Text passwords have been used in authentication systems for many decades. Users must recall the textual strings selected during registration to pass authentication. However, there are some serious problems with text passwords - recollectionand security. Hence, various graphical-password authentication systems have been proposed to solve the problems of text passwords. Previous studies indicate that humans are better at recognizing and recalling images than texts.
In 2005, Wiedenbeck et al. proposed PassPoints in which a password consists of a sequence of click-points (5 to 8) that a user chooses on an image. In the paper, we proposed an alternative system in which users can memorize fewer points while providing more security than PassPoints. Based on the idea of using an extremely large image as the password space, we propose a novel world map based graphical-password authentication system called PassMap in which a password consists of a sequence of 2 click-points that a user selects on an large world map. We also conducted a user study for evaluation. The result shows that the passwords of PassMap are easy to memorize for humans and PassMap is friendly to use in practice. Furthermore, PassMap provides higher entropy than PassPoints and also increases the cost of attacks.