Mixnets on a tightrope: Quantifying the leakage of mix networks using a provably optimal heuristic adversary
Sebastian Meiser, Debajyoti Das, Moritz Kirschte, Esfandiar Mohammadi, Aniket Kate
IEEE Symposium on Security and Privacy 2025 · Day 3 · Private and Secure Communication
This talk, presented by Sebastian Meiser from the University of Lübeck, introduces a novel approach to quantify the information leakage in **mix networks**, a crucial technology for anonymous communication. Titled "Mixnets on a tightrope: Quantifying the leakage of mix networks using a provably optimal heuristic adversary," the research addresses a long-standing challenge in network anonymity: how to accurately measure the privacy provided by mixnets against powerful, passive adversaries. The core contribution is a **heuristic adversary** that is both computationally efficient and provably optimal in its ability to determine the *ratio* of probabilities for an adversary to link a sender to a specific recipient, given an observed network state.