encrypt.js

// Base64.js
//https://raw.githubusercontent.com/davidchambers/Base64.js/master/LICENSE

  
  function InvalidCharacterError(message) {
    this.message = message;
  }
  InvalidCharacterError.prototype = new Error;
  InvalidCharacterError.prototype.name = 'InvalidCharacterError';

  // encoder
  // [https://gist.github.com/999166] by [https://github.com/nignag]
 
    function btoa (input) {
      var chars = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=';
      var str = String(input);
    for (
      // initialize result and counter
      var block, charCode, idx = 0, map = chars, output = '';
      // if the next str index does not exist:
      //   change the mapping table to "="
      //   check if d has no fractional digits
      str.charAt(idx | 0) || (map = '=', idx % 1);
      // "8 - idx % 1 * 8" generates the sequence 2, 4, 6, 8
      output += map.charAt(63 & block >> 8 - idx % 1 * 8)
    ) {
      charCode = str.charCodeAt(idx += 3/4);
      if (charCode > 0xFF) {
        throw new InvalidCharacterError("'btoa' failed: The string to be encoded contains characters outside of the Latin1 range.");
      }
      block = block << 8 | charCode;
    }
    return output;
  };

  // decoder
  // [https://gist.github.com/1020396] by [https://github.com/atk]
 
   function atob(input) {
    var chars = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=';

    var str = String(input).replace(/=+$/, '');
    if (str.length % 4 == 1) {
      throw new InvalidCharacterError("'atob' failed: The string to be decoded is not correctly encoded.");
    }
    for (
      // initialize result and counters
      var bc = 0, bs, buffer, idx = 0, output = '';
      // get next character
      buffer = str.charAt(idx++);
      // character found in table? initialize bit storage and add its ascii value;
      ~buffer && (bs = bc % 4 ? bs * 64 + buffer : buffer,
        // and if not first of each 4 characters,
        // convert the first 8 bits to one ascii character
        bc++ % 4) ? output += String.fromCharCode(255 & bs >> (-2 * bc & 6)) : 0
    ) {
      // try to find character in table (0-63, not found => -1)
      buffer = chars.indexOf(buffer);
    }
    return output;
  };



/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  */
/* AES implementation in JavaScript                                   (c) Chris Veness 2005-2016  */
/*                                                                                   MIT Licence  */
/* www.movable-type.co.uk/scripts/aes.html                                                        */
/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  */

/**
 * AES (Rijndael cipher) encryption routines,
 *
 * Reference implementation of FIPS-197 http://csrc.nist.gov/publications/fips/fips197/fips-197.pdf.
 *
 * @namespace
 */
var Aes = {};


/**
 * AES Cipher function: encrypt 'input' state with Rijndael algorithm [§5.1];
 *   applies Nr rounds (10/12/14) using key schedule w for 'add round key' stage.
 *
 * @param   {number[]}   input - 16-byte (128-bit) input state array.
 * @param   {number[][]} w - Key schedule as 2D byte-array (Nr+1 x Nb bytes).
 * @returns {number[]}   Encrypted output state array.
 */
Aes.cipher = function(input, w) {
    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 = Aes.addRoundKey(state, w, 0, Nb);

    for (var round=1; round<Nr; round++) {
        state = Aes.subBytes(state, Nb);
        state = Aes.shiftRows(state, Nb);
        state = Aes.mixColumns(state, Nb);
        state = Aes.addRoundKey(state, w, round, Nb);
    }

    state = Aes.subBytes(state, Nb);
    state = Aes.shiftRows(state, Nb);
    state = Aes.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;
};


/**
 * Perform key expansion to generate a key schedule from a cipher key [§5.2].
 *
 * @param   {number[]}   key - Cipher key as 16/24/32-byte array.
 * @returns {number[][]} Expanded key schedule as 2D byte-array (Nr+1 x Nb bytes).
 */
Aes.keyExpansion = function(key) {
    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);

    // initialise first Nk words of expanded key with cipher key
    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;
    }

