Early 1990s: password security tools COPS by Dan Farmer A local security auditing tool for Unix systems Includes detection of poor passwords as one of the features Crack (for Unix) by Alec Muffett Cracker Jack (for DOS and OS/2) by The Jackal goodpass.c, and later CrackLib by Alec Muffett "to be wired into "passwd" & "yppasswd", etc." npasswd, etc. with proactive password strength checking included