blockchain for industry 4.0: a comprehensive review · sudhanshu tyagi 2, (senior member, ieee),...

Charles Darwin University

Blockchain for Industry 4.0

A comprehensive review

Bodkhe, Umesh; Tanwar, Sudeep; Parekh, Karan; Khanpara, Pimal; Tyagi, Sudhanshu;Kumar, Neeraj; Alazab, MamounPublished in:IEEE Access

DOI:10.1109/ACCESS.2020.2988579

Published: 01/01/2020

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Citation for published version (APA):Bodkhe, U., Tanwar, S., Parekh, K., Khanpara, P., Tyagi, S., Kumar, N., & Alazab, M. (2020). Blockchain forIndustry 4.0: A comprehensive review. IEEE Access, 8, 79764-79800. [9069885].https://doi.org/10.1109/ACCESS.2020.2988579

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https://doi.org/10.1109/ACCESS.2020.2988579

https://researchers.cdu.edu.au/en/publications/8beb0a38-b373-4275-842f-11494c17f4ff

https://doi.org/10.1109/ACCESS.2020.2988579

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Received March 20, 2020, accepted April 6, 2020, date of publication April 17, 2020, date of current version May 12, 2020.

Digital Object Identifier 10.1109/ACCESS.2020.2988579

Blockchain for Industry 4.0:A Comprehensive ReviewUMESH BODKHE 1, SUDEEP TANWAR 1, (Member, IEEE), KARAN PAREKH1, PIMAL KHANPARA1,SUDHANSHU TYAGI 2, (Senior Member, IEEE), NEERAJ KUMAR 3,4, (Senior Member, IEEE),AND MAMOUN ALAZAB5, (Senior Member, IEEE)1Department of Computer Science and Engineering, Institute of Technology, Nirma University, Ahmedabad 382481, India2Department of ECE, Thapar Institute of Engineering and Technology, Deemed to be University, Patiala 147004, India3Department of CSE, Thapar Institute of Engineering and Technology, Deemed to be University, Patiala 147004, India4Department of Computer Science and Information Engineering, Asia University, Taichung 41354, Taiwan5College of Engineering, IT and Environment, Charles Darwin University, Casuarina, NT 0810, Australia

Corresponding authors: Neeraj Kumar ([email protected]) and Mamoun Alazab ([email protected])

This work was financially supported by the Department of Corporate and Information Services, NTG of Australia.

ABSTRACT Due to the proliferation of ICT during the last few decades, there is an exponential increase inthe usage of various smart applications such as smart farming, smart healthcare, supply-chain & logistics,business, tourism and hospitality, energy management etc. However, for all the aforementioned applications,security and privacy are major concerns keeping in view of the usage of the open channel, i.e., Internet fordata transfer. Although many security solutions and standards have been proposed over the years to enhancethe security levels of aforementioned smart applications, but the existing solutions are either based upon thecentralized architecture (having single point of failure) or having high computation and communicationcosts. Moreover, most of the existing security solutions have focussed only on few aspects and fail toaddress scalability, robustness, data storage, network latency, auditability, immutability, and traceability.To handle the aforementioned issues, blockchain technology can be one of the solutions. Motivated fromthese facts, in this paper, we present a systematic review of various blockchain-based solutions andtheir applicability in various Industry 4.0-based applications. Our contributions in this paper are in fourfold. Firstly, we explored the current state-of-the-art solutions in the blockchain technology for the smartapplications. Then, we illustrated the reference architecture used for the blockchain applicability in variousIndustry 4.0 applications. Then, merits and demerits of the traditional security solutions are also discussedin comparison to their countermeasures. Finally, we provided a comparison of existing blockchain-basedsecurity solutions using various parameters to provide deep insights to the readers about its applicability invarious applications.

INDEX TERMS Blockchain, consensus algorithms, cyber-physical systems, IoT, smart grid, supply chainmanagement, intelligent transportation.

I. INTRODUCTIONWith the wide popularity of Internet and related technologies,various Industry 4.0-based applications have been used acrossthe globe in which sensors and actuators sense, compute andcommunicate the data for industry automation. As in Industry4.0-based applications, data between different locations flowsusing an open channel, i.e., Internet, so threats to security andprivacy has also increased manyfold [1]. Such applications

The associate editor coordinating the review of this manuscript and

approving it for publication was Wei Wei .

deal with data in large volumes and hence, so it is necessaryto consider issues such as-data heterogeneity, data integrity,and data redundancy alongwith the security and privacy con-cerns. Moreover, different applications require datasets fromdifferent domains in different formats. Therefore, it is alsoneeded to standardize the data format so that it can be usedby different Industry 4.0-based applications.

