Born in
1944, Diffie is one of the most
august cryptographers in history, thanks to his contributions to
public-key encryption.
As a youth, Diffie tore through any book on mathematics he could get his grubby meathooks into. He later studied mathematics at MIT, took a few assorted computer security jobs in the late 60's and 70's, and many people label him as the first cypherpunk. This is due, at least in part, to the fact that he was one of the first cryptographers to not be perpetually employed by goverment agencies, such as the NSA.
Diffie worked on ARPANet, the military precursor to the internet, and predicted the coming of a day when private home users would network their computers together. Private citizens, he reasoned, might be interested in securing their messages to each other through encryption.
Teaming up with Martin Hellman and Ralph Merkle, Diffie came up with the idea of asymmetric key encryption (encryption using one-way functions such as modular arithmetic) which Hellman was able to use to create the Diffie-Hellman-Merkle key exchange system. This became the basis for RSA encyption, which Phil Zimmerman would later use to create PGP.
Diffie co-authored the books Privacy on the Line: The Politics of Wiretapping and Encryption with Susan Landau, and Cracking Codes : The Rosetta Stone and Decipherment with Richard Parkinson and Mary Fisher. He has written more papers than you can shake a really big shaking stick at.