An efficient privacy-preserving rank query over encrypted data in cloud computing

In cloud computing, for protecting the privacy of the sensitive cloud data, an effective methodology is to encrypt the data before outsourcing. However, data encryption makes data utilization, e. g. querying, a very challenging task. Though many solutions have been proposed, they are insufficient or even ineffective to achieve efficient multi-keyword rank query and flexible selective query authorization with multiple data owners while keeping strong privacy preserving. In this paper, we propose an efficient privacy-preserving rank query over encrypted data (RQED). Through the improved searchable public key encryption (PKES) with certificateless authentication, we establish the RQED framework. Based on the RQED framework, we design a more sound and privacy-preserving RQED rank function, and propose a hierarchical index based on dynamic Bloom filters. The theoretical analysis and experimental evaluation show that the proposed solutions indeed achieve powerful privacy guarantee, efficient query performance, low communication overhead and effective query authorization control.