Hiding user content interest while preserving P2P performance

The lack of privacy in P2P systems is an inherent characteristic of their design, as users have to expose their content interests. A variety of solutions have been proposed, offering several levels of protection to its users, from privacy to complete anonymity, but always at the cost of performance. However, most P2P users are reluctant to trade performance for privacy. In this paper we present a novel P2P system that hides user content interest without affecting performance. Our solution uses cover traffic in order to hide the user interests while improving the performance of the system. The cover traffic and performance benefits are provided through several techniques, such as caching, sub-announcing, relaying requests, and creating private swarms. We show that our system hides the real interests of a user from third parties, providing plausible deniability. We describe its design and implement it as an enhancement of the upcoming IETF P2P Streaming Protocol Internet standard. Our solution offers backwards compatibility and can also be integrated in other similar P2P protocols. Analysis of possible attacks shows that only an adversary who controls a very high percentage of the peers in the system can infer the content interest of the user, but even then, without complete certainty. Furthermore, using actual P2P client software, we show that our privacy enhancements do not lead to a performance loss.