Content use management system, content use management method, and client device

摘要

A content distribution system distributes a content key and content use conditions for controlling a content use in a client apparatus to the client apparatus, via a communication channel, from either a multicast distribution server or a unicast distribution server. A content distribution management server determines by which distribution method to send the content key and content use conditions of each content according to an attribute of the content (a compression format, a compression ratio, a content holder, and the like). An encrypted content distribution server distributes only encrypted content whose content key and content use conditions are to be distributed by the unicast, and the multicast distribution server distributes encrypted content whose content key and content use conditions are superimposed by the multicast.