New secret sharing scheme for multipartite access structures with threshold changeability

A secret sharing method that realizes a variation of the multipartite access structure is proposed in this paper. The method indirectly distributes shares of the main secret with one random secret among a set of players. Again the shares of some unknown random secrets are calculated by the players and shared among themselves. At each level, the players can change their threshold to any arbitrary value dynamically. Each subset of the players can only recover the secret corresponding to their own level. The main secret will be retrieved by any level players if and only if all the secrets in other levels are first recovered. The access structure that our scheme realizes is such that the players of different levels calculate secrets individually but to recover the main secret cooperation of players from all the levels are required.