chrisveness/index.html

## index.html
<!doctype html>
<html lang="en">
<head>
    <meta charset="utf-8">
    <title>AES client/server test</title>
    <link rel="stylesheet" href="//cdnjs.cloudflare.com/ajax/libs/normalize/3.0.3/normalize.min.css">
    <style>
        body    { font-size: 80%; padding: 1em; }
        form    { margin-top: 2em; }
        label   { display: inline-block; width: 6em; }
        input   { width: 36em; }
        form ul { list-style: none; padding: 0; }
        form li { margin: 0.5em 1em; }
        code    { display: inline-block; font-size: 80%; margin-left: 2em; }
    </style>
    <script src="//ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"></script>
    <script src="/js/aes.js"></script>
    <script src="/js/aes-ctr.js"></script>
    <script>
        $(document).ready(function() {
            var plaintext = Aes.Ctr.decrypt($('#ciphertext-server').html(), $('#password').val(), 256);
            $('output[name=plaintext-local]').html(plaintext);

            var ciphertext = Aes.Ctr.encrypt($('#plaintext').val(), $('#password').val(), 256);
            $('input[name=ciphertext]').val(ciphertext);
        });
    </script>
</head>

<body>
    <h1>JavaScript AES client/server interoperability test</h1>

    <p>The same AES JavaScript files are used both client-side and server-side.</p>
    <p>Client-side they are accessed by</p>
    <code>&lt;script src="/js/aes.js"&gt;&lt;/script&gt;<br>&lt;script src="/js/aes-ctr.js"&gt;&lt;/script&gt;</code>
    <p>Server-side they are accessed by</p>
    <code>const Aes = require('./public/js/aes.js');<br>Aes.Ctr   = require('./public/js/aes-ctr.js');</code>

    <form method="post">
        <fieldset><legend>Encrypt/decrypt</legend>
            <ul>
                <li>
                    <label for="plaintext">Plaintext</label>
                    <input name="plaintext" id="plaintext" value="pssst ... đon’t tell anyøne!">
                </li>
                <li>
                    <label for="password">Password</label>
                    <input name="password" id="password" value="L0ck it up ŝaf3">
                </li>
            </ul>

            <h2>Encrypt on server, decrypt on client</h2>
            <p>Cipher text (encrypted on server): <span id="ciphertext-server">{{ciphertext}}</span></p>
            <p>Plain text (decrypted on client): <output name="plaintext-local"></output></p>

            <h2>Encrypt on client, decrypt on server</h2>
            <p>Cipher text (encrypted on client): <input name="ciphertext" readonly></p>
            <p>Plain text (decrypted on server): <output name="plaintext-from-server">{{plaintext}}</output></p>

            <button type="submit">Submit</button>
        </fieldset>
    </form>

</body>
</html>

## package.json
{
  "name": "aes-client-server",
  "author": "Chris Veness",
  "version": "0.0.0",
  "main": "server.js",
  "scripts": {
    "start": "node server.js"
  },
  "dependencies": {
    "body-parser": "^1.15.0",
    "connect": "^3.4.1",
    "handlebars": "^4.0.5",
    "serve-static": "^1.10.2"
  }
}

## public—js—aes-ctr.js
/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  */
/*  AES Counter-mode implementation in JavaScript       (c) Chris Veness 2005-2014 / MIT Licence  */
/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  */

/* jshint node:true *//* global define, escape, unescape, btoa, atob */
'use strict';
if (typeof module!='undefined' && module.exports) var Aes = require('./aes'); // CommonJS (Node.js)


/**
 * 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)) return ''; // standard allows 128/192/256 bit keys
    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] = isNaN(password.charCodeAt(i)) ? 0 : password.charCodeAt(i);
    }
    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

    // 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 ciphertxt = 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)
        // 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]);
        }
        ciphertxt[b] = cipherChar.join('');
    }

    // use Array.join() for better performance than repeated string appends
    var ciphertext = ctrTxt + ciphertxt.join('');
    ciphertext = 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)) return ''; // standard allows 128/192/256 bit keys
    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] = isNaN(password.charCodeAt(i)) ? 0 : password.charCodeAt(i);
    }
    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 plaintxt = new Array(ciphertext.length);

    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 plaintxt with ciphered counter byte-by-byte --
            plaintxtByte[i] = cipherCntr[i] ^ ciphertext[b].charCodeAt(i);
            plaintxtByte[i] = String.fromCharCode(plaintxtByte[i]);
        }
        plaintxt[b] = plaintxtByte.join('');
    }

    // join array of blocks into single plaintext string
    var plaintext = plaintxt.join('');
    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') = 'Ã§a', and utf8Encode('Ã§a') = 'ÃÂ§a'*/
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 */
if (typeof String.prototype.base64Encode == 'undefined') {
    String.prototype.base64Encode = function() {
        if (typeof btoa != 'undefined') return btoa(this); // browser
        if (typeof Buffer != 'undefined') return new Buffer(this, 'binary').toString('base64'); // Node.js
        throw new Error('No Base64 Encode');
    };
}

