具有内部安全性的常数对无证书聚合签密方案

聚合签密不仅能够减少密文的验证计算量，而且能够保证数据的机密性和认证性。该文分析刘等人(2016)提出的无证书聚合签密(CLASC)方案，指出第2类攻击者可以伪造密文，刘方案不满足适应性选择密文攻击的不可区分性和适应性选择消息攻击的不可伪造性。为了提升CLASC方案的安全级别和聚合验证效率，该文提出CLASC的内部安全模型和具有内部安全性的CLASC方案。该方案聚合验证密文只需要3个双线性对，与现有同类方案相比，具有较高的验证效率。基于计算Diffie-Hellman困难假设，证明新方案在随机预言模型下，满足CLASC内部安全模型下的机密性和不可伪造性。

Certificateless Aggregate Signcryption Scheme with Internal Security and Const Pairings

Aggregate signcryption can not only reduce the cost of the verification of ciphertexts, but also ensure the confidentiality and authentication. Analyzed Liu et al s CertificateLess Aggregate SignCryption (CLASC) scheme with Const Pairings, it is found that type II adversary, who is the malicious key generator center, could forge the ciphertexts. It means that Liu et als scheme does not satisfy the indistinguishability under the adaptive chosen ciphertext attacks and unforgeability under the adaptive chosen message attacks. In order to improve the security level and verification efficiency of CLASC scheme, in this paper, the internal secure model of CLASC is defined and a concrete CLASC scheme with this property is presented. As the new scheme only needs 3 bilinear pairingis, it is more efficient than existing CLASC schemes. Based on the assumption of computational Diffie-Hellman, in the random oracle model and the internal security mode of CLASC, the new schems is proved to satisfy the confidentiality, unforgeability and public verification.