RT journal article T1 A Privacy-Preserving Behavioral Authentication Framework for Public Transport Applications A1 Monschein, David A1 Knecht, Markus A1 Al Samara, Mustafa A1 Peregrina, José Antonio A1 Piotrowski, Tim A1 Gohlke, Sascha A1 Bennis, Ismail A1 Azan, Wilfrid A1 Abouaissa, Abdelhafid A1 García de Prado Fontela, Alfonso A1 Gilg, Marc A1 Neumann, Eva Maria A1 Nochta, Zoltán A1 Ortiz Bellot, Guadalupe A1 Szilagyi, Ioan A1 Waldhorst, Oliver P. A1 Zirpins, Christian A2 Ingeniería en AutomáticaElectrónica, Arquitectura y Redes de Computadores A2 Ingeniería Informática K1 Behavioral Authentication K1 Behavioral Biometrics K1 Privacy-Preserving Machine Learning K1 Real-World Deployment K1 Federated Learning K1 Homomorphic Encryption K1 Authentication Infrastructure AB Public transportation systems increasingly rely on mobile services for ticketing, trip planning, and account management. These systems require secure and user-friendly authentication because traditional login mechanisms often disrupt the travel experience and only protect the initial login. In this context, behavioral authentication based on interaction patterns and sensor data offers a promising solution for continuous user verification. However, its practical deployment raises challenges related to privacy, robustness, distributed model training, and integration with existing authentication infrastructures. This paper presents the design and deployment of a privacy-preserving behavioral authentication framework for public transportation applications. The framework focuses on system-level integration of established privacy-preserving machine learning and authentication techniques. It combines client-side preprocessing and homomorphic encryption of behavioral data with server-side machine learning-based analysis. It further incorporates model optimization techniques to improve robustness against impersonation and supports collaborative model training across providers through federated learning with coordinated preprocessing and data governance. To enable practical deployment, the framework integrates behavioral authentication into existing OAuth 2.0 and OpenID Connect-based infrastructures, including authentication flows, token management, and cross-provider interoperability.We evaluated the proposed framework through preliminary experiments on a public dataset, a field test with a real-world public transport application, and a second field test exploring federated learning in a collaborative training scenario. The results demonstrate the practical feasibility of the proposed architecture and provide insights into the challenges of deploying behavioral authentication in real-world mobility ecosystems. PB IEEE (Institute of Electrical and Electronics Engineers) SN 2169-3536 YR 2026 FD 2026-06-02 LK http://hdl.handle.net/10498/39748 UL http://hdl.handle.net/10498/39748 LA eng NO Interreg Upper Rhine program (European Union) DS Repositorio Institucional de la Universidad de Cádiz RD 05-nov-2026