Abstract:Forward security and public verifiability are two important security features of signcryption schemes. How to design schemes satisfying the two security features at the same time is a public problem in signcryption study. According to the security defect of the signcryption in the Reference [1] put forward by Zhang Chuanrong et al, a new signcryption scheme is proposed through the introduction of secret information of the signcryptioner in this paper, which satisfies with forward security, public verifiability and resistting the PKG to entrap at the same time. Simultaneously, the new scheme can avoid the attrack of the evil information throngh unsigncrying the ciphertext after the signature verification in the process of unsigncryption.