Asymptotically idempotent aggregation operators for trust management in multi-agent systems

The study of trust management in multi-agent system, especially distributed, has grown over the last years. Trust is a complex subject that has no general consensus in literature, but has emerged the importance of reasoning about it computationally. Reputation systems takes into consideration the history of an entity’s actions/behavior in order to compute trust, collecting and aggregating ratings from members in a community. In this scenario the aggregation problem becomes fundamental, in particular depending on the environment. In this paper we describe a technique based on a class of asymptotically idempotent aggregation operators, suitable particulary for distributed anonymous environments

The trust management framework for peer-to-peer networks

Popularity of peer-to-peer (P2P) networks exposed a number of security vulnerabilities. Among those is a problem of finding reliable communication partners. In this thesis, we present an integrated trust framework for peer-to-peer networks that quantifies the trustworthiness of a peer via reputation-based trust mechanism and anomaly detection techniques. As opposed to other known techniques in P2P networks, our trust management schema is fully decentralized and does not rely on the co-operation of peers. Furthermore, the reputation computation is based on traffic coming from other peers. We also describe an anomaly detection procedure that analyses peer activity on the network and flags potentially malicious behavior by detecting deviation from peer profile. We present integration of our anomaly detection to trust management scheme and study the performance of reputation-based approach using implementation and performance of trust framework through simulation

PeerCredential: a support reputation-based trust framework for peer-to-peer applications

Peer-to-Peer and scientific networks, often require those that use the system (i.e. users) to utilize other nodes (i.e. resources) that are unknown. Users are unable to identify whether a resource will be honest, selfish, or malicious. In order for users to reduce the risk of using a malicious resource and to motivate nodes from being selfish, we propose an adaptive reputation-based trust framework for distributed system applications. In this framework, users are able to appraise a resource by using price and a quantifiable metric of trust that is gathered from its own view and the views of other peers (i.e. references) regarding the reputation of the resource. The appraisal process provides the user with a reliable metric that can be used in the process of resource scheduling and selection. In response, economic resources will compete with each other using a variety of strategies that attempt to maximize their profit. The simulation results show that the framework is user friendly by providing long-term high satisfaction, filters out malicious nodes, and encourages resources to provide reliable and high-quality service

Architecture Supporting Computational Trust Formation

Trust is a concept that has been used in computing to support better decision making. For example, trust can be used in access control. Trust can also be used to support service selection. Although certain elements of trust such as reputation has gained widespread acceptance, a general model of trust has so far not seen widespread usage. This is due to the challenges of implementing a general trust model. In this thesis, a middleware based approach is proposed to address the implementation challenges. The thesis proposes a general trust model known as computational trust. Computational trust is based on research in social psychology. An individual’s computational trust is formed with the support of the proposed computational trust architecture. The architecture consists of a middleware and middleware clients. The middleware can be viewed as a representation of the individual that shares its knowledge with all the middleware clients. Each application uses its own middleware client to form computational trust for its decision making needs. Computational trust formation can be adapted to changing circumstances. The thesis also proposed algorithms for computational trust formation. Experiments, evaluations and scenarios are also presented to demonstrate the feasibility of the middleware based approach to computational trust formation

Architecture and optimization for a peer-to-peer content management system

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2004.Includes bibliographical references (leaves 87-88).This thesis will explore the design and optimization of a peer-to-peer network application as a solution to complex content management problems. Currently, most content management systems are expensive, cumbersome and inflexible custom solutions that require knowledge workers to change their work habits. Peer-to-peer offers a uniquely decentralized and, potentially, scalable solution for knowledge workers by providing a simple and visual tool for file management, meta-data description and collaboration. This thesis will reference a client beta designed and developed by the author. Additionally, this thesis will address the need for content management solutions, the state of current solutions and a requirements document for a solution. Subsequently, the thesis will explore the design aspects of a peer-to-peer content management solution. As well as designing and developing a P2P client as proof of concept, this thesis will mathematically explore the implications of scaling the client to many users and methods to optimize performance. The last few chapters will cover the implementation of the client, proposed next steps for development and analysis of alternative architectures.by Dion M. Edge.S.M

