Towards digital rights protection in BitTorrent-like P2P systems

Both research and practice have shown that BitTorrent-like (BT) P2P systems are scalable and efficient for Internet content distribution. However, existing BT systems are mostly used for distributing non-copyrighted or pirated digital objects on the Internet. They have not been leveraged to distribute the majority of legal media objects because existing BT systems are incapable of copyright protection. On the other hand, existing Digital Rights Management (DRM) techniques are mainly based on a client-server model, and cannot be directly applied to peer-to-peer based BT systems. To leverage the efficiency and the scalability of BT systems for Internet content distribution, we propose a novel scheme to enable DRM in existing BT systems without demanding infrastructure changes. In our scheme, each file piece is re-encrypted at runtime before a peer uploads it to any other peer. Thus, the decryption keys are unique for both different peers and difference pieces. In addition, any user can take part in the content distribution while only legitimate users can access the plaintext of being distributed content. To evaluate the performance of our proposed scheme, we have conducted experiments on PlanetLab with an implemented prototype and compared with the original BT system. The results show that our proposed scheme introduces less than 10% of system throughput degradation for copyright protection when compared to BT systems without copyright protection.