Discouraging Improper Exploitation against Seeds in BitTorrent Swarms

Bit Torrent is arguably the most prevalent file sharing protocol on the Internet. In Bit Torrent swarms, seeds usually offer file chunks for free and thus induce free-riding behavior. Some anti-Bit Torrent companies even launch targeted attacks against the seeds. This paper proposes a batch mechanism for proper functioning of the seeds. It applies symmetric-key encryption and chunk mixing to plain chunks of the file, and enforces chunk recipients to do exchanges before they are able to obtain plain chunks. As a result, free-riding behavior and malicious attacks are discouraged. Also, the robustness of the batch mechanism is analyzed in detail under both fully and partial colluding scenarios.