Les règles de Cicco Simonetta pour le déchiffrement des écritures secrètes

In a compact set of folios from a 1595 Italian manuscript, a collection of notes once labeled a “diary” reveals the hand of Cicco Simonetta, the shrewd secretary who served the first Sforza dukes of Milan. Scholars have pieced together these fragments—account ledgers, catalogues and, most intriguingly, a series of rules for extracting secret letters—while debating whether the whole assemblage truly belonged to Simonetta. The pieces are dated and tied to the bustling courts of Pavia and Naples, grounding the work in a vivid slice of fifteenth‑century political life.

The core of the text presents Simonetta’s step‑by‑step instructions for decoding the fledgling cryptographic systems that spread across Italy after July 4, 1474. He explains how names were replaced by special signs, how ordinary letters could be swapped, reversed or paired with numbers, and why meaningless “null” symbols were inserted to throw off prying eyes. For anyone fascinated by the birth of modern secrecy, these rules offer a rare glimpse into the mind of a Renaissance master of hidden communication.