Crackstation
Crackstation, c'est un outil qui permet de récupérer des valeurs textuelles liées à des hashes.
CrackStation is a security awareness project started by Defuse Security. Its purpose is to raise awareness about insecure password storage in web applications, and to provide guidance to implementors of user authentication systems. By making large hash lookup tables freely available to the public, we make it easier for security researchers to demonstrate why password storage solutions, like non-salted hashing, are insecure.

Il y a aussi une partie explicative à propos du hashage : https://crackstation.net/hashing-security.htm et même du concept de "salt"