Continuous mobile authentication using user-phone interaction

This chapter aims to introduce and discuss continuous user authentication during natural user-phone interaction. Two types of user authentication are considered, including touch gesture-based and keystroke-based methods.We have described the threats encountered by the pervasive mobile devices, and that the goal of continuous user authentication is to balance security and usability duringnatural user-phone interaction. Literature on two types of user authentication has been reviewed, including touch gesture-based and keystroke-based authentication methods. General touch gesture features have also been elaborated as the feature basis for both types of methods. Three methods have been described: the first one using dynamic time warping, the second one using GTGF and statistical modelling, and the last one using virtual key typing features. The first two methods are good examples of continuous user authentication, which extract user identity from touch gestures throughout the usage sessions. The last method is a good example of user authentication, which takes effects when users apply virtual key typing. We have evaluated the effectiveness of the methods using collected databases as well as online testing user studies. Chapter Contents: • 8.1 Introduction • 8.2 Previous works • 8.2.1 Touch gesture-based mobile authentication • 8.2.2 Keystroke-based mobile authentication • 8.3 Touch gesture features • 8.4 User authentication schema overview • 8.5 Dynamic time warping-based method • 8.5.1 One nearest neighbor-dynamic time warping • 8.5.2 Sequential recognition • 8.5.3 Multistage filtering with dynamic template adaptation • 8.5.4 Experimental results • 8.6 Graphic touch gesture-based method • 8.6.1 Feature extraction • 8.6.2 Statistical touch dynamics images • 8.6.3 User authentication algorithms • 8.6.4 Experimental results • 8.7 Virtual key typing-based method • 8.7.1 Feature extraction • 8.7.2 User authentication • 8.7.3 Experiment results • 8.7.3.1 Login stage result • 8.7.3.2 Postlogin stage result • 8.8 Conclusion • Acknowledgments • References.