Signing in the Air w/o Constraints: Robust Gesture-Based Authentication for Wrist Wearables
Chenyu Huang, Zhice Yang, Huangxun Chen, Qian Zhang · 2017
Nowadays, wrist wearables are widely used in applications containing privacy sensitive data. Protecting these data from unauthorized access is highly demanded. However, Personal Identification Number(PIN)-based certificate is not convenient to use for wearables are small in size and have no/very limited input ways. Like signing on paper, signing a pattern in the air and authenticate the user according to the trait from motion sensors is a potential solution for the authentication needs on wearables. However, we observe the successful authentication rate of such approaches in existing designs is not high enough under different postures. We identify the problem is caused by the residue gravity acceleration in motion sensors which introduces inaccuracy in capturing signing dynamic. To this end, this paper proposes a robust gesture-based authentication method that can be used under different postures. Our key idea to use and only use the gyroscope sensor to capture the signing dynamics, so that to get rid of the impact from gravity. To realize this idea, we propose an accurate wrist dynamic capturing method with gyroscope sensor, through which behavior traits are extracted from both time and shape domain. Finally, by comparing the Dynamic Time Warping distance between the real time input and the traits template, signing user can be identified. We implement our method on android smart watch. Our evaluation involves 11 users and lasts for more than one month. The results show that our method can achieve 90.1% balanced accuracy and have stable performance under different postures.