You might have caught some spoofing events presented in the recent news. For example, C4ADS, an NGO conducting data-driven analysis of conflict and security matters, concluded that Russia has been extensively using GNSS spoofing to divert aerial drones from entering airspace in the vicinity of governmental figures, airports and sea ports .
Highly secure anti-spoofing protection with OSNMA
OSNMA secures Galileo signals against spoofing by enabling authentication of navigation data, which carries information about satellite location. Navigation data security is important because any modification of this information would result in erroneous positioning calculation.
OSNMA makes use of a hybrid Symmetric/Asymmetric cryptography technique. A secret key on the satellite is used to generate a digital signature. Then both signature and key are appended to the navigation data and transmitted to the receiver. OSNMA is designed to be backwards compatible, so that positioning without OSNMA will still work.
Authentication with OSNMA-enabled receivers
A sophisticated algorithm within the OSNMA-enabled receiver uses a public key to check the authenticity of the transmitted key. It then uses the transmitted key and the digital signature to check the authenticity of the navigation data. If a satellite signal is flagged as spoofed, it is excluded from the positioning calculation.