A 3 : An Extensible Platform for Application-Aware Anonymity

This paper presents the design and implementation of Application-Aware Anonymity (A 3 ), an extensible plat- form for deploying anonymity-based services on the In- ternet. A 3 allows applications to tailor their anonymity properties and performance characteristics according to specific communication requirements. To support flexible path construction, A 3 exposes a declarative language (A 3 LOG) that enables applications to compactly specify path selection and instantiation policies which are then executed using a declarative networking engine. We demonstrate that our declara- tive language is sufficiently versatile to represent novel multi-metric performance constraints as well as exist- ing relay selection algorithms used by Tor and other anonymity systems, using only a few lines of concise code. We experimentally evaluate the A 3 system using a combination of trace-driven simulations and deploy- ment on PlanetLab. Our experimental results demon- strate that A 3 can flexibly support a wide range of path selection and instantiation strategies at low per- formance overhead.