The design and implementation of the A3 application-aware anonymity platform

This paper presents the design and implementation of Application-Aware Anonymity (A3), an extensible platform for rapidly prototyping and evaluating anonymity protocols on the Internet. A3 supports the development of highly tunable anonymous protocols that enable applications to tailor their anonymity properties and performance characteristics according to specific communication requirements. To support flexible path construction, A3 uses a declarative language to compactly specify path selection and instantiation policies. We demonstrate that our declarative language is sufficiently expressive to encode novel multi-metric performance constraints as well as existing relay selection algorithms employed by Tor and other anonymity systems, using only a few lines of concise code. We experimentally evaluate A3 using a combination of trace-driven simulations and a deployment on PlanetLab, as well as a case-study of A3-enabled voice-over-IP communication. Our experimental results demonstrate that A3 can flexibly and efficiently support a wide range of path selection and instantiation strategies at low performance overhead.