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/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */↩
↩
/*↩
* AES Cipher function: encrypt 'input' with Rijndael algorithm↩
*↩
* takes byte-array 'input' (16 bytes)↩
* 2D byte-array key schedule 'w' (Nr+1 x Nb bytes)↩
*↩
* applies Nr rounds (10/12/14) using key schedule w for 'add round key' stage↩
*↩
* returns byte-array encrypted value (16 bytes)↩
*/↩
function Cipher(input, w) { // main Cipher function [§5.1]↩
var Nb = 4; // block size (in words): no of columns in state (fixed at 4 for AES)↩
var Nr = w.length/Nb - 1; // no of rounds: 10/12/14 for 128/192/256-bit keys↩
↩
var state = [[],[],[],[]]; // initialise 4xNb byte-array 'state' with input [§3.4]↩
for (var i=0; i<4*Nb; i++) state[i%4][Math.floor(i/4)] = input[i];↩
↩
state = AddRoundKey(state, w, 0, Nb);↩
↩
for (var round=1; round<Nr; round++) {↩
state = SubBytes(state, Nb);↩
state = ShiftRows(state, Nb);↩
state = MixColumns(state, Nb);↩
state = AddRoundKey(state, w, round, Nb);↩
}↩
↩
state = SubBytes(state, Nb);↩
state = ShiftRows(state, Nb);↩
state = AddRoundKey(state, w, Nr, Nb);↩
↩
var output = new Array(4*Nb); // convert state to 1-d array before returning [§3.4]↩
for (var i=0; i<4*Nb; i++) output[i] = state[i%4][Math.floor(i/4)];↩
return output;↩
}↩
↩
↩
function SubBytes(s, Nb) { // apply SBox to state S [§5.1.1]↩
for (var r=0; r<4; r++) {↩
for (var c=0; c<Nb; c++) s[r][c] = Sbox[s[r][c]];↩
}↩
return s;↩
}↩
↩
↩
function ShiftRows(s, Nb) { // shift row r of state S left by r bytes [§5.1.2]↩
var t = new Array(4);↩
for (var r=1; r<4; r++) {↩
for (var c=0; c<4; c++) t[c] = s[r][(c+r)%Nb]; // shift into temp copy↩
for (var c=0; c<4; c++) s[r][c] = t[c]; // and copy back↩
} // note that this will work for Nb=4,5,6, but not 7,8 (always 4 for AES):↩
return s; // see fp.gladman.plus.com/cryptography_technology/rijndael/aes.spec.311.pdf ↩
}↩
↩
↩
function MixColumns(s, Nb) { // combine bytes of each col of state S [§5.1.3]↩
for (var c=0; c<4; c++) {↩
var a = new Array(4); // 'a' is a copy of the current column from 's'↩
var b = new Array(4); // 'b' is a•{02} in GF(2^8)↩
for (var i=0; i<4; i++) {↩
a[i] = s[i][c];↩
b[i] = s[i][c]&0x80 ? s[i][c]<<1 ^ 0x011b : s[i][c]<<1;↩
}↩
// a[n] ^ b[n] is a•{03} in GF(2^8)↩
s[0][c] = b[0] ^ a[1] ^ b[1] ^ a[2] ^ a[3]; // 2*a0 + 3*a1 + a2 + a3↩
s[1][c] = a[0] ^ b[1] ^ a[2] ^ b[2] ^ a[3]; // a0 * 2*a1 + 3*a2 + a3↩
s[2][c] = a[0] ^ a[1] ^ b[2] ^ a[3] ^ b[3]; // a0 + a1 + 2*a2 + 3*a3↩
s[3][c] = a[0] ^ b[0] ^ a[1] ^ a[2] ^ b[3]; // 3*a0 + a1 + a2 + 2*a3↩
}↩
return s;↩
}↩
↩
↩
function AddRoundKey(state, w, rnd, Nb) { // xor Round Key into state S [§5.1.4]↩
for (var r=0; r<4; r++) {↩
for (var c=0; c<Nb; c++) state[r][c] ^= w[rnd*4+c][r];↩
}↩
return state;↩
}↩
↩
↩
function KeyExpansion(key) { // generate Key Schedule (byte-array Nr+1 x Nb) from Key [§5.2]↩
var Nb = 4; // block size (in words): no of columns in state (fixed at 4 for AES)↩
