Simpltry

We use EzCrypto because makes it very easy to store a key in a yaml file. We use different keys in development and production for security (its a breeze).

Unfortunately, it doesn’t have a way to store an explicit IV. You would use and explicit IV if you were sharing a key with a 3rd party that didn’t use the same technology as you. I am not exactly sure how Initialization Vectors (IV) work. It has to do with with how a key is used in encrypting and decrypting data.

So, I duck punched EzCrypto using the Evil Twin pattern, even though EzCrypto isn’t a plugin. Here is what the new yaml file looks like:

---
:created: Sun Mar 16 11:26:59 -0400 2008
:algorithm: des3
:key: SOMESECRETVALUE
:iv: ASECRETVALUEBASEDONTHEKEY

and the evil twin (that I store in a plugin):

EzCrypto::Key.class_eval do
  attr_accessor :iv
  def self.load(filename)
    require 'yaml'
    hash = YAML::load_file(filename)
    req = proc { |k| hash[k] or raise "Missing element #{k} in #{filename}" }
    key = self.new Base64.decode64(req.call(:key)) , :algorithm => req.call(:algorithm)
    key.iv = hash[:iv] if hash[:iv]
    return key
  end

  def iv=(base64_iv)
    @iv = Base64.decode64(base64_iv)
  end
end

EzCrypto::CipherWrapper.class_eval do
  def initialize(key,target,mode,algorithm)
    @cipher = OpenSSL::Cipher::Cipher.new(algorithm)
    if mode
      @cipher.encrypt
    else
      @cipher.decrypt
    end
    @cipher.key=key.raw
    @cipher.iv = key.iv if key.iv
    @cipher.padding=1
    @target=target
    @finished=false
  end
end