From: Rik Hemsley <rik@...>
Date: 2002-04-17T01:31:16+09:00
Subject: Re: crypting ruby source

#if Jim Freeze

> I think this is a good idea for some situations, especially
> as you mention above for storing data.
> And, I can't imagine this being too terribly difficult to implement.
>
> If I was implementing this I would do it as follows:
>   1. Write a controller in c. Granted, this is the weak part
>      of the system, but unless there is internal cooperation from the
>      ruby parser and encrypting of the AST's, then, as far as code
>      is concerned, the security if through obscurity.
>
>   2. Write a special require module (in c) that decrypts its source.
>
>   3. Use the c controller to load the encrypted ruby code, decrypt
>      the require'd modules and run as normal.
>
> Again, the reason for the c controller is so that it is not trivial
> to insert a watch point to read the code after it is un-encrypted.

Something like this, perhaps. (Write 'decrypt' in C):

--------------------------------
def crypt code
  [ code ].pack("m")
end

def decrypt buf
  buf.unpack("m").to_s
end

module Kernel

  alias oldload load

  def load(aFileName, wrap=false)
    if (aFileName =~ /.rx$/)
      puts "Loading encrypted file"
      File.open(aFileName) { |f|
        eval decrypt(f.read)
      }
    else
      oldload(aFileName, wrap)
    end
  end

end

load 'test.rx'
------------------------------

Quite lame, but I don't care :)

Rik