Improvement of an Identity-Based Aggregate Signature Protocol from Lattice

In 2022, Li et al. [1] proposed a quantum secure and non-interactive identity-based aggregate signature protocol from lattices. In the end of their paper, they claimed that their scheme has key escrow problem. Based on this fact, we improve their scheme and propose a lattice-based certificateless aggregate signature protocol (L-CASP). Furthermore, our scheme has same signature size as Li et al. scheme and can avoid key escrow problem. Finally, we prove that our scheme is existentially unforgeable against adaptive chosen message attacks (EUF-CMA) under type I adversary and a type II adversary in the random oracle model (ROM).