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From: ken@argus.UUCP (Kenneth Ng)
Newsgroups: net.crypt
Subject: Re: randomly adding bits/bytes
Message-ID: <437@argus.UUCP>
Date: Sat, 9-Aug-86 09:21:38 EDT
Article-I.D.: argus.437
Posted: Sat Aug  9 09:21:38 1986
Date-Received: Mon, 11-Aug-86 04:02:31 EDT
References: <8608042018.AA04376@ucbjade.Berkeley.Edu>
Organization: NJ Inst of Tech., Newark NJ
Lines: 43

In article <8608042018.AA04376@ucbjade.Berkeley.Edu>, simsong@wisdom.bitnet (Simson L. Garfinkel) writes:
> 
> There are other ways of making a message difficult to decrypt. Perhaps
> the best is to use a space-compression program on it first. When
> decrypting a message, people (and computers) take advantage of
> redundancy (sp?) in a file -- the same redundancy which space
> compression programs remove. Using compress(1) before using crypt(1) or
> a DES-based system is an excellent idea, as long as the person at the
> other ends knows to uncompress(1) the message afterwards.

Interesting idea, it just so happens that a project around here may be
using something very similar to that.  The scheme is using Lempal Ziv
compression to compress the text, resulting in essentially random
information, with redundent text removed.  The output of that is then
fed through a 256 byte translate table.  Thus both sides must have only
the translate table to communicate back and forth.  Does anyone know
how resistent to cracking this method would be?  It hasn't been
implemented yet, so if someone finds a hole in it, we'd like to know
about it soon.
> 
> (By the way, speaking of crypt(1) -- its been terribly broken. There's
> a program at MIT by Bob Baldwin that breaks even small samples of
> crypt(1) generated cyphertext. Don't use crypt(1))

Interesting, is that program commonly available?

>                         Simson L. Garfinkel
>                         MIT Media Lab
>                         Summer: Weizmann Institute of Science, Israel

-- 
Kenneth Ng:
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