Internet of Medical Things (IoMT) uses smart devices to collect medical data. In the health care system, IoMT plays an important role in providing security, accessing physicians, remote lab access and transmitting health care data electronically. It also provides real time-medical services like consulting physicians, through web and mobile applications. The benefits of IoMT are reducing the cost of health care data, faster decision-making process. Timely responses from the physicians and improvise in quality of health care treatment [1]. In smart health care data management system, real time health data is collected through medical sensors. Physicians can monitor the patient’s health status through collected data [2]. Patient’s sensitive information are stored in blockchain securely. To provide high dimensional security and transmitting data in a secure manner it needs to detect unauthorized users and prevent them to access the data. It ensures the integrity, validity, authenticity and preserving privacy in health data [3].

Patient’s requests are analyzed using a web application. The smart contract is a mediator to transfer health data between physician and patient in a secured manner [4]. A medical data transaction between two or more parties using blockchain in a secure manner without check for validity process is a key concern. In the decentralized blockchain network, each and every node contains copy of medical data and updates the content of nodes in the network [5,6]. Research works have been done in managing of health care data in a secure way. The main drawback of existing algorithm is lower-level security, unscalable, computation time is high. To overcome these issues this paper proposes PBFT-PoW. It gives double layer of security in high level, scalable, faster in access of health data in the blockchain network.

The consensus algorithm is used in open public blockchain technology such as Proof-of-Authority (PoAu), Proof-of-Work (PoW), Byz Coin, Delegated Proof-of-Stake (DPoS), Proof-of-Stake (PoS), Leased Proof-of-Stake (LPoS), Omni Ledger, Elastico, Proof-of-Burn (PoB). The main drawbacks in the open public blockchain are current state value cannot compete with existing system.

Private blockchain is called as permissioned blockchain in which Delegated Practical Byzantine Fault Tolerance (DPBFT), Practical Byzantine Fault Tolerance (PBFT), Proof-of-Elapsed-Time (PoET), Tender mint, RS Coin, Raft consensus protocols and Pore are used. For accessing the medical data this private blockchain network needs permission to access, contribute and transfer the medical data from one node to another node in the blockchain network. It provides higher levels of security, preserving privacy and accessed by authorized users only. They are also highly scalable because it needs only few nodes for managing the medical data. These characteristics makes the private blockchain network as optimal in the IoMT network. In the private blockchain network, parameters such as medical data size, accessing speed, trust preserving privacy, scalability is the much better than public blockchain network [7,8]. The contribution of this work is:

1. To implement consensus algorithm of Practical Byzantine Fault Tolerance with PoW (Proof of Work) (PBFT-PoW) to provide high level security in accessing of health care record in the blockchain network.

2. Evaluate the performance metric measures of Block propagation time, latency, energy consumption and accessing time.

3. Smart contracts are implemented in the verification of health care data to facilitate the identification and authorization of the user.

The paper has been organized as follows: Section 2 describes the review of literature; Section 3 introduces Secure Storage of Patient’s Health Care Data Management in IoMT Using Blockchain technology, Section 4 discusses about the experimented results and Section 5 concludes the paper with future directions.

Recently blockchain has been used in various security domains to store and process the data. In the article [9]. blockchain based applications is surveyed and its potentiality is studied briefly. Blockchain has been used in several applications like education, healthcare, share market, stock Exchange etc. Various opportunities and challenges in the block chain at different domains are discussed. The consensus algorithms used in blockchain like proof of work, proof of stack etc., was studied. This article helps to know the future research scope in blockchain security. Block chain characteristics [10] with the benefits are identified in different domains other than bit coin. Technical challenges in consensus protocol like scalability, privacy leakage, security challenges are discussed for proof of work and proof of stack.

The advanced internet communities like smart city, smart nation and smart vehicles etc. IoT devices can be placed in various locations of geographical region. Creation of Block chain, verification of blockchain using consensus algorithm and cryptographic techniques are discussed [11]. Communication support using wireless and wired networks in block chain is studied and 5G support efficiently. Smart home IoT device is rapidly increased due to advancement in internet technology in providing security [12]. Risk assessment on remote data access is focused on this research work. Remote data authentication using blockchain, signatures and authentication secret codes are presented in this article. The secure data communication using grid system based on mutual authentication is discussed in paper [13]. Privacy is ensured using key management in smart meter. In this research they use signature keyless method in blockchain. Result shows cost effective, robust, and scalable in providing security.

