Patent ID: 7360084

Claim:
A communication system comprising: a rendezvous point device that forwards multicast communication messages to members of a shared tree and is a root of the shared tree; a designated device in communication with the rendezvous point device via a number of intermediate devices; and a host device in communication with the designated device, wherein to join the shared tree: the host device forwards an authentication key, uniquely generated by a key server for the host device, to the designated device; the host device sends a join request to the designated device using a predetermined multicast group management protocol in order to join the shared tree for receiving the multicast communication messages forwarded by the rendezvous point device, the join request including the authentication key; the designated device receives the join request and forwards to the rendezvous point device via the number of intermediate devices an encoded join request, wherein the encoded join request comprises a tag field computed using a keyed hashed function and the authentication key; the rendezvous point device receives the encoded join request and authenticates the encoded join message-by comparing the authentication key received in the tag against a stored authentication key associated with the host device; wherein the host device is prevented from receiving the multicast communication messages forwarded by the rendezvous point device, if the rendezvous point device determines that the encoded join message is not authentic.