1. A method for securely establishing communication in a multicast group of nodes of a network, in which the nodes of the network include publishers and subscribers, the method comprising the steps of: registering a publisher and a subscriber with an event server; and generating, within the event server, a group session key for establishing a multicast group, wherein the multicast group includes the publisher and the subscriber, and the group session key is encrypted in a first message that has a prescribed format.