Eliminating Centralized Trust in VANETs: A Blockchain‐Assisted SSL‐PUF Authentication and Cross‐Domain Key Agreement Scheme

Vehicular ad hoc networks (VANETs) enable secure vehicle‐to‐vehicle (V2V) and vehicle‐to‐infrastructure (V2I) communications but still rely heavily on centralized trusted authorities, creating scalability limitations, single‐point failures, and increased authentication latency. This paper proposes a blockchain‐assisted decentralized authentication and cross‐domain key agreement scheme based on semiconductor superlattice physically unclonable functions (SSL‐PUFs). The proposed framework replaces centralized challenge–response pair (CRP) storage with blockchain‐maintained cryptographic commitments verified through consortium roadside unit (RSU) validators. Authentication combines blockchain commitment verification with fuzzy extractor reconstruction, whereas distributed entropy aggregation enables collaborative group key generation, and a lightweight roaming‐token mechanism supports efficient cross‐domain authentication. Security analysis demonstrates resistance against replay, impersonation, man‐in‐the‐middle, physical cloning, and single‐point compromise attacks. Experimental results show that the proposed scheme requires only 512 bytes per authentication session, reducing communication overhead by 50.0%–74.2% compared with recent PUF‐based protocols. Moreover, it achieves an authentication latency of 28.41 ms for 100 vehicles, increasing to only 50.31 ms for 500 vehicles, demonstrating excellent scalability. The framework also consumes only 12.47 mJ per authentication session, corresponding to energy savings of 49.4%–84.9% over representative benchmark schemes. These results demonstrate that the proposed framework provides an effective balance between decentralization, security, scalability, and lightweight performance for large‐scale VANET deployments.