# An Adaptive Biomedical Data Managing Scheme Based on the Blockchain Technique
## 1 Introduction  
The blockchain can be regarded as a chain of blocks that have already been time-labeled and stay connected by employing encryption features (cryptographic hashes). A block can include the communications of various users, which are publicly offered to all users within the network. Furthermore, each block embraces the hash of the earlier block as well as the traditional transaction data, which results in the generation of an immutable and secured, append-only chain. There is a continuous increase in chain length with the addition of each new block to the end of the chain [1]. The blockchain infrastructure is usually based on a peer-to-peer interaction, wherein both network users (transactions participators) as well as the blockchain \"miners\" (those that enable communications with a distributed ledger) are involved. The storing of the ledger is done in a decentralized node network, which is generated via cryptographic routes that have been computed by all the miners present in the network [2]. Furthermore, highly reliable storage capabilities are provided by the blockchain ledger since digital signatures, consensus mechanisms, and hash chains are employed forits creation, because of such unconventional features, blockchain technology offers many facilities, including information traceability, security, and non-repudiation, while at the same time keeping all information within a public decentralized way, thus maintaining privacy [3]. Figure 1 depicts the blockchain structure overview. With regards to the access and management of authorizations, three kinds of blockchains can be considered: Unrestricted, consortium, and private. An unrestricted (or permissionless) blockchain must be highly distributed, wherein any person can contribute via a miner. Even though this warrants maximum immutability, the efficiency is limited because of the collaborative achievement of consensus with the help of the highly extended miner network. While in a private blockchain where miners process blocks for a single organization, efficiency can be maximized and immutability can be altered. A consortium (or federated) blockchain can offer productivity like a private one, while a moderately distributed miner network is integrated, including nodes offered by the nominated organizations [4; 5]. The healthcare industry has various unique requirements in terms of privacy and security due to the need for additional legal compliance to safeguard the medical information of patients. In the age of the Internet, where cloud storage as well as the adoption of mobile health devices has facilitated the sharing of data and records, the number of malicious attacks and the possibility of private information becoming compromised during sharing have increased significantly. It has now become easy to obtain health information; patients use smart modules and consult multiple doctors, thus increasing the concerns regarding sharing and secrecy of this information. Furthermore, patients can get their medical history records easily through a widely accessible network without the need to request permission from every provider [6]. Healthcare utilities face the need for unique requirements with regards to interoperability, the transfer of biomedical data, authentication, data sharing, and the considerations regarding e-Health (mobile health) [7]. E-Health refers to the provision of health facilities by employing digital technology. In the e-Health area, research trends have been concentrated on employing electronic health records to perform tasks related to diagnoses and patient monitoring. Typically, a patient may be involved with various providers  
Figure 1: The overview of the blockchain structure. of healthcare services, including specialists, primary care physicians, and therapists [8]. Thus, in the industry and research community, health record exchanging/sharing has been garnering attention as well as causing concern pertaining to privacy preservation and data security.