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From: vinge@sdcsvax.UUCP
Newsgroups: mod.os
Subject: public key doubts
Message-ID: <2844@sdcsvax.UCSD.EDU>
Date: Wed, 11-Mar-87 03:00:56 EST
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Posted: Wed Mar 11 03:00:56 1987
Date-Received: Thu, 12-Mar-87 23:00:59 EST
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I have a crypto question.

Classically, it seems like any crypto scheme with a fixed size key
fails if the enemy has enough plaintext with corresponding ciphertext.

With public key encryption, the enemy *by definition* can generate
as much plaintext/ciphertext as he wishes. I don't see anyone talk about this,
but it seems to me that this puts a real (and low) time limit on how
long one can afford to use a given public/private key pair. 

Comments?

-- Vernor


Darrell Long
Department of Computer Science and Engineering, C-014
University of California, San Diego
La Jolla, California  92093

ARPA: Darrell@Beowulf.UCSD.EDU
UUCP: sdcsvax!beowulf!darrell