The fusion between Blockchain and IoT for healthcare systems

The fusion between Blockchain and IoT for healthcare systems Jovan Karamachoski, Liljana Gavrilovska Anis Sefidanoski FEIT, University Ss. Cyril and Methodius Skopje, Republic of Macedonia European University Skopje, Republic of Macedonia Abstract– Blockchain technology is new technology for digital asset tracking and management. Initially Blockchain was implemented as a financial solution, through the Bitcoin and its digital cryptocurrency. This was changed with the development of Ethereum new approach for management of digital assets. The existence of Smart contracts in the Ethereum Virtual Machine (EMV), introduced new ways for dealing the problems with third-parties. This opens opportunities for plethora of new Blockchain implementations for smart homes, smart objects, healthcare, finance management, insurance, supply chain management and many others. This survey paper addresses the state-of-the-art and highlights the possibilities for integration of Blockchain technology and IoT, with main focus to healthcare systems. Due to the Blockchain specifics, there are many unsolved issues and open challenges for the researchers in this area. evolved interest in the applications and practical implementations of Blockchain in non-financial use cases with main focus on the Internet of Things (IoT). In this paper we present the literature survey related to the Blockchain and IoT integration, with focus on healthcare applications. The paper also adresses the possibilities for other ongoing and proposed development and applications. Keywords – Blockchain; Smart contract; Bitcoin; Ethereum; IoT; Healthcare; Smart home; Smart objects I. INTRODUCTION The last few years there is rise in the interest for research in the area of Blockchain. The first and most popular Blockchain, introduced in 2009, is the Bitcoin [1]. Mainly, the Bitcoin is related to the financial aspect of Blockchain, allowing the transfer of digital currency. The Blockchain technology essentially bridges the gap between the parties included in lot of different assets’ transactions, and excluding the need for third-party entities. It also inclusies great number of parties that support the system, though keeping the data persistent. That makes the Blockchain to be seen as a long lasting database with inherit reliability and redundancy. With the release of the Ethereum Virtual Machine (EVM) and Ethereum Blockchain in 2014 [2], the researchers saw potential of using the Blockchain in another areas then finance, for example healthcare, smart things, environmental monitoring, supply chain and logistics, digital identity, etc. The capabilities of the EVM, are built upon the self-executing codes known as Smart contracts. This opens the possibilities to build systems that are present on Internet and that exist in a distributed cloud-like solution, without the need of middleman. Starting from 2015, when the EVM has shown its potential, the number of research articles and relevant publications is constantly increasing. There is II. BLOCKCHAIN BASICS Blockchain is an innovative technology for keeping the data persistent, immutable and reliable. The data structure of the Blockchain is organized in blocks, as depicted in Fig. 1. A block is created on predefined intervals depending on the protocol. Every block has at least the following information fields: timestamp, data, value of the previous block hash and nonce field. The newly created block is passed through hashing function to generate the hash value for the next block. Every participant can interact with Blockchain using simple encryption mechanisms based on asymmetric cryptography. The system can track the issuers of the transactions, can track data changes and can keep secure communications. The identity of the users is based on the wallet’s address, which is related to the user’s public key. The user’s identity is proved by the paired private key. The main hook for this technology is the decentralization introduced in the system. Basically the Blockchain network’s users are part of a flat architecture of nodes (peers), where every node is performing compute intensive calculations, to support the Blockchain network. This is so-called Proof-ofWork consensus mechanism [3]. The main reason for the existence of consensus mechanism is the need to obtain consensus over the correctness of the data, generated from the distributed nodes. Beyond this approach, there are several less popular consensus mechanisms (Proof-of-Stack, Proofof-Space, Proof-of-Burn, Delegated-Proof-of-Stake, etc.). Beside this decentralized public approach, there are also Figure 1. Blockchain data structuring private Blockchain solutions, with non-flat architecture and without necessity for implementation of consensus mechanism. These private Blockchains are orchestrated by governing nodes or validator nodes and very often are not even concerned as Blockchain technologies (since it resembles the classical centralized solutions). The main use cases of the Blockchain technology are the financial transactions and transfer of digital assets. Thanks to the advantages brought by this technology the Blockchain can be also implemented in other use case scenarios The