Ubiquitous and pervasive technologies contribute significantly to the quality of life of dependent people by providing personalized services in context aware environments. The deployment of these services within indoor and outdoor environments still require security, privacy and trust issues for dependent persons. Considering the strong links between these three issues, our challenging task was to integrate them in a common and flexible framework using contextual information. In this paper, we propose a security framework that integrates context awareness to perform authentication and access control in a very flexible and scalable model while ensuring both privacy and trust. The framework focuses on the authentication of users who request access to the resources of smart environment system through static devices (i.e. smart card, RFID, etc.), or dynamic devices (i.e. PDA, mobile phones, etc.)