Blockchain-Based Certificateless Public Key Encryption with Keyword Search

Searchable public key encryption (PEKS) allows users to access ciphertext stored on a cloud server (CS) and obtain search results without disclosing any information about the original data and keywords.However, existing PEKS schemes rarely take into account the correctness of search results and fairness in the search process.We devised a blockchain-based certificateless public key encryption with keyword search (BC-CLPEKS) scheme to try to overcome the challenge.The proposed scheme adopts a certificateless cryptosystem for information encryption, circumventing the issues associated with public key certificate management and key escrow.In BC-CLPEKS, the data owner (DO) stores the data ciphertext in the CS and the keyword ciphertext with index ciphertext into the blockchain.This guarantees the tamper resistance, integrity, and traceability of retrieval results.Furthermore, this scheme utilizes smart contracts to monitor and distribute monetary rewards, as well as to execute detection algorithms, thereby ensuring the fairness of transactions between the DO and the data user (DU).Under the random oracle model, the scheme satisfies the indistinguishability of keyword ciphertext under adaptive chosen keyword attacks (IND-CKA).The experimental results demonstrate that the proposed BC-CLPEKS scheme not only has excellent characteristics but also possesses notable advantages in terms of communication and computation overhead.