // get IV
+ − else {
+ − mode = "ECB";
+ − ct = new Array();
+ − }
+ −
+ − // convert plaintext to byte array and pad with zeros if necessary.
+ − plaintext = formatPlaintext(plaintext);
+ −
+ − expandedKey = keyExpansion(key);
+ −
+ − for (var block=0; block<plaintext.length / bpb; block++) {
+ − aBlock = plaintext.slice(block*bpb, (block+1)*bpb);
+ − if (mode == "CBC")
+ − for (var i=0; i<bpb; i++)
+ − aBlock[i] ^= ct[block*bpb + i];
+ − ct = ct.concat(encrypt(aBlock, expandedKey));
+ − }
+ −
+ − return ct;
+ − }
+ −
+ − // rijndaelDecrypt(ciphertext, key, mode)
+ − // Decrypts the using the given key and mode. The parameter "ciphertext"
+ − // must be an array of bytes. The parameter "key" must be an array of key
+ − // bytes. If you have a hex string representing the ciphertext or key,
+ − // invoke hexToByteArray() on it to convert it to an array of bytes. The
+ − // parameter "mode" is a string, either "CBC" or "ECB".
+ − //
+ − // An array of bytes representing the plaintext is returned. To convert
+ − // this array to a hex string, invoke byteArrayToHex() on it. To convert it
+ − // to a string of characters, you can use byteArrayToString().
+ −
+ − function rijndaelDecrypt(ciphertext, key, mode) {
+ − var expandedKey;
+ − var bpb = blockSizeInBits / 8; // bytes per block
+ − var pt = new Array(); // plaintext array
+ − var aBlock; // a decrypted block
+ − var block; // current block number
+ −
+ − if (!ciphertext || !key || typeof ciphertext == "string")
+ − return;
+ − if (key.length*8 != keySizeInBits)
+ − return;
+ − if (!mode)
+ − mode = "ECB"; // assume ECB if mode omitted
+ −
+ − expandedKey = keyExpansion(key);
+ −
+ − // work backwards to accomodate CBC mode
+ − for (block=(ciphertext.length / bpb)-1; block>0; block--) {
+ − aBlock =
+ − decrypt(ciphertext.slice(block*bpb,(block+1)*bpb), expandedKey);
+ − if (mode == "CBC")
+ − for (var i=0; i<bpb; i++)
+ − pt[(block-1)*bpb + i] = aBlock[i] ^ ciphertext[(block-1)*bpb + i];
+ − else
+ − pt = aBlock.concat(pt);
+ − }
+ −
+ − // do last block if ECB (skips the IV in CBC)
+ − if (mode == "ECB")
+ − pt = decrypt(ciphertext.slice(0, bpb), expandedKey).concat(pt);
+ −
+ − return pt;
+ − }
+ −
+ − function stringToByteArray(text)
+ − {
+ − result = new Array();
+ − for ( i=0; i<text.length; i++ )
+ − {
+ − result[result.length] = text.charCodeAt(i);
+ − }
+ − return result;
+ − }
+ −