Patent ID: 8130689

Claim:
A method for dynamically setting up and controlling temporarily formed communications groups with secure transmission, wherein nodes potentially participating in a communications group are connected via a common transmission medium that enables efficient transmission of broadcast and/or multicast messages between the nodes, the method which comprises the following steps: sending a broadcast message from an initiator node to all nodes connected to the initiator node via the common transmission medium, the broadcast message containing at least one group identifier, an identifier of the initiator node, information about the communications group, and an address of the initiator node; analyzing the received broadcast message by the nodes accessible via the common transmission medium, wherein the initiator node is authenticated by the nodes; responding with a first unicast message by nodes participating in the communications group to the initiator node, the first unicast message containing at least one identifier of a participating node and an address of the participating node; receiving first unicast messages by the initiator node and authenticating the participating nodes by the initiator node; sending a second unicast message from an initiator node to each node participating in the communications group, the second unicast message including at least one multicast identifier and a security key; if the initiator node leaves the communications group, the initiator node sends a special multicast message including at least an identifier thereof and a request for function transfer to all nodes participating in the communications group; all nodes that take over an initiator function send a third special unicast message that contains at least their identifier to the initiator node; after receiving this third unicast message and authenticating the responding nodes, the initiator node selects from the responding nodes a new initiator node in accordance with a predetermined procedure; the initiator node then transmits information about the communications group and about the participating nodes by way of a fourth unicast message; and a new initiator node then takes over the initiator function and generates a new security key, and the new initiator node sends the new security key encrypted and together with information about the new initiator node to each node present in the communications group by way of a fifth unicast message.