A Global Secure Ranked Multikeyword Search Based on the Multiowner Model for Cloud-Based Systems

Ensuring the privacy of data outsourced to the cloud, while also ensuring data usability, remains challenging. In this article, we propose a global secure ranked multikeyword search scheme based on multiple data owners in cloud-based systems. Compared to prior arts, our scheme improves search precision and efficiency and eliminates keyword redundancies. To improve search efficiency, we use a tree-based index structure, where we remove the need to search all related files. To improve search precision, we design a global computing scheme in which we compute the relevance score in a global manner with the global document frequency. To reduce the redundancies of keywords, we design a keyword conversion scheme, where we re-encrypt keywords with a third entity. As a result, the same keyword extracted by different data owners will be encrypted into the same form. Also, we present the security analysis and demonstrate the performance of the scheme with experiments.