var Nk = key.length/4 // key length (in words): 4/6/8 for 128/192/256-bit keys↩
var Nr = Nk + 6; // no of rounds: 10/12/14 for 128/192/256-bit keys↩
↩
var w = new Array(Nb*(Nr+1));↩
var temp = new Array(4);↩
↩
for (var i=0; i<Nk; i++) {↩
var r = [key[4*i], key[4*i+1], key[4*i+2], key[4*i+3]];↩
w[i] = r;↩
}↩
↩
for (var i=Nk; i<(Nb*(Nr+1)); i++) {↩
w[i] = new Array(4);↩
for (var t=0; t<4; t++) temp[t] = w[i-1][t];↩
if (i % Nk == 0) {↩
temp = SubWord(RotWord(temp));↩
for (var t=0; t<4; t++) temp[t] ^= Rcon[i/Nk][t];↩
} else if (Nk > 6 && i%Nk == 4) {↩
temp = SubWord(temp);↩
}↩
for (var t=0; t<4; t++) w[i][t] = w[i-Nk][t] ^ temp[t];↩
}↩
↩
return w;↩
}↩
↩
function SubWord(w) { // apply SBox to 4-byte word w↩
for (var i=0; i<4; i++) w[i] = Sbox[w[i]];↩
return w;↩
}↩
↩
function RotWord(w) { // rotate 4-byte word w left by one byte↩
w[4] = w[0];↩
for (var i=0; i<4; i++) w[i] = w[i+1];↩
return w;↩
}↩
↩
↩
// Sbox is pre-computed multiplicative inverse in GF(2^8) used in SubBytes and KeyExpansion [§5.1.1]↩
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];↩
↩
// Rcon is Round Constant used for the Key Expansion [1st col is 2^(r-1) in GF(2^8)] [§5.2]↩
var Rcon = [ [0x00, 0x00, 0x00, 0x00],↩
[0x01, 0x00, 0x00, 0x00],↩
[0x02, 0x00, 0x00, 0x00],↩
[0x04, 0x00, 0x00, 0x00],↩
[0x08, 0x00, 0x00, 0x00],↩
[0x10, 0x00, 0x00, 0x00],↩
[0x20, 0x00, 0x00, 0x00],↩
[0x40, 0x00, 0x00, 0x00],↩
[0x80, 0x00, 0x00, 0x00],↩
[0x1b, 0x00, 0x00, 0x00],↩
[0x36, 0x00, 0x00, 0x00] ]; ↩
↩
↩
/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */↩
↩
/* ↩
* Use AES to encrypt 'plaintext' with 'password' using 'nBits' key, in 'Counter' mode of operation↩
* for each block↩
* - outputblock = cipher(counter, key)↩
* - cipherblock = plaintext xor outputblock↩
*/↩
function AESEncryptCtr(plaintext, password, nBits) {↩
if (!(nBits==128 || nBits==192 || nBits==256)) return ''; // standard allows 128/192/256 bit keys↩
↩
// for this example script, generate the key by applying Cipher to 1st 16/24/32 chars of password; ↩
// for real-world applications, a more secure approach would be to hash the password e.g. with SHA-1↩
var nBytes = nBits/8; // no bytes in key↩
var pwBytes = new Array(nBytes);↩
for (var i=0; i<nBytes; i++) pwBytes[i] = password.charCodeAt(i) & 0xff;↩
var key = Cipher(pwBytes, KeyExpansion(pwBytes));↩
key = key.concat(key.slice(0, nBytes-16)); // key is now 16/24/32 bytes long↩
↩
// initialise counter block (NIST SP800-38A §B.2): millisecond time-stamp for nonce in 1st 8 bytes,↩
// block counter in 2nd 8 bytes↩
var blockSize = 16; // block size fixed at 16 bytes / 128 bits (Nb=4) for AES↩
var counterBlock = new Array(blockSize); // block size fixed at 16 bytes / 128 bits (Nb=4) for AES↩
var nonce = (new Date()).getTime(); // milliseconds since 1-Jan-1970↩
↩
// encode nonce in two stages to cater for JavaScript 32-bit limit on bitwise ops↩
