VMs: The Milanese Cipher ledger (revisited)...

[Nick Pelling <incoming@xxxxxxxxxxxxxxxxx>]

Hi everyone,

Yesterday, I had another look at Cerioni's analysis of the Milanese cipher 
ledger, and also read "Renaissance Diplomacy" by G. Mattingly.

The growth in use of ciphers in the 15th century only makes sense if you 
parallel it with the growth in agents and representatives (basically 
"ambassadors"). A few Italian city-states started being represented in the 
latter half of the 14th Century, but this didn't take off until the 15th 
Century.

Mantua was an early adopter of this idea: but it is believed that Milan 
became the most proactive.   Unfortunately the Castello Sforzesco was razed 
to the ground "by enthusiastic republicans" (says Mattingly) in 1447, so 
pre-1450 MIlanese documentary evidence is sparse. :-/

The reason that Milan was able to do this was because Florence and Venice 
both had merchant-controlled economies. For example, Cosimo de' Medici was 
then the most powerful private citizen in Florence - but he was far from 
being a ruler. This meant that there was a lot of bureaucracy that need to 
be sorted out in order to send a representative - voting, seconding, a 
contract, etc. Milan - because it was ruled by an individual - could send 
representatives as required, ie more dynamically.

After Francesco Sforza's takeover of Milan in 1450 (despite having married 
a Visconti, he wasn't actually in line for succession), he set up (or 
rather, Cicco Simonetta set up for him) a new cipher ledger under Francesco 
Tranchedino. The first - and, some might say, most important - cipher in 
the book was that of Nicodemus Tranchedini de Poltremo, who was to be 
Milan's eyes and ears in Florence for many years. He essentially bridged 
between the Medicis and the Sforzas.

Nicodemus Tranchedini's cipher show clear signs of having been expanded 
several times - not just letters, but also short words, diphthongs, and 
numerous vowel-consonant and consonant-vowel pairs, filling the whole page.

However, the next big event was the 1454 Treat of Lodi, which was where the 
Most Holy League was formed. Basically, all [eventually - Naples signed up 
in Jan 1455] the Italian city-states agreed, for the next twenty-five years 
(with possible renewal), to defend each others external borders, and not to 
attack each other... *too* much. This was largely triggered by a shared 
fear of the Turks, after the fall of Constantinople in 1453.

All the same, there was no shortage of small wars fought between the 
city-states during the period, so it might be argued that the Treaty didn't 
achieve *that* much. But it's hard to say.

This Treaty had one major structural weakness - it didn't specify how the 
various powers were supposed to communicate and maintain this balance of 
power. In practice, it led to a rapid explosion of agents/representatives 
being sent all through Italy... which required a correspondingly large 
explosion in the use of ciphers and codes, for "secure" communication.

For example, Tristano Sforza was sent as a representative of Milan to Roma 
(1464), Francia (1466, 1468), and Savoia (1472, 1475). However, it's worth 
noting that the cipher he had in 1451 (with the "4"/"4o" pair, similar to 
the VMS') was replaced in 1464. According to Cerioni:

	[He] became ambassador to Rome towards the end of 1464;
	this code also reveals a strong interest in the orient.

If you accept that the "4o" character links (in some way) the VMS' 
cipherbet and Tristano Sforza's 1451 cipherbet, then I think it's 
comfortable to infer that - by 1464 - it was no longer secure.

To me, this dates (with a high probability) the VMS' cipher to between 1450 
and 1464, as well as placing it near Milan.

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