    // expand the key into the remainder of the schedule
    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];
        // each Nk'th word has extra transformation
        if (i % Nk == 0) {
            temp = Aes.subWord(Aes.rotWord(temp));
            for (var t=0; t<4; t++) temp[t] ^= Aes.rCon[i/Nk][t];
        }
        // 256-bit key has subWord applied every 4th word
        else if (Nk > 6 && i%Nk == 4) {
            temp = Aes.subWord(temp);
        }
        // xor w[i] with w[i-1] and w[i-Nk]
        for (var t=0; t<4; t++) w[i][t] = w[i-Nk][t] ^ temp[t];
    }

    return w;
};


/**
 * Apply SBox to state S [§5.1.1]
 * @private
 */
Aes.subBytes = function(s, Nb) {
    for (var r=0; r<4; r++) {
        for (var c=0; c<Nb; c++) s[r][c] = Aes.sBox[s[r][c]];
    }
    return s;
};


/**
 * Shift row r of state S left by r bytes [§5.1.2]
 * @private
 */
Aes.shiftRows = function(s, Nb) {
    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 asmaes.sourceforge.net/rijndael/rijndaelImplementation.pdf
};


/**
 * Combine bytes of each col of state S [§5.1.3]
 * @private
 */
Aes.mixColumns = function(s, Nb) {
    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]; // {02}•a0 + {03}•a1 + a2 + a3
        s[1][c] = a[0] ^ b[1] ^ a[2] ^ b[2] ^ a[3]; // a0 • {02}•a1 + {03}•a2 + a3
        s[2][c] = a[0] ^ a[1] ^ b[2] ^ a[3] ^ b[3]; // a0 + a1 + {02}•a2 + {03}•a3
        s[3][c] = a[0] ^ b[0] ^ a[1] ^ a[2] ^ b[3]; // {03}•a0 + a1 + a2 + {02}•a3
    }
    return s;
};


/**
 * Xor Round Key into state S [§5.1.4]
 * @private
 */
Aes.addRoundKey = function(state, w, rnd, Nb) {
    for (var r=0; r<4; r++) {
        for (var c=0; c<Nb; c++) state[r][c] ^= w[rnd*4+c][r];
    }
    return state;
};


/**
 * Apply SBox to 4-byte word w
 * @private
 */
Aes.subWord = function(w) {
    for (var i=0; i<4; i++) w[i] = Aes.sBox[w[i]];
    return w;
};


/**
 * Rotate 4-byte word w left by one byte
 * @private
 */
Aes.rotWord = function(w) {
    var tmp = w[0];
    for (var i=0; i<3; i++) w[i] = w[i+1];
    w[3] = tmp;
    return w;
};


// sBox is pre-computed multiplicative inverse in GF(2^8) used in subBytes and keyExpansion [§5.1.1]
Aes.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]
Aes.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] ];

//https://github.com/chrisveness/crypto
/**
 * Aes.Ctr: Counter-mode (CTR) wrapper for AES.
 *
 * This encrypts a Unicode string to produces a base64 ciphertext using 128/192/256-bit AES,
 * and the converse to decrypt an encrypted ciphertext.
 *
 * See http://csrc.nist.gov/publications/nistpubs/800-38a/sp800-38a.pdf
 *
 * @augments Aes
 */
Aes.Ctr = {};


/**
 * Encrypt a text using AES encryption in Counter mode of operation.
 *
 * Unicode multi-byte character safe
 *
 * @param   {string} plaintext - Source text to be encrypted.
 * @param   {string} password - The password to use to generate a key for encryption.
 * @param   {number} nBits - Number of bits to be used in the key; 128 / 192 / 256.
 * @returns {string} Encrypted text.
 *
 * @example
 *   var encr = Aes.Ctr.encrypt('big secret', 'pāşšŵōřđ', 256); // 'lwGl66VVwVObKIr6of8HVqJr'
 */
Aes.Ctr.encrypt = function(plaintext, password, nBits) {
    var blockSize = 16;  // block size fixed at 16 bytes / 128 bits (Nb=4) for AES
    if (!(nBits==128 || nBits==192 || nBits==256)) throw new Error('Key size is not 128 / 192 / 256');
    plaintext = String(plaintext).utf8Encode();
    password = String(password).utf8Encode();