for (var i=0; i<4; i++) counterBlock[i] = (nonce >>> i*8) & 0xff;↩
for (var i=0; i<4; i++) counterBlock[i+4] = (nonce/0x100000000 >>> i*8) & 0xff; ↩
↩
// generate key schedule - an expansion of the key into distinct Key Rounds for each round↩
var keySchedule = KeyExpansion(key);↩
↩
var blockCount = Math.ceil(plaintext.length/blockSize);↩
var ciphertext = new Array(blockCount); // ciphertext as array of strings↩
↩
for (var b=0; b<blockCount; b++) {↩
// set counter (block #) in last 8 bytes of counter block (leaving nonce in 1st 8 bytes)↩
// again done in two stages for 32-bit ops↩
for (var c=0; c<4; c++) counterBlock[15-c] = (b >>> c*8) & 0xff;↩
for (var c=0; c<4; c++) counterBlock[15-c-4] = (b/0x100000000 >>> c*8)↩
↩
var cipherCntr = Cipher(counterBlock, keySchedule); // -- encrypt counter block --↩
↩
// calculate length of final block:↩
var blockLength = b<blockCount-1 ? blockSize : (plaintext.length-1)%blockSize+1;↩
↩
var ct = '';↩
for (var i=0; i<blockLength; i++) { // -- xor plaintext with ciphered counter byte-by-byte --↩
var plaintextByte = plaintext.charCodeAt(b*blockSize+i);↩
var cipherByte = plaintextByte ^ cipherCntr[i];↩
ct += String.fromCharCode(cipherByte);↩
}↩
// ct is now ciphertext for this block↩
↩
ciphertext[b] = escCtrlChars(ct); // escape troublesome characters in ciphertext↩
}↩
↩
// convert the nonce to a string to go on the front of the ciphertext↩
var ctrTxt = '';↩
for (var i=0; i<8; i++) ctrTxt += String.fromCharCode(counterBlock[i]);↩
ctrTxt = escCtrlChars(ctrTxt);↩
↩
// use '-' to separate blocks, use Array.join to concatenate arrays of strings for efficiency↩
return ctrTxt + '-' + ciphertext.join('-');↩
}↩
↩
↩
/* ↩
* Use AES to decrypt 'ciphertext' with 'password' using 'nBits' key, in Counter mode of operation↩
*↩
* for each block↩
* - outputblock = cipher(counter, key)↩
* - cipherblock = plaintext xor outputblock↩
*/↩
function AESDecryptCtr(ciphertext, password, nBits) {↩
if (!(nBits==128 || nBits==192 || nBits==256)) return ''; // standard allows 128/192/256 bit keys↩
↩
var nBytes = nBits/8; // no bytes in key↩
var pwBytes = new Array(nBytes);↩
for (var i=0; i<nBytes; i++) pwBytes[i] = password.charCodeAt(i) & 0xff;↩
var pwKeySchedule = KeyExpansion(pwBytes);↩
var key = Cipher(pwBytes, pwKeySchedule);↩
key = key.concat(key.slice(0, nBytes-16)); // key is now 16/24/32 bytes long↩
↩
var keySchedule = KeyExpansion(key);↩
↩
ciphertext = ciphertext.split('-'); // split ciphertext into array of block-length strings ↩
↩
// recover nonce from 1st element of ciphertext↩
var blockSize = 16; // block size fixed at 16 bytes / 128 bits (Nb=4) for AES↩
var counterBlock = new Array(blockSize);↩
var ctrTxt = unescCtrlChars(ciphertext[0]);↩
for (var i=0; i<8; i++) counterBlock[i] = ctrTxt.charCodeAt(i);↩
↩
var plaintext = new Array(ciphertext.length-1);↩
↩
for (var b=1; b<ciphertext.length; b++) {↩
// set counter (block #) in last 8 bytes of counter block (leaving nonce in 1st 8 bytes)↩
