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An omnidirectional approach to touch-based continuous authentication

Aaby, Peter; Giuffrida, Mario Valerio; Buchanan, William J; Tan, Zhiyuan


Mario Valerio Giuffrida


This paper focuses on how touch interactions on smartphones can provide a continuous user authentication service through behaviour captured by a touchscreen. While efforts are made to advance touch-based behavioural authentication, researchers often focus on gathering data, tuning classifiers, and enhancing performance by evaluating touch interactions in a sequence rather than independently. However, such systems only work by providing data representing distinct behavioural traits. The typical approach separates behaviour into touch directions and creates multiple user profiles. This work presents an omnidirectional approach which outperforms the traditional method independent of the touch direction - depending on optimal behavioural features and a balanced training set. Thus, we evaluate five behavioural feature sets using the conventional approach against our direction-agnostic method while testing several classifiers, including an Extra-Tree and Gradient Boosting Classifier, which is often overlooked. Results show that in comparison with the traditional, an Extra-Trees classifier and the proposed approach are superior when combining strokes. However, the performance depends on the applied feature set. We find that the TouchAlytics feature set outperforms others when using our approach when combining three or more strokes. Finally, we highlight the importance of reporting the mean area under the curve and equal error rate for single-stroke performance and varying the sequence of strokes separately.

Journal Article Type Article
Acceptance Date Feb 20, 2023
Online Publication Date Feb 23, 2023
Publication Date 2023-05
Deposit Date Feb 20, 2023
Publicly Available Date Feb 23, 2023
Print ISSN 0167-4048
Publisher Elsevier
Peer Reviewed Peer Reviewed
Volume 128
Article Number 103146
Keywords Behavioural biometric, Continuous authentication, Touch biometric, Smartphone security, Model selection


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