OverTorrent: Anticensorship without centralized servers

Anticensorship continues to be an arms race between citizens who use circumvention systems and the censors that find and block them. Many recently proposed circumvention systems have found ways to hide from deep-packet inspection (DPI), as well as active probing by the censors. However, many circumvention systems have trouble distributing the necessary resources to its users, and often use centralized distribution systems that can be easily blocked. In this paper, we design a censorship circumvention infrastructure called OverTorrent, that utilizes the BitTorrent protocol to allow peers to share their Internet connections with one another. As BitTorrent is a widely popular application, it remains largely uncensored even by technologically sophisticated censors such as China. Because OverTorrent is built on top of BitTorrent, it does not require any centralized infrastructure to operate. Peers are discovered while participating in the BitTorrent download of popular files that are unrelated to the OverTorrent protocol. Blocking OverTorrent requires blocking or actively interfering with certain types of popular BitTorrent clients. We believe this system could be used to disseminate other anticensorship tools or resources, or even allow access of websites directly.