D.3.1 – Privacy Breach Scenarios in SocioPlug

GDD_HCERES2020In SocioPlug, we have particular concerns about data protection. Services proposed by SocioPlug will conform to European regulations, during personal data collection and data access. In particular the right to oblivion, collection and access purposes should be explicitly determined by data owners. SocioPlug’s architecture is fully distributed and has no centralized server, thereafter, there is no centralized control about data and applications of users. The goal is to avoid the existence of a “big brother” vigilating every person of the social cloud. Nevertheless, collaboration implies accessing personal data of other users. As services and data will be distributed in a social cloud, participants must be responsible of their data but also of other’s data they collect and use. Thus, they must define usage policies for each shared data and people that collects and uses other’s data must preserve stated policies.From application scenarios described in deliverable D.4.1, in this report, we identify some important privacy breach scenarios that may appear in SocioPlug

Tracking Federated Queries in the Linked Data

Federated query engines allow data consumers to execute queries over the federation of Linked Data (LD). However, as federated queries are decomposed into potentially thousands of subqueries distributed among SPARQL endpoints, data providers do not know federated queries, they only know subqueries they process. Consequently, unlike warehousing approaches, LD data providers have no access to secondary data. In this paper, we propose FETA (FEderated query TrAcking), a query tracking algorithm that infers Basic Graph Patterns (BGPs) processed by a federation from a shared log maintained by data providers. Concurrent execution of thousand subqueries generated by multiple federated query engines makes the query tracking process challenging and uncertain. Experiments with Anapsid show that FETA is able to extract BGPs which, even in a worst case scenario, contain BGPs of original queries

Personal Linked Data: A Solution to Manage User's Privacy on the Web

National audienceWhile using modern applications, personal digital data is spread over hundreds of servers all around the world and users have very poor control over these data. To tackle this issue, based on the semantic Web, we are developing a framework, named Privacy-Lookout, to allow people to be on the lookout for transgressions of their personal data privacy. Concretely, we propose to construct a personal linked data view of individuals to organize and semantically enrich the meta information of their personal data existing in the Web. The mean idea is to allow users to know if the information the Web posses about them respects their privacy principles. This paper introduces the first ideas of such approach

Evaluating WUW, a service to enhance users' satisfaction in Content-Based Peer-to-Peer Networks

International audienceNowadays, Peer-to-Peer (P2P) architectures are becoming more popular in content delivery applications thanks to their valuable characteristics as scalability, performance and low maintenance costs. In those systems, peers share their resources automatically (bandwidth, storage, etc.) and not only download content but also upload content to other peers organized in a neighbourhood. Each peer' neighbourhood is based basically on QoS-related parameters (available bandwidth, number of connections, etc.) and the amount of exchanged content. We consider that peers are under control of users that are autonomous and free persons having rights, preferences and interests. As users' resources are the richness of P2P systems, we think it is important to satisfy their preferences beyond the QoS. In this paper we present first experimental results of WUW (What Users Want), a service located on top of a P2P layer and proposed to satisfy users' preferences during content exchange. In the current implementation we use the BitTorrent protocol for measuring to which extent users' preferences influence the P2P behaviour when WUW is used. We describe how the experimental scenarios are built using the resources provided by Grid'5000. Our preliminary results are encouraging because they show a low overhead of WUW on the global content sharing performance

Mobile Transaction Supports for DBMS

National audienceIn recent years data management in mobile environments has generated a great interest. Several proposals concerning mobile transactions have been done. However, it is very difficult to have an overview of all these approaches. In this paper we analyze and compare several contributions on mobile transactions and introduce our ongoing research: the design and implementation of a Mobile Transaction Service. The focus of our study is on execution models, the manner ACID properties are provided and the way geographical movements of hosts (during transaction executions) is supported

Performances de protocoles transactionnels en environnement mobile

National audience. L'omniprésence d'unités mobiles et le développement des réseaux sans fil motivent des avancées en matière de supports d'exécution pour une grande variété d'applications en envi-ronnement mobile. Des efforts importants sont faits pour offrir une bonne gestion des données malgré les caractéristiques limitées de tels environnements. La notion de transaction a été ré-étudiée pour proposer des modèles et des protocoles permettant d'assurer certaines propriétés transactionnelles. Les algorithmes et protocoles proposés tentent d'optimiser l'utilisation des ressources des unités mobiles et de surmonter les limitations du réseau mobile. Dans cet article nous nous intéressons spécifiquement aux protocoles de validation de transactions réparties sur plusieurs unités dont certaines mobiles. Nous présentons ici les résultats d'un travail qui iden-tifie des propriétés qualitatives et des indices de performance quantitatifs, et étudie ceux-ci sur quatre protocoles (2PC, UCM, CO2PC et TCOT). Trois de ces protocoles sont des propositions spécifiques pour des environnements mobiles et sont représentatifs des propositions actuelles. Nous nous intéressons à la phase de validation des transactions, ainsi qu'à l'influence des dif-férents protocoles sur les performances du déroulement de l'ensemble des transactions. ABSTRACT. This is an abstract. The omnipresence of mobile devices and wireless networks lead to a growing interest in supporting a wide variety of applications in mobile environments. Numerous efforts in providing appropriate data managements for such environments are made. Transaction supports have been revisited to propose adapted transaction models and properties. Proposed algorithms and protocols try to optimise the use of mobile units resources and to overcome wireless network limitations. This work concerns protocols to commit transactions distributed over several mobile and fixed units. Results presented here concern the identification of qualitative properties and quantitative performance indices that are studied on four protocols (2PC, UCM, CO2PC et TCOT). Three of them are specifics propositions for mobile environments and are representative of current proposals. The analysis concerns the transaction validation phase as well as the impact of the protocols on the performances during a transaction execution itself. MOTS-CLÉS : transactions mobiles , evaluation de performances, protocoles de validation

