goncalo-ribeiro/index.html

## index.html
<!doctype html>
<html>
<head>
      <title>Socket.IO chat</title>
      <style>
      * { margin: 0; padding: 0; box-sizing: border-box; }
      body { font: 13px Helvetica, Arial; }
      form { background: #000; padding: 3px; position: fixed; bottom: 0; width: 100%; }
      form input { border: 0; padding: 10px; width: 90%; margin-right: .5%; }
      form button { width: 9%; background: rgb(130, 224, 255); border: none; padding: 10px; }
      #messages { list-style-type: none; margin: 0; padding: 0; }
      #messages li { padding: 5px 10px; }
      #messages li:nth-child(odd) { background: #eee; }
      #messages { margin-bottom: 40px }
</style>
</head>
<body>
    <ul id="messages"></ul>
    <form action="">
        <input id="m" autocomplete="off" /><button>Send</button>
</form>
<script src="https://cdn.socket.io/socket.io-1.2.0.js"></script>
<script src="https://code.jquery.com/jquery-1.11.1.js"></script>
<script src="https://cdn.jsdelivr.net/npm/node-forge@0.7.0/dist/forge.min.js"></script>
<script>
    var key, iv;
    $(function () {
        var socket = io();
        $('form').submit(function(){

            var input = $('#m').val();
            console.log('input = ' + input);

            var encryptedInput = encrypt(input);
            console.log(encryptedInput)

            socket.emit('chat message', encryptedInput);
            $('#m').val('');
            return false;
        });
        socket.on('symetric_key', function(data){
            console.log(data)
            key = data.key;
            iv = data.iv;
        });
        socket.on('chat message', function(msg){
            console.log('received a new message!')
            console.log(msg)
            decrypt(msg)
        });

        function encrypt (bytesToEncrypt){
            cipher = forge.cipher.createCipher('AES-CBC', key);
            cipher.start({'iv': iv});
            cipher.update(forge.util.createBuffer(bytesToEncrypt));
            cipher.finish();
            var encrypted = cipher.output;
            console.log(bytesToEncrypt + ' => ' + encrypted.toHex());
            return encrypted
        }

        function decrypt (bytesToDecrypt){
            decipher = forge.cipher.createDecipher('AES-CBC', key);
            decipher.start({'iv': iv});
            decipher.update(bytesToDecrypt);
            var result = decipher.finish(); // check 'result' for true/false
            console.log('decryption result = ' + result);
            console.log(decipher.output.toString());
            return decipher.output.toString();
        }
    });
</script>
</body>
</html>

## index.js
var app = require('express')();
var http = require('http').Server(app);
var io = require('socket.io')(http);
var port = process.env.PORT || 3000;
var forge = require('node-forge');


app.get('/', function(req, res){
	res.sendFile(__dirname + '/index.html');
});

io.on('connection', function(socket){

	// generate a random key and IV
	// Note: a key size of 16 bytes will use AES-128, 24 => AES-192, 32 => AES-256
	var key = forge.random.getBytesSync(32);
	var iv = forge.random.getBytesSync(16);
	io.emit('symetric_key', {'key': key, 'iv': iv});

    function encrypt (bytesToEncrypt){
        cipher = forge.cipher.createCipher('AES-CBC', key);
        cipher.start({'iv': iv});
        cipher.update(forge.util.createBuffer(bytesToEncrypt));
        cipher.finish();
        var encrypted = cipher.output;
        console.log(encrypted.toHex());
        return encrypted
    }

    function decrypt (bytesToDecrypt){
        decipher = forge.cipher.createDecipher('AES-CBC', key);
        decipher.start({'iv': iv});
        decipher.update(bytesToDecrypt);
        var result = decipher.finish(); // check 'result' for true/false
        console.log('decryption result = ' + result);
        console.log(decipher.output.toString());
        return decipher.output.toString();
    }


	socket.on('chat message', function(msg){
		//this is where the error happens
		decrypt(msg)
		//never executed
		io.emit('chat message', encrypt("ola mundo"));
	});
});

