Abstract: Authentication maintains privacy of a user. Almost all authentication techniques have some vulnerabilities, these vulnerabilities are exploited by hacker in order to gain access to someone privacy without his or her permission which is illegal as per IT rules. This paper focuses on present method which uses alphanumeric password ,It increases the strength of a alphanumeric password and make it difficult to crack a password using common password cracking techniques such a dictionary based attack, rule based attack, password guessing and many more attack used by black hat hacker.

Keywords: brutus force, rule based attack, black hat hacker, Authentication.