An Efficient User Authentication using Captcha and Graphical Passwords-A Survey

CAPTCHA is an acronym for Completely Automated Public Turning Test to tell Computers and Humans Apart. Captcha is one of the widely used technique for preventing malicious program from accessing the web resource automatically. Now a days for web security there exists different type of Captcha such as text Captcha, image Captcha, audio Captcha and video captcha. In this paper online security scheme is constructed with text and graphical passwords. Captcha and Graphical passwords are integrated and a novel family of graphical password systems built on top of Captcha technology is called as Captcha as graphical passwords (CaRP). The CaRP scheme is enhanced with more attack handling mechanisms that improves the level of security in online application system and also provides better authentication.