We propose an efficient method of access control for hierarchical multimedia content. The proposed method simultaneously controls access to each medium contained in multimedia content and to each entity which is hierarchically organized in an individual medium. Even though this method achieves such fine control, it does not increase the computational complexity for key derivation. In our method, a service provider manages only a single key to control access to one multimedia content regardless of the number of media and the depth of hierarchy in each medium. The single managed key is not delivered to any user.
