This cryptographical collection dates back to 1475. The author was a collaborator of the famous Cicco Simonetta, head of the private chancellery of the Sforzas in Milano and at the same time one of the oldest important theoreticians in the field of cryptography. The manuscript, which came from the library of Philips Edward Fugger, is partly written in Tranchedino´s own hand. It contains 6 intercepted cyphers and 287 unknown and complete and 4 incomplete "keys" applied in the said chancellery. They are not always real keys. Indeed the clear (uncyphered) alphabet, bigrams, trigrams, etc. ... are often represented by arbitrary signs; there is also a code or a wordlist - consisting mostly of proper names - with code-transcription. Of course there are a lot of dummies (symbols without meaning inserted among the real cyphers to complicate decoding). It is very typical that all vowels have more cryptosigns than the consonants because of the supposed higher frequency of vowels in Italian.
We have 1 facsimile edition of the manuscript "Francesco Tranchedino: Secret Diplomatic Documents": Francesco Tranchedino: Diplomatische Geheimschriften facsimile edition, published by Akademische Druck- u. Verlagsanstalt (ADEVA), 1970