Encryption demo

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)

function textTo16Binary(string) {
    return string.split('').map(function (char) {
        return char.charCodeAt(0).toString(16);
    }).join(' ');
}

function binary26toText(string) {
    return string.split(' ').map(function (char) {
        return String.fromCharCode(parseInt(char, 16));
    }).join('');
}
/**
 * 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 = 8;  // 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('');

    return {
        ciphertext: textTo16Binary(ciphertext),
        blocks: ciphertxt.map((block) => {
            return textTo16Binary(block).split(' ').join('');
        })
    };
};


/**
 * 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 = 8;  // 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 = binary26toText(ciphertext);
    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') = '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 */
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

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>
</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</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 server</h2>
            <ul>
            {{#each blocks}}
                <li>Block #{{@index}} - {{ this }}</li>
            {{/each}}
            </ul>
            <p>Cipher text (encrypted on server): <span id="ciphertext-server">{{ciphertext}}</span></p>
            <p>Plain text (decrypted on server): <output>{{plaintext}}</output></p>
            <button type="submit">Submit</button>
        </fieldset>
    </form>
</body>
</html>

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, blocks } = AesCtr.encrypt(req.body.plaintext, req.body.password, 256);
            const plaintext = AesCtr.decrypt(ciphertext, req.body.password, 256);
            context = { 'ciphertext': ciphertext.split(' ').join(''), 'plaintext': plaintext, 'blocks': blocks };
            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));