[pypy-dev] Security ideas

[holger krekel]

Hi Armin, 

On Mon, Jul 17, 2006 at 20:02 +0200, Armin Rigo wrote:
> On Thu, Jul 13, 2006 at 08:02:29AM +0200, holger krekel wrote:
> >     def enter_bid(n):
> >         if n > highest_bid.value:
> >             highest_bid.value = n 
> >     enter_bid = secure(enter_bid)
> > 
> > Here the annotator analysis is supposed to prevent a leak of information
> > from the secret value.  But if the if-branch additionally contains:
> > 
> >             num_bids += 1
> > 
> > don't you run into a branching/code-dependent-on-secret-condition 
> > problem again?  Would the annotator prevent the manipulation of 
> > the global 'num_bids'?  Would it need to be a public value? 
> 
> You can't modify global values in RPython anyway.  But more generally,
> yes, the annotator would follow all mutations and propagate security
> levels.

Hum, sorry for having asked too many questions at once.  Obviously, 
i could have said "whatever.num_bids +=1". 
Anyway, it seems that we cannot avoid the "dependent code block" issue 
but you consider the annotator more suited than an object space 
to deal with it, right? 

Also, from your answers i gather that your focus is more on 
getting something at-or-beyond-state-of-the-art first rather
than to provide something directly practical.  Probably makes
sense. 

best, 

    holger