aes.js

var crypto = require('crypto');
var assert = require('assert');

var algorithm = 'aes256'; // or any other algorithm supported by OpenSSL
var key = 'password';
var text = 'I love kittens';

var cipher = crypto.createCipher(algorithm, key);  
var encrypted = cipher.update(text, 'utf8', 'hex') + cipher.final('hex');
var decipher = crypto.createDecipher(algorithm, key);
var decrypted = decipher.update(encrypted, 'hex', 'utf8') + decipher.final('utf8');

assert.equal(decrypted, text);

// credit: http://stackoverflow.com/a/6953606/1740273