Performance Evaluation of an Indistinguishability Based Attack Against Spreading Code Secured GNSS Signals

A growing number of services rely on global navigation satellite systems (GNSSs) for positioning and timing, but the widespread adoption of GNSSs has also increased the incentive to mount attacks against them, such as jamming and spoofing. While several security mechanisms have been proposed against these attacks, the most promising solution relies on spreading code authentication (SCA) or spreading code encryption (SCE). This paper analyzes the performance of a novel attack strategy targeting GNSS signals protected by SCE or SCA, assuming that the attacker has no prior knowledge about the secret part of the spreading code sequence. The considered attack strategy minimizes the distinguishability between authentic and forged signals, and turns out to be a linear transformation of the signal received at the attacker position, combined with an independent additive white Gaussian noise. The performance of the attack is evaluated through simulated GNSS signals, considering different scenarios and synchronization non idealities, such as code phase and carrier phase estimation errors.