Public Releases

The first public release of Crack was version 2.7a, which was posted to the Usenet newsgroups alt.sources and alt.security on 15 July 1991. Crack v3.2a+fcrypt, posted to comp.sources.misc on 23 August 1991, introduced an optimised version of the Unix crypt() function but was still only really a faster version of what was already available in other packages.

The release of Crack v4.0a on 3 November 1991, however, introduced several new features that made it a formidable tool in the system administrators arsenal.

• Programmable dictionary generator
• Network distributed password cracking

Crack v5.0a released in 2000 did not introduce any new features, but instead concentrated on improving the code and introducing more flexibility, such as the ability to integrate other crypt() variants such as those needed to attack the MD5 password hashes used on more modern Unix and Linux systems. It also bundled Crack v6 - a minimalist password cracker and Crack v7 - a brute force password cracker.

Crack is a Unix password cracking program designed to allow system administrators to locate users who may have weak passwords vulnerable to a dictionary attack.

Crack began in 1990 when Alec Muffett, a Unix system administrator at the University of Wales Aberystwyth was trying to improve Dan Farmer's 'pwc' cracker in COPS and found that by re-engineering its memory management he got a noticeable performance increase. This led to a total rewrite which became "Crack v2.0" and further development to improve usability.