[65815] in Cypherpunks
Re: a simple cypher scheme
daemon@ATHENA.MIT.EDU (Perry E. Metzger)
Wed Sep 18 17:06:23 1996
To: sjohnson@packetengines.com (stuart johnson)
Cc: cypherpunks@toad.com
In-Reply-To: Your message of "Tue, 17 Sep 1996 17:07:20 PDT."
<9609180005.AA14720@ns.tsinet.com>
Reply-To: perry@piermont.com
Date: Wed, 18 Sep 1996 12:41:34 -0400
From: "Perry E. Metzger" <perry@piermont.com>
stuart johnson writes:
> a co-worker here has
> come up with a 'cypher' scheme that he would like to use to send code to our
> clients. the scheme is this : he would take the file of code and pad all
> lines to the length of the longest line, he would then preform column swaps,
> and then row swaps, to 'mix up' the file. the person receiving the file
> would then preform the opposite functions to recover the file. it seems so
> simple that it can't be good. i've convenced him to use pgp, but i would
> like some input if possible on why his cypher scheme is not a good one.
This is a variant on a scheme called a transposition cipher. It was
okay, but not very good, technology in the Civil War, when it was last
seriously used. It can be broken with a technique called multiple
anagramming.
Perry
