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Reputation systems have been popular in estimating the trustworthiness and predicting the future behavior of nodes in a large-scale distributed system where nodes may transact with one another without prior knowledge or experience. One of the fundamental challenges in distributed reputation management is to understand vulnerabilities and develop mechanisms(More)
—Disruption Tolerant Networks (DTNs) are characterized by the low node density, unpredictable node mobility and lack of global network information. Most of current research efforts in DTNs focus on data forwarding, but only limited work has been done on providing effective data access to mobile users. In this paper, we propose a novel approach to support(More)
1 A number of recent applications have been built on distributed hash tables (DHTs) based overlay networks. Almost all DHT-based schemes employ a tight determin-istic data placement and ID mapping schemes. This feature on one hand provides assurance on location of data if it exists, within a bounded number of hops, and on the other hand, opens doors for(More)
A publish-subscribe overlay service is a wide-area communication infrastructure that enables information dissemination across geographically scattered and potentially unlimited number of publishers and subscribers. A wide-area publish-subscribe (pub-sub) system is often implemented as a collection of spatially disparate nodes communicating on top of a peer(More)
Location-based services, which employ data from smartphones, vehicles, etc., are growing in popularity. To reduce the threat that shared location data poses to a user's privacy, some services anonymize or obfuscate this data. In this paper, we show these methods can be effectively defeated: a set of location traces can be deanonymized given an easily(More)
In both the commercial and defence sectors a compelling need is emerging for the rapid, yet secure, dissemination of information across traditional organisational boundaries. In this paper we present a novel trust management paradigm for securing pan-organisational information flows that aims to address the threat of information leakage. Our trust(More)
The continued explosion of Twitter data has opened doors for many applications, such as location-based advertisement and entertainment using smartphones. Unfortunately, only about 0.58 percent of tweets are geo-tagged to date. To tackle the location sparseness problem, this paper presents a methodical approach to increasing the number of geo-tagged tweets(More)
1 This paper describes a decentralized peer-to-peer model for building a Web crawler. Most of the current systems use a centralized client-server model, in which the crawl is done by one or more tightly coupled machines, but the distribution of the crawling jobs and the collection of crawled results are managed in a centralized system using a centralized(More)