Historic cipher mapping

[Mark Knowles]

So I'm not surprised to see Mark taking an interest specifically in Florentine diplomatic ciphers, though I don't know if it's for this reason or some other one.

What you have written about the Polybius square is definitely interesting.

In Meister's book we can see that by 1424 the Florentine ciphers had advanced some way. 1424 was the year of the 1st war in Lombardy between the Republic of Florence and the Duchy of Milan. This cipher key was generated from enciphered letters by the 19th Florentine Archivist Abbot Pietro Gabrielli. He deciphered over 1000 historic ciphers and the keys he generated from those ciphers can be found in the Florence State Archives.

There is a very interesting cipher key, I think, also from 1424 that Gabrielli generated from enciphered letters. He labels this key Zaninus & Conradinus. (And a second identical key labelled Johannes) I am surely this refers to the secretary to the Duke of Milan, Zanino Riccio and to Conradino Vicecomes. I am very keen to see the original enciphered letters from which Gabrielli in the 19th century generated the key. I see no reason why these letters should not have survived the last 150 years. Meister isn't alive to answer why he did not include that key in his book; I suspect as it is a bit unusual and he was not sure what to make of it or who produced it.