Under the table: tap authentication for smartphones

Current smartphone authentication methods are known to be susceptible to even rudimentary attacks based on observation. In this paper, we propose an approach to authentication based on rich tapping patterns that addresses this problem. We present a novel tapping detection technique, using a single example as a template. We also report on two user studies (N = 30 and N = 19) where tapping authentication is compared to the leading alternatives, both in an “out in the open” and in an “under the table” condition. Results indicate that the tapping method approximates current standards of security and usability, but also affords inconspicuous authentication, thus allowing the user to self-protect in social settings.