Patent ID: 8230010

Claim:
A communication system comprising: a plurality of multicast devices forming a shared multicast distribution tree; a host device with a processor; a key server; and a designated device with a processor, separate from the key server, through which the host device requests access to the shared tree associated with a group, wherein: the host device obtains access information from the key server for the host device to enable the host device to request access to the shared tree associated with the group, the access information including authentication information unique to the host device/group pair, the authentication information including an access token comprising a host identifier, a token identifier and an authentication key for authenticating the host with the designated device; the designated device obtains the access information associated with the host device/group pair from the key server for enabling the host device to access the shared tree; the host device sends an access control message to the designated device to join the shared tree; and the designated device uses the access information to authenticate the host device before adding the host device to the shared tree, including using the token identifier to obtain a group identifier and authentication key from memory in order to verify authentication of the host device.