An Efficient Attribute-Based Multikeyword Searchable Encryption With Access Policy Hiding in IoT Using Blockchain

With the rapid development of the Internet of Things (IoT), data is experiencing exponential growth. To ensure security and privacy, more data is being stored encrypted. Consequently, performing secure and efficient encrypted data search has become a critical challenge. Attribute-based searchable encryption (ABSE) provides fine-grained access control and encrypted search capabilities, making it an effective solution to this problem. However, the high computational overhead of bilinear pairing operations results in increased query latency, imposing a significant burden on resource-constrained IoT devices. Moreover, the security of access policy remains a critical challenge, as improper handling can lead to leakage of user privacy. In this paper, we propose an efficient attribute-based multi-keyword searchable encryption with access policy hiding in IoT using blockchain. Our scheme adopts an attribute bloom filter for access policy protection and query pre-filtering, enabling the rapid elimination of invalid requests that do not satisfy the access policy. This reduces the computational burden of bilinear pairing operations and improves search efficiency. The filtered requests are processed by a cloud server to perform access policy verification and multi-keyword search. Additionally, our scheme employs the InterPlanetary File System (IPFS) for large-scale encrypted data storage, further enhancing storage efficiency. The blockchain ensures the traceability and tamper resistance of search records, thereby enhancing security. Security analysis and performance evaluation validate the effectiveness and practicality of our scheme, making it suitable for IoT environments.