Secure Communications in Next Generation Digital Aeronautical Datalinks

The work

Where it appeared

Abstract

Critical infrastructures enable our everyday life and their protection is vital to a nation’s sovereignty and the safety and security of its citizen. Transportation, and among it, civil aviation, is one vital sector that allows for the international travel of goods and passengers. As of 2022, Air Traffic Management (ATM) is in the process of becoming gradually digitized, which is crucial to automate and secure data transmission in civil aviation. For that purpose, the Single European Sky ATM Research (SESAR) project investigates several new digital data links. One such data link is the L-band Digital Aeronautical Communications System (LDACS), which is a cellular, ground-based digital communications system for flight guidance and communications related to the safety and regularity of flight. Unfortunately, many existing and new datalinks in the aeronautical communications ecosystem lack link layer security measures. Among them is LDACS. In this doctoral thesis, we introduce a cybersecurity architecture for LDACS, which presents a first step in integrating sound, long-term cybersecurity to the aeronautical communications ecosystem. The chosen modular security approach allows for seamless integration of various pre- and post-quantum security algorithms and by that ensuring longevity of the security solution. The LDACS cybersecurity architecture thereby pays attention to the various aspects of LDACS use cases, such as digital Air Traffic Network (ATN) data, digital landing augmentation information in the form of the Ground-Based Augmentation System (GBAS), and voice transmissions along with offering Alternative Positioning Navigation and Timing (APNT). Due to the multitude of applications and services, a variety of security measures to protect LDACS user-data and control-data is developed. Among them are two new authentication and key establishment protocols and a novel approach to secure control-data of resource constraint wireless communications system. On the one hand, the security of aforementioned protocols is carefully analyzed with techniques of provable security. On the other hand, practical applicability of the developed security solution is demonstrated in software simulations and in flight trials. Evaluations in an aeronautical communications simulation framework show an added latency of 576 milliseconds when an aircraft attaches to a cell and an added data overhead of 5% to 10%. Lastly, experiments in flight trials show a > 99% GBAS over LDACS availability, which represents an important milestone since GBAS over LDACS has never been demonstrated before. Additionally, LDACS adds security measures to GBAS, which was previously an entirely unsecured system. The presented security solutions enable future aeronautical applications, such as 4D trajectories, hence virtual waypoints that aeronautical vehicles follow automatically, and thus pave a way into a digitized, automatized future of civil aviation.