Smart devices became Marc Weiser's Computer of the 21st Century. Due to their versatility a lot of private data enriched by context data are stored on them. Even the health industry utilizes smart devices as portable health monitors and enablers for telediagnosis. So they represent a severe risk for information security. Yet the platform providers' countermeasures to these threats are by no means sufficient. In this paper we describe how information security can be improved. Therefore, we postulate requirements towards a secure handling of data. Based on this requirements specification, we introduce a secure data container as an extension for the Privacy Management Platform. Since a complete isolation of an app is usually not practicable, our approach also provides secure data sharing features. Finally, we evaluate our approach from a technical point of view as well as a security point of view and show its applicability in an eHealth scenario.