Performance of Eyes-Free Mobile Authentication

Abstract

Mobile device users avoiding observational attacks and coping with situational impairments may employ techniques for eyes-free mobile unlock authentication, where a user enters his/her passcode without looking at the device. This study supplies an initial description of user accuracy in performing this authentication behavior with PIN and pattern passcodes, with varying lengths and visual characteristics. Additionally, we inquire if tactile-only feedback can provide assistive spatialization to support users when interacting with the mobile interface, finding that orientation cues prior to unlocking do not help. A within-group, randomized study was conducted with 26 participants. 1,021 passcode entry gestures were performed under eyes-free conditions. Edit distance measurements were then calculated. Gesture traces and subjective feedback were recorded for subsequent analysis. We found that users who focused on orienting themselves to position the first digit of the passcode using the tactile feedback performed better in the task. These results could be applied to better define eyes-free behavior in further research, and to design better and more secure methods for eyes-free authentication.