摘要：The method of broadcast encryption has been applied to the transmission of digital information such as multimedia, software, and paid TV on the open network. In this broadcast encryption method, only authorized users can gain access to digital information. When broadcast message is transmitted, authorized users can first decode the session key using the previously given private key and get digital information using this session key. This way, users retrieve a message or a session key using the key transmitted by broadcasters. For their part, broadcasters need to generate and distribute keys. Broadcasters should also carry out efficient key renewal when users subscribe or un-subscriber. In this paper we present a DRM model, which satisfies the requirement of the contents and includes also the concept of a broadcast encryption. Using this model, we can offer the authority to copy as the number of reproduction as many as user wants
