Whitfield “Whit” Diffie is an American cryptographer and one of the pioneers of public-key cryptography.

Diffie and Martin Hellman’s paper New Directions in Cryptography was published in 1976. It introduced a radically new method of distributing cryptographic keys that went far toward solving one of the fundamental problems of cryptography, key distribution. It has become known as Diffie–Hellman key exchange.

Globally recognized as a leader in public-key cryptography, encryption and network security, Diffie has a long and distinguished career as a leading force for innovative thought. He brings extensive experience in the design, development and implementation of security methods for networks.

Diffie served as Vice President, Fellow, and Chief Security Officer with Sun Microsystems from 1991 to 2009. At Sun, Diffie focused on the most fundamental security problems facing modern communications and computing with emphasis on public policy as well as technology. Prior to joining Sun, Diffie was Manager of Secure Systems Research for Northern Telecom, where he played a key role in the design of Northern’s first packet security product and in developing the group that was later to become Entrust.

Diffie received a Bachelor of Science degree in mathematics from the Massachusetts Institute of Technology in 1965 and a Doctorate in Technical Sciences from the Eidgenössische Technische Hochschule Zürich in 1992. Diffie has received many awards throughout his career and was awarded a Degree of Doctor of Science (Honoris Causa) in 2008 by Royal Holloway College of the University of London. He received the Louis E. Levy Medal in 1997 from the Franklin Institute in Philadelphia and the National Computer Systems Security Award, given jointly by NIST and NSA, in 1996. Diffie is a fellow of the Marconi Foundation and a visiting fellow of the Isaac Newton Institute. He is a 2015 recipient of the A.M. Turing award presented by the Association for Computing Machinery.

With Susan Landau, he is the author of the 1998 book Privacy on the Line: The Politics of Wiretapping and Encryption.