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The following archive was created by hippie-mail 7.98617-22 on Sat Apr 10 1999 - 01:18:25
Jim Gillogly (jim@acm.org)
Wed, 03 Feb 1999 09:32:08 -0800
Guillaume Chelius writes:
> I'm writing a library to provide "chaffing" abilities to classical
> networks ( cryptography is illegal in France ). The aim is to apply Rivest's
Have you taken into account Prime Minister Jospin's announcement on 19 Jan 1999
that domestic use of 128-bit encryption is now allowed, pending the preparation
of a law that will liberalize crypto use further? You may not need to go to the
trouble of chaffing and winnowing. See Bert-Jaap Koops' excellent page at:
http://cwis.kub.nl/~frw/people/koops/cls2.htm#fr
In any case, I think the chaffing/winnowing proposal was primarily a thought
experiment designed to show that US export laws were silly, rather than a
serious
effort to create a high-bandwidth secure channel without cryptography.
> I have the problem to optimize the volume of chaff without loosing
> security. Has anyone thought about it?
Yes. Take an N-bit message and use an all-or-nothing transform on it
(another Rivest invention -- see his web site). This transform is unkeyed,
and therefore in itself is not crypto-controlled. Send N-k bits of this as a
normal message. The remaining k bits are sent in individually authenticated
chaff/data pairs of 1-bit messages. In the limit for large messages this gives
virtually no bandwidth overhead and provides 2^k protection (OK, it has a
constant overhead of k * (1 + hash-size + packet-overhead) independent of
length).
Whether the crypto police will find this a convincing circumvention will depend
on the quality of your lawyer and the technical sophistication of the court.
-- Jim Gillogly 13 Solmath S.R. 1999, 17:13 12.19.5.16.8, 2 Lamat 1 Pax, Fourth Lord of Night
The following archive was created by hippie-mail 7.98617-22 on Sat Apr 10 1999 - 01:18:25