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From: jbn@glacier.STANFORD.EDU (John B. Nagle)
Newsgroups: sci.crypt
Subject: Re: New PubKey System Coming
Message-ID: <13887@glacier.STANFORD.EDU>
Date: Fri, 2-Jan-87 13:40:02 EST
Article-I.D.: glacier.13887
Posted: Fri Jan  2 13:40:02 1987
Date-Received: Fri, 2-Jan-87 21:00:16 EST
References: <3859@utcsri.UUCP>
Organization: Stanford University
Lines: 29
Summary: Is the algorithm being disclosed?


       Is the patent out in any country yet?  I'm interested in seeing how
it works.  A patent number for any country would be appreciated.  In
any case, these things can't be considered secure until they've stood
considerable scrutiny.  Always remember Friedman's remark, "No new cypher
is worth looking at unless it comes from someone who has already broken a very
difficult one."
       The big problem with public key systems is that one needs some
suitable function whose inverse is enormously harder to compute than the
function itself.  The two functions most discussed to date are the knapsack
problem and the factorization of large numbers, and advances in mathematics
have made both problems much more tractible in the last few years.  If
someone has a new function, it may be a significant step forward.  Or
it may not.  One would like a problem with a provable lower bound, but the
theory of lower bounds is very weak as yet.
       With the advent of good, fast, modem technogies, and good voice
digitization and compression schemes, the use of digital encryption for
voice over voice-grade lines without serious loss of quality is already
possible.  If this new scheme works, one could produce secure telephones
for consumer use which would automatically exchange public keys at startup
and then go to encrypted digital mode when talking to another of their
own kind.  This sounds expensive and complicated, but it will eventually 
come down to one chip with a small number of pins.  
       This has definite product potential.  Let's hear more details about
the technology.

					John Nagle

					John Nagle