DRMFS: A file system layer for transparent access semantics of DRM-protected contents

In many digital rights management (DRM) schemes, only a specialized application can decode DRM-protected contents. This restriction is harmful to users because they want to use their purchased digital contents with their preferred applications. To relax this restriction, DRM technology should provide transparent access semantics of DRM-protected contents to authorized applications. Some previous schemes achieve limited transparent access semantics but have efficiency and applicability problems. In this paper, we propose a DRM control scheme at the file system layer (DRMFS) that achieves transparent access semantics of DRM-protected contents with efficiency, applicability, and portability. Since DRMFS is working at the file system layer, any authorized application can access DRM-protected content in the same way as using general files. To implement a prototype of DRMFS, we use the Filesystem in Userspace (FUSE) library that is a well known library used to develop user level file systems. We explain details of the implementation and evaluate its performance. The evaluation results show that DRMFS has acceptable overheads.