Aimed at the deficiencies of Zheng sign cryptic scheme and SK sign cryptic scheme, this paper proposes improved schemes respectively by utilizing the principle, i.e. sign cryptic information and open information for restoring the information needed by sign decryptic scheme to the needs of safety and efficiency. The difficulty of solving oneway function is utilized to improve Zheng sign cryptic scheme. The security has been greatly improved compared with the original scheme without affecting the efficiency of the case, and has forward security and public verifiability. The bilinear pairing of elliptic curve and identitybased cryptosystem are used to improve SK sign cryptic scheme, and the safety and the efficiency of the improved scheme both have been greatly improved with the public verifiability, and the communication cost and the computation cost are reduced. The results show that the safety and the efficiency of the improved schemes have been improved and meet the basic requirements of sign cryptic scheme.