    // use AES itself to encrypt password to get cipher key (using plain password as source for key
    // expansion) - gives us well encrypted key (though hashed key might be preferred for prod'n use)
    var nBytes = nBits/8;  // no bytes in key (16/24/32)
    var pwBytes = new Array(nBytes);
    for (var i=0; i<nBytes; i++) {  // use 1st 16/24/32 chars of password for key
        pwBytes[i] = i<password.length ?  password.charCodeAt(i) : 0;
    }
    var key = Aes.cipher(pwBytes, Aes.keyExpansion(pwBytes)); // gives us 16-byte key
    key = key.concat(key.slice(0, nBytes-16));  // expand key to 16/24/32 bytes long
    log("Key is =")
    log(JSON.stringify(key))
    // initialise 1st 8 bytes of counter block with nonce (NIST SP800-38A §B.2): [0-1] = millisec,
    // [2-3] = random, [4-7] = seconds, together giving full sub-millisec uniqueness up to Feb 2106
    var counterBlock = new Array(blockSize);

    var nonce = (new Date()).getTime();  // timestamp: milliseconds since 1-Jan-1970
    var nonceMs = nonce%1000;
    var nonceSec = Math.floor(nonce/1000);
    var nonceRnd = Math.floor(Math.random()*0xffff);
    // for debugging: nonce = nonceMs = nonceSec = nonceRnd = 0;

    for (var i=0; i<2; i++) counterBlock[i]   = (nonceMs  >>> i*8) & 0xff;
    for (var i=0; i<2; i++) counterBlock[i+2] = (nonceRnd >>> i*8) & 0xff;
    for (var i=0; i<4; i++) counterBlock[i+4] = (nonceSec >>> i*8) & 0xff;

    // and convert it 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]);

    // generate key schedule - an expansion of the key into distinct Key Rounds for each round
    var keySchedule = Aes.keyExpansion(key);

    var blockCount = Math.ceil(plaintext.length/blockSize);
    var ciphertext = '';

    for (var b=0; b<blockCount; b++) {
        // set counter (block #) in last 8 bytes of counter block (leaving nonce in 1st 8 bytes)
        // done in two stages for 32-bit ops: using two words allows us to go past 2^32 blocks (68GB)
        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 = Aes.cipher(counterBlock, keySchedule);  // -- encrypt counter block --

        // block size is reduced on final block
        var blockLength = b<blockCount-1 ? blockSize : (plaintext.length-1)%blockSize+1;
        var cipherChar = new Array(blockLength);

        for (var i=0; i<blockLength; i++) {
            // -- xor plaintext with ciphered counter char-by-char --
            cipherChar[i] = cipherCntr[i] ^ plaintext.charCodeAt(b*blockSize+i);
            cipherChar[i] = String.fromCharCode(cipherChar[i]);
        }
        ciphertext += cipherChar.join('');

        // if within web worker, announce progress every 1000 blocks (roughly every 50ms)
        if (typeof WorkerGlobalScope != 'undefined' && self instanceof WorkerGlobalScope) {
            if (b%1000 == 0) self.postMessage({ progress: b/blockCount });
        }
    }

    ciphertext =  (ctrTxt+ciphertext).base64Encode();

    return ciphertext;
};


/**
 * Decrypt a text encrypted by AES in counter mode of operation
 *
 * @param   {string} ciphertext - Cipher text to be decrypted.
 * @param   {string} password - Password to use to generate a key for decryption.
 * @param   {number} nBits - Number of bits to be used in the key; 128 / 192 / 256.
 * @returns {string} Decrypted text
 *
 * @example
 *   var decr = Aes.Ctr.decrypt('lwGl66VVwVObKIr6of8HVqJr', 'pāşšŵōřđ', 256); // 'big secret'
 */
Aes.Ctr.decrypt = function(ciphertext, password, nBits) {
    var blockSize = 16;  // block size fixed at 16 bytes / 128 bits (Nb=4) for AES
    if (!(nBits==128 || nBits==192 || nBits==256)) throw new Error('Key size is not 128 / 192 / 256');
    ciphertext = String(ciphertext).base64Decode();
    password = String(password).utf8Encode();

