Privacy-Preserving Centralized Authentication for Smart Vehicular Environments

As intelligent transportation systems and dense IoT environments expand, efficient and privacy-preserving authentication becomes essential. Traditional centralized methods often suffer from latency, limited scalability, and privacy risks, especially under high user density. This paper presents a centralized group authentication protocol that enables simultaneous, anonymous authentication of multiple users using polynomial interpolation over elliptic curve groups. Each user holds a private share derived from a secret polynomial, and authentication is performed by aggregating their elliptic curve contributions. To ensure operability with small groups, publicly known dummy identifiers are introduced, preserving both functionality and user unlinkability. The protocol also embeds a lightweight key establishment mechanism without requiring explicit key exchange. Security analysis confirms resistance against impersonation, replay, and collusion attacks, while performance results show significant improvements in computation and communication overhead. These features make the scheme well-suited for scalable, privacy-aware authentication in V2X and IoT systems.