Whitfield Diffie, who was the Gonville and Caius GC Steward Fellow in the Lent term of 1996, is the public discoverer of the concept of public-key cryptography, published in the paper "New Directions in Cryptography", published jointly with Martin Hellman in 1976. Public-key cryptography now underlies the basic protocols of internet security.

Subsequent to leaving Stanford, Diffie held the positions of Manager of Secure Systems Research for the laboratory of the Canadian telephone system and that of Chief Security Officer for Sun Microsystems. He retired in 2009 and has served as an advisor to various organisations.

Diffie won the Association for Computing Machinery's Alan M. Turing Award for 2015, jointly with his co-author Martin Hellman. In 2017 he was admitted as a foreign member of the Royal Society and in 2020 inducted into the US National Security Agency Hall of Honor.

Diffie is the author, along with Susan Landau, of the book Privacy on the Line which explores the long-running discussion of the right of private and commercial organizations to use of cryptography. More recently, working jointly with Jim Reeds and J.V. Field, he has published Breaking Teleprinter Ciphers at Bletchley Park an historical edition of the final report of the group that developed Colossus, most immediate ancestor of the modern stored-program computer.

Today, Diffie is active in studying, writing, and speaking on all aspect of security technology, its history, and associated policy issues.

Diffie received a Bachelor of Science degree in mathematics from the Massachusetts Institute of Technology in 1965, and was awarded a Doctorate in Technical Sciences (Honoris Causa) by the Swiss Federal Institute of Technology in 1992 for the creation of a new field of science.