METHOD AND SYSTEM FOR SECURE DISTRIBUTION OF CRYPTOGRAPHIC KEYS ON MULTICAST NETWORKS

A method and apparatus for secure and scalable key management in a multicast network environment is provided. In a first portion, one or more seed nodes on the network receive a multicast transmission request for a cryptographic key from a requesting node. The seed node compares the identity of the requesting node with an authenticated predetermined list of nodes having permission to receive the cryptographic key. If the comparison indicates the requesting node is not a member of the authenticated predetermined list, the seed node denies the multicast request. However, if the comparison indicates that the requesting node is a member of the predetermined list of nodes, the cryptographic key is transmitted using a secure unicast key distribution technique such as SKIP. A second portion concerns the requesting node which generates a multicast request to obtain the cryptographic key from one or more seed nodes and one or more keyed nodes on the internetwork. The multicast request for the cryptographic key is initially transmitted a minimum hop count over the internetwork to locate the closest seed node. The requesting node delays a brief time period waiting for at least one response from at least one seed node or keyed node on the internetwork. If the at least one response is not received within this time period, the minimum hop count is increased by a hop count increment and the requesting node repeats the above steps. Eventually, the requesting node increases the hop count and receives the cryptographic key over a secure unicast key management technique such as SKIP. As a final step, the requesting node is convered into a keyed node. The keyed node acts as a seed node and provides the cryptographic key to other requesting nodes on the internetwork.