Secret Sharing in User Hierarchy: Share Generation, Distribution and Renewal

Secret sharing in user hierarchy represents a challenging area for research. A lot of research work has already been done in this direction. This book presents a novel approach to share a secret among a hierarchy of users while overcoming the limitations of the already existing mechanisms. Traditional (k + 1; n)-threshold secret sharing, is secure as long as an adversary can compromise not more than k secret shares. But in real life it is often feasible for an adversary to obtain more than k shares over a long period of time. Here we present a way to overcome this vulnerability, while implementing our hierarchical secret sharing scheme. The use of Elliptic Curve Cryptography makes the computations easier and faster in our work. At present, a number of efficient schemes exist for sharing a secret into a group of users who are arranged into a hierarchy. Incidentally, all existing schemes have been developed considering non-overlapping hierarchies. This book presents a generalization of the existing hierarchical secret sharing schemes, which is applicable to an overlapping or tangled user hierarchy.