BACTDS: Blockchain-Based Fined-Grained Access Control Scheme with Traceablity for IoT Data Sharing

Due to the growing prevalence of Internet of Things (IoT) services, there is an opportunity to leverage the data generated by IoT devices to create greater value. However, how individuals can ensure user privacy and data security when sharing their private data remains a major challenge. To address the above problems, we propose a trackable and fine-grained private data sharing access control scheme (BACTDS) based on blockchain. First, to ensure data security, in our proposed system model, data users can interact with the cloud to obtain ciphertext information only if they have permission information and can decrypt the obtained ciphertext to obtain plaintext information only if they meet access policies. Second, we store the user's identity information in the probability polynomial. With the help of the traceability algorithm, our proposed scheme supports the tracking of malicious users who have leaked private keys. The malicious user's identity is recovered through lagrangian interpolation polynomials and then traced to malicious users, this prevents illegal sharing and misuse of keys. Finally, we provide a formal security proof of our scheme under the assumption of the random oracle model, which demonstrates its provable security. Moreover, experimental results and performance analysis indicate that our scheme (BACTDS) is time-efficient and cost-effective.