Alec David Edward Muffett (born 22 April 1968) is an Anglo-American internet security expert and software engineer. His work includes Crack, the original password cracker for Unix, and for the CrackLib password-integrity testing library. He is active in the open-source software community.

Muffett joined Sun Microsystems in 1992, working initially as a systems administrator. He rose through the ranks to become the principal engineer for security, a position which he held until he was retrenched, with many others, in 2009^[1] (shortly before Oracle acquired Sun). While at Sun he was one of the researchers who worked on the factorization of the 512 bit RSA Challenge Number; RSA-155 was successfully factorized in August 1999.^[2]

In 2015, Muffett was named as one of the top six influential security thinkers by SC Magazine.^[3] In October of that year he co-authored^[4] RFC 7686 "The '.onion' Special-Use Domain Name", with Jacob Appelbaum.

More recently, Muffett assisted the New York Times with the creation of their own Tor onion site.^[5] Following that he created a temporary Onion Wikipedia site, accessible only over Tor,^[6] and assisted building further onion sites for BBC News,^[7] Brave,^[8] Twitter,^[9] The Guardian,^[10] and Reddit.^[11]