Whitfield Diffie is an American cryptographer best known for co-inventing public-key cryptography. In 1976, with Martin Hellman of Stanford University, he published “New Directions in Cryptography” in the IEEE Transactions on Information Theory. That paper, listed on Hellman’s Stanford publications page, carries both names as authors and introduced the ideas of public-key cryptosystems, public key exchange, and digital signatures.
The central problem Diffie and Hellman set out to solve was key distribution. In the paper they argued that the widening use of teleprocessing had created a need for cryptographic systems that minimize the need for secure key distribution channels and that can supply the equivalent of a written signature. Their answer broke with thousands of years of cryptographic practice in which both parties had to share a secret key in advance.
Diffie was also a prominent public advocate for the right of civilians to use and study strong cryptography, a stance that put academic researchers in conflict with parts of the United States government during the period Hellman describes on his own pages as the first crypto war.
For their work, Diffie and Hellman received the ACM Turing Award, which Hellman’s Stanford home page describes as the million-dollar award often called the Nobel Prize of Computer Science.