基于Cocks身份密码体制的高效签密方案

Efficient signcryption scheme based on Cocks’identity cryptosystem

现有的基于身份签密方案多是基于双(多)线性对构造的,针对其复杂的对运算导致签密效率低下的问题,基于Cocks的身份密码体制提出了一种新的高效签密方案。首先,形式化所提方案的安全模型,给出了保密性和不可伪造性的定义;然后,利用二次剩余难解问题实现了所提方案的具体构造,进一步结合雅可比符号运算巧妙地在一个逻辑步骤内实现了签密算法设计;最后,在随机预言模型下,给出了所提方案满足保密性和不可伪造性的安全性证明。效率分析表明,相对于已有的基于身份签密的方案,所提方案较大幅度地提升了运算效率,同时具备基于身份密码的良好特性。

Most of the existing identity-based signcryption schemes are based on bilinear or multilinear pairing operations construction.To solve the problem of low efficiency caused by complex pair operation,a new efficient signcryption scheme based on the identity cryptosystem of Cocks was proposed.Firstly,the security model of the proposed scheme was formalized,and the definition of confidentiality and unforgeability was given.Secondly,the quadratic residue problem was used to realize the concrete construction of the proposed scheme,and the signature algorithm was designed in a logical step by combining Jacobi symbol operation.Finally,the security proofed that the scheme satisfied the confidentiality and unforgeability was given under the random prediction model.The efficiency analysis shows that compared with the existing identity-based signcryption scheme,the proposed scheme greatly improves the computing efficiency and has good characteristics of identity-based cryptosystem.