Trustworthy Cooperation among Peers

In a peer-to-peer (P2P) overlay network, a peer process (peer) communicates with other peers and manipulates objects in local and remote peers. 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. We discuss subjective and objective types of the trustworthiness of each acquaintance pj . In the subjective approach, a peer obtains the trustworthiness of an acquaintance by itself through communicating with an acquaintance. On the other hand, a peer takes trustworthiness opinions on an acquaintance from other peers, i.e. how other peers trust the acquaintance in the objective approach. The subjective and objective types of trustworthiness on an acquaintance may be similar. In this paper, if the peer is more and less confident of its subjective trustworthiness, the subjective and objective types of trustworthiness are taken, respectively.