A New Dynamic Threshold Secret Sharing Scheme from Bilinear Maps

In a (t, n) threshold secret sharing scheme, any t- out-of-n participants could recover the shared secret, and any less than t participants could get nothing about the shared secret. Most of the existing secret sharing schemes are not flexible enough for the fixed threshold. In this paper, a new dynamic threshold secret sharing scheme was proposed, which is based on bilinear maps. The basic idea of this scheme is as follows: The system is consisted of some participants and a dealer. Each participant holds only one permanent private key. The dealer is responsible to choose the shared secret, and to construct a system of linear equations by using the participants ´public keys. The dynamic threshold is realized by adjusting the number of linear equations. Compared with most existing schemes, the proposed scheme is not dependent on any secure channel between the dealer and the participant. The analysis shows that this scheme could correctly reconstruct the shared secret, the security of the shared secret could be guaranteed, and the cheater could be identified easily. Moreover, because this scheme is constructed on elliptic curve, much computation overhead, storage overhead and bandwidth overhead are saved.