Optimal unconditionally secure ID-based key distribution scheme for large-scaled networks

Efficient ID-based key sharing schemes are desired worldwide in order to ob tain secure communications on the Internet and other related networks, and Key Pre-distribution System (KPS) is one of the majority of such key sharin g schemes. The remarkable property of KPS, is that, user need only input th e partner's identifier to the secret KPS-algorithm in order to share a key between them. Although this is just a small part of many advantages KPS has in terms of efficiency, an enormous amount of memory is always required to achieve perfect security. While the conventional KPS methods can establish communication links between any pair of entities in a communication system , in most of the practical communication environment, such as in a broadcas t system, not all links will be required. In this article, we achieved a de sirable method to remove the unnecessary communication links between any pa ir of entities in a communication system. In our scheme, required memory si ze per entity was just proportional to the number of entities of the partne r's, while that in conventional KPS, it is proportional to the number of en tities of the whole communication system. As an example, if an entity commu nicates with only 1/r others, the memory requirement is reduced to 1/r of t he conventional KPS's. Furthermore, it was proven that the obtained memory size was optimum. Overall, our scheme confirmed greater efficiency to achie ve secure communication particularly suited in large-scale networks.