Cryptographer

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, 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 it 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.

Pre-computer

• Charles Babbage, UK, 19th century mathematician who, about the time of the Crimean War, secretly developed an effective attack against polyalphabetic substitution ciphers. His development was published independently a few years later by Friedrich Kasiski, a Prussian officer. Babbage also designed, and had partially built, the first programmable digital computer, the Analytical Engine. He first designed and had partially built the Difference engine for reduced errors in the preparation of mathematical tables -- specifically including navigational tables, thus accounting for the interest of the British Government in the project.
• Alistair Denniston, UK, director of GC&CS at Bletchley Park during WWII.
• Nigel de Grey, UK, member of the Room 40 British codebreaking team who played an important role in the decryption of the Zimmermann Telegram during WWI
• Elizebeth Friedman, US, wife of William F, and cryptographer in her own right for the Coast Guard, Treasury Department, and assorted other US Government agencies in the 1920ss and 1930s. Co-author of the most respected book on cyphers in Shakespeare. The spelling of her name is correct with three 'e's.
• William F. Friedman, US, introduced statistical methods into cryptography; some would describe him as the founder of modern cryptography. Cryptography and genetics director at the Riverbank Laboratories before WWI, wrote extensively on cryptographic theory and practice, and became the US Army's chief (and for some time only) cryptographer, patented several cryptography related inventions some of which are still secret 60+ years later, including some aspects of the SIGABA machine. Co-author of the most respected book on cyphers in Shakespeare.
• Friedrich Kasiski, author of the first published attack on the Vigenère cipher, now known as the Kasiski test (although Charles Babbage discovered a similar attack a few years earlier -- his work was not published).
• Auguste Kerckhoffs, whose design principles have become axioms.
• Dilwyn Knox, UK, Classics scholar and eccentric; WWI Room 40 member who stayed with cryptography between the Wars, becoming the chief cryptanalyst of the GC&CS before WWII. Broke commercial Enigma. Famous for solving problems in the bath.
• Solomon Kullback, US, one of William Friedman's first three employees at the SIS in the 30's.
• Leo Marks, UK, World War II cryptographer and SOE cryptography director, playwright, author of Between Silk and Cyanide.
• John Joseph Rochefort, US, mustang Navy officer (ie, ex enlisted) who early specialized in cryptography and languages, following Safford. A Japanese speaker. Became director of Station Hypo in Hawaii which made major contributions to the break into JN-25 after the attack on Pearl Harbor which led to the successful ambush at Midway. Casualty of power struggle within USN cryptography organization, was forced out of cryptography, and finished WWII in command of a dry dock in California. Honored posthumously for his Hawaiian cryptography work.
• Frank Rowlett, US, leader of the team that broke Purple, contributor to the design of SIGABA. One of William Friedman's first three employees at the SIS.
• Claude Elwood Shannon, US, founded the modern theory of cryptography (ca WWII), proved the one-time pad to be unbreakable, founded and invented/developed information theory and major aspects of communication theory, one of the principal developers of the theory of error-correcting codes (with Richard Hamming), made major advances in logic circuit design in his Master's thesis.
• Laurence Safford, US, chief cryptographer for the US Navy for 2 decades+. Also its first. Pioneered what became OP-20-G in WWII. One of the first Japanese speaking officers in the US Navy.
• Abraham Sinkov, US, one of William Freidman's first three employees at the SIS in the 1930s.
• John Tiltman, UK, British Army officer from Scotland, talented cryptographer/cryptanalyst. Contributed significantly before WWII in the era of hand cryptanalysis and during/after WWII in the era of machine assisted cryptanalysis. Worked at Bletchley Park and GCHQ.
• Alan Mathison Turing, UK, one of the most original minds of the 20th century and one the chief cryptographers at Bletchley Park during World War II. Made major contributions to the theory of computation, and can even be regarded as its originator. Made major contributions to the engineering design and development of early computer hardware and software at the NPL and later at Manchester University.
• Gordon Welchman, UK, Turing's associate in the Naval Enigma Hut at Bletchley Park during WWII. Made major contributions to its cryptanalysis.
• Sir Charles Wheatstone, inventor or the so-called Playfair cipher and general polymath.
• Herbert Yardley, US, best known for his book "The American Black Chamber". Gambler, raconteur, roving cryptographer for hire (eg, Canada, Japan) after MI8 was closed.

