Trustworthiness in Peer-to-Peer (P2P) Systems

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A large number of peer processes are distributed in a peer-to-peer (P2P) overlay network. It is difficult, may be impossible for a peer to perceive the membership and location of every resource object due to the scalability and openness of a P2P network. In this paper, we discuss a fully distributed P2P system where there is no centralized controller. Each peer has to obtain service information from its acquaintance peers and also sends its service information to the acquaintance peers. An acquaintance peer of a peer p is a peer about whose service the peer p knows and with which the peer p can directly communicate in an overlay network. Some acquaintance peer might hold obsolete service information and might be faulty. Each peer has to find a more trustworthy one in acquaintance peers. There are many discussions on how to detect peers which hold a target object. However, a peer cannot manipulate an object without being granted access rights (permissions) . In addition to detecting wh … More at peers hold a target object, we have to find peers granted access rights to manipulate the target object. The trustworthiness of each acquaintance is defined in terms of the satisfiability and ranking factor in this paper. The satisfiability of an acquaintance peer shows how much each peer can trust the acquaintance peer through direct communication to not only detect target objects but also obtain their access rights. On the other hand, the ranking factor of an acquaintance peer indicates how much the acquaintance peer is trusted only by trustworthy acquaintance peers differently from the traditional reputation concept. We designed a new flooding type of detection algorithm names CBF (charge-based flooding) algorithm where areas including the more trustworthy peers are the more deeply searched. We evaluate how the trustworthiness of acquaintance peer is changing through interactions among peers in the detection algorithm. We showed that we can reduce the number of messages transmitted in the network and increase the hit ratio of a target object in the network even if the trustworthiness of each peer is changing. Less