Blockchain-enabled data sharing for IoT: A lightweight, secure and searchable scheme

With the popularity of Internet of Things (IoT) applications, data sharing among IoT devices has become more frequent. Many researchers have proposed fine-grained access control schemes and searchable encryption algorithms to support privacy-preserving data sharing. But there still exist two challenges. First, the existing schemes are computationally intensive, making them unsuitable for resource-limited IoT terminals. Second, they rely on a central server to honestly conduct search operations, making them unable to tackle malicious servers. To this end, we propose a blockchain-enabled data-sharing scheme for IoT that supports lightweight, secure, and searchable data sharing. We design an outsourcing attribute-based encryption algorithm to alleviate the overhead of resource-limited IoT terminals, which reduces the local encryption and decryption to a constant level. Instead of relying on central servers, we leverage smart contract to execute ciphertext retrieval, ensuring the accuracy of search results. Formal security analysis demonstrates that the proposed scheme is chosen-plaintext secure under the DBDH assumption. Experimental simulation shows that it reduces the search time by at least 79.9%, the encryption and decryption complexities to both $O\left(1\right)$.