Pitch in: A Secure Extension Signature Based on SM9.

SM9 is the identity-based cryptography (IBC) promulgated by the State Cryptography Administration of China. SM9-IBS has become an international standard in 2017 (the main part of ISO/IEC 14888-3/AMD1 standard). SM9-IBS reduces the certificate application and verification phases, which has obvious advantages in identity authentication in mobile Internet, Internet of things (IoT), big data, and other fields. Many researchers use SM9 as the underlying cryptography and have successively proposed extended signatures such as group, ring, and two-party cooperation. In order to further promote the application of SM9, reduce the pressure of root KGC and improve the reliability of the system, we present a secure and feasible hierarchical SM9 signature scheme which is the first SM9-IBS (Identity-based Signature) extension. Also, we prove its security is existentially unforgeable under adaptive chosen message and identity attacks (EUF-CMIA) in the standard model. At the same time, the implementation of our scheme using Java does not lead to an additional performance burden based on the SM9 algorithm.