/* Extend String object with method to decode base64 */
if (typeof String.prototype.base64Decode == 'undefined') {
    String.prototype.base64Decode = function() {
        if (typeof atob != 'undefined') return atob(this); // browser
        if (typeof Buffer != 'undefined') return new Buffer(this, 'base64').toString('binary'); // Node.js
        throw new Error('No Base64 Decode');
    };
}


/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  */
if (typeof module != 'undefined' && module.exports) module.exports = Aes.Ctr; // ≡ export default Aes.Ctr

## public—js—aes.js
/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  */
/*  AES implementation in JavaScript                     (c) Chris Veness 2005-2014 / MIT Licence */
/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  */

/* jshint node:true *//* global define */
'use strict';


/**
 * 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] ];


/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  */
if (typeof module != 'undefined' && module.exports) module.exports = Aes; // ≡ export default Aes

## server.js
/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  */
/*  JavaScript AES client/server interoperability             (c) Chris Veness 2016 / MIT Licence */
/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  */

'use strict';

const fs          = require('fs');           // nodejs.org/api/fs.html
const connect     = require('connect');      // simple middleware framework
const serveStatic = require('serve-static'); // serve static files
const bodyParser  = require('body-parser');  // http request body parsing
const handlebars  = require('handlebars');   // handlebars templating

const AesCtr      = require('./public/js/aes-ctr.js');

const app = connect();

app.use(serveStatic('public')); // for .js files

app.use(bodyParser.urlencoded({ 'extended': false })); // parse request bodies into req.body

app.use(function processRequest(req, res, next) {
    let context = null;
    switch (req.method) {
        case 'GET':
            context = { };
            break;
        case 'POST':
            const ciphertext = AesCtr.encrypt(req.body.plaintext, req.body.password, 256);
            const plaintext = AesCtr.decrypt(req.body.ciphertext, req.body.password, 256);
            context = { 'ciphertext': ciphertext, 'plaintext':  plaintext };
            break;
    }
    const template = fs.readFileSync('index.html', 'utf-8');
    const templateFn = handlebars.compile(template);
    const html = templateFn(context);
    res.setHeader('Content-Type', 'text/html');
    res.end(html);
});

app.listen(process.env.PORT||8080);
console.log('Listening on port '+(process.env.PORT||8080));
	<!doctype html>
	<html lang="en">
	<head>
	<meta charset="utf-8">
	<title>AES client/server test</title>
	<link rel="stylesheet" href="//cdnjs.cloudflare.com/ajax/libs/normalize/3.0.3/normalize.min.css">
	<style>
	body { font-size: 80%; padding: 1em; }
	form { margin-top: 2em; }
	label { display: inline-block; width: 6em; }
	input { width: 36em; }
	form ul { list-style: none; padding: 0; }
	form li { margin: 0.5em 1em; }
	code { display: inline-block; font-size: 80%; margin-left: 2em; }
	</style>
	<script src="//ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"></script>
	<script src="/js/aes.js"></script>
	<script src="/js/aes-ctr.js"></script>
	<script>
	$(document).ready(function() {
	var plaintext = Aes.Ctr.decrypt($('#ciphertext-server').html(), $('#password').val(), 256);
	$('output[name=plaintext-local]').html(plaintext);

	var ciphertext = Aes.Ctr.encrypt($('#plaintext').val(), $('#password').val(), 256);
	$('input[name=ciphertext]').val(ciphertext);
	});
	</script>
	</head>

	<body>
	<h1>JavaScript AES client/server interoperability test</h1>

	<p>The same AES JavaScript files are used both client-side and server-side.</p>
	<p>Client-side they are accessed by</p>
	<code><script src="/js/aes.js"></script><br><script src="/js/aes-ctr.js"></script></code>
	<p>Server-side they are accessed by</p>
	<code>const Aes = require('./public/js/aes.js');<br>Aes.Ctr = require('./public/js/aes-ctr.js');</code>

	<form method="post">
	<fieldset><legend>Encrypt/decrypt</legend>
	<ul>
	<li>
	<label for="plaintext">Plaintext</label>
	<input name="plaintext" id="plaintext" value="pssst ... đon’t tell anyøne!">
	</li>
	<li>
	<label for="password">Password</label>
	<input name="password" id="password" value="L0ck it up ŝaf3">
	</li>
	</ul>

	<h2>Encrypt on server, decrypt on client</h2>
	<p>Cipher text (encrypted on server): <span id="ciphertext-server">{{ciphertext}}</span></p>
	<p>Plain text (decrypted on client): <output name="plaintext-local"></output></p>

