Deliverable D2.1 provides a detailed description of the conceptual architecture of ENTRUST, which will provide the basis for the design, implementation, and integration activities of all ENTRUST components to be performed throughout the lifecycle of the project. To this end, we first provide an analysis of the status in the medical device domain, and we define the motivation of ENTRUST considering the most recent developments in the field of medical device cybersecurity. In addition, we provide details on existing standardization and regulatory efforts related to the use of medical devices by medical organizations and identify gaps in the existing standards. The aforementioned analysis provides the basis for the identification of the core research pillars considered in the context of ENTRUST, and the formulation of the research agenda to be followed. Next, for each of these pillars, we provide a state-of-the-art analysis, as well as the positioning of ENTRUST within the corresponding research domain. In addition, the analysis on existing standards yielded an exhaustive list of functional, security, operational, legal, and ethical requirements, which has been refined and adapted to the specific needs of ENTRUST. Based on all the above, the conceptual architecture of ENTRUST is defined, including all components and their interconnectivity. The action workflow is split into three core phases, namely manufacturing, pre-deployment, and runtime, and we provide sequence diagrams depicting the action workflows for the processes to be performed in the context of the framework. Finally, we provide detailed description of the four envisioned use case demonstrators where the validation of the ENTRUST framework will be performed, and we define preliminary versions of the User Stories and Key Performance Indicators (KPIs) based on which the experimental activities will be performed.