cryptoanalysis 002
Peter M Allan
peter.allan at aeat.co.uk
Thu Aug 22 07:06:09 PDT 1996
> From: Scottauge at aol.com
> Date: Tue, 20 Aug 1996 18:36:45 -0400
> Subject: cryptoanalysis 002
> For example, if the crypto-alphabet for e is 23, 45, 190, 200, etc, one can
> remove some of the frequency for a letter. This definately makes it harder
> to attack with the frequency analysis method because the "resolution" of the
> distribution for the letter is lessened to a near randomness. (So it looks,
> there are still clues, eh?)
I think (from memory) this is called "homoalphabetic".
Encyclopaedia Brittanica (Cryptology - article by Gus Simmons)
says that it is still vulnerable to frequencies of digraphs, trigraphs
etc. But even Gauss was keen on it once.
I guess it might have value as a part of another system, making a known plaintext
into one of many. Whether it's worth the increased cyphertext size in a system
you'd hope to be immune to known plaintext attacks anyway is another question.
PA
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