Abstract
Searchable encryption (SE) allows users to search over encrypted data without decrypting. In most existing SE schemes, server returns all matched files without relevance ranking, and the update mechanism are suffering with high communication and computation cost, which are not efficient enough to satisfy the real-life dynamic scenario. Addressing the above issues, we proposed TS-RDSE—a Two-Server Ranked Dynamic Searchable Encryption scheme. We integrate orthogonal vector and efficient homomorphic encryption cryptosystems to build a vector-level dynamic secure index, which simultaneously supports efficient dynamic update operations like deletion and insertion of files flexibly. Moreover, in order to rank the search results by relevance without decryption, we build a secure sorting protocol based on the widely-used tf-idf weighting formula and addition property of partial homomorphic encryption, which achieves accurate sorting for the search results while protecting the privacy of relevance scores. We give a comprehensive analysis of the correctness of TS-RDSE in the aspect of searching and sorting with mathematical proofs. The security analysis shows that TS-RDSE is secure against adaptive dynamic chosen-keyword attacks (CKA2) by honest-but-curious adversaries in random oracle model. The performance analysis shows that TS-RDSE has both a very light user workload and a moderate server workload, and it is superior to the existing approaches in terms of functionalities and expansibility. Extensive experiments on the real-world dataset validate our analysis and show that TS-RDSE is suitable for the real world cloud storage environment.
Highlights
Addressing the above issues, we studied the state-of-art updatable search index structure and MPC-based comparison methods, and proposed TS-RDSE—-a two-server ranked dynamic searchable encryption scheme that supports efficient updating and secure sorting
Extensive experiments on the real-world dataset validate our analysis and show that TS-RDSE is superior to the existing approaches in terms of functionalities and suitable for the real world cloud storage environment
From the above schemes we can reach that the dynamic update mechanisms in Searchable encryption (SE) would either cause extra information leakage when updating files, or needs high computation overload to build and update index structure which still leads to low update efficiency and allows only limited times update operations
Summary
With the rapid development of computer technology and the widespread of 5G service scenarios [1], outsourced data and applications are growing rapidly. Many ranked SE schemes [12]–[15] proposed to return all the files that match the search request to the user, who rank the result in the local based on relevance weights. It is demand that the cloud server has the ability to sort the search results according to their correlation with search request, and place the most relevant files to user, to avoid transfer of irrelevant files and, minimize the communication and computation cost at the user side. Addressing the above issues, we studied the state-of-art updatable search index structure and MPC-based comparison methods, and proposed TS-RDSE—-a two-server ranked dynamic searchable encryption scheme that supports efficient updating and secure sorting. We build a two-server secure sorting protocol to achieve ranked search on encrypted domain obliviously In this protocol, two non-collusive servers play the role of cloud service provider. Extensive experiments on the real-world dataset validate our analysis and show that TS-RDSE is superior to the existing approaches in terms of functionalities and suitable for the real world cloud storage environment
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