LAUSR

Despite of having many revocable group signatures schemes proposed in recent years, backward security, which prevents a revoked signer from generating group signatures for future time periods, was still missing the concern. In this paper, we introduce a security model that contains the definition of backward security, and propose a revocable group signatures scheme that is more efficient and scalable compared to previous ones, especially for Sign and Verify algorithms, which are performed much more frequently than others. In addition, considering the heavy workload of the group manager, we divide the whole group into groups by employing a decentralized model to make our scheme more scalable, and thus more practical in real-life applications.