Enhancing usability and security in click-based visual password systems

Security and usability are key elements in system design. A bad design might result in unnecessary inverse proportion between the two, while a good design must find a balance to achieve usable security. In this paper we present and discuss the results of a user study to show how good application of click-based systems can produce a system people can easily use while maintaining security. In this study, participants were asked to do trials using 5 different prototypes of the system. A comparison between them helped to find the best criteria where there is an acceptable balance between security and usability. For instance, using a relatively small tolerance distance enhances security by increasing the password space, the comparison helps to find how small the distance can be while maintaining usability. Another objective of this study was to distinguish between two types of images; the results revealed that using cartoon images have positive impact on usability. Nevertheless, hotspots occurred and that makes particular images more vulnerable to dictionary attacks. Experiments also show that, if they can chose, users select images more vulnerable to hotspots.