Sharif Digital Repository

People usually use trust and reputation when they encounter uncertainty in the nature. Graphs are good tools to model and analysis of trust’s problems. If we show human and computer agents by graph’s nodes and trust values by its edges, in literature, the output graph is so-called Web of Trust. Most recently, there are three major research areas in which trust is studied. First area is policy-based trust which uses policies, digital signature and authentication methods. Second area is reputation-based trust which uses reputation and social network tools to estimate trust where past interactions or performance for an entity are combined to assess its future behavior. Third area is trust... 

Traditional security approaches prevented participants of an environment from malicious behavior by closely monitoring every transaction of the network. Such approaches are very costly in modern autonomous systems, besides, they are also impossible to apply in many cases. Trust management mechanisms are developed in order to ensure safe interactions with unknown parties in such open environments. Most trust management mechanisms rely on testimonies of interaction participants as the source of information to estimate a peer’s reputation. The first challenge that arises here is the lack of incentives for providing such information. Even if interaction parties are encouraged to report the... 

Nowadays trust has become one of the main challenges of every online social network. The open and decentralized nature of Peer-to-Peer network makes it vulnerable to be exploited by malicious users to distribute tampered and harmful contents. We propose a dynamic computational trust model based on a neuro-fuzzy approach and implemented it on Gnutella network. The model is a novel application of control systems approach for evaluating trust and reputation in P2P networks. We utilize Local Linear Model Tree (LOLIMOT) to perform a nonlinear dynamic system identiffcation and thus to approximate trust. The performance of our reputation-based trust model is evaluated by simulation. We create a... 

Trust management is a new security solution for situations that there is not enough information about the members of a system. As other security solutions, trust management solutions are not secure against attacks and malicious behaviors. Collusion is one of the most destructive malicious behaviors in these systems. Colluders seek to unfairly affect the trust system. Most of the trust models are vulnerable against this malicious behavior or consider only a limited set of collusion scenarios to resist. Some other mitigation approaches are specific to a trust model and cannot be used by other models. One of the methods to implement trust is exploiting reputation. Reputation systems can be... 

In auction-based cloud investment environments, consumers desire the least possible cost and high satisfaction, while providers seek strategies to maximize profit and return on investment. In these environments designing an adequate resource allocation that can satisfy both consumers and providers is of utmost importance. Yet, most available models in resource allocation focus on providers’ needs and do not concern themselves with the consumers. Therefore the present study aims to present an efficient and optimum model for resource allocation problem that takes into account various factors, e.g. resource price, service quality, reputation and fairness, and is capable of satisfying all honest...