Confidential ADS-B

Automatic dependent surveillance-broadcast (ADS-B) technology offers significant safety and efficiency benefits to the growing worldwide air transport industry. Its use is widespread and continues to grow as countries near or pass their equipage deadlines. As an interoperable extension of air traffic control radar beacon system (ATCRBS) and Mode S, Mode S - Extended Squitter (Mode S-ES) is a widely used ADS-B protocol which is void of security features generally found in modern information transmission systems. The historical and future requirements for interoperability among air surveillance systems also cause difficulty in implementing modern security technology. Many proposals exist for ADS-B security protocols which have sound technology but sacrifice interoperability. By decomposing security principles to focus only on the requirement for confidentiality, we devise a confidential subprotocol for Mode S-ES which is lightweight and interoperable while using industry standard cryptography. The use of format preserving encryption (FPE) with unidirectional asymmetric cryptography allows users who require confidentiality to fully participate in ADS-B without impacting those who do not.