Beyond Classical PKI: A Quantum-Safe Authentication Framework for Automotive OTA Updates

The automotive industry is transitioning to software-defined architectures, making Over-the-Air (OTA) updates essential for managing the long-term lifecycles of modern vehicles, which often exceed a decade. Although Public Key Cryptography (PKC) currently secures these updates, it remains vulnerable to emerging quantum threats. While Post-Quantum Cryptography (PQC) is a feasible solution, its improper adoption in the automotive sector may lead to larger key storage requirements and higher computational costs, thereby hindering the security of resource-constrained devices. To address long-term deployment concerns and comply with vehicle software update requirements, we propose a quantum-safe authentication protocol to deliver software OTA updates securely over the vehicle-to-cloud (V2C) link. Our protocol employs Leighton-Micali Signatures (LMS) for Original Equipment Manufacturer (OEM) server identification and the Module-Lattice-Based Key-Encapsulation Mechanism (ML-KEM) to establish session keys for OTA updates. To mitigate server-side bottlenecks in bursty-request scenarios, we introduce a one-time ticket-gating approach that filters out invalid requests, preventing flooding or DoS attacks against the OEM server. Security analysis demonstrates that our protocol preserves authenticity, confidentiality, integrity, and anti-rollback properties while resisting critical threats, including replay and quantum attacks. Comprehensive performance results show that it achieves more security traits with adequate functional overhead compared to existing works in the context of automotive systems.