A Quantum-Enhanced Key Agreement and Signature Protocol for Securing Transportation Cyber-Physical Systems

Transportation Cyber-Physical Systems (T-CPS) integrate transportation information with physical elements, enabling advanced features such as real-time vehicle tracking, collision avoidance, and intelligent traffic management. However, this also increases the need for improved security protocols to safeguard the critical identity-based data they transmit through vulnerable wireless networks, such as Vehicle Identification Numbers (VINs) and live Global Positioning System (GPS) coordinates. These T-CPS, traditionally protected by classical encryption algorithms, are now vulnerable due to the rise in quantum computing. Existing solutions are hindered by their complex security features and high computational overhead. To address these challenges, we propose Quantum Key Agreement and Signature Verification (QKASV), a post-quantum protocol that integrates Quantum Key Distribution (QKD) and Quantum Signatures for T-CPS. QKASV uses identity-tied QKD-based keys for session creation, followed by either individual or group quantum signatures. Signatures are created by applying basic quantum gates sequentially rather than lattice-based or certificate-based schemes. Hence, this speeds up the overall key generation, distribution, and management process without compromising the enhanced security. Formal security analysis using standard security models and the Scyther cryptographic protocol verification tool proves that QKASV meets standard security requirements. Further, comparison with similar schemes shows that QKASV operates on the least communication rounds required per signature, and reduces the computational overhead by at least 12%. Therefore, QKASV offers a better security solution compared to existing schemes.