Forward Private Multi-Client Searchable Encryption with Efficient Access Control in Cloud Storage

Through Searchable Symmetric Encryption (SSE), a user can make search over encrypted documents that are stored on an untrusted cloud server. Multi-client SSE schemes require that one client can search documents contributed by other clients and upload documents. Nevertheless, existing multi- client SSE schemes implement the fine-grained access control with high complexity. Although fine-grained access control adapts to complex scenarios, it is not necessary anytime and may cause heavy costs over computation in SSE schemes. Moreover, it is crucial to support documents updating and forward privacy. To combat that, we design a multi-client SSE scheme with efficient access control over dynamic encrypted documents. Specifically, we first modify Symmetric Hidden Vector Encryption (SHVE) and utilize Bloom filter to implement the access control, which reduces much of computation overhead. We then employ Oblivious Dynamic Cross-Tag (ODXT) protocol to preserve the forward privacy of our scheme. Finally, the corresponding security and experimental evaluation demonstrate both security and practicality of our scheme, respectively.