Basic Node.js crypto cipher/decipher example.

encrypt-decrypt.js

var crypto = require('crypto')
  , key = 'salt_from_the_user_document'
  , plaintext = 'password'
  , cipher = crypto.createCipher('aes-256-cbc', key)
  , decipher = crypto.createDecipher('aes-256-cbc', key);
  
cipher.update(plaintext, 'utf8', 'base64');
var encryptedPassword = cipher.final('base64')

decipher.update(encryptedPassword, 'base64', 'utf8');
var decryptedPassword = decipher.final('utf8');

console.log('encrypted :', encryptedPassword);
console.log('decrypted :', decryptedPassword);

Encryption and decryption should be

    var encryptedPassword = cipher.update(plaintext, 'utf8', 'base64');
    encryptedPassword += cipher.final('base64')
    console.log('encrypted :', encryptedPassword);
  
    var decryptedPassword = decipher.update(encryptedPassword, 'base64', 'utf8');
    decryptedPassword += decipher.final('utf8');      
    console.log('decrypted :', decryptedPassword);

Dont ignore output of update()