    // use AES to encrypt password (mirroring encrypt routine)
    var nBytes = nBits/8;  // no bytes in key
    var pwBytes = new Array(nBytes);
    for (var i=0; i<nBytes; i++) {
        pwBytes[i] = i<password.length ?  password.charCodeAt(i) : 0;
    }
    var key = Aes.cipher(pwBytes, Aes.keyExpansion(pwBytes));
    key = key.concat(key.slice(0, nBytes-16));  // expand key to 16/24/32 bytes long

    // recover nonce from 1st 8 bytes of ciphertext
    var counterBlock = new Array(8);
    var ctrTxt = ciphertext.slice(0, 8);
    for (var i=0; i<8; i++) counterBlock[i] = ctrTxt.charCodeAt(i);

    // generate key schedule
    var keySchedule = Aes.keyExpansion(key);

    // separate ciphertext into blocks (skipping past initial 8 bytes)
    var nBlocks = Math.ceil((ciphertext.length-8) / blockSize);
    var ct = new Array(nBlocks);
    for (var b=0; b<nBlocks; b++) ct[b] = ciphertext.slice(8+b*blockSize, 8+b*blockSize+blockSize);
    ciphertext = ct;  // ciphertext is now array of block-length strings

    // plaintext will get generated block-by-block into array of block-length strings
    var plaintext = '';

    for (var b=0; b<nBlocks; 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) >>> c*8) & 0xff;
        for (var c=0; c<4; c++) counterBlock[15-c-4] = (((b+1)/0x100000000-1) >>> c*8) & 0xff;

        var cipherCntr = Aes.cipher(counterBlock, keySchedule);  // encrypt counter block

        var plaintxtByte = new Array(ciphertext[b].length);
        for (var i=0; i<ciphertext[b].length; i++) {
            // -- xor plaintext with ciphered counter byte-by-byte --
            plaintxtByte[i] = cipherCntr[i] ^ ciphertext[b].charCodeAt(i);
            plaintxtByte[i] = String.fromCharCode(plaintxtByte[i]);
        }
        plaintext += plaintxtByte.join('');

        // if within web worker, announce progress every 1000 blocks (roughly every 50ms)
        if (typeof WorkerGlobalScope != 'undefined' && self instanceof WorkerGlobalScope) {
            if (b%1000 == 0) self.postMessage({ progress: b/nBlocks });
        }
    }

    plaintext = plaintext.utf8Decode();  // decode from UTF8 back to Unicode multi-byte chars

    return plaintext;
};


/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  */

/* Extend String object with method to encode multi-byte string to utf8
 * - monsur.hossa.in/2012/07/20/utf-8-in-javascript.html
 * - note utf8Encode is an identity function with 7-bit ascii strings, but not with 8-bit strings;
 * - utf8Encode('x') = 'x', but utf8Encode('ça') = 'ça', and utf8Encode('ça') = 'ça'*/
if (typeof String.prototype.utf8Encode == 'undefined') {
    String.prototype.utf8Encode = function() {
        return unescape( encodeURIComponent( this ) );
    };
}

/* Extend String object with method to decode utf8 string to multi-byte */
if (typeof String.prototype.utf8Decode == 'undefined') {
    String.prototype.utf8Decode = function() {
        try {
            return decodeURIComponent( escape( this ) );
        } catch (e) {
            return this; // invalid UTF-8? return as-is
        }
    };
}

/* Extend String object with method to encode base64
 * - developer.mozilla.org/en-US/docs/Web/API/window.btoa, nodejs.org/api/buffer.html
 * - note: btoa & Buffer/binary work on single-byte Unicode (C0/C1), so ok for utf8 strings, not for general Unicode...
 * - note: if btoa()/atob() are not available (eg IE9-), try github.com/davidchambers/Base64.js */

    String.prototype.base64Encode = function() {
        return btoa(this); // browser
    };

/* Extend String object with method to decode base64 */
    String.prototype.base64Decode = function() {
        return atob(this); // browser
    };


/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  */
/*  SHA-256 implementation in JavaScript                (c) Chris Veness 2002-2014 / MIT Licence  */
/*                                                                                                */
/*  - see http://csrc.nist.gov/groups/ST/toolkit/secure_hashing.html                              */
/*        http://csrc.nist.gov/groups/ST/toolkit/examples.html                                    */
/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  */


/**
 * SHA-256 hash function reference implementation.
 *
 * @namespace
 */
var Sha256 = {};


