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

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