Use Case Analysis of Quantum Key Distribution in Railway Systems

With unprecedented computational capabilities, quantum computers pose a threat to IT security. Just like other domains, the railway domain is increasingly digitalized. Safety and efficiency are at stake. Quantum Key Distribution (QKD) is one approach to increase security in the post-quantum era. We identify 10 use cases for QKD in railway systems, involving interlockings, radio block centers, location cases, on-board units, infrastructure monitoring, dispatchers, drivers, conductors, platform supervisors, and remote operators. We characterize the use cases based on estimated demands for key exchange, confidentiality, integrity, availability, safety, and latency. Following the standard ETSI GS QKD 014, we consider integrations into the Transport Layer Security (TLS) protocol, which is also commonly used in railway applications. Especially for 5 use cases, we see a need for further research due to the mobility of communication endpoints, which may not even be capable of exchanging QKD keys directly.

Keywords: Railway, QKD, Command and Control Signalling (CCS), EULYNX, European Train Control System (ETCS).