关键词: 无证书签密, 双线性对, 不可伪造性, 机密性, 公钥替换攻击

Abstract: The paper presents that a certificateless signcryption scheme proposed recently is easily attacked by public key replacements, and then points out the relevant attack instances. A new certificateless signcryption scheme without bilinear pairings is also proposed in this paper. Cryptography is executed in entities’ certificateless public key authentication and escrow public key authentication separately, which ensure that the new scheme would not experience the similar public key replacement attacks. In the standard model, the new scheme is verified secure, and the new scheme can achieve the unforgeability and confidentiality of certificateless signcryption. Comparative analysis shows that the new scheme not only ensure strong security but also better computing performance.

Key words: certificateless signcryption, bilinear pairing, unforgeability, confidentiality, public key replacement attack