Social applications mine user social graphs to improve performance in search, provide recommendations, allow resource sharing and increase data privacy. When such applications are implemented on a peer-to-peer (P2P) architecture, the social graph is distributed on the P2P system: the traversal of the social graph translates into a socially-informed routing in the peer-to-peer layer. In this work we introduce the model of a projection graph that is the result of decentralizing a social graph onto a peer-to-peer network. We focus on three social network metrics: degree, node betweenness and edge betweenness centrality and analytically formulate the relation between metrics in the social graph and in the projection graph. Through experimental evaluation on real networks, we demonstrate that when mapping user communities of sizes up to 50-150 users on each peer, the association between the properties of the social graph and the projection graph is high, and thus the properties of the (dynamic) projection graph can be inferred from the properties of the (slower changing) social graph. Furthermore, we demonstrate with two application scenarios on large-scale social networks the usability of the projection graph in designing social search applications and unstructured P2P overlays.
The management of social data in a P2P architecture has been addressed in systems such as PeerSoN @cite_1 , Vis- a -Vis @cite_13 , Safebook @cite_31 , LifeSocial.KOM @cite_0 and Prometheus @cite_43 . In some cases (PeerSoN, Vis- a -Vis, Safebook, LifeSocial.KOM), the information of a user is isolated from other users, and peers access them individually. Thus, the @math is fragmented into 1-hop neighborhoods, one for each user, and distributed across all peers, with potentially multiple fragments stored on the same peer. In contrast, in Prometheus @cite_43 , a peer can mine the collection of social data entrusted to it by a group of (possibly socially connected) users. In all these systems, regardless of the way peers are organized in the P2P architecture (e.g., in a structured or unstructured overlay), the @math model can be applied for studying and improving system and application routing.
@cite_1 @cite_0 @cite_43 @cite_31 @cite_13
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To address privacy concerns over Online Social Networks (OSNs), we propose a distributed, peer-to-peer approach coupled with encryption. Moreover, extending this distributed approach by direct data exchange between user devices removes the strict Internet-connectivity requirements of web-based OSNs. In order to verify the feasibility of this approach, we designed a two-tiered architecture and protocols that recreate the core features of OSNs in a decentralized way. This paper focuses on the description of the prototype built for the P2P infrastructure for social networks, as a first step without the encryption part, and shares early experiences from the prototype and insights gained since first outlining the challenges and possibilities of decentralized alternatives to OSNs. The phenomenon of online social networks reaches millions of users in the Internet nowadays. In these, users present themselves, their interests and their social links which they use to interact with other users. We present in this paper LifeSocial.KOM, a p2p-based platform for secure online social networks which provides the functionality of common online social networks in a totally distributed and secure manner. It is plugin-based, thus extendible in its functionality, providing secure communication and access-controlled storage as well as monitored quality of service, addressing the needs of both, users and system providers. The platform operates solely on the resources of the users, eliminating the concentration of crucial operational costs for one provider. In a testbed evaluation, we show the feasibility of the approach and point out the potential of the p2p paradigm in the field of online social networks. Recent Internet applications, such as online social networks and user-generated content sharing, produce an unprecedented amount of social information, which is further augmented by location or collocation data collected from mobile phones. Unfortunately, this wealth of social information is fragmented across many different proprietary applications. Combined, it could provide a more accurate representation of the social world, and it could enable a whole new set of socially-aware applications. We introduce Prometheus, a peer-to-peer service that collects and manages social information from multiple sources and implements a set of social inference functions while enforcing user-defined access control policies. Prometheus is socially-aware: it allows users to select peers that manage their social information based on social trust and exploits naturally-formed social groups for improved performance. We tested our Prometheus prototype on PlanetLab and built a mobile social application to test the performance of its social inference functions under realtime constraints. We showed that the social-based mapping of users onto peers improves the service response time and high service availability is achieved with low overhead. Online social network applications severely suffer from various security and privacy exposures. This article suggests a new approach to tackle these security and privacy problems with a special emphasis on the privacy of users with respect to the application provider in addition to defense against intruders or malicious users. In order to ensure users' privacy in the face of potential privacy violations by the provider, the suggested approach adopts a decentralized architecture relying on cooperation among a number of independent parties that are also the users of the online social network application. The second strong point of the suggested approach is to capitalize on the trust relationships that are part of social networks in real life in order to cope with the problem of building trusted and privacy- preserving mechanisms as part of the online application. The combination of these design principles is Safebook, a decentralized and privacy- preserving online social network application. Based on the two design principles, decentralization and exploiting real-life trust, various mechanisms for privacy and security are integrated into Safebook in order to provide data storage and data management functions that preserve users' privacy, data integrity, and availability. Preliminary evaluations of Safebook show that a realistic compromise between privacy and performance is feasible. Online Social Networks (OSNs) have become enormously popular. However, two aspects of many current OSNs have important implications with regards to privacy: their centralized nature and their acquisition of rights to users' data. Recent work has proposed decentralized OSNs as more privacy-preserving alternatives to the prevailing OSN model. We present three schemes for decentralized OSNs. In all three, each user stores his own personal data in his own machine, which we term a Virtual Individual Server (VIS). VISs self-organize into peer-to-peer overlay networks, one overlay per social group with which the VIS owner wishes to share information. The schemes differ in where VISs and data reside: (a) on a virtualized utility computing infrastructure in the cloud, (b) on desktop machines augmented with socially-informed data replication, and (c) on desktop machines during normal operation, with failover to a standby virtual machine in the cloud when the primary VIS becomes unavailable. We focus on tradeoffs between these schemes in the areas of privacy, cost, and availability.