The usage of smart phones and smart applications for per-sonal, professional, and social activities is increasing expo-nentially across the globe. It results an increase in both thenetwork data traffic (in GBs) and overall expenditure (in

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https://orcid.org/0000-0002-8751-9205

U. Bodkhe et al.: Blockchain for Industry 4.0: Comprehensive Review

FIGURE 1. Statistics of (a) Data traffic per month region wise and (b) Application-wise expenditure on Industry 4.0.

FIGURE 2. (a) Increase in identity theft and (b) Generation of data traffic.

Billions USD) as shown in Fig. 1 (a) and (b) as per thereport mentioned in [2], [3]. According to this report, smartindustries would spend $40B on IoT by 2020 in various sec-tors including transportation and manufacturing. However,due to the large number of data exchanges over the Internet,maintaining confidentiality, privacy, and integrity becomesa major issue in Industry 4.0 [4]. Moreover, according tothe surveys conducted by different agencies [5], [6] nearly60 millions people are affected by identity theft and 12 billionpeoples records misused in 2018 and expected to increase to33 billion by 2023 as shown in Fig. 2 (a). Fig. 2(b) showsthe 10 recent security breaches incidents reported tillJuly 2018, which are expected to increase in the years tocome.

Security and privacy preservation are important concernsfor Industry 4.0 applications [4], [7]. There may be chances ofunauthorized data breaching or information leakage leadingto the financial losses to Industry 4.0-based applications.In the absence of robust security architecture, the systemalong with data are prone to various types of attacks (such

as DDoS, ARP spoofing attacks, data rate alteration, net-work congestion, manipulation, noise interference, phishingand config threats) which can harm the confidentiality andintegrity of data and can affect the overall functioning of anysystem. For such types of attacks, prevention is better thanany reactive defense mechanisms to assure confidentiality,integrity, and privacy within the legal compliance rules [8].It has been found in the literature that with an increasing rateof automation in Industry 4.0., the probability of violatingthe security rules and launching new type of cyber-attacksis also increasing. Access control, authorization, confiden-tiality, availability, and integrity are the prime concerns inIndustry 4.0.

To mitigate the aforementioned threats, current Indus-try solutions are using the centralized, client-server basedarchitecture in which the centralized authority holds all theprivileges. But, if the centralized authority is compromisedthen the entire system may crash. Conventional securitymechanisms such as Data Encryption Standard (DES), andAdvanced Encryption Standard (AES) and their variants are

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also being used but they have high computation and commu-nication overhead. However, a revolution in this area camewith the introduction of the concept of ‘‘Bitcoins’’ [9]. Forexample, Authors of [10] illustrated that how blockchaintechnology can be used to deal with privacy & security issuesin Industry 4.0 [11].

The blockchain technology has the potential to handlevarious security attacks as it can eliminate the need of thecentralized authority to perform various operations. In theblockchain technology, a number of users participate in trans-action verification and validation [12]–[17]. It uses a struc-tural distributed database which stores data from all the nodesin an encrypted form validated using various checks such asMerkle hash tree (MHT) and Elliptical Curve Cryptography(ECC) [17]. As the database is distributed, so there is a risk ofgetting crashed or corrupted. Transactions are linked togetherwith cryptographic keys and immutable ledgers whichmakes it difficult for attackers to manipulate or delete therecorded information. Data is always stored in an immutablemanner using timestamps, public audit and consensus mech-anisms [18], [19]. The use of these mechanisms makessecurity architecture a robust and assures data integrity andprivacy [20].

A. SCOPE OF THIS SURVEY ARTICLEThe blockchain reduces the risk of single point of failure andnetwork attacks using the distributed network nodes. Use ofthe decentralized platform reduces fraud by time stampingentries, and information of users is stored in immutable ledgeracross the network using the smart contact. Blockchain elim-inates manual processes like reconciliation between multi-ple isolated ledger and administrative processes which helpsto reduce the cost of the system. Due to the use of var-ious cryptographic linked chains, the speed of transactionand level of security is enhanced manyfold. Several sur-veys are conducted by the researchers using the blockchaintechnology for Industry 4.0 which are summarized asfollows [21].

