LBRAKA: Lattice-Based Robust Authenticated Key Agreement for VANETs

Authenticated key agreement between vehicles and roadside units (RSUs) is crucial for securing vehicular ad-hoc networks (VANETs). However, most of relative works cannot withstand quantum attacks due to the adoption of conventional cryptographic algorithms, such as those based on discrete logarithm and large integer factorization problems. Although some solutions generally employ lattice problems to resist against quantum attacks, they lack a privacy preserving mechanism to provide the unlinkability of vehicle public keys or certificates, as well as robust conditional traceability. In this study, we propose a lattice-based robust authenticated key agreement (LBRAKA) scheme for VANETs, which facilitates anonymous authentication and key negotiation between vehicles and RSUs and employs the ring learning with errors problem to withstand quantum attacks. Specifically, obfuscated expiration times are allocated to vehicle public keys and certificates for achieving the unlinkability of public keys. Vehicles and a central authority are required to create commitments to the vehicle's real identity and public key, in order to support robust conditional traceability. Security analysis demonstrates that LBRAKA not only ensures anonymity, conditional privacy, unlinkability, key escrow freedom, public verification of traceability, and tracing robustness, but also effectively thwarts most known attacks. Comparative experimental results show the promising usability of LBRAKA.