BCVSE: Verifiable Searchable Encryption Scheme With Blockchain Supporting Fuzzy Query

In new generation of Internet applications such as smart healthcare and digital finance, sharing data to gain its value has become popular. However, some data contains personal privacy, and resource-limited devices generally delegate data to a Cloud Service Provider (CSP). CSP may not only be curious, but also selfish to save computation or download bandwidth. Therefore, the verifiable searchable encryption (VSE) scheme is applied to let CSP queries on encrypted data and ensure the integrity of results. Unfortunately, most existing VSE schemes require a trusted third party, which makes it difficult to provide reliable proof or make fair judgments when there occur disputes. With the assistance of blockchain technology, our proposed scheme blockchain-based verifiable searchable encryption (BCVSE) scheme has the following benefits: (1) Trusted proof: The traceability nature of blockchain can provide reliable transaction proof to help resolve disputes. (2) Fair judgment: Smart contracts that are natively supported by blockchain can publicly, transparently, and fairly conduct dispute adjudication and verify the integrity of results without trusted third parties. Furthermore, existing schemes generally make fuzzy queries by extracting data features first and then using similarity-matching algorithms. This leads to an increase in more false positives and a massive result set, making them more suitable for image data rather than text data which have more accurate query conditions. Therefore, we build the Verifiable Accumulator Trie (VAT), which is the core authenticated data structure for both verifiability and fuzzy query on text data. Formal security analysis and performance simulation demonstrate that BCVSE is secure and suitable for various blockchains.