## 2 Literature Study
It was achievable in the eHealth field, by applying several rules wherein the management of patients' data must adhere to several regulations while staying accessible to officially authorized healthcare practitioners. Most people were aware of distributed ledger technology because of its most popular application in the payment industry, Bitcoin [34]. According to [PERSON] et al., the distributed ledger system has various advantages that include the protection of personal and confidential information, removing intermediates, etc. Unlike centralized networks, the functioning of the network remains even if individual nodes fail. It enhances confidence since the intermediary or other network members' trustworthiness is not appraised by people. Data security was also supported by the absence of intermediaries, because the involvement of intermediaries also leads to data security breaches. By utilizing distributed ledger technology, intermediaries may become obsolete, significantly boosting the user's safety [35]. The security and confidentiality problems of personal information management were highlighted in a paper by the MIT Media Lab, which emphasized all blockchain technology deployments. The worth of data processing is that it is safe in the sense that it cannot be tampered with. Data privacy and protection were another facet of data security. Enigma, for example, is a decentralized computer platform with assured anonymity and a blockchain innovation. Enigma's mission is to allow inventors to create peer-to-peer decentralized applications that are \"privacy by design\" without the need for intermediaries. The blockchain is an \"operating system\" for safe collaborative tasks performed by nodes in a network. Enigma is an extension to distributed ledger technology because processing and data storage are completed outside the blockchain [36]. The blockchain was described as a safe house for processing all types of delicate data. It defined the distributed ledger as a decentralized system. A large number of business difficulties can be solved by this technology. Encryption safeguards the records in a blockchain transaction, and each block is backward-connected to previous blocks by the hashing technique. Transactions were validated with different consensus algorithms. Blockchains will eventually achieve transparency, allowing each user to trace transactions at any moment. A smart contract is a secure method of preventing intervention by intermediaries. Ethereum is a public blockchain which is powered by smart contracts. This aids creators in the creation of markets for the long-term movement of money based on instructions issued in the past. Decentralization, immutability, rapid transfers, payment, and confirmation in real time are the major aspects of blockchains [37]. Authors took advantage of cloud technology to swiftly detect user behaviors and harvest data from the source. They developed and executed a model for the gathering and authentication of data origins, by embedding historical data into distributed ledger transactions. Data gathering and data validation from historical information were the three main steps of the proposed model. According to performance evaluation findings, ProvChain improved security for cloud-based storage systems which includes customer confidentiality and minimal overhead dependability, [38]. The current healthcare industry has a number of issues. Patients' health records contain sensitive and important information. Without a proper access control policy, these records can be misused by unauthorized users. In conventional approaches, proving the ownership of data is a tough task. Secondly, it is also discovered that the \"names\" were not those of real people, and a considerable number of names had different spellings. There are also some concerns with health insurance coverage. To begin with, exchanging information with many stakeholders is a time-consuming procedure. In the traditional approach, tracing a fraudulent insurance claim is extremely difficult.