Question

I’m encrypting with Ruby and decrypting with JavaScript using AES-256 but I’m having trouble crossing platforms, i.e. the JS returns gibberish when decrypting the output from Ruby.

I’m using the JS AES implementation from here: http://www.movable-type.co.uk/scripts/aes.html

var decrypted = Aes.Ctr.decrypt(encrypted, key, 256);

and OpenSSL / Ruby:

def encrypt(string, key)
  Base64.encode64(aes(key, string)).gsub /\s/, ''
end

def aes(key,string)
  cipher = OpenSSL::Cipher::Cipher.new("aes-256-cbc")
  cipher.encrypt
  cipher.key = Digest::SHA256.digest(key)
  cipher_text = cipher.update(string)
  cipher_text << cipher.final
  return cipher_text
end

In ruby I get:

encrypt("This is a test", "password")
# => "zDMm47GniTQ2p5a5UqSDbg=="

But when decrypting in JS, I get:

Aes.Ctr.decrypt("zDMm47GniTQ2p5a5UqSDbg==", "password", 256);
# => "Ü}$> 3"

Any ideas? Thanks in advance.

Answer 1

In the end I used Gibberish AES which has both a Ruby and JavaScript implementation written by the same author:

https://github.com/mdp/gibberish-aes

https://github.com/mdp/gibberish