Efficient access control scheme for heterogeneous signcryption based on blockchain in VANETs

Access control refers to the mechanisms and policies determining which vehicles or entities can access certain network resources, services, or information. Nevertheless, the dynamic nature of a VANET, the necessity to support a wide range of services, and the importance of protecting users' personal information make access control a challenging issue in vehicle contexts. This study presents an efficient access control scheme based on a blockchain to enhance efficiency and security in heterogeneous signcryption (AC-HSC). Additionally, the AC-HSC protocol incorporates blockchain technology for revocation transparency, allowing roadside units to efficiently verify revoked pseudo-identities without relying on a central unit. The AC-HSC effectively fulfills various security criteria, including integrity, privacy preservation, authentication, traceability, unlinkability, non-repudiation, and resistance against replay attacks. Moreover, the formal analysis carried out in a random oracle model (ROM) proves that the proposed protocol is secure against indistinguishability under chosen-ciphertext attack (IND-CCA2) under the Computational Diffie-Hellman (CDH) assumption and existential unforgeability under chosen message attack (EUF-CMA) under the Discret-Logarithm (DL) assumption. In addition, the proposed protocol effectively addresses the issue of key escrow and successfully eliminates the challenges associated with certification management. Finally, the AC-HSC protocol implemented with a free pairing demonstrates reduced computational costs by 3.57%, 50%, 53.53%, 72.22%, 32.66%, 50.90%, 3.57%, and 57.14%, respectively, and the total energy consumption of the VANET nodes in our protocol reduced by about 4.16%, 45.03%, 50.04%, 68.37%, 31.52%, 49.67%, 4.16%, and 53.68%, respectively, as compared with the existing signcryption schemes.