Subjective and Objective Trustworthiness of Acquaintance Peers

Abstract

In a peer-to-peer (P2P) overlay network, a peer process (peer) communicates with other peers and manipulates objects like databases in the peers. Service of each peer is characterized in terms of types of methods and quality of objects supported by the peer. It is critical to obtain service information on what peers support what service. In a fully distributed, unstructured P2P network, there is no centralized coordinator like index and super peer. Each peer has to communicate with its acquaintance peers and obtain service information of other peers. It is critical for a peer to identify which acquaintance is trustworthy since acquaintances may support obsolete service information and may be faulty. There are subjective and objective types of the trustworthiness, of each acquaintance peer. In the subjective approach, a peer obtains the trustworthiness of an acquaintance peer by itself through communicating with an acquaintance. On the other hand, a peer takes trustworthiness opinions on an acquaintance from other peers, that is, how other peers trust the acquaintance peer in the objective approach. In this chapter, a peer only takes opinions of trustworthy peers by excluding faulty peers differently from the traditional reputation concepts. The types of trustworthiness on an acquaintance peer are not always similar. A peer has to decide on which trustworthiness type is taken. In this chapter, we postulate the more confident of its trustworthiness opinion the peer is, the more significantly the subjective trustworthiness is taken into account. If the peer is less confident, the subjective and objective types of trustworthiness are taken respectively. We also discuss how to define the confidence.