Symmetric searchable encryption with supporting search pattern and access pattern protection in multi‐cloud

Abstract

Symmetric searchable encryption (SSE) enables users to search the ciphertext stored on the untrusted cloud without revealing the search keywords, effectively protecting users' privacy. However, most of the existing SSE schemes reveal the search or access pattern during the keyword query, which can be used by the adversary to infer the sensitive information in ciphertext, thus posing a great threat to users' privacy. To address this, we propose an SSE scheme supporting search pattern and access pattern protection in multi-cloud, called SAPM-SSE. In our scheme, an index shuffle protocol is proposed to change the content and location of the index after each query, which helps to achieve the protection of search and access pattern. Furthermore, with the purpose of improving the efficiency of shuffling, we construct a shuffling algorithm based on index cache, the number of index entries for shuffling reduced from γ to γ/n (n≥1).Besides, our scheme supports the dynamic update of documents and achieves the forward security in update. Finally, security analysis and experimental results show that our scheme can achieve the protection of search pattern and access pattern with high efficiency.