XTRA—eXtended bit-Torrent pRotocol for Authenticated covert peer communication

Today, peer-to-peer (P2P) networks have risen to the top echelon of information sharing on the Internet. Consequently, it is a daunting task to prevent sharing of both legitimate and illegitimate information such as—music, movies, software, and child pornography—on P2P overt channels. Considering that, preventing covert channel information sharing is inconceivable given even its detection is near impossible. The standard P2P bit-torrent peer wire communication protocol uses a very simple handshake process and as such does not provide peer authentication service. In this paper, we propose XTRA—a framework for covert communication using the standard bit-torrent protocol with a robust handshake process for authentication among covert peers. Under this framework, covert peers authenticate each other prior to covert message exchanges. Participating peers send data over an encrypted covert channel making use of only the standard bit-torrent message types. We have validated the performance XTRA through a working prototype implementation and present results comparing it with two state-of-the-art techniques. Finally, we have analyzed the robustness of XTRA to popular security attacks.