ADS-B Signal Transmission Authenticity Reckoner (ASTAR)

Civil Aviation Authorities around the world are incrementally converting the existing ground based radar airspace surveillance systems to airborne Automatic Dependent Surveillance Broadcast (ADS-B) systems. Being global in scope, ADS-B incorporates openly published standards and allows for readily available COTS equipment. Open standards preclude typical authentication mechanisms involving encryption keys and digital signatures that can be deployed to prevent unauthorized and malicious usage. ADS-B can thus be anonymously spoofed to deny airspace to other aircraft including those on DoD missions. Under this effort, we propose to develop a novel approach that exploits the physical characteristics of the ADS-B transmission signal to determine its validity and may even be able to localize the source under certain conditions. We will leverage our proven transmitter localization algorithms along with multi-target tracking filters to develop a ADS-B message authentication system. Phase I effort will evaluate and compare the various feasible approaches using metrics such as detection latencies and false positive and negative alarm rates. Phase II effort will implement a retrofit prototype system in collaboration with Raytheon that will be used to demonstrate performance of the proposed algorithms using the above defined metrics under real-time actual air-traffic conditions and injected spoofed ADS-B messages. BENEFIT: The proposed ADS-B authentication system has both military as well as commercial applications. DoD will certainly benefit by having a robust countermeasure against potential malicious denial of airspace. Besides being able to flag the spoofed ADS-B messages, under certain conditions, the proposed system may be able to provide a localization solution that could be used to suppress the spoof attack source from generating further attacks. Commercial applications may involve working with the standards groups and avionics manufacturers to incorporate the proposed authentication system either within the Minimum Operations Performance Standards (MPS) for ADS-B or be offered as a standard capability of the transponder equipment and will provide an independent check for bad data that may be generated due to system malfunctions on the transmitting or receiving system (which may be an airborne or a ground receiver).