http.listen(port, function(){
	console.log('listening on *:' + port);
});
	<!doctype html>
	<html>
	<head>
	<title>Socket.IO chat</title>
	<style>
	* { margin: 0; padding: 0; box-sizing: border-box; }
	body { font: 13px Helvetica, Arial; }
	form { background: #000; padding: 3px; position: fixed; bottom: 0; width: 100%; }
	form input { border: 0; padding: 10px; width: 90%; margin-right: .5%; }
	form button { width: 9%; background: rgb(130, 224, 255); border: none; padding: 10px; }
	#messages { list-style-type: none; margin: 0; padding: 0; }
	#messages li { padding: 5px 10px; }
	#messages li:nth-child(odd) { background: #eee; }
	#messages { margin-bottom: 40px }
	</style>
	</head>
	<body>
	<ul id="messages"></ul>
	<form action="">
	<input id="m" autocomplete="off" /><button>Send</button>
	</form>
	<script src="https://cdn.socket.io/socket.io-1.2.0.js"></script>
	<script src="https://code.jquery.com/jquery-1.11.1.js"></script>
	<script src="https://cdn.jsdelivr.net/npm/node-forge@0.7.0/dist/forge.min.js"></script>
	<script>
	var key, iv;
	$(function () {
	var socket = io();
	$('form').submit(function(){

	var input = $('#m').val();
	console.log('input = ' + input);

	var encryptedInput = encrypt(input);
	console.log(encryptedInput)

	socket.emit('chat message', encryptedInput);
	$('#m').val('');
	return false;
	});
	socket.on('symetric_key', function(data){
	console.log(data)
	key = data.key;
	iv = data.iv;
	});
	socket.on('chat message', function(msg){
	console.log('received a new message!')
	console.log(msg)
	decrypt(msg)
	});

	function encrypt (bytesToEncrypt){
	cipher = forge.cipher.createCipher('AES-CBC', key);
	cipher.start({'iv': iv});
	cipher.update(forge.util.createBuffer(bytesToEncrypt));
	cipher.finish();
	var encrypted = cipher.output;
	console.log(bytesToEncrypt + ' => ' + encrypted.toHex());
	return encrypted
	}

	function decrypt (bytesToDecrypt){
	decipher = forge.cipher.createDecipher('AES-CBC', key);
	decipher.start({'iv': iv});
	decipher.update(bytesToDecrypt);
	var result = decipher.finish(); // check 'result' for true/false
	console.log('decryption result = ' + result);
	console.log(decipher.output.toString());
	return decipher.output.toString();
	}
	});
	</script>
	</body>
	</html>
	var app = require('express')();
	var http = require('http').Server(app);
	var io = require('socket.io')(http);
	var port = process.env.PORT \|\| 3000;
	var forge = require('node-forge');


	app.get('/', function(req, res){
	res.sendFile(__dirname + '/index.html');
	});

	io.on('connection', function(socket){

	// generate a random key and IV
	// Note: a key size of 16 bytes will use AES-128, 24 => AES-192, 32 => AES-256
	var key = forge.random.getBytesSync(32);
	var iv = forge.random.getBytesSync(16);
	io.emit('symetric_key', {'key': key, 'iv': iv});

	function encrypt (bytesToEncrypt){
	cipher = forge.cipher.createCipher('AES-CBC', key);
	cipher.start({'iv': iv});
	cipher.update(forge.util.createBuffer(bytesToEncrypt));
	cipher.finish();
	var encrypted = cipher.output;
	console.log(encrypted.toHex());
	return encrypted
	}

	function decrypt (bytesToDecrypt){
	decipher = forge.cipher.createDecipher('AES-CBC', key);
	decipher.start({'iv': iv});
	decipher.update(bytesToDecrypt);
	var result = decipher.finish(); // check 'result' for true/false
	console.log('decryption result = ' + result);
	console.log(decipher.output.toString());
	return decipher.output.toString();
	}


	socket.on('chat message', function(msg){
	//this is where the error happens
	decrypt(msg)
	//never executed
	io.emit('chat message', encrypt("ola mundo"));
	});
	});

	http.listen(port, function(){
	console.log('listening on *:' + port);
	});