DRM, Trusted Computing and Operating System Architecture

Robust technological enforcement of DRM licenses assumes that the prevention of direct access to the raw bit representation of decrypted digital content and the license enforcement mechanisms themselves is possible. This is difficult to achieve on an open computing platform such as a PC. Recent trusted computing initiatives namely, the Trusted Computing Group (TCG) specification, and Microsoft's Next Generation Secure Computing Base (NGSCB) aim in part to address this problem. The protection architecture and access control model of mainstream operating systems makes them inappropriate as a platform for a DRM content rendering client because decrypted content cannot be protected against a privileged process. If a DRM client is to be deployed on an open computing platform, the operating system should implement the reference monitor concept, which underpins the mandatory access control model. The TCG model of trusted computing has important limitations when combined with an operating system enforcing discretionary access control. We argue that the TCG services of sealed storage and remote attestation which are important in DRM applications, cannot operate in a secure and efficient manner on such an operating system