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From: mjr@hussar.dco.dec.com (Marcus J. Ranum)
Newsgroups: sci.crypt,gnu.misc.discuss,comp.org.eff.talk
Subject: bizarre question...
Keywords: RSA patent rpem
Message-ID: <1991May23.005453.4406@decuac.dec.com>
Date: 23 May 91 00:54:53 GMT
References: <1991May16.201709.3086@msuinfo.cl.msu.edu> <1991May20.183038.9967@watson.ibm.com>
Organization: Digital Equipment Corp., Washington Ultrix Resource Center
Lines: 22

metzger@watson.ibm.com (Perry E. Metzger) writes:
>
>You have done nothing by simply implementing the algorithm. ONLY USE
>OF, OR SALE OF, A PATENTED INVENTION IS ACTIONABLE.

	Can you prove that I did, in fact, encrypt my data with an RSA
scheme, in court, without my being forced to incriminate against myself?

The intuitive argument: the way to prove that in fact I had been using
RSA to encrypt my data would be to decrypt it, thereby proving that you
know the encryption scheme.

	Otherwise I can just claim that I used a one-time pad, and that
you're just reading what you want to see out of the noise.

	Am I totally off base? My uderstanding of cryptography is limited,
but I thought the better cryptosystems tend to make the ciphertext look
like random noise. How, then, do you tell? (code-breakers must have a
reasonable array of tools that can certainly imply what kind of system
you used, but can you *PROVE* it to a jury of ignorami?)

mjr.