结合在线/离线方法的无证书签密

作为密码学原语，签密同时具有签名的认证性与加密的机密性。在线/离线签密结合了在线/离线的方法，在已有基础上提高了系统的效率。但目前的在线/离线签密方案大多数都是在基于身份的环境下实现的，都存在密钥托管的安全问题。基于无证书密码体制撤销证书管理及无密钥托管问题的优点，提出了一种安全的在线/离线的无证书签密方案，满足离线阶段不需要确定接收者身份信息的条件，并在随机预言模型中证明了方案的安全性。

Certificateless signcryption with online/offline technique

Signcryption as a cryptographic primitive is a splendid combination of signature with authentication and encryption with confidentiality simultaneously. Online/offline signcryption, with the online/offline technique, provides higher efficiency for the system. However, most of the present signcryption schemes are implemented in the identity-based setting in which there exists key escrow problem. Based on the certificateless cryptography system's advantages with revocation of certificate management and without key escrow problem, a secure online/offline certificateless signcryption scheme was proposed. The proposed scheme satisfied the requirement that there is no need to determine the recipient's information in the offline stage. Moreover, its security was proved in the Random Oracle Model (ROM).