Whitfield Diffie is a consulting scholar at CISAC. He was a visiting scholar in 2009-2010 and an affiliate from 2010-2012. He is best known for the discovery of the concept of public key cryptography, in 1975, which he developed along with Stanford University Electrical Engineering Professor Martin Hellman. Public key cryptography, which revolutionized not only cryptography but also the cryptographic community, now underlies the security of internet commerce.

During the 1980s, Diffie served as manager of secure systems research at Northern Telecom. In 1991, he joined Sun Microsystems as distinguished engineer and remained as Sun fellow and chief security officer until the spring of 2009.

Diffie spent the 1990s working to protect the individual and business right to use encryption, for which he argues in the book Privacy on the Line, the Politics of Wiretapping and Encryption, which he wrote jointly with Susan Landau. Diffie is a Marconi fellow and the recipient of a number of awards including the National Computer Systems Security Award (given jointly by NIST and NSA) and the Franklin Institute's Levy Prize.