Session A4: GNSS Security: Interference, Jamming and Spoofing 1

Investigation of the Effectiveness of Defenses Against the Forward Estimation Attack on Galileo OSNMA
Cillian O'Driscoll, Independent Consultant; Ignacio Fernandez Hernandez, European Commission; Jon Winkel, Independent Consultant
Location: Seaview Ballroom
Date/Time: Thursday, Jan. 25, 10:40 a.m.

Peer Reviewed

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 .