Abstract—Vehicular ad-hoc networks (VANETs) have drawn

a lot of attention for their potential to improve traffic efficiency

and safety. To deal with anonymous authentication and message integrity during communication, many protocols have been

designed. One important approach is using Ring Signature to

obtain superior security and better efficiency. However, most

of the previous Ring Signature-Based authentication protocols

could not support the Trusted Authority (TA) to revoke the

vehicle user’s identity whenever it wanted. In this paper, we

solve this problem and realize Conditional Privacy-Preservation

Authentication successfully. As part of our work, we propose

the first Lattice-based Revocable Ring Signature scheme, and

prove its security under the random oracle model, which could be

of independent interest. It is quantum-resistant, highly efficient,

and suitable for scenarios where the TA needs to be accountable.

Lastly, it is worth mentioning that we adopted a similar structure

with the NIST signature standard CRYSTALS-Dilithium, which

will increase the richness of the algorithm and standardization.

Index Terms—Conditional Privacy-Preservation Authentication (CPPA), Lattice, Post-Quantum Cryptography, Ring Signature, Vehicular Ad-Hoc Networks (VANETs).