Optimal Construction of Unconditionally Secure ID-Based Key Sharing Scheme for Large-Scale Networks

E cient ID based key sharing schemes are desired world widely for secure communica tions on Internet and other networks The Key Predistiribution Systems KPS are a large class of such key sharing schemes The remarkable property of KPS is that in order to share the key a participant should only input its partner s identi er to its secret KPS algorithm Although it has a lot of advantages in terms of e ciency to achieve unconditional security a large amount of memory is required While conventional KPS establishes communication links between any pair of entities in a communication system in many practical commu nication systems such as broadcasting not all links are required In this article we show the optimal method to remove these unnecessary communication links In our scheme the required memory for each entity is just proportional to the number of its partners while that in conventional KPS is proportional to the number of entities in the whole system As ex ample if an entity communicates only with r of others the required memory is reduced to be r of that of conventional KPS Furthermore this memory size is proven to be optimal Our scheme provides a more e cient way for secure communication especially in large scale networks