A Blockchain-Based Secure Framework for Distributed Data Storage and Transmission in IoT-Cloud Environments

With the widespread adoption of the Internet of Things (IoT) and cloud computing in various intelligent systems, data transmission and storage in multi-source, heterogeneous, and distributed environments face significant security challenges, including data tampering, leakage, and unauthorized access. To address these issues, this paper proposes a blockchain-based distributed data security strategy that integrates smart contract-driven access control, on-chain data hash verification, and off-chain encrypted storage. The proposed architecture establishes a multi-layered data processing and control flow between edge nodes and the blockchain, enabling end-to-end verifiable data integrity and access protection. Experimental results demonstrate that, under simulated high-frequency data interactions and multi-user concurrent access scenarios, the proposed system outperforms traditional security architectures in key performance indicators such as tamper detection accuracy, access response time, and throughput. Furthermore, the system shows stronger resilience against typical threats such as man-in-the-middle attacks and unauthorized access. This study provides a practical solution for secure data exchange in distributed environments and offers a solid foundation for the further application of blockchain technology in the field of data security.