/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  *//* * 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 *                           - see http://csrc.nist.gov/publications/nistpubs/800-38a/sp800-38a.pdf *   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  }