Quantum-resistant ring signature-based authentication scheme against secret key exposure for VANETs

Abstract

Vehicular ad-hoc networks (VANETs) can improve traffic management efficiency and driving safety to support the construction of Intelligent Transportation System. Privacy protection in VANETs is one of the challenges that cannot be ignored. To this end, the ring signature is a promising cryptographic primitive for providing privacy protection and authentication. However, in practical ring signature-based VANETs, secret keys of vehicle users used for signing are often exposed because of network attacks or careless use. So far, most predecessors do not guarantee security from secret key exposure. Moreover, many existing ring signature-based systems for VANETs are fragile under quantum computer attacks. In this paper, we construct the first forward secure ring signature scheme from lattices. Based on this scheme, we then design a ring signature-based authentication system for VANETs to guarantee privacy-preserving authentication, message integrity, forward security, and post-quantum security. Our scheme combines the binary tree and lattice basis delegation technique to realize a one-way key update mechanism, where secret keys are ephemeral and updated with generating nodes in the binary tree. Thus, the adversary cannot forge the past signature even if the users’ present secret keys are revealed, which can reduce the damage from key exposure. Furthermore, we give rigorous security proof under the hardness assumption of the underlying Small Integer Solution (SIS) problem in lattice-based cryptography to realize post-quantum security. Finally, we show simulation experiments and comparative analysis to evaluate its performance.