enc_dec.rb

class EncDec

  KEY = "FA 0E 3C 9B 4F A2 C7 AA 37 0F CA 9B 5A 91 64 08"
  IV  = "AA AD 8B 4C 00 E1 3F 53 B8 E7 16 BC B5 F4 D1 B9"

  attr_reader :cipher, :message, :key, :iv

  def initialize(message, key = nil, iv = nil)
    @key, @iv = key, iv
    @cipher  = OpenSSL::Cipher::AES128.new(:CBC)
    @message = message

    cipher.key = key || KEY.delete(' ')
    cipher.iv  = iv || IV.delete(' ')
  end

  def decrypt
    cipher.decrypt
    cipher.update(message) + cipher.final
  end

  def encrypt
    cipher.encrypt
    cipher.update(message) + cipher.final
  end

end