Content key acquisition protocols hiding the usage information in DRM system

Digital Rights Management (DRM) systems have often been accused of violating the user privacy for over-collecting the individual information and tracking the usage information by the license server. However, users have the rights to hide their information to the copyright holder and protect their privacy. In this paper, we present a content key acquisition scheme and propose two efficient key acquisition protocols for it. After analyzing the license generation process of the DRM system WMRM (Windows Media Rights Manager), we apply blind signature in our scheme and design two protocols based on RSA algorithm and ElGamal algorithm independently. To solve the problem of the usage information leak, the license server can not obtain the plaintext of the KeyID or get anything about the content playing. In this way, we can realize the usage information hiding and protect the privacy of the user.