Today, the numerous applications of the Internet of Things (IoT) can significantly improve the daily life of users. Thanks to these applications, it is possible to remotely control the various devices in the home, monitor a patient's vital signs and automatically alert their doctor in case of a problem. However, security and privacy issues prevent users from fully trusting these applications, which can have the effect of slowing down the overall adoption of these technologies and their widespread deployment. To address these security and privacy issues, several solutions have been proposed. However, several challenges remain to be addressed to enable widespread adoption of these applications. The user-centric approach seems to be very relevant to address many of these challenges. To provide user-centric security and privacy and enable support for many IoT applications, the work in this thesis proposes to adapt the implementation of security and privacy mechanisms based on the user context. First, this thesis presents the CASPaaS (Context-Aware Security and Privacy as a Service) architecture. This context-aware security and privacy architecture for the IoT is based on the 'as a service' approach. It ensures dynamic and personalized adaptation of security and privacy services according to the user's context. Thanks to the 'as a service' design, this architecture is characterized by a high degree of flexibility that allows it to support a wide range of IoT many IoT applications. In a second step, this thesis presents a system to manage the security and reliability of the CASPaaS architecture itself. This system, called SETUCOM (SEcure and TrUstworthy COntext Management) manages the security of the contextual data exchanged within the CASPaaS architecture as well as the trust of the data sources. This allows to mitigate a large number of attacks that can lead to the malfunctioning of our CASPaaS architecture.
In a third step, this thesis presents a new decentralized context-sensitive authorization management system for the IoT. This system, also based on the 'as a service' approach, offers the user a dynamic, decentralized and simple authorization management. Finally, this thesis focuses on the deployment of the CASPaaS service closer to the users based on an Edge Computing infrastructure. In this context, we propose a new dynamic placement strategy for this service. This strategy uses artificial intelligence techniques to ensure an efficient placement while optimizing the different performances (network, service, Edge nodes capacities, placement process itself, etc.).