From: Mike Ingle <MIKEINGLE@delphi.com>
Date: Wed, 1 Jun 94 04:53:51 PDT
To: cypherpunks@toad.com
Subject: Clipper in patent trouble?
Message-ID: <01HD0J5OIAOO90S1RA@delphi.com>
MIME-Version: 1.0
Content-Type: text/plain


(From alt.security.pgp)

Rich Lethin <lethin@toast.ai.mit.edu> wrote:
>
>I was chatting today with someone moderately well-informed about the
>clipper controversy (unlike me).  He pointed out the following work to me
>by Prof. Silvio Micali at LCS on a technical scheme which can serve as a
>compromise between the needs of society for legitimate wiretaps and the
>need of individuals for strong privacy.  Basically, it seems to be a
>protocol for extending a public key algorithm into a k-escrow system.  This
>apparently differs from the Clipper chip in that algorithmic details are
>well publicized.
>
>The work was in Crypto '92 apparently, and an MIT lab for CS tech report
>numbered TR-579b. 

Even worse, Micali is claiming that his patent on fair cryptosystems
(#5,276,737) covers Clipper as well.  In the Wall Street Journal (May 31,
1994, p. B6):

    Mr Micali, whose patent was issued in January, says his patent
    covers the concept of breaking an encryption key into multiple
    parts that are guaranteed to work, and are held by escrow
    agents.

It seems to me that Clipper does not guarantee that the multiple parts
will work in anywhere near the same way as his scheme does (see my book
for details); Clipper is simply a secret splitting scheme.  On the other
hand, Micali filed his patent application in Apr 92, a full year before
Clipper became public.

Bruce

**************************************************************************
* Bruce Schneier
* Counterpane Systems         For a good prime, call 391581 * 2^216193 - 1
* schneier@chinet.com
**************************************************************************