Protection of content streamed through the retransmission

A multicast transport scheme allows a plurality of users to receive the same content. It solves the waste of resource in network use in proportion to the number of users. However, since a current network environment of the Internet does not support the multicast transport, it is unavailable. Thus, a method of distributing a network load on a server through inter-PC re-transmission is currently used in place of the multicast transport. In the case of content service through re-transmission, since the content service is provided by ordinary individuals, as well as a content service provider, a copyright protection scheme needs to consider the ordinary users who perform the re-transmission. In this paper, we propose the protection scheme for relayed content. It provides the secure and efficient key distribution scheme.