Abstract: Signcryption schemes can achieve confidentiality and authentication simultaneously by combining public-key encryption and digital signatures，at lower computational costs and communication overheads than the traditional signature-then-encryption approach.Due to the importance of signcryption schemes and the advantage of certificateless cryptography，a provable security certificateless parallel signcryption scheme is put foword for the first time.It is based on a certificateless encryption scheme and a certificateless signature scheme，which have been proved secure respectively.The analysis shows that the signcryption scheme satisfies the security requirements such as non-repudiation，public verifiability and forward security for a signcryption scheme.

Key words: certificateless cryptography, signcryption, bilinear pairing, confidentiality, unforgeability

摘要： 签密能够同时完成公钥加密和数字签名两项任务，实现消息既保密又认证的双重功能。同时，签密的计算量和通信代价都要低于传统的保密认证方法——先签名后加密。鉴于签密重要性和无证书密码系统的优点，首次提出了一个可证安全的无证书并行签密方案。该签密方案建立在已分别被证明是安全的无证书加密方案和签名方案基础之上。分析显示该签密方案满足诸如不可否认性、可公开验证性和前向安全性等安全性质。

关键词: 无证书密码系统, 签密, 双线性映射, 保密性, 不可伪造性