Double-X: Towards double-cross-based unlock mechanism on smartphones

Thanks to the convenience and the increasing functionalities, mobile devices especially smartphones are becoming an essential electronic device in people’s daily lives. Users can take the smartphone for online shopping and payment, as well as chatting with friends. However, with more private and sensitive information stored on such devices, how to secure the phone data becomes an open challenge. To protect a smartphone from unauthorized access, a direct and intuitive approach is to deploy an unlock mechanism, which requires users to input a correct pattern and unlock the phone. In the literature, combining behavioral biometrics can further enhance the security of unlock mechanisms, e.g., Android unlock patterns. In this work, we develop Double-X, a double-cross-based unlock scheme that requires users to unlock the phone by inputting two cross shapes on the selected dots. To authenticate the user, Double-X has to check the selected dots and the behavioral features when drawing the cross shapes. To examine the scheme performance, we perform two user studies with 80 participants with several typical supervised algorithms. The results indicate that participants can achieve a good success rate (e.g., 95%) under our scheme compared with two similar schemes.