Taxis: Scalable Strong Anonymous Communication

Anonymity protocols are a privacy-enhancing technology for Internet-based communication. Two important characteristics are the strength of anonymity provided, and the overhead required for anonymous communication. In this paper, we focus on the latter characteristic, and develop simple performance models for two anonymous communication protocols. Practical Buses and Taxis. We show that the message latency of Practical Buses scales quadratically with the number of participants, while that of Taxis scales linearly with the number of participants. Both models are validated with experimental measurements from prototype implementations. We show that Taxis provides more scalable anonymous communication, without compromising the strength of anonymity provided.