Re: VMs: Playfair cipher and triplets

["Jeff" <jeff@xxxxxxxxxxxxxxxxxxxxxx>]

Nick Pelling incoming@xxxxxxxxxxxxxxxxx
on 20 January 2004 10:16


> 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.....
>

Well maybe Steve Ekwall is right, or at least going in the right direction.

Jeff


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