Bluebear: Exploring Privacy Threats in BitTorrent

http://www-sop.inria.fr/members/Arnaud.Legout/Projects/bluebear.html

BitTorrent is arguably the most efficient peer-to-peer protocol for content replication. However, BitTorrent has not been designed with privacy in mind and its popularity could threaten the privacy of millions of users. Surprisingly, privacy threats due to BitTorrent have been overlooked because BitTorrent popularity gives its users the illusion that finding them is like looking for a needle in a haystack. The goal of this project is to explore the severity of the privacy threats faced by BitTorrent users.

We argue that it is possible to continuously monitor from a single machine most BitTorrent users and to identify the content providers (also called initial seeds) [LLL_LEET10, LLL_TR10]. This is a major privacy threat as it is possible for anybody in the Internet to reconstruct all the download and upload history of most BitTorrent users.

To circumvent this kind of monitoring, BitTorrent users are increasingly using anonymizing networks such as Tor to hide their IP address from the tracker and, possibly, from other peers. However, we showed that it is possible to retrieve the IP address for more than 70% of BitTorrent users on top of Tor [LMC_POST10]. Moreover, once the IP address of a peer is retrieved, it is possible to link to the IP address other applications used by this peer on top of Tor.