Privacy-preserving Multi-cloud based Dynamic Symmetric Searchable Encryption

Symmetric searchable encryption (SSE) provides a secure and efficient way for users to search on the encrypted data stored on the cloud. Most of the existing SSE schemes reveal the search pattern and access pattern during the query of keywords, which can be used to derive the keyword to query or contained in documents. To solve this problem, we propose a privacy-preserving multi-cloud based dynamic SSE scheme, called PMD-SSE, which implements the privacy protection and dynamic update of SSE. To protect the search pattern and access pattern, we divide the index into blocks of the same size and distribute them to multiple clouds, and an index cache is conducted to improve the efficiency of shuffling. We shuffle and re-encrypt the entities in index cache after each query, and then redistribute them to clouds randomly. Furthermore, PMD-SSE supports dynamic update of SSE, and realizes the forward security in dynamic update through the pseudo-random function. At last, formal security analysis show that PMD-SSE is adaptive secure against malicious attacks.