A Lightweight Authentication and Group Key Distribution Protocol based on Sub-group Hierarchical for Smart Traffic Light Systems

Smart Traffic Light Systems (STLS) are vital for managing traffic congestion and enhancing mobility in modern smart cities. Ensuring real-time communication among traffic lights, key generation, and distribution must be highly efficient to avoid delays that could impact system responsiveness and security. However, existing group key distribution protocols remain inadequate regarding computational efficiency and limited scalability in resource-constrained environments. To address this challenge, we propose a lightweight authentication and group key distribution scheme integrating two-layer mutual authentication based on Lucas polynomials with a sub-group hierarchical structure formed by K-Means clustering. This design reduces the polynomial degree to the sub-group size and employs lightweight primitives such as hash and XOR to minimize computation. The scheme was validated through NS-2 simulations using real traffic light deployment data from Surabaya, Indonesia. These improvements directly result in enhanced energy efficiency with up to 41%. Scalability analysis shows that energy increases only by 0.000144 J per node, confirming sub-linear scalability. Comparative evaluation shows reductions of 78% in computation time, 72% in setup time, and 87% in latency. The scheme also ensures robust security, maintaining key confidentiality, resistance to node compromise, and replay resistance, making efficient and secure real-time STLS.