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：假名被广泛应用于合作式智能交通系统（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，即恶意车辆可以同时伪装成多辆车辆。在本文中，我们提出了一种名为零知识证明的不同身份（zk-PoDI）的新协议，该协议允许车辆证明其在本地区域内并非另一假名的所有者，同时无需泄露其真实身份。Zk-PoDI基于丢番图方程和zk-SNARK，且不依赖任何特定的假名设计方案或基础设施支持。我们证明了zk-PoDI满足实用抗女巫攻击假名系统的所有要求，并具有低延迟、可调节难度、适中的计算开销以及极低的通信成本。此外，我们还讨论了在未来城市规模仿真环境中实现和评估zk-PoDI的后续工作方向。