You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: encryptor.rb
    path of file: ./repos/encrypted_cookie/lib/encrypted_cookie
    
    the code of the file until where you have to start completion: require 'openssl'

module Rack
  modu
    
        def encrypt_message(message)
          aes = OpenSSL::Cipher.new(@cipher).encrypt
          aes.key = @encryption_key
          iv = aes.random_iv
          aes.iv = iv
          iv + (aes.update(message) << aes.final)
        end