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Re: VMs: Playfair cipher and triplets

Hi Jim,

At 20:25 19/01/2004 -0800, Jim Gillogly wrote:
The statistics aren't anything like a polyalphabetic or digraphic
cipher... at least not using the things that look like letters to
be the unit of the cipher.

I've tried out several hundred types of the kind of pairings/groupings one might expect for a verbose cipher, and have yet to see any resulting stats even remotely like those of a progressive-key polyalphabetic or a Porta-style digraphic cipher at any level - in fact, there's structure almost everywhere you look. :-o

BTW: from Alberti's codewheel-change every few words, I infer that the "you need roughly 30 letters to break a monoalphabetic cipher" rule must have been reasonably well-known circa 1470: and if you accept (from the historical evidence) that this is the VMs' rough date of production, the only reasonable inference is that the VMs (if some kind of cipher) must involve some kind of cipher change every few words.

The only problem here is that this is what Steve Ekwall has been saying all along. :-)

Cheers, .....Nick Pelling.....

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