Mettler [22] explored how blockchain technologyrevolutionized the healthcare alongwith various open chal-lenges [23], [24]. Yli-Huumo et al. [25] reviewed the currentscenario of the blockchain technology and its research gapsand challenges. They have also discussed the suitability of theblockchain for various smart applications. Ahram et al. [26]discussed the various components in blockchains such asdecentralized techniques and immutability of ledger thatmakes it difficult to attack the system [27].

Weiss et al. [28] discussed about blockchain publichealthcare applications. They have also explored how theblockchain technology eliminates the centralized authorityduring the verification process, its digital signatures [29]for safe data repository, its architecture, and also thechallenges. Zhang et al. [30] evaluated the metrics ofblockchain-based decentralized applications. In this paper,they considered the evolution metrics, security, and chal-lenges which are important for various applications like

healthcare, smart-agriculture, IoT, and tourism & hospitality.Krieger et al. [31] explored an advanced blockchain architec-ture for the electronic health systems. They focused on theregulatory compliance for the data privacy of blockchain, itsarchitecture, limitations, and benefits [32]. Duan et al. [33]explored educational applications of the blockchain technol-ogy. In this paper, an automated evaluation software as a toolwith blocks is proposed, which contains graduation marksalong with the certificate. They also highlighted how blocksare recorded, Merkle hash tree, hash functions, digital signa-tures, and timestamp mechanisms during the verification ofvarious transactions.

Radanović and Likić et al. [34] explored the opportunityof applying blockchain technology in the medical domain.Authors focused on the areas such as supply-chain of drugs,pharmaceuticals, and health insurance with associated chal-lenges. They also discussed how the blockchain can be usedin countries like USA and India for the land registration.Vujičić et al. [35] gave an overview of blockchain bit-coin and Etheruem cryptocurrency platforms. In this paper,the authors explained the architecture, security parameters,and challenges for implementation of blockchain in variousapplications.

Chen [36] discussed the tokenization of money that usesthe blockchain. In this paper, the working of the token andtheir types such as token, initial coin offering, and its currencyare discussed. Gatteschi et al. [37] explained whether theadoption of the blockchain in different industries can improvetheir productivity. Authors showed the blockchains has beenused in various smart applications. Authors also described thefunctionality, architecture, techniques used, security parame-ters, and open research areas. Kumara andMallickb et al. [38]explored the blockchain security, issues and challenges inIoT systems. They discussed various existing security andprivacy issues related to IoT devices and the possible solu-tions by the adoption of blockchain technology [39]–[41].Konstantinidis et al. [42] presented various blockchain-basedsmart business applications.

From the above-mentioned proposals, we found that mostof the recent surveys on the blockchain technology haveconcentrated on various smart application areas in Industry4.0 and its security parameters [43], [44]. The comparativeanalysis of pre-existing surveys on Blockchain with the pro-posed survey is given in Table 1.

B. RESEARCH CONTRIBUTIONS OF THIS PAPERFollowing are the research contributions of this paper:• A detailed taxonomy of blockchain-based Industry4.0 applications is presented.

• A reference architecture having various modules andcomponents for applicability of blockchain in Industry4.0 is presented.

• The merits and demerits of the current security solutionswhich are applicable in Industry 4.0 are discussed.

• Finally, the Open issues and challenges in Industry4.0 based smart applications are presented.

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TABLE 1. Comparative analysis of pre-existing surveys on Blockchain with the proposed survey.

C. ORGANIZATION OF THE PAPERThe structure of the survey is as shown in Fig. 3.Table 2 lists all the acronyms used in the paper. Restof the paper is organized as follows. The backgroundand history of the blockchain technology is presented inSection 2. A reference architecture of blockchain is dis-cussed in Section 3. In Section 4, blockchain deployment

for various smart applications is discussed in detail. Then,Open issues and research challenges in smart applica-tions are presented in Section 5. In Section 6, two casestudies on smart farming and tourism and hospitality arepresented to give more insights to the readers. Finally,in Section 7, the paper is concluded with future researchdirections.

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TABLE 2. Acronyms and their meanings.

FIGURE 3. Organization of the survey.

II. BACKGROUND AND HISTORY OF BLOCKCHAINA. TRADITIONAL SECURITY SYSTEM AND BLOCKCHAINIn the present era, most of the database systems use acentralized client-server based architecture. In this systems,a client (user) has the authority to modify the data storedin the centralized server. The control of the entire serverdatabase is with the centralized authority who can control and

take decisions with respect to various access control policiesdefined on the data stored in the database. They also havethe authority to authenticate users credentials before theyaccess the database. To resolve the issues in the traditionalcentralized systems, blockchain can be an effective solution.

