On the Use of CSK for GNSS Anti-Spoofing

Many proposals for GNSS anti-spoofing have been presented by the research community in the past decade. Some operate at the receiver side, for instance by exploiting advanced signal processing algorithms, or by making use of additional information, such as that coming from inertial sensors, as a means to detect, and possibly mitigate, interferences and spoofing attacks. Another class of mechanisms, instead, foresee the introduction of new features into the GNSS signals, in order to make it harder to mount spoofing attacks, and make it easier for the reciever to detect them. This paper focuses on the possible use of CSK as an anti-spoofing mechanism, that was proposed for GNSS. In this context, the benefits of this modulation choice to the cryptographic integrity protection of the GNSS signal are taken for granted, on the grounds of its higher symbol cardinality and unpredictability. However a quantitative evaluation of such advantage was never carried out. Our aim is to investigate to what extent CSK is beneficial agains spoofing, evaluating the increase in the necessary attack complexity, and showing results obtained with GNSS simulators and software receivers.