Towards Face Unlock: On the Difficulty of Reliably Detecting Faces on Mobile Phones

Currently, reliable face detection and recognition are becoming more important on mobile devices - e.g. to unlock the screen. However, using only frontal face images for authentication purposes can no longer be considered secure under the assumption of easy availability of frontal snapshots of the respective device owners from social networks or other media. In most current implementations, a sufficiently high-resolution face image displayed on another mobile device will be enough to circumvent security measures. In this paper, we analyze current methods to face detection and recognition regarding their usability in the mobile domain, and then propose an approach to a Face Unlock system on a smart phone intended to be more secure than current approaches while still being convenient to use: we use both frontal and profile face information available during a pan shot around the user's head, by combining camera images and movement sensor data. Current results to face detection are promising, but reliable face recognition needs further research.