Extended PIN Authentication Scheme Allowing Multi-Touch Key Input

In this paper, we report our trial to make a better form of personal identification number(PIN) authentication for a mobile device. We think that mobile users should be given a more secure alternative authentication because PIN authentication has well-known flaws. However, proposed alternative schemes change the authentication method drastically and that may discomfort mobile users. Our approach is to just change the input operation of PIN authentication by allowing more than one number at a time using a multi-touch enabled screen. We implemented a web-based prototype system and conducted an informal user study using it. The results of the study indicate that PIN input time, input errors and secret memorability of the proposed scheme were no worse than those of conventional PIN authentication. We also discuss the mathematical security level and other advantages of the scheme.