Group-based negotiations in p2p systems

In P2P systems, groups are typically formed to share resources and/or to carry on joint tasks. In distributed environments formed by a large number of peers conventional authentication techniques are inadequate for the group joining process, and more advanced ones are needed. Complex transactions among peers may require more elaborate interactions based on what peers can do or possess instead of peers' identity. In this work, we propose a novel peer group joining protocol. We introduce a highly expressive resource negotiation language, able to support the specification of a large variety of conditions applying to single peers or groups of peers. Moreover, we define protocols to test such resource availability customized to the level of assurance required by the peers. Our approach has been tested and evaluated on an extension of the JXTA P2P platform. Our results show the robustness of our approach in detecting malicious peers, detected both during the negotiation and during the peer group lifetime. Regardless of the peer group cardinality and interaction frequency, the peers always detect possible free riders within a small time frame.