Pervasive systems enable us to have an overview of what digital environments will look like in the future. Opportu- nities given by pervasive systems, both in terms of applica- tions and services to the user are manifold and very promis- ing. From the user point of view, privacy and security of her personal data is a real issue, which must be addressed to make pervasive systems accepted. A wide adoption of per- vasive systems can not be possible without an integrated approach to security. We propose a model of security and privacy for pervasive environments, integrated with an ar- chitecture, namely PerSE, in which privacy is a main con- cern and is at the core of the conception.