1994-06-21 - Re: DE-crypting (trivial case)

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From: cort <cort@ecn.purdue.edu>
To: dwomack@runner.utsa.edu (David L Womack)
Message Hash: af74f8133464eebfe54902e0e5bb76ff3ca614220621238a1f3257ba0b3e0b88
Message ID: <199406211616.LAA06569@en.ecn.purdue.edu>
Reply To: <9406211522.AA12298@runner.utsa.edu>
UTC Datetime: 1994-06-21 16:17:12 UTC
Raw Date: Tue, 21 Jun 94 09:17:12 PDT

Raw message

From: cort <cort@ecn.purdue.edu>
Date: Tue, 21 Jun 94 09:17:12 PDT
To: dwomack@runner.utsa.edu (David L Womack)
Subject: Re: DE-crypting (trivial case)
In-Reply-To: <9406211522.AA12298@runner.utsa.edu>
Message-ID: <199406211616.LAA06569@en.ecn.purdue.edu>
MIME-Version: 1.0
Content-Type: text

> 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?

There is stuff to be had.  Look on the ftp sites (especially ripem.

crypt200 by John K. Taber helps solve transposition and substitution

> 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?

Again, lots of statistics gathering software in the crypt directories
lying around the internet.

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

I have examined a couple of these software packages and found some
of them very powerful.  However, all I have seen are interactive.
I want a pipe (ciphertext in; plaintext out).  This is completely
feasible for large classes of substitution/transposition ciphers.

I have ideas and _some_ code.

Some of the concepts to look for include isomorphisms and cross

Good luck!