Patent ID: 8369527

Claim:
A multicast host for communicating information published about any one topic of a set of topics to one or more authorized subscribers to those topics, the set of topics being partitioned into one or more partition elements, each partition element having a partition element encryption key associated therewith, wherein each of the one or more partition elements is a disjoint proper subset of the set of topics in which no two partition elements intersect, the host comprising: means for receiving information relating to a root topic, wherein the root topic is depicted as a root node in a topic hierarchical tree; means for determining a partition element for the root topic, wherein the partition element is depicted in the topic hierarchical tree as a topic leaf in the topic hierarchical tree, and wherein the partition element is part of a group identified and defined by the root topic; means for retrieving a partition element encryption key associated with the partition element, wherein each partition element encryption key is unique for a specific partition element, wherein the partition element encryption key is depicted as a key leaf on a key hierarchical tree, and wherein each node in the key hierarchical tree matches a corresponding topic leaf in the topic hierarchical tree; means for encrypting the information with a retrieved partition element encryption key; means for communicating the information to the one or more authorized subscribers, wherein the one or more authorized subscribers have access to all represented keys for a group located in a path from the key leaf to a root of the key hierarchical tree; means for transmitting said all represented keys to said one or more authorized subscribers; and means for, in response to an identification of a topic changing and a new subscriber of the topic being added, generating a new topic key for the topic, wherein the new topic key replaces an old topic key for the topic, and wherein the old topic key is hidden from the new subscriber to prevent the new subscriber from decrypting previously transmitted multicast messages.