Stop to Unlock - Improving the Security of Android Unlock Patterns

Abstract

Android unlock patterns are among the most common authentication mechanisms on mobile devices. They are fast and easy to use but also lack security as user-chosen gestures are easy to guess and easy to observe. To improve the traditional pattern approach, we propose Stop2Unlock, a usable but more secure modification of the traditional pattern lock. Stop2Unlock allows users to define nodes where they stop for a limited amount of time before swiping to the next node. We performed a lab study (n=40) and a field study (n=14) to show that this small change in user interaction can have a significant impact on security with a minimal impact on usability. That is, user-selected Stop2Unlock patterns are significantly harder to guess while being comparable in terms of usability. Additional analysis showed that users perceived the stop component as a rhythmic and memorable cue which supported the selection of higher entropy patterns.