A blockchain is a chain of blocks which can be used tostore and share data in a distributed, transparent and tamperresistant manner. Each block consists of data and is linkedwith other blocks using pointers. Such linkages ensure theintegrity and tamper resistance in the blockchain. When anew data is added to the blockchain, link to the free end iscreated which extends the blockchain by one block or unit.As more data is added to the blockchain, it gets longer andchain grwos in size. If one of the blocks is modified in thechain, it breaks cryptographic links which disrupts the wholeblockchain. It also allows the user to verify the integrity ofthe stored data.

The risk of the centralized control system can be elimi-nated with an implementation of decentralized systems. Thedatabase authority holds the centralized control on the secu-rity needed for all the users for the required access. Theblockchain stores the data and builds the structural datastorage which makes the network more secure. Due to this,the blockchain technologymakes easy records or transactionswith heterogeneous information in the databases.

B. BACKGROUND OF BLOCKCHAINThe idea of blocks connection by cryptographic chains wasintroduced by Stuart Haber and Scott Stornetta in 1991. Theydesigned a system, in which information or transaction storedwith timestamps can not be modified or tampered. After that

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FIGURE 4. Generations of Blockchain.

Bayer, Haber, and Stornetta proposed verification and vali-dation of various transactions using the Merkle tree. In theMerkle tree, recorded data was gathered into a single blockwith an improved quality.

Satoshi Nakamoto created the initial blockchain networkin 2008 [9]. He introduced the hash function method to createblocks in the chain. The major attempt was to improve thearchitecture and development of the blockchain in whichthere was no need of sign by the clients or the users. Thisimplementation build the network for cryptocurrency recog-nized as bitcoin. The bitcoin network is publicly availableledger for all the transaction records. In his research work,blocks and chain were separate words which are combinedtogether known as blockchain. They got the bitcoin networkfile size and the records of its transactions reached up to20 GB by 2014, which went to 30 GB between the last quarterof 2014 to 2015. The bitcoin network was pushed from 50GBto 100 GB in January 2017.

The blockchain is used in the finance or cryptocurrencyapplications as it enhances the quality of various applicationswith respect to speed, security ease of use, and confidentiality.To explore the possibilities of applying blockchain technol-ogy in various industries, many companies have establishedtheir research centers for growth of this technology. Forexample, IBM has its research center in Singapore whichwas inaugurated in July 2016. In November 2016, the groupof world economic forum discussed the development ofthe governance models for the blockchain technology. Theglobal blockchain forum introduced the chamber of digi-tal commerce in 2016 by Accenture’s trade group. EmmaMacclarkin suggested the use of blockchain to enhance thetrade which was executed by the European parliament’s tradein 2018.How blockchain revolutionized: The revolution of

blockchain technology from inception to till today isexplained in detail as shown in Fig 4.

1) BLOCKCHAIN 1.0The first generation of the technology was started with thebitcoin network in 2009, which is known as blockchain 1.0.In this generation, the creation of the first cryptocurrencieswas introduced. The idea was all about payment and itsfunctionalities to generate cryptocurrency.

2) BLOCKCHAIN 2.0In the second level of the blockchain technology, smart con-tract and financial services for various applications wereintroduced in 2010. The development of blockchain withEtheruem and Hyperledger frameworks was proposed in thisgeneration.

3) BLOCKCHAIN 3.0In this generation of blockchains, the convergence towardsthe decentralized applications was introduced. Variousresearch areas such as health, governance, IoT, supply-chain,business, and smart city were considered for building decen-tralized applications [46]. In this level, etheruem, hyper-ledger, and other platforms were used which having theability to code smart contracts for a variety of decentralizedapplications [47], [48].

4) BLOCKCHAIN 4.0This generation mainly focused on services such as pub-lic ledger and distributed databases in real-time. This levelhas seamless integration of Industry 4.0-based applications.It uses the smart contract which eliminates the need forpaper-based contracts and regulates within the network by itsconsensus [49].Blockchain Requirements:• Smart Contracts: It is a protocol which allows the per-formance of transactions in absence of third party thatmakes transactions irreversible and traceable.

• Tokenization: It is one of the most important thingsthat must to be included in the blockchain. It facilitatesdigital representation of the goods, services, and rightswith the help of tokens. It allows the exchange of valuesand trust for different users without involving the centralauthority.

