Michael Merritt
The Bell Labs researcher who, with Steve Bellovin, showed that a weak password can yield a strong key, as long as the attacker never gets to test guesses offline.
Merritt and Bellovin published Encrypted Key Exchange (EKE) in 1992. The core idea is that the password is never used to encrypt anything an eavesdropper could check guesses against. Someone recording the traffic has nothing to run a dictionary attack on and must try passwords one at a time against the live server. It was the start of the whole PAKE family of protocols.
Augmented EKE followed a year later, sparing the server from storing the password itself. AT&T patented the technique, which kept it out of standards for years and handed alternatives such as SRP a head start. Outside cryptography, Merritt has worked mainly on the theory of distributed algorithms.