Hierarchical Key Sharing
In this paper, the authors consider the problem of secret sharing with hierarchical structure. Here, the secret will be shared among group of m members, i.e., divided into different levels. Members are said to be authorized if they have at least m0 members form the highest levels, as well as at least m1 > m0 members from two highest levels and so on. Members will differ in their authority and the presence of higher level member is essential in order to recover the secret. None of the existing system addresses the setting where a bank transfers should be signed by three employees, where in at least one of them must be a department manager.