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：假名被广泛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使得女巫攻击成为可能——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区分证明（zk-PoDI）的新型协议，该协议允许车辆在不泄露真实身份的情况下，证明其并非本地区域内另一假名的所有者。Zk-PoDI基于丢番图方程和zk-SNARK，不依赖任何特定假名设计或基础设施辅助。研究表明，zk-PoDI满足实用抗女巫攻击假名系统的全部要求，具有低延迟、难度可调、计算开销适中以及通信成本可忽略的特性。我们还讨论了在真实城市规模仿真环境中实施与评估zk-PoDI的未来工作方向。