Blockchain in Cloud EHR Systems: Security and Privacy Challenges and Solutions^*

With the adoption of blockchain technology in cloud-based Electronic Health Record (EHR) systems, many avenues in the effective management of crucial challenges related to data security and privacy are now open. Growing healthcare organizations have been using cloud infrastructures to manage and share patient's information in an efficient manner, and concerns about access by unauthorized persons, breach of data, and compliance with regulations have grown. Blockchain: This decentralized, tamper-resistant structure offers solutions for the preservation of confidentiality, integrity, and traceability of health data. In this paper, various blockchain-based techniques that were presented for the purpose of securing the cloud EHR systems have been surveyed based on their merits and demerits. Further in the study, the focus was given to privacy-preserving encryption, decentralized data management, and federated learning for improving scalability and performance within EHR systems. It also points to the complexity that would be involved in incorporating blockchain with existing healthcare infrastructures and possible solutions to overcome such challenges while being HIPAA compliant. The paper aims to contribute to the development of secure and efficient blockchain-cloud EHRs that are compatible with patient trust and security in modern healthcare.