HotPETs _ Session 2: There Must Have Been a Mix-Up

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Talk: Simulation for mixnets

Author: Iness Ben Guirat, Devashish Gosain, Claudia Diaz

Abstract: How can we design an anonymous communication network (ACN) architecture, such as a mixnets, that satisfies a set of requirements and threats? Although many security protocols can be shown to be secure via cryptographic proofs, privacy is a complex subject that can not be easily reduced to cryptographic proofs, as privacy has to deal with the context and the flow of information. Previous work in the designs such as onion-routing and mixnets have produced a large variety of systems, but comparison between these systems is difficult and often can not, due to the complexity and real-world requirements, be done with purely analytic or theoretical methods. With our general-purpose simulator for mixnets, we can evaluate the entropy for a wide variety of parameters across mixnets designs. In general,there has been theoretical results that there is anonymity trilemma between strong anonymity, low bandwidth overhead and low Latency, but these questions have never been approached systematically from a practical perspective for mixnets, which the simulator allows to be done over large classes of design and comprehensively evaluated. This provides fundamental insights into the design space and trade-offs for mix networking that cannot be obtained without large-scale simulation. Simulation is not only useful to understand the anonymity and security provided by mixnets, but also to deal with real-world engineering such as latency, capacity,scalability, and performance.

Talk: CLAPS: Client-Location-Aware Path Selection in Tor

Authors: Florentin Rochet, Ryan Wails, Aaron Johnson, Prateek Mittal, Olivier Pereira

Abstract: Location-aware path selection has been explored as a promising way to complicate the surveillance of Tor users by powerful actors. We propose the CLAPS framework as a novel way to design path selection algorithms that focus on satisfying security constraints while also optimizing relay usage and keeping the network balanced. We applied our framework to several recent proposals (Counter-Raptor and DeNASA) and demonstrate that the CLAPS strategy leads to substantial improvements, both in network performance and in security, for natural relay configurations derived from recent states of the Tor network.