Sensor nodes are often deployed in large numbers to monitor extended sensor fields. In such scenarios data aggregation plays a crucial role on summarizing data forwarded to base stations in sensor networks. As sensor networks are commonly deployed in open and unattended areas, they are vulnerable to physical tampering as well as remote attacks. Existing security techniques focus primarily on me...

As Web-based online communities are rapidly growing, the agents in social groups need to know their measurable belief of trust for safe and successful interactions. In this paper, we propose a formal model of reputation resulting from available feedbacks in online communities. The notion of trust can be defined as an aggregation of consensus given a set of reputations. The expected trust of an ...

Trust models that rely on recommendation trusts are vulnerable to badmouthing and ballot-stuffing attacks. To cope with these attacks, existing trust models employ different trust aggregation techniques to process the recommendation trusts and combine them with the direct trust values to form a combined trust value. However, these trust models are biased as recommendation trusts that deviate to...

Typical wireless sensor networks (WSNs) applications are characterized by a certain number of different requirements such as: data accuracy, localization, reputation, security, and confidentiality. Moreover, being often battery powered, WSNs face the challenge of ensuring privacy and security despite power consumption limitations. When the application scenario allows their use, data aggregation...

When users rate objects, a sophisticated algorithm that takes into account ability or reputation may produce a fairer or more accurate aggregation of ratings than the straightforward arithmetic average. Recently a number of authors have proposed different co-determination algorithms where estimates of user and object reputation are refined iteratively together, permitting accurate measures of b...

I nternet applications have evolved from centralized and private computing platforms to distributed and collaborative networked computing systems. Collaboration is a fundamental Internet computing capability, and collaborative computing represents a significant step toward the continued promotion of openness and social intelligence as Internet systems and applications evolve. However, trust and...

In recent years, Peer-to-Peer (P2P) systems and computational Grids are evolving into a new distributed computing model, called P2P Grid. This paper presents a new approach to solving the trust and security problems in a P2P Grid. Establishing trust in P2P Grids is essential to build lasting working relationships among the peers joining collective Grid applications. A P2P reputation system is t...

Distributed trust management addresses the challenges of eliciting, evaluating and propagating trust for service providers on the distributed network. By delegating trust management to brokers, individual users can share their feedbacks for services without the overhead of maintaining their own ratings. This research proposes a two-tier trust hierarchy, in which a user relies on her broker to p...

Wireless sensor networks (WSNs) as an emerging technology faces numerous challenges. Sensor nodes are usually resource constrained. Sensor nodes are also vulnerable to physical attacks or node compromises. Answering queries over data is one of the basic functionalities of WSNs. Both resource constraints and security issues make designing mechanisms for data aggregation particularly challenging....