How to make Ruby AES-256-CBC and PHP MCRYPT_RIJNDAEL_128 play well together

Question

I\'m generating data to send from a Ruby stack to a PHP stack. I\'m using the OpenSSL::Cipher library on the Ruby side and the \'mcrypt\' library in PHP. When I encrypt us

Answer 1

I had troubles because the PHP was using a password smaller than 8 characters. In this case one needs to add the 0, to make it compatible with PHP:

mcrypt-encrypt manual page "key

The key with which the data will be encrypted. If it's smaller than the required keysize, it is padded with '\0'. It is better not to use ASCII strings for keys. http://php.net/manual/en/function.mcrypt-encrypt.php It is recommended to use the mhash functions to create a key from a string."

require 'openssl'
cipher = OpenSSL::Cipher.new('DES-ECB')
cipher.encrypt
key =  'passwrd'[0...7].ljust(8, 0.chr)  #Pad the key smaller than 8 chars
cipher.key = key
encrypted = cipher.update('33')
encrypted << cipher.final
dec = Base64.encode64(encrypted).strip()