for (var c=0; c<4; c++) counterBlock[15-c] = ((b-1) >>> c*8) & 0xff;↩
for (var c=0; c<4; c++) counterBlock[15-c-4] = ((b/0x100000000-1) >>> c*8) & 0xff;↩
↩
var cipherCntr = Cipher(counterBlock, keySchedule); // encrypt counter block↩
↩
ciphertext[b] = unescCtrlChars(ciphertext[b]);↩
↩
var pt = '';↩
for (var i=0; i<ciphertext[b].length; i++) {↩
// -- xor plaintext with ciphered counter byte-by-byte --↩
var ciphertextByte = ciphertext[b].charCodeAt(i);↩
var plaintextByte = ciphertextByte ^ cipherCntr[i];↩
pt += String.fromCharCode(plaintextByte);↩
}↩
// pt is now plaintext for this block↩
↩
plaintext[b-1] = pt; // b-1 'cos no initial nonce block in plaintext↩
}↩
↩
return plaintext.join('');↩
}↩
↩
/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */↩
↩
function escCtrlChars(str) { // escape control chars which might cause problems handling ciphertext↩
return str.replace(/[\0\t\n\v\f\r\xa0'"!-]/g, function(c) { return '!' + c.charCodeAt(0) + '!'; });↩
} // \xa0 to cater for bug in Firefox; include '-' to leave it free for use as a block marker↩
↩
function unescCtrlChars(str) { // unescape potentially problematic control characters↩
return str.replace(/!\d\d?\d?!/g, function(c) { return String.fromCharCode(c.slice(1,-1)); });↩
}↩
/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */↩
↩
/*↩
* if escCtrlChars()/unescCtrlChars() still gives problems, use encodeBase64()/decodeBase64() instead↩
*/↩
var b64 = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";↩
↩
var o1, o2, o3, h1, h2, h3, h4, bits, i=0, enc='';↩
↩
str = encodeUTF8(str); // encode multi-byte chars into UTF-8 for byte-array↩
↩
do { // pack three octets into four hexets↩
o1 = str.charCodeAt(i++);↩
o2 = str.charCodeAt(i++);↩
o3 = str.charCodeAt(i++);↩
↩
bits = o1<<16 | o2<<8 | o3;↩
↩
h1 = bits>>18 & 0x3f;↩
h2 = bits>>12 & 0x3f;↩
h3 = bits>>6 & 0x3f;↩
h4 = bits & 0x3f;↩
↩
// end of string? index to '=' in b64↩
if (isNaN(o3)) h4 = 64;↩
if (isNaN(o2)) h3 = 64;↩
↩
// use hexets to index into b64, and append result to encoded string↩
enc += b64.charAt(h1) + b64.charAt(h2) + b64.charAt(h3) + b64.charAt(h4);↩
} while (i < str.length);↩
↩
return enc;↩
}↩
↩
function decodeBase64(str) {↩
var o1, o2, o3, h1, h2, h3, h4, bits, i=0, enc='';↩
↩
do { // unpack four hexets into three octets using index points in b64↩
h1 = b64.indexOf(str.charAt(i++));↩
h2 = b64.indexOf(str.charAt(i++));↩
h3 = b64.indexOf(str.charAt(i++));↩
h4 = b64.indexOf(str.charAt(i++));↩
↩
bits = h1<<18 | h2<<12 | h3<<6 | h4;↩
↩
o1 = bits>>16 & 0xff;↩
o2 = bits>>8 & 0xff;↩
o3 = bits & 0xff;↩
↩
if (h3 == 64) enc += String.fromCharCode(o1);↩
else if (h4 == 64) enc += String.fromCharCode(o1, o2);↩
else enc += String.fromCharCode(o1, o2, o3);↩
} while (i < str.length);↩
↩
return decodeUTF8(enc); // decode UTF-8 byte-array back to Unicode↩
}↩
↩
function encodeUTF8(str) { // encode multi-byte string into utf-8 multiple single-byte characters ↩
