中文摘要：

Liu等在2010年提出了一种在标准模型下可证明安全的无证书签密算法（简称LHZ算法）,但后续的研究成果显示LHZ算法实际上是不安全的。为了克服LHZ算法的不足,首先改进LHZ签密算法,然后以此为基本的签密算法提出一种新的无证书广义签密算法。同时给出了抵抗有预谋的KGC被动攻击（malicious-butpassive KGC attack）的无证书广义签密算法的安全性模型,并在标准模型下证明了该算法在判定性双线性Diffie-Hellman困难问题和计算性Diffie-Hellman困难问题假设下是安全的。此外,数值实验结果表明所提方案是有效的。

英文摘要：

In 2010, Liu, et al. proposed a certificateless signcryption scheme in the standard model, but many analyses revealed that Liu＇s scheme was insecure in fact. To overcome the disadvantages, the scheme was improved and a certificateless generalized signcryption scheme was constructed. In addition, a formal security model for the proposed scheme against the malicious-but-passive KGC attacks was introduced. Furthermore, the proposed scheme was proven to be secure under the decisional bilinear Diffie-Hellman and the computational Diffie-Hellman intractability assumptions in the standard model. Numerical results illustrate that the proposed algorithm is efficient.