From: "Perry E. Metzger" <perry@imsi.com>
Date: Tue, 21 Jun 94 08:42:58 PDT
To: dwomack@runner.jpl.utsa.edu (David L Womack)
Subject: Re: DE-crypting (trivial case)
In-Reply-To: <9406211522.AA12298@runner.utsa.edu>
Message-ID: <9406211542.AA08068@snark.imsi.com>
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David L Womack says:
> Fellow C'punks:
> 
> I was wondering if anyone knew of software that
> does decryption of weakly encrypted messages,
> i.e., similar to ROT13, but perhaps ROT(x) where
> 0<x<26?  Or maybe a bit more sophisticated, but
> not even at the single DES level?

Between Caesar ciphers and DES lies an enormous range of encryption
systems -- much as an enormous range of transport options lie between
crawling on hands and knees and flying a space shuttle. Single DES is
an extremely sophisticated encryption system -- its just a bit out of
date. Breaking Caesar ciphers can be done by hand by a child with no
knowledge of statistics. Breaking the traffic from an M209 is quite
doable, but not exactly something you could explain in five minutes to
someone, or even necessarily an hour.

> Also...anyone know of any histogram software?
> i.e., I input a file, it counts how many
> letters of each type, and outputs it in a
> table and/or a graph?

You can write that yourself in about three or four minutes in PERL.
Just keep an array of N elements corresponding to each of the ASCII
codes (or whatever) and count. Its between four and fifteen lines,
depending on how fancy you want to get with the printout.

> If not, I'll have to (horrors!) write code!

Probably good for your soul.

Perry