	<h2>Encrypt on client, decrypt on server</h2>
	<p>Cipher text (encrypted on client): <input name="ciphertext" readonly></p>
	<p>Plain text (decrypted on server): <output name="plaintext-from-server">{{plaintext}}</output></p>

	<button type="submit">Submit</button>
	</fieldset>
	</form>

	</body>
	</html>
	{
	"name": "aes-client-server",
	"author": "Chris Veness",
	"version": "0.0.0",
	"main": "server.js",
	"scripts": {
	"start": "node server.js"
	},
	"dependencies": {
	"body-parser": "^1.15.0",
	"connect": "^3.4.1",
	"handlebars": "^4.0.5",
	"serve-static": "^1.10.2"
	}
	}
	/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
	/* AES Counter-mode implementation in JavaScript (c) Chris Veness 2005-2014 / MIT Licence */
	/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

	/* jshint node:true // global define, escape, unescape, btoa, atob */
	'use strict';
	if (typeof module!='undefined' && module.exports) var Aes = require('./aes'); // CommonJS (Node.js)


	/**
	* 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)) return ''; // standard allows 128/192/256 bit keys
	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] = isNaN(password.charCodeAt(i)) ? 0 : password.charCodeAt(i);
	}
	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

	// 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 ciphertxt = 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)
	// 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]);
	}
	ciphertxt[b] = cipherChar.join('');
	}

	// use Array.join() for better performance than repeated string appends
	var ciphertext = ctrTxt + ciphertxt.join('');
	ciphertext = 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)) return ''; // standard allows 128/192/256 bit keys
	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] = isNaN(password.charCodeAt(i)) ? 0 : password.charCodeAt(i);
	}
	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+bblockSize, 8+bblockSize+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 plaintxt = new Array(ciphertext.length);

	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 plaintxt with ciphered counter byte-by-byte --
	plaintxtByte[i] = cipherCntr[i] ^ ciphertext[b].charCodeAt(i);
	plaintxtByte[i] = String.fromCharCode(plaintxtByte[i]);
	}
	plaintxt[b] = plaintxtByte.join('');
	}

	// join array of blocks into single plaintext string
	var plaintext = plaintxt.join('');
	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') = 'Ã§a', and utf8Encode('Ã§a') = 'ÃÂ§a'*/
	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 */
	if (typeof String.prototype.base64Encode == 'undefined') {
	String.prototype.base64Encode = function() {
	if (typeof btoa != 'undefined') return btoa(this); // browser
	if (typeof Buffer != 'undefined') return new Buffer(this, 'binary').toString('base64'); // Node.js
	throw new Error('No Base64 Encode');
	};
	}

	/* Extend String object with method to decode base64 */
	if (typeof String.prototype.base64Decode == 'undefined') {
	String.prototype.base64Decode = function() {
	if (typeof atob != 'undefined') return atob(this); // browser
	if (typeof Buffer != 'undefined') return new Buffer(this, 'base64').toString('binary'); // Node.js
	throw new Error('No Base64 Decode');
	};
	}


	/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
	if (typeof module != 'undefined' && module.exports) module.exports = Aes.Ctr; // ≡ export default Aes.Ctr
	/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
	/* AES implementation in JavaScript (c) Chris Veness 2005-2014 / MIT Licence */
	/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

	/* jshint node:true // global define */
	'use strict';


	/**
	* 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[4i], key[4i+1], key[4i+2], key[4i+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] ];


	/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
	if (typeof module != 'undefined' && module.exports) module.exports = Aes; // ≡ export default Aes
	/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
	/* JavaScript AES client/server interoperability (c) Chris Veness 2016 / MIT Licence */
	/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

	'use strict';

	const fs = require('fs'); // nodejs.org/api/fs.html
	const connect = require('connect'); // simple middleware framework
	const serveStatic = require('serve-static'); // serve static files
	const bodyParser = require('body-parser'); // http request body parsing
	const handlebars = require('handlebars'); // handlebars templating

	const AesCtr = require('./public/js/aes-ctr.js');

	const app = connect();

	app.use(serveStatic('public')); // for .js files

	app.use(bodyParser.urlencoded({ 'extended': false })); // parse request bodies into req.body

	app.use(function processRequest(req, res, next) {
	let context = null;
	switch (req.method) {
	case 'GET':
	context = { };
	break;
	case 'POST':
	const ciphertext = AesCtr.encrypt(req.body.plaintext, req.body.password, 256);
	const plaintext = AesCtr.decrypt(req.body.ciphertext, req.body.password, 256);
	context = { 'ciphertext': ciphertext, 'plaintext': plaintext };
	break;
	}
	const template = fs.readFileSync('index.html', 'utf-8');
	const templateFn = handlebars.compile(template);
	const html = templateFn(context);
	res.setHeader('Content-Type', 'text/html');
	res.end(html);
	});

	app.listen(process.env.PORT\|\|8080);
	console.log('Listening on port '+(process.env.PORT\|\|8080));