Experiences in Implementing a Kernel-Level DRM Controller

The enforcement of DRM licenses is performed by a DRM controller, and it can be implemented at the application level, the operating system level and at a hardware level. In this paper we discuss our experiences in implementing an operating system level DRM controller based on the GNU-Linux kernel. This paper investigates the feasibility of creating a transparent, application independent DRM controller and the performance implications thereof. Our investigation has revealed, that while a number of access control rules can be enforced transparently at the operating system level, there are also a number of rules that require application level enforcement. Thus, we recommend separation of rights to two levels of enforcement to take advantage of transparent enforcement at the kernel level. Our performance analysis shows promise with minimal user observable time impact for small files less than 25 MB in size. However, there is still a significant performance impact and a very noticeable user observable time performance impact for larger files. Thus improvements are necessary if DRM controllers are to be deployed in multi-user, high-load environments like file servers.