Francesco Tranchedino: Secret Diplomatic Documents Facsimile Edition

This cryptographical collection originates from the year 1475 and was penned by Francesco Tranchedino, an associate of the renowned Cicco Simonetta, who led the Sforza's private secretariat in Milan and was also among the earliest significant theorists in cryptography. Originating from the library of Philip Edward Fugger, the manuscript is partially inscribed by Tranchedino himself. It encompasses six deciphered ciphers, alongside 287 complete and four partial "keys" that were utilized within the aforementioned chancellery. However, not all entries qualify as actual keys; the manuscript also uses arbitrary symbols to represent the plaintext alphabet, digraphs, trigraphs, and more.

Included is a code or lexicon, predominantly composed of proper nouns, accompanied by their coded equivalents. Interspersed within the genuine ciphers are numerous "dummies" — meaningless symbols included to thwart deciphering efforts. Notably, the vowels are assigned more cryptographic symbols than consonants, reflecting their anticipated higher occurrence in Italian text.