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

[Nick Pelling <incoming@xxxxxxxxxxxxxxxxx>]

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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