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Diss. (sammanfattning) Sundsvall : Mittuniversitetet, 2025

As a key component of Intelligent Transportation Systems (ITS), Vehicular Ad Hoc Networks (VANETs) enable real-time data exchange, traffic optimization, and smarter mobility. However, large-scale deployment raises critical security and privacy concerns, including message integrity, user anonymity, and protection against unauthorized access. This thesis proposes lightweight cryptographic protocols for secure and privacy-preserving authentication in both centralized and decentralized VANETs. The solutions are designed for real-time efficiency, scalability, and strong security. A primary contribution is the development of a localized task management system that significantly reduces authentication latency in centralized VANETs, achieving vehicle verification within a fraction of a millisecond. In decentralized settings, the proposed protocols employ advanced cryptographic mechanisms, including elliptic curve digital signatures (ECDSA) and non-interactive zero-knowledge proofs (NIZKPs), to establish distributed trust without incurring high computational overhead. These techniques provide strong, provable security while preserving user anonymity during authentication and message exchange. To enhance group communication in VANETs, the thesis introduces efficient group key-sharing schemes that support secure, direct interactions among vehicles. Furthermore, a novel localized revocation mechanism immediately removes malicious vehicles from the network, addressing a key limitation in existing frameworks. This ensures fast, secure authentication for time-sensitive message transfers while limiting the propagation of malicious data. The thesis also investigates the proposed protocol’s performance under dynamic conditions, such as high traffic density, large-scale decentralized deployments, and remote authentication scenarios.