Nowadays, each user or organization is already connected to a large number of sensor nodes which generate a substantial amount of data, making their management not an obvious issue. In addition, these data can be confidential. For these reasons, developing a secure system managing the data from heterogeneous sensor nodes is a real need. In the first part, we developed a composite-based middleware for wireless sensor networks to communicate with the physical sensors for storing, processing, indexing, analyzing and generating alerts on those sensors data. Each composite is connected to a physical node or used to aggregate data from different composites. Each physical node communicating with the middleware is setup as a composite. The middleware has been used in the context of the European project Mobesens in order to manage data from a sensor network for monitoring water quality. In the second part of the thesis, we proposed a new hybrid authentication and key establishment scheme between senor nodes (SN), gateways (MN) and the middleware (SS). It is based on two protocols. The first protocol intent is the mutual authentication between SS and MN, on providing an asymmetric pair of keys for MN, and on establishing a pairwise key between them. The second protocol aims at authenticating them, and establishing a group key and pairwise keys between SN and the two others. The middleware has been generalized in the third part in order to provide a private space for multi-organization or -user to manage his sensors data using cloud computing. Next, we expanded the composite with gadgets to share securely sensor data in order to provide a secure social sensor network

Le développement des réseaux de capteurs sans fil fait que chaque utilisateur ou organisation est déjà connecté à un nombre important de nœuds. Ces nœuds génèrent une quantité importante de données, rendant la gestion de ces données non évident. De plus, ces données peuvent contenir des informations concernant la vie privée. Les travaux de la thèse attaquent ces problématiques. Premièrement, nous avons conçu un middleware qui communique avec les capteurs physiques pour collecter, stocker, traduire, indexer, analyser et générer des alertes sur les données des capteurs. Ce middleware est basé sur la notion de composants et de composites. Chaque nœud physique communique avec un composite du middleware via une interface RESTFul. Ce middleware a été testé et utilisé dans le cadre du projet Européen Mobesens dans le but de gérer les données d'un réseau de capteurs pour la surveillance de la qualité de l'eau. Deuxièmement, nous avons conçu un protocole hybride d'authentification et d'établissement de clés de paires et de groupes. Considérant qu'il existe une différence de performance entre les noeuds capteur, la passerelle et le middleware, nous avons utilisé l'authentification basé sur la cryptographie basée sur les identités entre la passerelle et le serveur de stockage et une cryptographie symétrique entre les capteurs et les deux autres parties. Ensuite, le middleware a été généralisé dans la troisième partie de la thèse pour que chaque organisation ou individu puisse avoir son propre espace pour gérer les données de ses capteurs en utilisant le cloud computing. Ensuite, nous avons portail social sécurisé pour le partage des données des réseaux de capteurs / Nowadays, each user or organization is already connected to a large number of sensor nodes which generate a substantial amount of data, making their management not an obvious issue. In addition, these data can be confidential. For these reasons, developing a secure system managing the data from heterogeneous sensor nodes is a real need. In the first part, we developed a composite-based middleware for wireless sensor networks to communicate with the physical sensors for storing, processing, indexing, analyzing and generating alerts on those sensors data. Each composite is connected to a physical node or used to aggregate data from different composites. Each physical node communicating with the middleware is setup as a composite. The middleware has been used in the context of the European project Mobesens in order to manage data from a sensor network for monitoring water quality. In the second part of the thesis, we proposed a new hybrid authentication and key establishment scheme between senor nodes (SN), gateways (MN) and the middleware (SS). It is based on two protocols. The first protocol intent is the mutual authentication between SS and MN, on providing an asymmetric pair of keys for MN, and on establishing a pairwise key between them. The second protocol aims at authenticating them, and establishing a group key and pairwise keys between SN and the two others. The middleware has been generalized in the third part in order to provide a private space for multi-organization or -user to manage his sensors data using cloud computing. Next, we expanded the composite with gadgets to share securely sensor data in order to provide a secure social sensor network

When police and state services fail to provide security, other actors often take on the role of making their communities safer. By exploring the different constellations of actors providing security, this thesis seeks to understand the variation of urban violence on a local level. This topic is particularly relevant as violence has been found to vary across and within cities. To deepen our knowledge of these variations, I ask: how do different forms of hybrid security governance influence levels of urban collective violence? I propose a novel theoretical framework and argue that power balances within a hybrid security arrangement should decrease levels of violence. A qualitative comparative case study is conducted to test the theory on three communities in Cape Town, South Africa. Data collection consisted of in-depth interviews and was carried out over the course of three months in 2022. The main finding is that balanced forms of hybrid security governance appear to have an impact on some forms of collective violence, especially violence types occurring within communities. More research is needed to fully understand and assess these dynamics.