Fuzzy Keyword Searchable Encryption Scheme Based on Blockchain

Searchable encryption is a keyword-based ciphertext retrieval scheme, which can selectively retrieve encrypted documents on encrypted cloud data. Most existing searchable encryption schemes focus only on exact keyword searches and cannot return data of interest in fuzzy search. In addition, during the searchable encryption, the cloud server may return invalid results to the data user to save computing costs or for other reasons. At the same time, the user may refuse to pay the service fee after receiving the correct result. To solve the above problems, this paper proposes a fuzzy keyword searchable encryption scheme based on blockchain, which uses edit distance to generate fuzzy keyword sets and generates a secure index with verification tags for each fuzzy keyword set to verify the authenticity of the returned results. The penalty mechanism is introduced through the blockchain to realize the fairness of service payment between users and cloud servers. Security analysis shows that the scheme achieves non-adaptive semantic security. Performance analysis and functional comparison show that the scheme is effective and can meet the requirements of searching applications in the cloud environment.