One forward-secure signature scheme using bilinear maps and its applications

Forward-secure signatures are proposed to deal with the key exposure problem. Compared to regular signatures, forward-secure signatures have a special update algorithm that can evolve the new private key in each time period. Therefore, it can protect the security of signatures previous to the time period of key exposure. The efficiency is an important issue of forward-secure signatures. In this paper, we construct a new forward-secure signature scheme using bilinear maps. In this scheme, all performance parameters have complexities of log magnitude in terms of the total time periods. In addition, our scheme needs very few (only triple) pairing operations in the verifying algorithm, which is very important because the pairing operation is very time-consuming. This scheme is proved to be forward secure in the random oracle model assuming the CDH problem is hard. Finally, we give some applications of this scheme including constructing an intrusion-resilient signature scheme and constructing a forward-secure threshold signature scheme.