List of cryptographers

See also: Cryptographers for an exhaustive list.

Pre twentieth century

Charles Babbage, UK, 19th century mathematician who, about the time of the Crimean War, secretly developed an effective attack against polyalphabetic substitution ciphers.
Leone Battista Alberti, polymath/universal genius, inventor of polyalphabetic substitution, 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, 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 that he did not invent the cipher named after him, as other substitution ciphers were in use well before his time.
Friedrich Kasiski, author of the first published attack on the Vigenère cipher, now known as the Kasiski test.
Auguste Kerckhoffs, known for contributing cipher design principles.
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, deciphered Spanish messages for William the Silent during the Dutch revolt against the Spanish.
Sir Charles Wheatstone, inventor or the so-called Playfair cipher and general polymath.

WWI and WWII Wartime Cryptographers

Nigel de Grey, UK, Room 40, played an important role in the decryption of the Zimmermann Telegram during WWI
Marian Rejewski, Poland, Biuro Szyfrów, a Polish mathematician and cryptologist who, in 1932, solved the Enigma machine with plugboard, the main cipher device then in use by Germany.
Alistair Denniston, UK, director of GC&CS at Bletchley Park during WWII.
William F. Friedman, US, SIS, introduced statistical methods into cryptography.
Solomon Kullback, US, SIS.
Dillwyn Knox, UK, Room 40 and GC&CS, broke commercial Enigma cipher in various situations.
Leo Marks, UK, SOE cryptography director, author and playwright.
John Joseph Rochefort, US, made major contributions to the break into JN-25 after the attack on Pearl Harbor.
Frank Rowlett, US, SIS, leader of the team that broke Purple.
Jerzy Różycki, Poland, Biuro Szyfrów, helped break German Enigma ciphers.
Laurance Safford, US, chief cryptographer for the US Navy for 2 decades+, including WWII.
Abraham Sinkov, US, SIS.
John Tiltman, Brigadier, UK, {{GC&CS]], Bletchley Park, GCHQ, NSA. Extraordinary lenght and range of cryptographic service.
Alan Mathison Turing, UK, Bletchley Park, chief cryptographer Bletchley Park, pioneering logician, and renowned computer scientist, and pioneer.
William Tutte, UK, Bletchley Park, broke Lorenz SZ 40/42 encryption machine (codenamed Tunny) using theory carried out using the Colossus computer.
Gordon Welchman, UK, head of Bletchley Park's Hut Six (German Army and Air Force cipher decryption).
Herbert Yardley, US, MI8, author "The American Black Chamber", worked in China as a cryptographer and briefly in Canada.
Henryk Zygalski, Poland, Biuro Szyfrów, helped break German Enigma ciphers.

Other pre-computer

Elizebeth Friedman, US, Coast Guard and US Treasury Department cryptographer.
Claude Elwood Shannon, US, founder of information theory, proved the one-time pad to be unbreakable.

Modern

See also: Modern cryptographers for an exhaustive list.

Government cryptographers

Clifford Cocks, UK, GCHQ, secret inventor of the algorithm later known as RSA.
James H. Ellis, UK, GCHQ, secretly proved the possibility of asymmetric encryption.
Malcolm Williamson, UK, GCHQ, secret inventor of the protocol later known as Diffie-Hellman.