# Generic Patient-Centered Blockchain-Based EHR Management System
## 2 Related Work  
This section covers the study related to using blockchain technology in the e-healthcare industry to guarantee safe data storage and effective access management. Blockchain technology offers a cryptographic fix to the security issues that are hindering the growth of electronic health systems. Medical enterprises have encountered taxing challenges over the past 20 years as a result of incidents involving record breaches in major medical data centers [6]. MedRec became the first organization to suggest a blockchain-based electronic patient record management system in the early days of blockchain technology [7]. At that time, the Ethereum blockchain and smart contracts preserve detailed accessible healthcare records. However, the medical records are stored in third-party databases operated by healthcare providers, instead on the blockchain network. As a result, the violation or misuse of these records is still a possibility. Healthcare management framework encrypts patient keys during the process of creating or updating data on the blockchain [8]. To decrypt the record, healthcare personnel and lab technician would have to request authorization from a patient's public key. This is starkly in contrast to our approach, as patients are the sole party with access to and control over their data. Any node can connect to the network and conduct transactions on the public blockchain [9]. A blockchain-based application called Medchain allows patients, pharmacists, and hospitals to exchange healthcare data [10]. This architecture stores data on-chain, and thus, presents scalability and privacy issues. A blockchain-based IoT solution may utilize smart contracts to track patients' health [11]. The authors in [12] proposed a blockchain-driven system for maintaining electronic medical records, while [13] presented a blockchain-based architecture that incorporates distributed health records with node models to optimize the replication of healthcare records. The researchers in [14] used blockchain smart technology, a decentralized network with smart contracts, to save and transfer data in a secure manner. In a study by [15], a privacy-preserving system was developed for remote patient surveillance. A permissioned blockchain with an access control audit log was also developed to store health records, but it raises privacy concerns owing to the distribution of the audit log with all interested parties [16]. The authors of [17] argued about the robustness of blockchain technology in storing medical records and raised concerns about the scalability and privacy issues concerning the framework. In another study by [18], they proposed a ring structure-based access control that ensures privacy, but inadvertently leads to an unstable system as the data is maintained in an on-chain database. Ref. [19] also proposed an intelligent data management framework for the cyber system. The decentralized storage and access of records, as described in [20], effectively utilize the network's power and resources. In another study by [21], they employed high-end privacy-enhancing technologies such as homomorphic encryption, which permits data processing while maintaining complete encryption to avoid vulnerability problems. Meanwhile, the researchers in [22] adopted the zero-knowledge proofs approach, along with proof authority consensus for mutual authentication to enhance privacy by ensuring that nodes were not engaging in a malicious manner. Using blockchain technology, several cryptographic mechanisms for preventing tampering and becoming an effective data storage and sharing solution are shown in Table 2.