Modern

• Carlisle Adams, Can, co-developer of the CAST series of encryption algorithms, one of which was an AES contest participant. Initials accidentally correspond to first 2 letters of CAST. See also Stafford Tavares.
• Leonard Adleman, US, the 'A' in RSA, now at the University of Southern California. Has done pioneering work using DNA as a computer.
• Ross Anderson, UK, Cambridge University Professor, Department Director, author of many books and articles who has done important work on several aspects of cryptography and information security, including analysis of trusted computing devices, security of bank systems, robustness of protocols, steganography, "Soft TEMPEST"; cryptanalysed a number of algorithms; designed several including co-designing Serpent (an AES finalist) and Tiger a message digest algorithm. See
• Daniel J. Bernstein, US, got US regulations on control of software cryptography code changed in Bernstein v. United States and also proposed interesting ideas for the factorization of large composite numbers, the goal being to break bigger RSA keys. See
• George Blakley, US, independent inventor of secret sharing
• Matt Blaze, US, demonstrated a security problem with the NSA Clipper chip design, published a description of a (long known 'to the trade') security problem with master keying of physical locks, and designed and implemented the Cryptographic File System for the Unix Operating System. See
• Don Coppersmith, US, one of the IBM team which designed the entry in the NBS competition which resulted in (after NSA / NBS modification) the Data Encryption Standard
• Joan Daemen, Belgian, co-developer of Rijndael which became the AES encryption algorithm. Prolific developer of cryptographic algorithms.
• Whitfield Diffie, US, one of the public inventors of asymmetric key cryptography and author
• James Ellis, UK, staff member of GCHQ who proved the possibility of 'non-secret' encryption. That proof led Clifford Cocks to invent (first) what has become known as the RSA encryption algorithm, and Malcolm Williamson (note: not the composer) to invent (first) what has become known as the Diffie-Hellman protocol.
• Taher ElGamal, US(?), inventor of the ElGamal discrete log cryptosystem, and chief designer of the SSL protocol while at Netscape Communications Corporation
• Horst Feistel, US. Involved in early work on block ciphers at IBM, including Lucifer, DES, SP-networks and Feistel networks.
• Lars Knudsen, Denmark, designed and analysed a large number of symmetric algorithms.
• Paul Kocher, US, discovered differential power analysis and designed SSLv3 See http://www.cryptography.com
• Mitsuru Matsui, Japan, discovered linear cryptanalysis, and helped design the MISTY and Camellia algorithms.
• Vincent Rijmen, Belgian, co-developer of Rijndael which became the AES algorithm. See http://www.esat.kuleuven.ac.be/~rijmen
• Ronald L. Rivest, US, the 'R' in RSA, Professor at MIT and prolific crypto algorithm inventor. See http://theory.lcs.mit.edu/~rivest/
• Adi Shamir, Israel, the 'S' in RSA now at Weizmann Institute, Israel. A prolific inventor of crypto algorithms, protocols, and cryptanalytic techniques.
• Bruce Schneier, US, CTO and founder of Counterpane Internet Security, Inc., one of the developers of Twofish, an AES contest finalist, several other encryption algorithms, a random number generator or two, etc. Author of Crypto-Gram a monthly newsletter on cryptography topics and several influential books. See http://www.counterpane.com (Counterpane Internet Security, Inc.) or http://www.schneier.com/ (personal website),
• Stafford Tavares, Can, co-developer of the CAST series of encryption algorithms, one of which was an AES contest participant. Initials accidentally correspond to last 2 letters of CAST. See also Carlisle Adams.
• David Wagner, US, discovered attacks on many widely deployed algorithms and was one of the developers of Twofish, an AES contest finalist

See also

• Cryptography