Enhancing Privacy for Digital Rights Management

This chapter addresses privacy issues in DRM systems. These systems provide a means of protecting digital content, but may violate the privacy of users in that the content they purchase and their actions in the system can be linked to specific users. The chapter proposes a privacy-preserving DRM system in which users interact with the system in an pseudonymous way, while preserving all security requirements of usual DRM systems. To achieve this goal, a set of protocols and methods is proposed for managing user identities and interactions with the basic system during acquisition and consumption of digital content. Privacy-enhancing extensions are also proposed. Unlinkable purchase of content, which prevents content providers from linking all content purchased by a given user, is discussed. Moreover, a method which allows a user to transfer content rights to another user without the two users being linked by the content provider is provided.