Blockchain can patch the mechanisms for providing privacy and security, can bring trust in the communication between the parties, can be omnipresent database or just a reference database, can keep the network up to date or just bridge the need for third-parties. The actual need for implementation of Blockchain in production, comes from the main characteristics of the Blockchain: decentralization, persistency, anonymity and auditability [4]. The characteristics of the Blockchain are based on the mechanism that builds the system and the protocol for communication that are in details described in [1], [2]. It integrates cryptographic procedures to provide decentralization, liveness, fault tolerance, trust, provenance, privacy and security, immutability, non-repudiation, transparency, etc. [5] [6]. We must bear in mind that there are few, but very important, disadvantages and open issues, mainly related to the scalability, security and privacy attacks and slow transaction rates. The possible implementation use cases and the feasibility of Blockchain in other areas, are analyzed in [7], [8], where the main focus of implementation of Blockchain is set to the following areas: healthcare, supply chain and logistics, notary, eVoting, asset management, insurance claims, smart objects and environment, digital identity, etc. This paper gives the survey and highlights the state-of-the-art of the integration of Blockchain and IoT (especially in healthcare and smart environment) due to persistant interest and increasing number of publications. III. INTEGRATION OF BLOCKCHAIN IN IOT The IoT is a paradigm for internetworking small devices, sensors and actuators introduced in 1999 [9]. The beginnings of the IoT promised high penetration of these technologies in all domains of humans’ life. However, it struggles to fulfil these expectations. The problem was the unstructured, nonstandardized and expensive IoT products. The following years, lot of companies put effort to make the IoT more available and easier for deployment. Thanks to the cloudbased solutions and omnipresence of the mobile technologies, but also, the decrease of the prices, nowadays the IoT solutions are offered as a cloud services with high variety of powerful hardware support and mobile device integration. In most of the cases the IoT devices are intended to commute private data through public network and expose the sensitive data of the users to potential malicious nodes. In order to solve most of the problems with security, privacy and diversity, the companies are choosing the centralized architecture with cloud-based services. These give the IoT networks a momentum to rise and spread more rapidly. The centralization of the IoT’s management in private companies, resolves many problems, but also rises concerns. Due to centralization, there is a risk for privacy and security flaws, while the companies can read, analyze, sell and manage the collected data. Furthermore, the centralized system is prone to failures and loses of data. A network with centralized architecture has single point of access, which is a bottleneck that can cause QoS and QoE performance decrease in high demanding IoT systems. The Blockchain as a public ledger and distributed database (or just database relay, storing pointers to particular data) can relay the process of storing the data. The Blockchain technology is closely related to the Smart contract mechanisms. The Smart contract exists on the Blockchain as a procedure publically open and transparent. The trust in the Blockchain systems (especially the public ones) piles up because of the transparency in the coding process, the openness of the code and the chaining between the data blocks. The Smart contract is code capable to automate the access control and restriction, manage credentials and policies, and execute predefined codes of any type. It makes the Blockchain a potential problem solver for the IoT networks eliminating the need of third-parties in the communication. The main advantage that hooks the researchers to think of the possible IoT and Blockchain fusion is the introduction of the privacy-by-design to the system that can increases its security. Beside the great benefits, there are also few problems mainly connected to the small transaction rate and the scalability issues of the Blockchain protocol. IV. RELATED WORK This paper presents an academic survey of the possibilities for implementation of Blockchain in IoT networks. We are aware of the existence of commercial or community based solutions, lacking the research approach. This is done intentionally, due to high level of scams related to the Blockchain and huge number of ICO (Initial Coin Offerings) from suspicious teams and finances. The intention was to determine the level of interest and potentials for continuing the research of Blockchain and IoT integration. The main focus in this survey is on papers and publications presenting the application ideas and practical implementations (where the Blockchain is integrated into the IoT networks), but also on papers describing related frameworks, reviews and surveys, and publications presenting performance testing results. Our special interest is the integration of Blockchain and IoT in healthcare