Pseudonyms are widely used in Cooperative Intelligent Transport Systems (C-ITS) to protect the location privacy of vehicles. However, the unlinkability nature of pseudonyms also enables Sybil attacks, where a malicious vehicle can pretend to be multiple vehicles at the same time. In this paper, we propose a novel protocol called zero-knowledge Proof of Distinct Identity (zk-PoDI,) which allows a vehicle to prove that it is not the owner of another pseudonym in the local area, without revealing its actual identity. Zk-PoDI is based on the Diophantine equation and zk-SNARK, and does not rely on any specific pseudonym design or infrastructure assistance. We show that zk-PoDI satisfies all the requirements for a practical Sybil-resistance pseudonym system, and it has low latency, adjustable difficulty, moderate computation overhead, and negligible communication cost. We also discuss the future work of implementing and evaluating zk-PoDI in a realistic city-scale simulation environment.

翻译：假名广泛应用于协作式智能交通系统（C-ITS）中以保护车辆的位置隐私。然而，假名的不可链接性也催生了Sybil攻击，即恶意车辆可同时伪装成多辆车辆。本文提出一种名为零知识身份唯一性证明（zk-PoDI）的新型协议，使车辆无需透露真实身份即可证明其并非本地区域内另一假名的持有者。Zk-PoDI基于丢番图方程与zk-SNARK技术，不依赖于任何特定假名设计或基础设施辅助。研究表明，zk-PoDI满足实用抗Sybil假名系统的全部需求，具有低延迟、难度可调、计算开销适中及通信成本可忽略的特性。本文还讨论了在真实城市规模仿真环境中实施并评估zk-PoDI的未来工作方向。