Investigation of the Effectiveness of Defenses Against the Forward Estimation Attack on Galileo OSNMA

Cillian O’Driscoll, Ignacio Fernandez-Hernandez, Jón Winkel

Peer Reviewed

Abstract: The Forward Estimation Attack (FEA) is an attack on GNSS Navigation Message Authentication (NMA) that takes advantage of the presence of Forward Error Correction (FEC) to predict symbols in advance of their being broadcast. This permits a potential attacker to introduce a timing advance into a spoofed signal, that would otherwise not be possible. Prior work has focused on the development of the attack and on identifying those symbols that cannot be predicted by such an attack. In this work we develop a modification to the FEA attack that utilizes a soft-decision approach based on the belief propagation algorithm, that should provide advantages in low C/N0 conditions, and also more fully develop a defense against the attack. The resulting algorithms are tested on real Galileo Open Service Navigation Message Authentication (OSNMA) data from an open sky environment, and it is shown that the defense mechanism can very reliably detect a FEA attack with a probability of about 99 % for false alarm rates down to 10^?3 .
Published in: Proceedings of the 2024 International Technical Meeting of The Institute of Navigation
January 23 - 25, 2024
Hyatt Regency Long Beach
Long Beach, California
Pages: 403 - 416
Cite this article: O’Driscoll, Cillian, Fernandez-Hernandez, Ignacio, Winkel, Jón, "Investigation of the Effectiveness of Defenses Against the Forward Estimation Attack on Galileo OSNMA," Proceedings of the 2024 International Technical Meeting of The Institute of Navigation, Long Beach, California, January 2024, pp. 403-416. https://doi.org/10.33012/2024.19541
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