A Low-Latency Post-Quantum Group Authentication Framework for VANETs

Vehicular Ad Hoc Networks (VANETs) require ultra-low-latency authentication in high-mobility scenarios, decentralized trust, and emerging post-quantum security threats. This paper proposes a lightweight blockchain-assisted group authentication framework that integrates post-quantum cryptography with decentralized trust management. The scheme leverages CRYSTALS-Kyber for secure group key distribution, CRYSTALS-Dilithium for message authentication, and zero-knowledge proofs to achieve conditional anonymity and unlinkability. A permissioned Hyperledger Besu blockchain logs encrypted group keys and dynamically updated roadside unit reputation scores, enabling scalable and accountable authentication without monetary transaction overhead. Formal security analysis under the Dolev–Yao adversary model demonstrates confidentiality, authentication, replay resistance, and unlinkability based on standard post-quantum assumptions. Performance evaluation using OMNeT++ and SUMO shows up to 52.7% reduction in communication overhead and a group key update latency of 1.2 ms in dense traffic scenarios, while maintaining high throughput and effective Sybil attack detection. These results highlight the practicality of the proposed framework for post-quantum secure VANET authentication.