Assessment of cryptographic approaches for a quantum-resistant Galileo OSNMA

TL;DR

The paper analyzes the vulnerability of Galileo OSNMA to quantum threats and evaluates the feasibility of integrating Post-Quantum Cryptography (PQC) within its current design. It reviews OSNMA’s TESLA-PKC hybrid architecture, summarizes NIST PQC candidates, and maps their requirements onto OSNMA’s constrained message and transmission formats. The authors conclude that the current OSNMA design cannot support PQC over-the-air within existing bandwidth and field sizes, rendering the system not yet quantum-resistant, though cryptographic agility and out-of-band PQC distribution offer short-term mitigation. They propose directions for interim safeguards and longer-term redesigns to achieve quantum-resistant OSNMA, highlighting the practical impact for space-based navigation security and other low-bandwidth, embedded systems.

Abstract

Quantum computing becomes more of a reality as time passes, bringing several cybersecurity challenges. Modern cryptography is based on the computational complexity of specific mathematical problems, but as new quantum-based computers appear, classical methods might not be enough to secure communications. In this paper, we analyse the state of the Galileo Open Service Navigation Message Authentication (OSNMA) to overcome these new threats. This analysis and its assessment have been performed using OSNMA documentation, reviewing the available Post Quantum Cryptography (PQC) algorithms competing in the National Institute of Standards and Technology (NIST) standardization process, and studying the possibility of its implementation in the Galileo service. The main barrier to adopting the PQC approach is the size of both the signature and the key. The analysis shows that OSNMA is not yet prepared to face the quantum threat, and a significant change would be required. This work concludes by assessing different temporal countermeasures that can be implemented to sustain the system's integrity in the short term.

Figures (9)

• Figure 1: I/NAV Message Structure (european_gnss_supervisory_authority_european_2021)
• Figure 2: Allocation of odd OSNMA data within the I/NAV (european_gnss_supervisory_authority_european_2021)
• Figure 3: TESLA high level processing logic
• Figure 4: OSNMA information distribution
• Figure 5: OSNMA processing logic (european_gnss_supervisory_authority_galileo_2022)