Handling Identity in Peer-to-Peer Systems

As IP addresses have become a scarce resource most computers on the Internet no longer have permanent addresses. For client computers this is usually not a big problem but with the advent of P2P systems, where every computer acts both as a client and as a server, this has become increasingly problematic. In advanced P2P systems ad-hoc connections to peers have to be established, which can only be done if the receiving peer has a permanent IP address. In this paper we propose an approach for a completely decentralized, self-maintaining, light-weight, and sufficiently secure peer identification service that allows us to consistently map unique peer identifications onto dynamic IP addresses in environments with low online probability of the peers constituting the service. For security we apply a combination of PGPlike public key distribution and a quorum-based query scheme. We describe the algorithm as implemented in our P-Grid P2P lookup system and give a detailed analytical performance analysis demonstrating the efficiency and robustness of our approach. Our approach also can easily be adapted to other application domains, i.e., be used for other name services, because we do not impose any constraints on the type of mappings.