MULTICAST SECURITY USING KEY GRAPHS AND SECRET SHARING

Abstract

Multicast communication is increasingly used in applications where the volume of network traffic needs to be minimized. Security of the packets delivered from a source to a large group of receivers presents one of the most challenging research problems for the network architecture. A majority of the proposals for scalable secure multicasting makes use of hierarchical key distribution trees. The Centralized Tree-Based Key Management scheme assigns a unique key to each of the nodes in a member’s path to the root. The group key is used by a central server to encrypt multicast data until a member joins or leaves the group. For multicast applications such as pay-per-view where the content has very high value, the group key may need to change frequently. In this paper, we introduce a new approach based on secret sharing in which the server assigns unique secret shares to the nodes in the distribution tree. Our proposal is a prepositioned shared secret scheme that allows the reconstruction of different keys by communicating different activating shares for the same prepositioned information, i.e., the shares stored at the key nodes in the tree.