Post-Quantum Security Evaluation of Aeronautical Communications

The L-Band Digital Aeronautical Communication System (LDACS) aims to transform aviation communications into a quantum-safe setup, where recent proposals utilize Physical Unclonable Functions (PUFs) as an authentication mechanism and quantum-safe algorithms as a Key Encapsulation Mechanism (KEM). However, the existence of novel techniques that predict the behavior of PUFs, along with severe vulnerabilities in PostQuantum Cryptography (PQC) schemes being exploitable by attacks running on classical computing infrastructures, raises concerns about their security. In this context, the paper performs a security assessment of LDACS and the extent to which the secret quantities used during the mutual authentication between an aircraft and ground control can be disclosed. It is shown that an intelligent quantum preimage algorithm can reveal these aforementioned PUF secret quantities, which are also susceptible to sophisticated side channel attacks even on isolated workstations. In addition, information set decoding and entropy are used to evaluate the strength of the proposed KEMs for LDACS, which are also benchmarked to identify trade-offs between security and performance. Overall, our findings suggest a hardware implementation of CRYSTALS-Kyber as KEM, to further reduce latency, and the utilization of a public key infrastructure for authentication.