Trust Evaluation of a System for an Activity

International audienceWhen users need to perform a digital activity, they evaluate available systems according to their functionality, ease of use, QoS, and/or economical as- pects. Recently, trust has become another key factor for such evaluation. Two main issues arise in the trust management research community. First, how to de- fine the trust in an entity, knowing that this can be a person, a digital or a physical resource. Second, how to evaluate such value of trust in a system as a whole for a particular activity. Defining and evaluating trust in systems is an open problem because there is no consensus on the used approach. In this work we propose an approach applicable to any kind of system. The distinctive feature of our pro- posal is that, besides taking into account the trust in the different entities the user depends on to perform an activity, it takes into consideration the architecture of the system to determine its trust level. Our goal is to enable users to have a per- sonal comparison between different systems for the same application needs and to choose the one satisfying their expectations. This paper introduces our approach, which is based on probability theory, and presents ongoing results

System Modeling and Trust Evaluation of Distributed Systems

International audienceNowadays, digital systems are connected through complex architectures. These systems involve persons, physical and digital resources such that we can consider that a system consists of elements from two worlds, the social world and the digital world, and their relations. Users perform activities like chatting, buying, sharing data, etc. Evaluating and choosing appropriate systems involve aspects like functionality, performance, QoS, ease of use, or price. Recently, trust appeared as another key factor for such an evaluation. In this context, we raise two issues, (i) how to formalize the entities that compose a system and their relations for a particular activity? and (ii) how to evaluate trust in a system for this activity? This work proposes answers to both questions. On the one hand, we propose SOCIOPATH, a metamodel based on first order logic, that allows to model a system considering entities of the social and digital worlds and their relations. On the other hand, we propose two approaches to evaluate trust in systems, namely, SOCIOTRUST and SUBJECTIVETRUST. The former is based on probability the- ory to evaluate users’ trust in systems for a given activity. The latter is based on subjective logic to take into account uncertainty in trust values

Graph-Based Trust Model for Evaluating Trust Using Subjective Logic

50 pagesBefore using a digital system, it is necessary to evaluate it according to different parameters. Lately trust emerged as a momentous aspect of evaluation. Evaluating trust in a system is a complex issue that becomes more challenging when systems use distributed architectures. In a previous work, we proposed SocioTrust, a trust model that is based on probability theory to evaluate trust in a system for an activity. In SocioTrust, trust values are considered as the probability, by which a trustor believes that a trustee behaves as expected. A limita- tion of using traditional probability is that users cannot express their uncertainties about some actors of their activity. In real situations, not everyone is in possession of all the necessary information to provide a dogmatic opinion about something or someone. Subjective logic thus emerged to facilitate the expression of trust as a subjective opinion with degrees of uncertainty. In this paper, we propose SubjectiveTrust, a graph-based trust model to evaluate trust in a system for an activity using subjective logic. The distinctive features of our proposal are (i) user's un- certainties are taken into account in trust evaluation and (ii) besides taking into account the trust in the different entities the user depends on to perform an activity, it takes into consideration the architecture of the system to determine its trust level

FETA: Federated QuEry TrAcking for Linked Data

International audienceFollowing the principles of Linked Data (LD), data providers are producing thousands of interlinked datasets in multiple domains including life science, government, social networking, media and publications. Federated query engines allow data consumers to query several datasets through a federation of SPARQL endpoints. However, data providers just receive subqueries resulting from the decomposition of the original federated query. Consequently, they do not know how their data are crossed with other datasets of the federation. In this paper, we propose FETA, a Federated quEry TrAcking system for LD. We consider that data providers collaborate by sharing their query logs. Then, from a fed-erated log, FETA infers Basic Graph Patterns (BGPs) containing joined triple patterns, executed among endpoints. We experimented FETA with logs produced by FedBench queries executed with Anapsid and FedX federated query engines. Experiments show that FETA is able to infer BGPs of joined triple patterns with a good precision and recall