Garlic Cast: Lightweight and Decentralized Anonymous Content Sharing

Anonymous content sharing over the Internet protects user privacy and content confidentiality. Most overlay anonymous communication protocols employ some relay nodes as the proxies to forward content and require relays to perform cryptography or coding operations on messages. They have two major limitations. First, extra computation overhead may discourage overlay nodes from serving as relays. Second, long forwarding latency at relays makes an anonymous path easier to fail under network churn. In this paper, we present a lightweight and decentralized anonymous content sharing system named Garlic Cast, which requires near-zero computation cost on relays and does not rely on any centralized service. Garlic Cast uses random walks to find proxies in overlay networks and an security-enhanced Information Dispersal Algorithm to search and deliver content files. We have implemented a prototype of Garlic Cast and performed extensive simulation on real overlay topologies. Evaluation results show that the throughput of Garlic Cast is higher than that of RSA-based anonymous routing by over two orders of magnitude. Garlic Cast provides high level of anonymity and is robust to various attacks.