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There are many discussions on agreement protocols of multiple peer processes where every peer just aims at agreeing on one value out of values shown by the peers. In human societies, agreement procedures are so flexible that persons can change their opinions and can use not only all-condition but also various types of agreement conditions in a meeting. In this paper, we discuss a flexible agreement...
The characteristics of P2P networks which are open, anonymous, and loosely coupled inter-node lead to false resources, malicious evaluation, and syndicates. A related cluster based trust model for P2P networks named RCTrust is presented in this paper. Peers gather in clusters according to their interest similarity and communication history. There are two kinds of trust relationships. In RCTrust, measure...
The use of social norms has proven to be effective in the self-governance of decentralised systems in which there is no central authority. Axelrod's seminal model of norm establishment in populations of self-interested individuals provides some insight into the mechanisms needed to support this through the use of metanorms, but is not directly applicable to real world scenarios such as online peer-to-peer...
In peer-to-peer networks (P2Ps), many autonomous nodes without preexisting trust relationships share resources (e.g., files) between each other. Due to their open environment, P2Ps usually employ reputation systems to provide guidance in selecting trustworthy resource providers for high system reliability and security. A reputation system computes and publishes reputation score for each node based...
Failure management is a key component in the attempt to provide a reliable environment. This article proposes a solution to increase the reliability of distributed systems based on the Chord Peer-to-Peer overlay. our solution is aimed at providing accurate failure information about the nodes in the system. This is a very difficult task in Peer-to-peer networks due to their dynamic nature and the inability...
This paper presents a new way of deploying security properties and trust in an open peer-to-peer network. The originality is that the security properties are freely defined by the user and are attached to the exchanged resources that are associated with domains. The paper proposes an implementation of a monitoring agent that looks after an open source peer-to-peer client and detects any attempt of...
Establishing trust in a subject requesting access to a sensitive resource object is fundamental in history-aware access control models. A subject's past behaviour could be used as an indication about the subject's trustworthiness. In fact, a subject's trust plays a significant role in deciding the associated access rights in, for example, context-aware access control models. Recently, there have been...
There has been a spurt of works showing that the existence of sybil attacks is a serious threat to Peer-to-Peer networks, where one or more attackers can forge a large number of fictitious identities. In this paper, we present a distributed protocol to reduce the adverse effects of sybil attacks in free riding problem. Our approach focuses on restricting nodes to obtain the number of service units...
Distributed resource sharing in P2P networks has received a great deal of attention. Resources overload make users increasingly difficult to locate the right resource. Recommender systems have been proven to resolve this problem. But Recommender systems have natural weaknesses such as their vulnerability to various attacks. So, in this paper, we present a model of recommender system based on trust...
Finding a document or resource in an unstructured peer-to-peer network can be an exceedingly difficult problem. In this paper we propose a dynamic query routing approach that accounts for arbitrary overlay topologies, nodes with heterogeneous processing capacity and heterogenous class-based likelihoods of query resolution at nodes, reflecting the query loads and manner in which files/resources are...
In this work, we present a model of social network showing non-trivial effects on the dynamics of trust and communication. Our model's results meet the characteristics of a typical social network, such as the limited node degree, assortativeness, clustering and communities formation. Simulations have been run first to present some of the most fundamental relations among the main model's attributes...
Recently, with the variety of contents in video streaming services, the demand for system assisting users' content selection is increasing. P2P live streaming distribution is one of the solutions to reduce load of distributors. In P2P live streaming, users select desired contents with the help of content catalog. Users join content network and then, play back some contents. In traditional streaming...
Opportunistic networks enable users to communicate in the absence of network infrastructure. But forwarding messages in such a network incurs costs for nodes in terms of energy and storage. This may lead to nodes being selfish and not forwarding messages for other nodes, resulting in degraded network performance. This paper presents a novel incentive mechanism for opportunistic networks that uses...
Anonymity in Bit coin, a peer-to-peer electronic currency system, is a complicated issue. Within the system, users are identified by public-keys only. An attacker wishing to de-anonymize its users will attempt to construct the one to-many mapping between users and public-keys and associate information external to the system with the users. Bitcoinfrustrates this attack by storing the mapping of a...
Distributed environments hosting specific and dedicated computing resources are serving nowadays more and more scientific and commercial applications. Finding the right resource in distributed environments in term of performance is not an obvious task. This paper is addressing the issue of selecting the right service deployed in a distributed environment for any applications or workflow engines that...
Unexpected disconnections, long transmission latencies and network heterogeneity that DTN is meant to support make the routing problem in DTN very complicated. In DTN, probabilistic based routing protocols make use of nodes' mobility history to gauge delivery likelihood of nodes. However, the delivery likelihood of the nodes is not the only factor that affects the message delivery likelihood. In this...
Recently, with the development of cloud computing, business opportunities emerge gradually for some internet service providers. Content sharing service will grow dramatically with the convenience of consuming cloud resources. But the traditional security threats toward content sharing systems are still not solved. Malicious adversaries can inject a massive number of spam, advertisements, or even viruses...
Many peer-to-peer (P2P) systems require accurate information about their peer's available bandwidth, e.g., for load balancing. Determining this information is difficult, as a suitable approach must address two challenges. First, it must be able to deal with fluctuating bandwidth. Second, it must incur low overhead to prevent interference with the operation of the P2P system. In this paper we present...
Online social networks (OSN) have attracted millions of users worldwide. This enormous success is not without problems; the centralized architectures of OSNs, storing the users' personal data, provides ample opportunity for privacy violation — a fact that has raised the demand for open, decentralized alternatives. We tackle the research question: is it possible to build a decentralized OSN over a...
Pervasive healthcare, is an important application of pervasive computing technologies that has seen a vast development in recent years. It enables patients to access healthcare services, anywhere, anytime ubiquitously. But, patients using these devices have to confront the problem of unknown healthcare providers and other security issues. This paper proposes an integrated trust management mechanism...
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