Defying Censorship with Multi-Circuit Tor and Linear Network Coding

Abstract

Anonymity networks are an increasingly important part of Internet evolution to providing practical mechanisms to enhance anonymity and security of network users. The best known anonymity network, The Onion Routing (Tor), is not only subject to user deanonymization attacks but also subject to censorship attacks by blocking the public and secret Tor entry routers, e.g., bridges, or by jamming Tor traffic to prevent users to access Tor network. To help further evolution of anonymity networks, we focus in this work on censorship attacks, and propose to enhance the well-known multipath Tor technique with linear network coding (LNC). We analyze anonymity, privacy and censorship success considering different types of adversaries and the amount of honest and compromised components in the Tor and in the underlying network. The results show that LNC can significantly improve the robustness of Tor against censorship and maintain sufficient anonymity and privacy levels.