摘要:
动态对称可搜索加密(dynamic symmetric searchable encryption, DSSE)在近年来已经成为数据隐私保护方面至关重要的原语，它能够允许客户端对保存于云服务器的加密数据执行高效的检索和更新操作，而仅向服务器泄露少量经过严格定义的信息，如搜索模式、访问模式、更新模式和容量泄露.然而，越来越多的研究发现，一些强大的敌手能够利用DSSE的泄露执行特定攻击，从而破坏数据和检索的隐私性.以往方案往往利用隐私数据查询，茫然随机存取器和存储补齐等技术来压缩甚至消除泄露信息，这些技术能够提供较好的安全性，但是存在计算、通信和存储复杂度过高的问题，难以实用.为了实现更好的安全和效率平衡，提出想法：首先引入差分隐私这一安全概念，提出了一种新的填充方法-差分隐私填充(differential privacy padding, DPP)，在保证安全性的同时降低了存储负载.随后在多服务器模式下提出了一种称为“MDSSE”(multi dynamic searchable symmetric encryption)的动态搜索更新方案，通过对DPP的动态运用实现容量、更新以及搜索模式隐藏，保证了前向安全和后向安全.对于方案的安全性证明，扩展了对于更新历史的定义，提出了适用于方案的差分更新历史DP-Update.实验表明：方案可以抵御泄露滥用攻击，并具有较高的存储与通信效率.
Abstract:
Dynamic Symmetric Searchable Encryption (DSSE) has become one of the most important primitives for data privacy protection in recent years. It allows clients to efficiently retrieve and update encrypted data stored in cloud servers. Only a small amount of strictly defined leakage is disclosed to the server, such as search pattern, access pattern, update pattern, and volume pattern. However, a growing number of studies have found that some powerful adversaries can exploit DSSE leakage to carry out specific attacks that undermine the privacy of data and retrieval. In the past, Private Information Retrieval, Oblivious Random Access Machine and storage padding are often used to compress or even eliminate the leaked information. These technologies can provide better security, but they are difficult to be applied because of the high complexity of computation, communication and storage. In order to achieve a better balance between safety and efficiency, this paper proposes the following ideas: We first introduce a meaningful security concept-differential privacy and propose a new padding method, differential privacy padding(DPP), which can reduce the storage load while ensuring the security. Then a Dynamic search update scheme called “MDSSE” is proposed in the multi-server mode. Through DPP apply to our scheme, volume, update and search pattern hiding are realized. The forward privacy and back privacy security are guaranteed at the same time. For the security proof of the scheme, we extend the definition of update history and propose a differential Update history DP-Update which is suitable for this scheme. Experimental results show that our scheme can resist leakage and abuse attacks, it also provides high storage and communication efficiency.
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