Counteracting free riding in pure peer-to-peer networks

Ankara : The Department of Computer Engineering and The Institute of Engineering and Science of Bilkent University, 2008.Thesis (Ph.D.) -- Bilkent University, 2008.Includes bibliographical references leaves 119-127.The peer-to-peer (P2P) network paradigm has attracted a significant amount of interest as a popular and successful alternative to traditional client-server model for resource sharing and content distribution. However, researchers have observed the existence of high degrees of free riding in P2P networks which poses a serious threat to effectiveness and efficient operation of these networks, and hence to their future. Therefore, eliminating or reducing the impact of free riding on P2P networks has become an important issue to investigate and a considerable amount of research has been conducted on it. In this thesis, we propose two novel solutions to reduce the adverse effects of free riding on P2P networks and to motivate peers to contribute to P2P networks. These solutions are also intended to lead to performance gains for contributing peers and to penalize free riders. As the first solution, we propose a distributed and localized scheme, called Detect and Punish Method (DPM), which depends on detection and punishment of free riders. Our second solution to the free riding problem is a connection-time protocol, called P2P Connection Management Protocol (PCMP), which is based on controlling and managing link establishments among peers according to their contributions. To evaluate the proposed solutions and compare them with other alternatives, we developed a new P2P network simulator and conducted extensive simulation experiments. Our simulation results show that employing our solutions in a P2P network considerably reduces the adverse effects of free riding and improves the overall performance of the network. Furthermore, we observed that P2P networks utilizing the proposed solutions become more robust and scalable.Karakaya, K MuratPh.D

Reputation-based Trust Management in Peer-to-Peer File Sharing Systems

Trust is required in file sharing peer-to-peer (P2P) systems to achieve better cooperation among peers and reduce malicious uploads. In reputation-based P2P systems, reputation is used to build trust among peers based on their past transactions and feedbacks from other peers. In these systems, reputable peers will usually be selected to upload requested files, decreasing significantly malicious uploads in the system. This thesis surveys different reputation management systems with a focus on reputation based P2P systems. We breakdown a typical reputation system into functional components. We discuss each component and present proposed solutions from the literature. Different reputation-based systems are described and analyzed. Each proposed scheme presents a particular perspective in addressing peers’ reputation. This thesis also presents a novel trust management framework and associated schemes for partially decentralized file sharing P2P systems. We address trust according to three identified dimensions: Authentic Behavior, Credibility Behavior and Contribution Behavior. Within our trust management framework, we proposed several algorithms for reputation management. In particular, we proposed algorithms to detect malicious peers that send inauthentic files, and liar peers that send wrong feedbacks. Reputable peers need to be motivated to upload authentic files by increasing the benefits received from the system. In addition, free riders need to contribute positively to the system. These peers are consuming resources without uploading to others. To provide the right incentives for peers, we develop a novel service differentiation scheme based on peers’ contribution rather than peers’ reputation. The proposed scheme protects the system against free-riders and malicious peers and reduces the service provided to them. In this thesis, we also propose a novel recommender framework for partially decentralized file sharing P2P systems. We take advantage from the partial search process used in these systems to explore the relationships between peers. The proposed recommender system does not require any additional effort from the users since implicit rating is used. The recommender system also does not suffer from the problems that affect traditional collaborative filtering schemes like the Cold start, the Data sparseness and the Popularity effect. Over all, our unified approach to trust management and recommendations allows for better system health and increased user satisfaction

Peer-to-Peer Systems: The Present and the Future

Nowadays Peer-to-Peer (P2P) systems became an important part of Internet, millions of users have been attracted to use their structures and services. The popularity of Peer-to-Peer systems speed up academic research joining researchers from systems, networking and theory. The most popular P2P applications support file-sharing and content distribution, new applications are emerging in different fields, Internet telephony is an example. This paper discusses the issues of P2P systems such as characteristics, structures, protocols, drawbacks, open problems and futures fields of development.Facultad de Informátic

Gridella: an open and efficient Gnutella-compatible Peer-to-Peer System based on the P-Grid approach

This thesis describes the Peer-to-Peer Application Gridella. The decentralized architecture of P2P systems enables each peer to fulfill search requests solely by local interactions. The system described in this thesis scales to high numbers of peers and data items and remains available in spite of failing peers. Further, probabilities for successful search requests can be given. Gridella is based on the P-Grid approach~\cite{infosysdb:Aberer01a, infosysdb:Aberer02c} and is designed to be compatible with Gnutella `` infiltrate'' the existing Gnutella infrastructure and enable an simple migration. P-Grid increases the efficiency of search requests, and reduces the required bandwidth for system maintenance. On the basis of an analysis of the existing Gnutella infrastructure and its problems I describe the foundations of P-Grid. The developed application supports the existing Gnutella and the new Gridella protocol. Then the architecture and the communication between the systems are described in detail