systems. We are aware about the possible limitations of the results, but generally they will provide guidelines for future research opportunities. Most of the papers positively promote the integration of the Blockchain and IoT. Despite the supporting papers, there are papers exposing the disadvantages of the integration, pointing out that the current Blockchain technologies are lacking mechanisms to overcome the excisting problems of the IoT networks. Despite all dissadvantages, the possible integration seams promissing. First research references related to Blockchain and IoT (BC-IoT) integration, are originating in 2015, when the Ethereum was released. In [10], [11] we can find the description of the first projects and proof-of-concepts. IBM and Samsung introduced the first solution based on the integration between the IoT and Blockchain in the project ADEPT. The project mainly is a proof-of-concept based on three existing technologies and protocols (BitTorrent for file sharing, Ethereum for smart contract execution, TeleHash for messaging). The final product is intended to ease the integration of smart home devices. Filament is another project related to the BC-IoT integration with main focus on industry, machine-to-machine communication and other industrial solutions. The initial possitive views for potential solution for any integration of Blockchain in IoT is presented in [12] pointing out on a transaction processing tool, ledger and coordination body. There are papers proposing framework and incentivizing a solution for artificial intelligence living on decentralized agents, seeing the potential of the openness on the data, omnipresence of the data and self-execution of the procedures [13]–[15]. Also there are papers [16], [17] which are supporting the development of the IoT solutions with built-in Blockchain capabilities with some financial aspect. The researchers are analyzing the advantages and disadvantages of the integration and trying to extract the best characteristics from both technologies. The positioning and review papers [18]–[23] are strongly supporting the potential integration with respect to the implementation in e-Business solutions, smart objects, healthcare and safety and privacy enhancement solutions. They clearly point out that the integration BC-IoT should be done by context, because the biggest problems in large IoT networks is scalability where the huge number of nodes will generate high volume of data. These papers are concluding that the possible solution will ease the access control mechanisms for IoT networks, can leverage the privacy and security in the network and bring new business ideas to life. Also Blockchain is seen as a missing link for success of the IoT, in the process of bringing the privacy to another level. This is essential for the healthcare solutions, but also for the insurance companies and their customers. The openness of the Blockchain, can further attract users and increase the adoption rate. The implementation of the Blockchain in IoT devices, will leverage the autonomy of the devices, and enhance the commodity of the people. The main challenge in the current Blockchain protocol (the Ethereum protocol), that is a bottleneck for future IoT applications, is the high price for data recording and small transaction rate. Contrary to the potential risk of failure due to scalability issues or other problems, there are huge amount of papers related to application descriptions and practical implementation deployments or performance testing. In [24], [25] the authors are describing the practical implementation aspect of the BC-IoT integrated solution in a healthcare system. The main concerns are the security and privacy, which are rising with-in healthcare systems. The provided solutions are managing the access rights of the patients and the access control of the patients’ data. Another important aspect related to the healthcare system is the huge volume of data generated by the healthcare system, especially in a globally set system. The solution for the data storage problem is addressed in [26]–[29]. It requires extended feasibility evaluation of integration between the Blockchain and IoT with offloading of heavy data files in local or cloud based (potentially IPFS – InterPlanetary File System) storage. This approach will involve additional feasibility evaluation for the newly added system based on cloud-based storage, or IPFS storage. In the papers [30]–[33] the authors are working toward the next generation networks by virtualization of the resources and setting up the Blockchain as a service for the IoT devices. These papers are practically implementing the ideas for software-defined IoT nodes managed by the Blockchain-based technology for enhanced simplicity of the networks and better management. The virtualization of the resources and edge computing (as a direction for the 5G networks) will lower the complexity of the management of the networks and increase the service availability with better QoS performance parameters. From the evaluation of the performances presented in these papers, we can see that the idea for software-defined IoT and Blockchain as a service are feasible. The authors in [22], [34]–[38] are showing the feasibility