Re: US Congress already discussing bans on strong crypto

From: Kris Kennaway (kris@obsecurity.org)
Date: 09/18/01 

Date: Mon, 17 Sep 2001 20:05:34 -0700
From: Kris Kennaway <kris@obsecurity.org>
To: Scott Corey <Scott@bsdprophet.org>

On Mon, Sep 17, 2001 at 12:42:02PM -0500, Scott Corey wrote:
> Michael Richards wrote:
> >
> > I think it would be just as effective if they were to pass a law
> > requiring all terrorist organisations to provide backdoor keys to
> > their encrypted communications.
> >
> > Since things like DES and RSA are so widely published there really
> > isn't a way to make these "go away". If you're planning on hijacking
> > aircraft and flying them into buildings, I don't think you will care
> > that much about a little law against sending PGP'd email.
> <snip>
>
> What makes you think there are no backdoors now?

There's nowhere to put a "backdoor" in the RSA algorithm. There's
room to put a backdoor in the DES algorithm, and in fact when the DES
algorithm was under consideration back in the early 70's the NSA did
request a change to the "S-Boxes" of the candidate algorithm submitted
by IBM which was eventually accepted. This change may have seemed
suspicious, until a number of years later when civilian cryptographers
discovered the technique of differential cryptanalysis and realised
that the NSA's changes were to improve the resilience of DES against
that attack, which they evidently already knew about.

As for backdoors in other algorithms: well, that's why peer review of
cryptosystems by trained cryptographers is so important. People spend
their lives trying to break cryptosystems. If you listen to their
recommendations, you'll do pretty well.

Kris

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