Supervision : Pierre SENS

Co-supervision : MARIN Olivier

Building Trustworthy Services in P2P networks

Building trust is a major concern in Peer-to-Peer networks as several kinds of application rely on the presence of trusted services. However, the presence of untrusted peers may hinder the robustness and degrade the overall performance of applications. Untrusted nodes in the network may be faulty, malicious, selfish, or even act together to attack the application. Traditional techniques for countering untrusted node activity do not scale, produce very high overhead, or rely on unrealistic assumptions. This thesis aims to provide a framework to build trustworthy applications over structured Peer-to-Peer networks. We describe and evaluate both a reputation system and a membership algorithm which builds a community of reputable peers. Our reputation system introduces the concept of risk to make applications aware of several malicious node behaviours. We propose a risk metric that complements the reputation value and show that it significantly reduces the number of malicious transactions. We propose a new membership algorithm to build a scalable pseudo-trusted ring within a Distributed Hash Table. Our algorithm uses a reputation-based approach to decide whether a node can participate to the ring. We demonstrate the benefits of this approach, present some example applications and evaluate how much it improves the reliability of a trusted routing service.

2009-2016 Publications