Block chain technology in paper [14] used in secured data access of internet of vehicles (IoV). IoV is most significant mobile based application used in real time traffic management, speed control alert, direction alert, accidents etc. Consensus algorithm is used in blockchain for secured transmission. Key distribution technique is used for formation of new nodes in block chain. The resource limitation in IoT is overcome by using outsourcing bilinear pairing with permission blockchain [15]. Major potential of permission blockchain is security, scalability, and availability. The new tactile internet in paper [16] is used for intelligent transport energy trading system. Blockchain was used in providing security of energy trading.

Electrical vehicle uses blockchain for secured energy trading based on the request. SDN architecture is used for effective computation with less latency.

VANET was communicated with environment via wireless medium for efficient monitoring technique. Major advantages like weather monitor during emergency, intelligent path management etc. They proposed a blockchain with privacy assistance [17] using authentication technique for vehicle data. It helps to monitor the behavior of vehicle and communication records are traced. Block chain advantages and effectiveness is surveyed in article [18]. It states the importance on consensus algorithm with its principal and performance analysis. Different algorithm on consensus protocol is used to check the performance. Group decision is suggested in reaching consensus was implemented in paper [19]. It initiates and proposes minimum cost soft model in consensus algorithm. it is used in loan problem. The symmetric and asymmetric cryptographic method is used as hybrid scheme in blockchain technology [20]. It combines both techniques to provide efficient security in data storage. The IoT are now days used wide variety applications like nano robots, nano technology etc. internet of nano health care [21,22] applications required high security infrastructure for medical data process.

The limitations of above literature work are still need of additional security and do not support dynamic entry of device in the network. some technology does not support blockchain concepts and some research works are insecure when the devices are stolen.

Storing of patient’s health care data electronically, in the IoMT by using sensor devices, wearable devices status of patient’s health details is collected based upon some predefined parametric measures of oxygen saturation, pulse rate, calories, temperature, Blood sugar etc. These data are collected from wearable devices and permanently stored in Ethereum based blockchain technology. All patient’s health status is a sensitive information, and it must be kept in safe and more confidential one. This paper proposes Ethereum blockchain technology of smart contracts with various consensus protocols of Practical Byzantine Fault Tolerance, PoW (PBFT-PoW). Fig. 1. shows that architecture of PBFT-PoW.

This PBFT-PoW is composed of sensor and wearable devices that connect with web application as well as mobile application which collects and monitors the patient’s health care data.

This blockchain based secure storage of patient’s health care data management in IoMT is implemented by using PBFT-PoW. It’s a double layer concept of providing security. In the blockchain technology set of blocks which contains patient’s health care data in a secure manner. Fig. 3 shows that performance analysis of energy consumption using various algorithms.

In the Fig. 3. shows that our proposed work got low energy consumption compared it with other existing algorithms of PBFT and PoW. Tab. 2 shows the comparison of PBFT-PoW with parametric attributes with our proposed work.

From the Tab. 2, our proposed work PBFT-PoW supports with all attributes of blockchain based IoMT compared it with other existing work, and it offers promising solution in Health care data management [28–36]. The blockchain with decentralized security model using smart contracts enable to manage the patients’ health care data. This PBFT-PoW work is evaluated using following performance parameter.

This paper proposes PBFT-PoW using smart contract in health care data are stored in the cloud network, where data collected from wearable devices. Health care data is stored in decentralized and provides security, scalability, preserve privacy and effectively. The experimental results show that PBFT-PoW achieves transmitting of health care data between physician/user. This PBFT-PoW of HCD access control system protects patient health care data from external attacks. Our proposed work requires minimum consumption time when it is compared with existing algorithm. This PBFT-PoW is a decentralized storage of data and which preserves data privacy. In order to get the optimized solution for PBFT-PoW number of sealers should be less than nodes in the network. It minimizes the delay in synchronization and propagation. The accuracy rate of PBFT is 90.15%, for PoW is 92.75% and our proposed work PBFT-PoW is 99.88%. In future this PBFT-PoW will be improving in terms of reducing number of replicas, involving various protocols.