Abstract:

Identity Based Public Key Encryption with Keyword Search（IBEKS） using identity information as a public key realizes the public key and user natural binding, avoiding the complicated digital certificate in PKI and eliminating the step of certificate authentication, but it also brings some problems, such as key escrow, key revocation. So that, on the basis of existing Certificateless Identity-Based Encryption scheme（CL-IBE）, the scheme of Certificateless Public Key Encryption with Keyword Search（CL-PEKS） is firstly proposed. And the proof of the consistence for the algorithm is given, the complexity of the algorithm is analyzed. The definition of CL-PEKS which is indistinguishable against CCA2 is also presented. The program can provide the function of protecting the security of keyword under the circumstance of big data to the third-party server storage, at the same time the key escrow problem in IBEKS is solved.

Key words: Public Key Encryption with Keyword Search（PEKS）, Certificateless Public Key Encryption with Keyword Search（CL-PEKS）, Bilinear Diffie-Hellman problem（BDH）, key escrow

摘要：

基于身份的可搜索加密方案（IBEKS）使用身份等信息作为公钥，绑定了公钥和用户（私钥），省去了CA认证的环节，但是也带来了一些问题，比如密钥托管、密钥撤销等。基于此，首次提出无证书的可搜索方案（CL-PEKS）的抽象定义和构造算法，对算法的一致性进行了验证，并且分析了算法复杂度。同时给出了抵抗第一、二类选择关键词密文攻击（type I、type II IND-CCA2）语义安全的CL-PEKS定义。该方案实现了密文关键词可搜索功能，同时解决了IBEKS中的密钥托管问题。

关键词: 可搜索加密, 无证书的可搜索加密, 双线性Diffie-Hellman问题, 密钥托管