From: Raph Levien <raph@c2.org>
Date: Sun, 19 Nov 1995 03:43:15 +0800
To: cypherpunks@toad.com
Subject: Re: Design proposal: crypto-capable generic interface
In-Reply-To: <Pine.BSD.3.91.951118163828.463A-100000@usr3.primenet.com>
Message-ID: <199511181926.LAA26947@infinity.c2.org>
MIME-Version: 1.0
Content-Type: text/plain


atilla brings up many good points, including:
> one of the biggest problems with _any_ crypto system, and pgp is 
> no exception, is tmp files, followed closely by insecure memory.
> insecure memory is a separate issue, but some of the temporary file
> problems can be relegated to reduced risk by passing the daemon the
> user's preferred location for tmp file --for instance, [...]

   An even better solution is to design the cryptosystem so that it
doesn't _need_ temp files int he first place. MOSS wins, PGP loses. I
don't know enough about S/MIME to say.

   In a related vein, Darren New <dnew@sgf.fv.com> sent me a pointer
to First Virtual's SMXP (Simple Mime eXchange Protocol). This is a
cool protocol that does about 50% of what I'm talking about. If you're
interested, here it is:
      ftp://ftp.fv.com/pub/docs/smxp-spec.{ps,txt}

   In order to adapt SMXP into something that's useful for what I've
proposed, numerous changes would need to be made:

* Unix Domain Sockets instead of TCP

* Add negotiation

* Add authentication

   Without these three changes, the system is nearly useless for
crypto. Further, there are two "aesthetic" points I'd like to see
claned up given the chance. First, SMXP makes the "ASCII assumption."
Since the daemon and app will be tightly coupled, definitely running
on the same machine, there is no reason to exclude binary MIME
objects. On the other hand, as far as I know, all of the MIME crypto
protocols are ASCII based (somebody please correct me if S/MIME is the
exception).
   Second, in order to support operation without temp files, it's
necessary to interleave the operations of transferring the object from
the app to the daemon and vice versa. I have a proposal for a
lower-level spec which can handle this quite readily, if anyone is
interested.

   Unfortunately, the proposal doesn't look much like SMXP. However,
the possibility of creating a prototype based on SMXP is intriguing.

Raph

P.S. Did anyone see the mention of the perl/RSA CJR in the latest
Wired? Managed to get the attribution wrong. Still no response.