Re: crypting ruby source

On Mon, Apr 15, 2002 at 11:28:53PM +0900, Mark Probert wrote:
> 
> At 02:20 PM 4/14/2002 +0900, Ed wrote:
> >Ludo <[e-mail]> wrote in message news:<[e-mail]>...
> > > Hi,
> > >
> > > Is there anybody aware of a method to crypt the sources of ruby software
> > > please ?
> >
> >The reasons for doing this are obvious, $$.  You want to distribute
> >your work without anyone learning your secrets.  I think more folks
> >would use Ruby if it had this feature.
> 
> There are other reasons as well.  I want to be able to distribute
> data collection on customer sites.  One of the requirements is that
> I be able to get into various boxes that require a fixed password.
> This based on the date of the box, and then apply the date to an
> algorithm to generate the password.  And I don't want the customer to
> have that password algorithm ...
> 

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.

Now, how does one get the encryption key to the controller program.
The nice part of ruby is that it would not be difficult to write a
challenge-response system as part of the controller so a customer 
may gain access to their program and data.

Jim

-- 
Jim Freeze
If only I had something clever to say for my comment...
~