Assume that there are players and an eavesdropper Eve of unlimited computational power and that several pairs of players have shared secret keys beforehand. In a key sharing graph, each vertex corresponds to a player, and each edge corresponds to a secret key shared by the two players corresponding to the ends of the edge. Given a key sharing graph, a player wishes to send a message to another player so that the eavesdropper Eve and any other player can get no information on the message. In this paper, we first give a necessary and sufficient condition on a key sharing graph for the existence of such a unicast protocol. We then extend the condition to the case where a multiple number of players other than the sender and receiver passively collude. We finally give a sufficient condition for the existence of a secure multicast protocol.
This paper proves multicast management belongs to problems of HDP, provides the cost analytical model of multicast logical key tree which applies HDPT. Based on the above analysis, the author proposes an improved multicast logical key management scheme termed as L-R logical key tree management scheme. L-R logical key tree management scheme is a kind of imbalanced multicast logical key tree, which is based on periodic re-key, according member nodes’ joining and leaving different probability, it employs different multicast key management strategy. The paper provides the design and calculation of the scheme, and realizes it in a simulation. By comparing this scheme with the typical LKH one, it shows clearly the scheme proposed in the paper is of high effect and low cost.
ABSOLUTELY SECURE MESSAGE TRANSMISSION USING A KEY SHARING GRAPH