Leon Battista Alberti

Leon Battista Alberti (1404 to 1472) was an Italian Renaissance humanist, best known as an architect and author, who also worked as a poet, priest, linguist, philosopher and cryptographer. In computing history he matters as a founder of European cryptography: he is credited with inventing the first polyalphabetic cipher, now called the Alberti cipher, and with machine-assisted encryption using his cipher disk. His essay on cryptography, De componendis cifris, is counted among his minor but pioneering studies, alongside the first Italian grammar. The cryptography historian David Kahn called him the Father of Western Cryptography, pointing to the earliest Western exposition of cryptanalysis, the invention of polyalphabetic substitution and the invention of enciphered code. Because the polyalphabetic cipher was not properly used for several hundred years, its practical influence came late, though it is described as the most significant advance in cryptography since classical times. The claim to the first exposition of cryptanalysis is qualified, since Al-Kindi, a 9th-century Arab polymath, gave a known explanation six centuries earlier.