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    可证明安全的基于SGX的公钥认证可搜索加密方案

    Provably Secure Public Key Authenticated Encryption with Keyword Search Based on SGX

    • 摘要: 公钥可搜索加密(public key encryption with keyword search,PEKS)技术使用户能够搜索存储在不可信云服务器上的加密数据,这对于数据隐私保护具有重要意义,也因此受到了广泛关注. 公钥认证可搜索加密要求数据发送方使用接收方的公钥对关键词进行加密,同时还使用其自身私钥对关键词进行认证,使得敌手无法构造关键词密文,从而抵抗公钥可搜索加密面临的关键词猜测攻击(keyword guessing attack,KGA). 提出了一个可证明安全的基于软件防护扩展(software guard extensions,SGX)的公钥认证可搜索加密(public key authenticated encryption with keyword search,PAEKS)方案,通过在云服务器上建立一个可信区并运行一个执行关键词匹配的飞地程序来完成对密文数据的搜索. 正式的安全性证明显示方案具备密文不可区分性和陷门不可区分性,即可抵抗关键词猜测攻击. 进一步地,给出搜索模式隐私性的定义,确保敌手无法仅通过陷门来判断2次搜索是否针对同一关键词,从而避免向外部敌手泄露部分隐私. 此外,所提方案具有易扩展的优势,很容易被扩展为支持复杂搜索功能或者具备其他增强隐私保护性质的方案,如前向安全. 作为示例,给出了多关键词搜索、搜索能力分享这2个功能扩展方案以及具备前向安全性的扩展方案的简单介绍. 真实环境中的实验表明,与其他对比方案相比,所提方案在效率上同样具有出色的表现.

       

      Abstract: PEKS (public key encryption with keyword search) enables users to search over encrypted data stored in the untrusted cloud server, which is of great significance for data privacy protection and is of increasing interest for this reason. PAEKS (public key authenticated encryption with keyword search) requires that a data sender not only uses the receiver’s public key to encrypt the keyword, but also uses his own private key to authenticate the keyword. PAEKS ensures that the adversaries cannot construct a keyword ciphertext, thus resisting the keyword guessing attacks (KGAs) that PEKS is facing. In this paper, we propose a scheme for public key authenticated encryption with keyword search based on SGX (software guard extensions), which supporting searching on encrypted data by creating a trusted zone and running a keyword comparison enclave program in the cloud server. The formal security proof of the scheme is provided and shows that the scheme satisfies the ciphertext indistinguishability and trapdoor indistinguishability, that is, the scheme can resist keyword guessing attacks. Further, the search pattern privacy (SP-Privacy) is defined, which ensures that adversaries cannot judge whether two searches are the same keyword only through the trapdoors, so as to avoid revealing some privacy to external adversaries. In addition, the scheme can be easily extended to support complicated search functionalities and enhance privacy protection, e.g. forward security. As examples, brief descriptions about how to extend the scheme to support multi-keyword search, search capability sharing, as well as forward security are given. Experiments in real scenario show the better efficiency of the scheme compared with some other typical schemes.

       

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