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Re: VMs: A comment on Jacques Guy's table

Hi Petr,

At 22:27 20/12/2003 +0100, Petr Kazil wrote:
However, the other book about Papal cryptography - that's too fragile to
scan - has a lot of interesting ideas. In later years the Vatican didn't use
phantasy character sets anymore, but switched to numbers entirely. Usually
they kept all the old mechanisms intact - multiple caesars, nulls, syllable
codes, nomenclators.

AIUI, in the Quattrocento, Milan was the centre for (symbol) ciphers and Florence was the centre for (number) codes. As the Tranchedino ledger continues (remember that all the ciphers are basically ordered by [ascending] date), more and more number-like codes start making their way into the ciphers - many of them ended up a hotchpotch of cipher & code.

So, perhaps this change in system was more a sign of Florence's rising influence over the Vatican? It's probably not relevant to the VMs, but is perhaps an interesting angle on history. :-)

Then there is mention of ciphers with several alphabets twhere one alphabet
would be used for a few lines and then "after a sign that is apparent only
to the initiated" the second alphabet would be used and so on.

What I mean to say is that apparently the concept of "state" and "state
transitions" was widely known and used in cryptography. This means that
Markov-chains, statistical-correlations and clustering approaches might all
bring us nearer to a solution.

Now... I only recall reading about such ciphers in the context of Renaissance cryptography (say, 1550 or later). However, that's not to say that they couldn't have been devised earlier... though it's perhaps notable that none of the hundreds of ciphers in the Milanese ledgers (there's *another* cipher ledger in the Milanese archives, but it's not half so fascinating as the Tranchedino one) has the concept of more than one state (so far as I can see). Does the book give a date for this idea?

Then it says  Leo Baptista Alberti died in Rome in 1472. He wrote a treatise
on cryptography that is older than Cicco Simonetta's treatise (1474 Milan).
Matteo Argenti is his (grand?) son and he was still practicing cryptography
in 1605. BTW - Vigenere visited Rome in 1549 and 1566-67.

It's well documented that Alberti wrote a private work on *cryptography* (ie on making codes) about then (but which was only published much later). However, there had been many works on cryptography written in previous centuries (particularly in Arabic, AIUI).

What particularly distinguished Simonetta's short treatise was that it was on *cryptology* (ie on breaking codes).

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

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