Smartphone-Based Continuous Authentication Based on Flick Input Features Using Japanese Free Text

Abstract

With the rapid spread of smartphones, user authentication on smartphones has become essential. However, conventional user authentication methods using PINs, passwords, pattern locks, etc. have a problem in that users are not authenticated continuously after the first successful authentication; therefore, there is a risk that an authenticated smartphone might be used improperly by unauthorized individuals. To address this problem, continuous authentication that verifies the user’s identity without burdening the user by continuously acquiring biometric information from his/her daily smartphone usage has been proposed. Specifically, as smartphones are utilized for various purposes, ensuring the authenticity of the user during text input actions is crucial. Therefore, in this paper, we focus on achieving continuous authentication on smartphones on the basis of flick input behavior, which is a typical text input action by many smartphone users. We aimed to extract user-specific features from Japanese free text input through flick operations in daily usage and evaluated the effectiveness of continuous authentication on the basis of these extracted features. The simulation results indicated that a certain level of authentication accuracy can potentially be maintained by appropriately selecting suitable features.