/**
 * Generates SHA-256 hash of string.
 *
 * @param   {string} msg - String to be hashed
 * @returns {string} Hash of msg as hex character string
 */
Sha256.hash = function(msg) {
    // convert string to UTF-8, as SHA only deals with byte-streams
    msg = msg.utf8Encode();
    
    // constants [§4.2.2]
    var K = [
        0x428a2f98, 0x71374491, 0xb5c0fbcf, 0xe9b5dba5, 0x3956c25b, 0x59f111f1, 0x923f82a4, 0xab1c5ed5,
        0xd807aa98, 0x12835b01, 0x243185be, 0x550c7dc3, 0x72be5d74, 0x80deb1fe, 0x9bdc06a7, 0xc19bf174,
        0xe49b69c1, 0xefbe4786, 0x0fc19dc6, 0x240ca1cc, 0x2de92c6f, 0x4a7484aa, 0x5cb0a9dc, 0x76f988da,
        0x983e5152, 0xa831c66d, 0xb00327c8, 0xbf597fc7, 0xc6e00bf3, 0xd5a79147, 0x06ca6351, 0x14292967,
        0x27b70a85, 0x2e1b2138, 0x4d2c6dfc, 0x53380d13, 0x650a7354, 0x766a0abb, 0x81c2c92e, 0x92722c85,
        0xa2bfe8a1, 0xa81a664b, 0xc24b8b70, 0xc76c51a3, 0xd192e819, 0xd6990624, 0xf40e3585, 0x106aa070,
        0x19a4c116, 0x1e376c08, 0x2748774c, 0x34b0bcb5, 0x391c0cb3, 0x4ed8aa4a, 0x5b9cca4f, 0x682e6ff3,
        0x748f82ee, 0x78a5636f, 0x84c87814, 0x8cc70208, 0x90befffa, 0xa4506ceb, 0xbef9a3f7, 0xc67178f2 ];
    // initial hash value [§5.3.1]
    var H = [
        0x6a09e667, 0xbb67ae85, 0x3c6ef372, 0xa54ff53a, 0x510e527f, 0x9b05688c, 0x1f83d9ab, 0x5be0cd19 ];

    // PREPROCESSING 
 
    msg += String.fromCharCode(0x80);  // add trailing '1' bit (+ 0's padding) to string [§5.1.1]

    // convert string msg into 512-bit/16-integer blocks arrays of ints [§5.2.1]
    var l = msg.length/4 + 2; // length (in 32-bit integers) of msg + ‘1’ + appended length
    var N = Math.ceil(l/16);  // number of 16-integer-blocks required to hold 'l' ints
    var M = new Array(N);

    for (var i=0; i<N; i++) {
        M[i] = new Array(16);
        for (var j=0; j<16; j++) {  // encode 4 chars per integer, big-endian encoding
            M[i][j] = (msg.charCodeAt(i*64+j*4)<<24) | (msg.charCodeAt(i*64+j*4+1)<<16) | 
                      (msg.charCodeAt(i*64+j*4+2)<<8) | (msg.charCodeAt(i*64+j*4+3));
        } // note running off the end of msg is ok 'cos bitwise ops on NaN return 0
    }
    // add length (in bits) into final pair of 32-bit integers (big-endian) [§5.1.1]
    // note: most significant word would be (len-1)*8 >>> 32, but since JS converts
    // bitwise-op args to 32 bits, we need to simulate this by arithmetic operators
    M[N-1][14] = ((msg.length-1)*8) / Math.pow(2, 32); M[N-1][14] = Math.floor(M[N-1][14]);
    M[N-1][15] = ((msg.length-1)*8) & 0xffffffff;


    // HASH COMPUTATION [§6.1.2]

    var W = new Array(64); var a, b, c, d, e, f, g, h;
    for (var i=0; i<N; i++) {

        // 1 - prepare message schedule 'W'
        for (var t=0;  t<16; t++) W[t] = M[i][t];
        for (var t=16; t<64; t++) W[t] = (Sha256.σ1(W[t-2]) + W[t-7] + Sha256.σ0(W[t-15]) + W[t-16]) & 0xffffffff;

