Analysis and Design of Distributed Key Distribution Centers

A Key Distribution Center of a network is a server who generates anddistributes secret keys to groups of users for secure communication. A Distributed Key Distribution Center is a set of servers that jointly realizes a Key Distribution Center. In this paper we describe in terms of information theory a model for Distributed Key Distribution Centers, and we present lower bounds holding in the model for the main resources needed to set up and manage a distributed center, i.e., memory storage, randomness, and bandwidth. Then we show that a previously proposed protocol which uses a bidimensional extension of Shamir's secret sharing scheme meets the bounds and is, hence, optimal.