str = str.replace(↩
/[\u0080-\u07ff]/g, // U+0080 - U+07FF = 2-byte chars↩
function(c) { ↩
var cc = c.charCodeAt(0);↩
return String.fromCharCode(0xc0 | cc>>6, 0x80 | cc&0x3f); }↩
);↩
str = str.replace(↩
/[\u0800-\uffff]/g, // U+0800 - U+FFFF = 3-byte chars↩
function(c) { ↩
var cc = c.charCodeAt(0); ↩
return String.fromCharCode(0xe0 | cc>>12, 0x80 | cc>>6&0x3F, 0x80 | cc&0x3f); }↩
);↩
return str;↩
}↩
↩
function decodeUTF8(str) { // decode utf-8 encoded string back into multi-byte characters↩
str = str.replace(↩
/[\u00c0-\u00df][\u0080-\u00bf]/g, // 2-byte chars↩
function(c) { ↩
var cc = (c.charCodeAt(0)&0x1f)<<6 | c.charCodeAt(1)&0x3f;↩
return String.fromCharCode(cc); }↩
);↩
str = str.replace(↩
/[\u00e0-\u00ef][\u0080-\u00bf][\u0080-\u00bf]/g, // 3-byte chars↩
function(c) { ↩
var cc = (c.charCodeAt(0)&0x0f)<<12 | (c.charCodeAt(1)&0x3f<<6) | c.charCodeAt(2)&0x3f; ↩
return String.fromCharCode(cc); }↩
);↩
return str;↩
}↩
↩
↩
function byteArrayToHexStr(b) { // convert byte array to hex string for displaying test vectors↩
var s = '';↩
for (var i=0; i<b.length; i++) s += b[i].toString(16) + ' ';↩
return s;↩
}↩
↩
/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */↩
↩
↩
var plainText = "ROMEO: But, soft! what light through yonder window breaks?\n\↩
It is the east, and Juliet is the sun.\n\↩
Arise, fair sun, and kill the envious moon,\n\↩
Who is already sick and pale with grief,\n\↩
That thou her maid art far more fair than she:\n\↩
Be not her maid, since she is envious;\n\↩
Her vestal livery is but sick and green\n\↩
And none but fools do wear it; cast it off.\n\↩
It is my lady, O, it is my love!\n\↩
O, that she knew she were!\n\↩
She speaks yet she says nothing: what of that?\n\↩
Her eye discourses; I will answer it.\n\↩
I am too bold, 'tis not to me she speaks:\n\↩
Two of the fairest stars in all the heaven,\n\↩
Having some business, do entreat her eyes\n\↩
To twinkle in their spheres till they return.\n\↩
What if her eyes were there, they in her head?\n\↩
The brightness of her cheek would shame those stars,\n\↩
As daylight doth a lamp; her eyes in heaven\n\↩
Would through the airy region stream so bright\n\↩
That birds would sing and think it were not night.\n\↩
See, how she leans her cheek upon her hand!\n\↩
O, that I were a glove upon that hand,\n\↩
That I might touch that cheek!\n\↩
JULIET: Ay me!\n\↩
ROMEO: She speaks:\n\↩
O, speak again, bright angel! for thou art\n\↩
As glorious to this night, being o'er my head\n\↩
As is a winged messenger of heaven\n\↩
Unto the white-upturned wondering eyes\n\↩
Of mortals that fall back to gaze on him\n\↩
When he bestrides the lazy-pacing clouds\n\↩
And sails upon the bosom of the air.";↩
↩
var password = "O Romeo, Romeo! wherefore art thou Romeo?";↩
↩
var cipherText = AESEncryptCtr(plainText, password, 256);↩
var decryptedText = AESDecryptCtr(cipherText, password, 256);↩