In this research work, some low complexity and efficient cryptanalysis approaches are proposed to decrypt password (encryption keys). Passwords are still one of the most common means of securing computer systems. Most organizations rely on password authentication systems, and therefore, it is very important for them to enforce their users to have strong passwords. They usually ignore the importance of usability of the password for the users. The more complex they are the more they frustrate users and they end up with some coping strategies such as adding “123” at the end of their passwords or repeating a word to make their passwords longer, which reduces the security of the password, and more importantly there is no scientific basis for these password creation policies to make sure that passwords that are created based on these rules are resistance against real attacks. The current research work describes different password creation policies and password checkers that try to help users create strong passwords and addresses their issues. Metrics for password strength are explored in this research and efficient approaches to calculate these metrics for password distributions are introduced. Furthermore, efficient technique to estimate password strength based on its likelihood of being cracked by an attacker is described. In addition, a tool called PAM has been developed and explained in details in this paper to help users have strong passwords using these metrics; PAM is a password analyzer and modifier.
