Avoid illegal encrypted DRM content sharing with non-transferable re-encryption

Digital rights management (DRM) technology enables valuable electronic media content distribution while preserving content providers´ rights and revenues. Traditional DRM system utilizes security techniques to restrict copying of media content or allow only a single copy to be made. However consumers are demanding for the right to make copies for personal use or the right to use content on any device. Several DRM infrastructures have been proposed for secure content sharing. These infrastructures usually require cooperation and participation of both DRM technology providers and content providers; however there is a popular flaw in these schemes: the malicious employees of DRM technology providers can distribute DRM enabled contents to any consumers or make copies of a purchased content accessible to any devices without letting content provider know, thus reducing content providers´ benefit. In this paper, we propose a novel DRM infrastructure which is based on a non-transferable re-encryption scheme to solve the above problem inherent in existing DRM infrastructures. In the proposed infrastructure, DRM technology providers and content providers are required to cooperate to make a purchased digital content for a specific device accessible by other different devices, and get extra profit from providing such services. The system preserves DRM technology providers and content providers´ security properties while achieving secure and mutual profitable DRM content sharing. Furthermore, we allow content providers to trace the content, and control the content sharing rights. Even when malicious employees in DRM technology providers and DRM agent collude, they cannot re-delegate access rights to any device without permission from content provider, thus preserving content provider´s benefit.