可搜索公钥加密关键安全性问题的研究

Searchable public key encryption enables the ciphertext search by an untrusted third-party without decryption, so as to ensure the security of the encrypted data stored by the untrusted third-party. In recent years, searchable public key encryption, due to its unique advantages, has been extensively researched and widely used. But there still exist various inadequacy and imperfection. Many issues remain unsolved: susceptibility to keyword guessing attack, reliance on the random oracle model, dependence on the secure channel, reliance on the pairings with significant computational cost. To solve these problems, (1) we try to design a searchable public key encryption in the standard model without the need of secure channel and the use of pairings, which is secure against keyword guessing attack; (2) we will design an efficient and secure searchable public key conditional proxy re-encryption scheme that supports the "OR" and "AND" combination of multiple keywords search; (3) we attempt to construct an efficient and secure public key searchable conditional proxy re-encryption scheme that supports conjunctive-subset keywords search; (4) we will also present an efficient and secure searchable public key conditional proxy re-encryption scheme supporting keywords search with wildcards; (5) we will establish an efficient and secure searchable conditional proxy re-encryption scheme supporting range queries. The findings have important theoretical significance and practical value for the application of searchable public key encryption in cloud security.

可搜索公钥加密实现了非可信第三方在不解密的条件下对密文的搜索，从而保证了存储在第三方的加密数据的安全性。已有的研究虽然取得了一些成果，但是仍然存在很多安全性问题：依赖大计算量的双线性对、容易遭受关键字猜测攻击、依赖随机预言机、依赖安全信道；缺少支持多关键字组合匹配的可搜索的条件代理重加密方案。为了解决上述问题，拟做如下研究：(1) 设计标准模型下不使用双线性对的无需安全信道的抗关键字猜测攻击的可搜索公钥加密方案；(2)设计高效安全的多关键字"and"和 "or"组合匹配的可搜索的条件代理重加密方案；(3)设计高效安全的支持多关键字子集匹配的可搜索的条件代理重加密方案；(4)设计高效安全的支持关键字通配符匹配的可搜索的代理重加密方案；(5)设计高效安全的支持关键字范围匹配的可搜索的代理重加密方案。上述研究结果对促进可搜索公钥加密在云安全中的应用具有十分重要的理论意义和参考价值。

依据本项目申请计划，本项目主要针对已有的研究存在的安全性问题展开了研究，包括依赖大计算量的双线性对、容易遭受关键字猜测攻击、依赖随机预言机、依赖安全信道；缺少支持多关键字组合匹配的可搜索的公钥加密方案。为了解决上述问题，本项目依据立项时的研究内容与目标，研究成果如下：完成了标准模型下不使用双线性对的无需安全信道的抗关键字猜测攻击的可搜索公钥加密方案设计；完成了高效安全的多关键字“and”和 “or”组合匹配、多关键字子集匹配、关键字范围匹配的多个可搜索的条件代理重加密方案设计。相关研究成果共计发表SCI/EI检索论文15篇，申请发明专利4项。因为可搜索公钥加密实现了非可信第三方在不解密的条件下对密文的搜索，从而保证了存储在第三方的加密数据的安全性。所以上述研究结果对促进可搜索公钥加密在云安全中的应用具有十分重要的理论意义和参考价值。