List of cryptographers

Pre-19th century

• Leone Battista Alberti, polymath/universal genius, inventor of polyalphabetic substitution (see frequency analysis for the significance of this -- missed by most for a long time and 'dumbed down' in the Vigenère cipher), and what may have been the first mechanical encryption aid.
• Giovanni Battista della Porta, author of a seminal work on cryptanalysis.
• Julius Caesar, Roman general/politician/author/assassination victim, has the Caesar cipher is named after him, and a lost work on cryptography by Probus (probably Valerius Probus) is claimed to have covered his use of military cryptography in some detail. It is likely, however, that he did not invent the cypher named after him, as other substitution ciphers were in use well before his time.
• Johannes Trithemius, mystic and first to describe tableaux (tables) for use in polyalphabetic substitution. Wrote an early work on steganography and cryptography generally.
• Philips van Marnix, lord of Sint-Aldegonde, decyphered Spanish messages for William the Silent during the Dutch revolte against the Spanish.