An improved efficient self-healing group key distribution

In Donggang Liu et al. (2003), the authors presents new group key distribution techniques for large and dynamic groups over unreliable channels. The techniques are based on the self-healing key distribution methods (with revocation capability) recently developed by Staddon et al. (2002). By introducing a novel personal key distribution technique, this paper reduces the communication overhead of personal key share distribution and the communication overhead of self-healing key distribution with t-revocation capability where t is the maximum number of colluding group members. Because this technique adopts the polynomial to realize, the degree of these polynomials determine the threshold of the number of colluding group members. And because this scheme is based on ID, so the identity of the excluded member will be open. In this paper, we improved a new scheme based on exponential function to avoid the limitation of threshold and at the same time, our scheme is not based on ID, the identity of member can be protected effectively. All these results are achieved without sacrificing the unconditional security of key distribution and overhead of communication and personal storage. In addition, two techniques proposed in Donggang Liu et al. (2003) to allow trade-off between the broadcast size and the recoverability of lost session keys are also adaptive in our scheme.