# A Security-Oriented Data-Sharing Scheme Based on Blockchain
## 2 Related Works  
Initially, electronic tools such as email were primarily used for communication and data sharing, but these lacked systematic data protection, leading to significant security vulnerabilities in transmission and storage. Moreover, the need for repetitive file transfers in multi-user scenarios increased time inefficiencies and reduced the effectiveness of data sharing. As technology has advanced, the importance of secure data sharing has become increasingly evident. In 2018, [PERSON] et al. [12] proposed a hybrid cloud IoT model for healthcare applications of IoT, aiming to process and analyze sensor data from different sources without human intervention. The scheme leverages cloud service technology to counter potential attacks, but there remains a significant scope for enhancing security and optimizing real-time performance. Traditional centralized data sharing suffers from issues such as single points of failure, easy data loss, easy manipulation, and difficulty protecting private data [13]. Scholars began considering the use of distributed methods to investigate data exchange. For instance, in 2017, [PERSON] et al. [14] presented a novel distributed data storage strategy to securely and flexibly share data with external parties. This technique, based on identification and encapsulation principles, establishes a robust framework for secure and flexible data sharing. However, the reliance on a trusted third party in current data-sharing research poses a risk of data leakage, highlighting security concerns within the process. Blockchain technology is catalyzing the advancement of decentralized data sharing, an increasingly significant research domain. Researchers are increasingly integrating blockchain into data-sharing frameworks to enhance the efficiency of transmitting and storing large data sets, reducing associated costs, and enhancing data integrity. In 2017, [PERSON] et al. [15] presented a blockchain-based healthcare data-sharing architecture, which realized quick, safe, and easy data exchange by incorporating an enhanced consensus mechanism. In 2018, [PERSON] et al. [5] developed a new decentralized data-sharing model and enhanced security using differential privacy and secure multi-party computation. For more dependable data interchange, [PERSON] et al. 's work [16] proposed a dual-chain blockchain structure in which one chain stores the transaction data and the other stores the original data. This is implemented in conjunction with the proxy re-encryption method. In addition to providing guidance on transferring medical records between healthcare facilities using patient-specified access controls, [PERSON] et al. [17] also described a blockchain-enabled method--a dual-chain structure of blockchain--for limiting access to electronic data in order to preserve privacy. The proposed solution involves a dual-chain architecture: a public chain for storing patient health data with temporary IDs and a private chain for securing patient information using real IDs. While this design alleviates data storage pressures, it incurs significant costs and raises concerns about cost escalation and security in inter-chain transactions. In 2019, [PERSON] et al. [18] proposed a framework for healthcare data sharing that uses blockchain medical centers and Fast Healthcare Interoperability Resource (FHIR) technology. This framework improves operability by storing the registry on the blockchain while keeping the raw data in a database. In 2020, [PERSON] et al. [19] proposed a lightweight, blockchain-based access control scheme for electronic medical records that enables patients to upload and query their medical records through a smart contract API interface. [PERSON] [20] et al. proposed a scheme for data sharing based on the Hyperledger architecture framework, establishing a blockchain network between patients and healthcare organizations for the safe and secure sharing of patient data. However, the above scheme remains imperfect in terms of authentication and data traceability.