The expansion of Digital Health brings increasing data privacy and security challenges, mainly due to data collection by service providers and third parties. The decentralized approach of Self-Sovereign Identity emerges as a solution, offering users direct control over their data. This paper proposes the SmartMed system for controlling access to private medical data by attribute-based access control implemented on smart contracts. The paper investigates the performance limitations of the Ethereum, Besu, and Hyperledger Fabric blockchain platforms in controlling access to medical data. The proposal develops smart contracts to perform attribute-based access control and to store log records on the blockchain, highlighting the detailed performance analysis on both tested platforms. The results reveal the superiority of the Hyperledger Fabric platform over Ethereum and Besu, indicating a higher transaction throughput. Our proposal innovates by proposing a system based on smart contracts to guarantee the authenticity of medical data, complemented by the use of Keycloak in managing access to healthcare systems.

The COVID-19 pandemic has highlighted the necessity for agile health services that enable reliable and secure information exchange, but achieving proper, private, and secure sharing of EMRs remains a challenge due to diverse data formats and fragmented records across multiple data silos, resulting in hindered coordination between healthcare teams, potential medical errors, and delays in patient care. While centralized EMR systems pose privacy risks and data format diversity complicates interoperability, blockchain technology offers a promising solution by providing decentralized storage, ensuring data integrity, enhancing access control, eliminating intermediaries, and increasing efficiency in healthcare. By focusing on a Brazilian case study, this paper explores the significance of EMR standards, security challenges, and blockchain-based approaches to promote interoperability and secure data sharing in the healthcare industry.