Blockchain-based verifiable and dynamic multi-keyword ranked searchable encryption scheme in cloud computing

Abstract

Rational miners in the blockchain may admit the validity of search results directly to conserve calculation overhead without executing the validation. Such phenomenon is known as the Verifier's Dilemma that the search results of the blockchain-based searchable encryption scheme would be claimed to have been verified but devoid of valid verification. Besides, the top-k query technique utilized by most existing searchable encryption schemes fails to filter the search results from the user demands during retrieval, which results in massive ineffective access lists with high complexity. Aiming at the two problems, we present a blockchain-based multi-keyword ranked searchable encryption scheme and design a fair payment protocol for multi-user scenarios. Our scheme may achieve public verifiability and user fairness by leveraging the TrueBit network, while the data owner (DO) can withdraw search privileges from the authorized data user (DU). Also, we extend the searchable encryption scheme based on inverted index to multi-DO/multi-DU scenarios, and the HashMap index is used to diminish the response time and space complexity. Moreover, the proposed scheme supports the update of index keywords and files dynamically. To enhance retrieval accuracy, we modify the information divergence algorithm in machine learning and utilize the monotonically weighted aggregation function, which improves retrieval accuracy to around 97%. Finally, Security analysis illustrates correctness and resilience against typical attacks to verify the robustness and utility of the proposed scheme.