Attacking and Improving the Tor Directory Protocol
Zhongtang Luo, Adithya Bhat, Kartik Nayak, Aniket Kate
IEEE Symposium on Security and Privacy 2024 · Day 3 · Continental Ballroom 4
Tor, short for The Onion Router, stands as the largest anonymous communication service globally, serving approximately 4 million users daily. Its fundamental operation relies on clients obtaining a list of available volunteer relay nodes from a set of **directory servers**, subsequently routing traffic through a randomly selected three-hop path to its destination. While extensive research has historically focused on the security of this three-hop relay path, this talk, presented by Zhongtang Luo and his collaborators, shifts focus to a critical, yet often overlooked, component: the security of the initial step where clients acquire network information from directory servers.
AI review
This research uncovers a fundamental equivocation vulnerability in Tor's Directory Protocol v3, enabling silent, undetectable attacks that bypass public audit. The proposed DieCast protocol offers a robust, proactive solution for interactive consistency, critical for Tor's long-term integrity, while TorEQ provides immediate reactive detection.