Multi-keyword ranked searchable encryption scheme with access control for cloud storage

With the advent of cloud computing, data owners are motivated to outsource their data to public clouds for decreasing the cost of management systems. For protecting data privacy, sensitive data must be encrypted before outsourcing. So, equipping cloud server with search service over encrypted data is an important issue. Considering the large number of data users and documents in the cloud, users may be interested to perform multi-keyword search and receive the most related data. In this paper, we investigate the Pasupuleti et al.’s scheme which is a multi-keyword ranked search over encrypted cloud data. Their scheme has problems in index construction, trapdoor generation and search procedures. We address these problems and suggest a multi-keyword ranked search over encrypted data on cloud storage. The proposed ranked searchable encryption scheme enhances system usability by ranking results instead of just sending undifferentiated results and ensures file retrieval accuracy. We also use the relevance score from information retrieval to build a secure searchable index, and apply an additive order-preserving encryption to protect the sensitive scores of files. Our scheme also guarantees access control of users during the data retrieval by attribute-based encryption. Analysis shows that our scheme is secure and efficient for cloud storage.