        // 2 - initialise working variables a, b, c, d, e, f, g, h with previous hash value
        a = H[0]; b = H[1]; c = H[2]; d = H[3]; e = H[4]; f = H[5]; g = H[6]; h = H[7];

        // 3 - main loop (note 'addition modulo 2^32')
        for (var t=0; t<64; t++) {
            var T1 = h + Sha256.Σ1(e) + Sha256.Ch(e, f, g) + K[t] + W[t];
            var T2 =     Sha256.Σ0(a) + Sha256.Maj(a, b, c);
            h = g;
            g = f;
            f = e;
            e = (d + T1) & 0xffffffff;
            d = c;
            c = b;
            b = a;
            a = (T1 + T2) & 0xffffffff;
        }
         // 4 - compute the new intermediate hash value (note 'addition modulo 2^32')
        H[0] = (H[0]+a) & 0xffffffff;
        H[1] = (H[1]+b) & 0xffffffff; 
        H[2] = (H[2]+c) & 0xffffffff; 
        H[3] = (H[3]+d) & 0xffffffff; 
        H[4] = (H[4]+e) & 0xffffffff;
        H[5] = (H[5]+f) & 0xffffffff;
        H[6] = (H[6]+g) & 0xffffffff; 
        H[7] = (H[7]+h) & 0xffffffff; 
    }

    return Sha256.toHexStr(H[0]) + Sha256.toHexStr(H[1]) + Sha256.toHexStr(H[2]) + Sha256.toHexStr(H[3]) + 
           Sha256.toHexStr(H[4]) + Sha256.toHexStr(H[5]) + Sha256.toHexStr(H[6]) + Sha256.toHexStr(H[7]);
};


/**
 * Rotates right (circular right shift) value x by n positions [§3.2.4].
 * @private
 */
Sha256.ROTR = function(n, x) {
    return (x >>> n) | (x << (32-n));
};

/**
 * Logical functions [§4.1.2].
 * @private
 */
Sha256.Σ0  = function(x) { return Sha256.ROTR(2,  x) ^ Sha256.ROTR(13, x) ^ Sha256.ROTR(22, x); };
Sha256.Σ1  = function(x) { return Sha256.ROTR(6,  x) ^ Sha256.ROTR(11, x) ^ Sha256.ROTR(25, x); };
Sha256.σ0  = function(x) { return Sha256.ROTR(7,  x) ^ Sha256.ROTR(18, x) ^ (x>>>3);  };
Sha256.σ1  = function(x) { return Sha256.ROTR(17, x) ^ Sha256.ROTR(19, x) ^ (x>>>10); };
Sha256.Ch  = function(x, y, z) { return (x & y) ^ (~x & z); };
Sha256.Maj = function(x, y, z) { return (x & y) ^ (x & z) ^ (y & z); };


/**
 * Hexadecimal representation of a number.
 * @private
 */
Sha256.toHexStr = function(n) {
    // note can't use toString(16) as it is implementation-dependant,
    // and in IE returns signed numbers when used on full words
    var s="", v;
    for (var i=7; i>=0; i--) { v = (n>>>(i*4)) & 0xf; s += v.toString(16); }
    return s;
};


/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  */


/** Extend String object with method to encode multi-byte string to utf8
 *  - monsur.hossa.in/2012/07/20/utf-8-in-javascript.html */
if (typeof String.prototype.utf8Encode == 'undefined') {
    String.prototype.utf8Encode = function() {
        return unescape( encodeURIComponent( this ) );
    };
}

/** Extend String object with method to decode utf8 string to multi-byte */
if (typeof String.prototype.utf8Decode == 'undefined') {
    String.prototype.utf8Decode = function() {
        try {
            return decodeURIComponent( escape( this ) );
        } catch (e) {
            return this; // invalid UTF-8? return as-is
        }
    };
}

var password = 'badpassword';
var plaintext = 'This is a secrect message';
var ciphertext = Aes.Ctr.encrypt(plaintext, password, 256);
log("ciphertext is = "+ciphertext)
var origtext = Aes.Ctr.decrypt("rbMCFw06agYuVcS5N/yRp3OFmIlVeogLcgVZItgYlpYasfGjoD5sPwBpYg==", password, 256);


var sha = Sha256.hash("This is a test")

log("Hash is:"+sha)