Self-healing Key Distribution Schemes with Sponsorization

In a self-healing key distribution scheme a group manager enables a large and dynamic group of users to establish a group key over an unreliable network. The group manager broadcasts in every session some packet of information in order to provide a common key to members of the session group. The goal of self-healing key distribution schemes is that, even if the broadcast is lost in a certain session, the group member can recover the key from the broadcast packets received before and after the session. This approach to key distribution is quite suitable for wireless networks, mobile wireless ad-hoc networks and in several Internet-related settings, where high security requirements need to be satisfied. In this work we provide a generalization of previous definitions in two aspects. The first one is to consider general structures instead of threshold ones to provide more flexible performance to the scheme. The second one is to consider the possibility that a coalition of users sponsor a user outside the group for one session: we give the formal definition of selfhealing key distribution schemes with sponsorization, some bounds on the required amount of information. We also give a general construction of a family of self-healing key distribution schemes with sponsorization by means of a linear secret sharing scheme. Our construction differs from previous self-healing key distribution schemes in the fact that the length of the broadcast is almost constant. Finally we analyze the particular case of this general construction when Shamir’s secret sharing scheme is