A hybrid graphical user authentication scheme

Graphical password has been introduced as an alternative to text based approaches motivated by the fact that humans can remember images better than text. In this paper we have proposed a graphical user authentication scheme that is a hybrid technique, combination of recognition based scheme and dynamic graphics. The scheme basically focuses on resistivity to shoulder surfing attacks without sacrificing usability, while at the same time improving strength against guessing attacks. The proposed work exploits novel concept of dynamic graphics in which colored objects are associated with the individual password portfolio images and on the screen the color of these objects changes rapidly. The user is required to click at the instant when the desired color associated with the portfolio image is displayed on the screen. User study demonstrated that the scheme is robust, secure and offers high usability and memorability. Hence, can be easily adopted for authentication in public places such as ATMs, access control, cyber cafes, mobile phones etc. without requiring any hardware changes in the existing set-up.