of the integration BC-IoT through practical implementation in the finance transactions for micro payments, but also smart home and smart object applications (like supply chain tracking systems, smart grids, smart meters, smart vehicles, smart agriculture, smart waste management, smart cities). In [34] the authors are presenting practical implementation for a modern agriculture and food supply model for tracing of food production and market supply monitoring based on Blockchain. This kind of application will increase the value of the food and the trust in the manufacturers. The huge benefit of the existence of Blockchain is the possibility to use the digital currency aspect of the Blockchain digital assets to increase the micro payment transactions (especially the machine-to-machine automatic payment). In [35] there is a practical implementation for micro payment solution. Toward the financial aspect of the Blockchain, but in tight relation to the IoT networks, are the smart grids where the Blockchain is seen as enabler for secure and fast micro electricity market expansion [36]. This will enable the users to manage the selection of electricity supplier smoothly, and much faster. Toward the enhancement of the humans’ lives are also the smart home solutions [37] and smart city solutions [38], where the management of the in-home resources and community resources will be much easier. V. OPEN ISSUES AND FUTURE WORK The literature review guide us to narrow the possible topics of interest for further research. Through in-depth analysis of the reviews and survey papers content, the data storage and data management related papers, and privacy and security papers [26], open huge horizont of different opportunities, the topic related to healthcare and medical records management (or so called healthcare systems) seams promissing. This topic is chosen mainly because there are several open issues and possible problems to be solved. The problems related to the healthcare systems are partly common with other IoT systems, but they also have specific problems targeting the particular healthcare solution. The major problem is scalability. Even in a small healthcare system networks (micro or medium solutions), where the scalability will not a big issue, the throughput will be affected due to small number of allowed transaction per minute. Other problem related to the general IoT networks is the data storage and management. Due to potential circulation of high volume of data in the health care systems, there is concern for storing the data on the Blockchain, though making the system too expensive and data-heavy. There are several proposals [26][39][40][41][42] in offloading the Blockchain. Few of them are targeting more precisely the medical records and patient data. This will be further analyzed, in correlation with the scalability and complexity of the system. The scalability and throughput of the system, generally, varies depending on the data storage system solution. The issue of privacy and security regarding the data storage and data management, and especially the health related data, could be solved by implementation of Blockchain design. Generally speaking, the basic Blockchain solution gives an anonymity solution, which differs from the privacy. The difference between anonymity and privacy, in case of Blockchain, lies in the possibility of determination of the users through data tracing. The anonymity is basically hiding of the identity of a patient behind the wallet address, and the privacy should provide intractability of the patient identity (wallet address) through encryption mechanisms or relay nodes (TOR). The advance of using TOR versus the privacy obtained by Blockchain can be found in more details in [43]. Taking in account the amount of data in circulation in a global healthcare system, one of the solutions for the scalability is seen in the sub-blockchain solutions (e.g. clustering). The idea is to generate separate Blockchains for different organizations, with feature that will enable the Blockchains to communicate in-between [44][45]. Another potential solution is development of a new consensus mechanism that will handle the large number of transactions and will be scalable. Opposite to the public Blockchain with the new consensus mechanism, there is still great potentials for private Blockchain solutions. The private Blockchains have the same concerns as the centralized architecture solutions, but are much easier implementable and manageable. VI. CONCLUSION There is rather high interest for potential solutions based on the integration between the BC-IoT. The presented literature search and plethora of publications show that the main solutions are related to smart grids, supply chains and logistics, edge computing virtual resources management, smart homes, healthcare and medical records management, firmware update procedures and other smart solution. The fusion, obviously is possible, with lot of benefits. With the up-to-date Blockchain solutions we can achieve better security and privacy, data storage management, access management, smart things management, but still there are open issues related to scalability and throughput. 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