Secure conjunctive multi-keyword ranked search over encrypted cloud data for multiple data owners

Recently, secure search over encrypted cloud data has become a hot research spot and challenging task. A number of secure search schemes have been proposed to try to meet this challenge. However, most of them only consider the single data owner model. In this paper, we propose a conjunctive multi-keyword ranked secure search scheme for multiple data owners. To guarantee data security and system flexibility in the multiple data owners environment, we design an ingenious secure query scheme that allows each data owner to adopt randomly chosen temporary keys to build secure indexes for different data files. An authorized data user does not need to know these temporary keys of constructing indexes and can instead randomly choose another temporary query keys to encrypt query keywords, while the cloud server can correctly perform keywords matching over encrypted data files. To rank the query results of a conjunctive multi-keyword query, the cloud server computes the similarity scores between the query and its query results according to encrypted relevance scores of keywords without obtaining any sensitive information. Extensive experiments demonstrate the correctness and practicality of the proposed scheme. (C) 2019 Elsevier B.V. All rights reserved.