• Data security: Security compliance is a major and essen-tial requirement of blockchain technology with a legalpoint of view.

• Decentralised data storage: It is a basic requirement ofthe distributed system.

• Immutability: All the records on the network shouldnot be modified or tampered in the shared ledger. Thisenables the integrity of the stored data.

• Consensus: Transactions should only be updated whenall the verified users in the network agree for the same.

• Typed Blocks: It is required for the smart contract and forhigh speed payment in business transactions. So, dataformatting of the different types of blocks include itstime, consensus algorithm [50], number of transactionper blocks, and its content data types.

• Sharding: It is required for the separation of content oversubsets of nodes in a way, that not all the nodes need tocarry all processing load or any burden.

• Access rights management: Encryption based privateand public key cryptography and distributed databaseswith user identification is required to assign and manageaccess rights.

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• Standards used to manage permissioned blockchains:Immutability of the blockchain network makes the dataaccess in a specific order. The public certificates areavailable in public blockchain, but without having theprivate key, authorization cannot be provided to theusers. So, all the data should be managed in order of dataelements like user’s internet protocol (IP) address, name,its code, and extensible markup language. These all arepublished to the consortium with the communicationprocess.

• Standard data formatting: In the blockchain system,it is also needed to standardize the data formats withrespect to Application Programming Interfaces (API).Each organization in the blockchain network needs touse the same data format or APIs to communicate in thesame network.

• Updatability: The need for data updation in thedistributed ledger is most important for records. In apeer-to-peer network, data needs to be structured andsystematically updated for each node that transactswithin the network.

• P2P encryption between blockchain nodes: Encryptionis needed to secure the transactions between the endnodes that may link together in the blockchain protocol.

• UX: One of the major factors in a system is the userinterface design that provides an easy and convenientapplication environment to the users. The main differ-ence between the blockchain-based and non-blockchain-based systems is the manner in which the userperceives it.

• Development operation: The main step in the productionof the system is the selection of platforms that requiresless time and the setup complexity.

III. BLOCKCHAIN ARCHITECTURE AND ITS COMPONENTSA. BASIC BLOCKCHAIN BASED ARCHITECTUREIn the basic architecture of the blockchain, each transactionneeds to be verified which can not be altered as shownin Fig. 5.

1) ADDITION OF TRANSACTIONS IN THE BLOCK STRUCTUREA blockchain transaction has various steps. First, a networknode or user requests for a new transaction. After that,the transaction is recorded in the block format or structure.The block structure consists of the index, time-stamp, data,previous hash, and current block hash.

2) TRANSMISSION TO PEER NODESA block of transactions is broadcasted to the peer nodesavailable in the network.

3) VALIDATION OF TRANSACTIONSThe blockchain network uses SHA-256 algorithm for creatinga unique hash. Each block in the blockchain is linked withthe hash of the previous block which makes an unbreakable

FIGURE 5. The basic blockchain-based architecture.

network of transactions. If someone tries to append a trans-action, then it must be validated by the network nodes or bysmart contracts, and consensus. This immutable ledger can-not be modified, it can only be appended to the transaction ofblocks, which results in a secured and reliable decentralizedsystem. Various algorithms are used to validate transactionsand user status.

4) BLOCK ADDED TO LEDGERThe new transactions are first verified by the other nodes andthen they are added in a new block for the ledger or chain. Theexisting blockchain is extended by addition of a new blockthat is unalterable and undeletable for any other users.

B. REFERENCE ARCHITECTUREThe blockchain reference architecture consists of three dif-ferent networks which combine together and run the wholeblockchain application for the users. The three different net-works are the public network, cloud network, and enterprisenetwork as shown in Fig 6. Each has its own capabilities andfunctionalities for the smooth working of the decentralizedapplications.

1) PUBLIC NETWORKIn this network, the users, edge services, and peer cloudproviders are connected or linked together.

a: USERSIn the public network, the users manage the distribution andcreation of the blockchain decentralized application and exe-cute the operations with the help of the blockchain network.Users have different roles as follows:

b: DEVELOPERDevelopers make various types of applications for the clientor users with different functionalities. They develop the smart

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FIGURE 6. A blockchain-based reference architecture.

contract for the interaction with the users which helps toadd transactions or records within the blockchain network.The developers can also build the inheritance applications forfacilitating communication in the blockchain.

c: ADMINISTRATORThe functionality of the administrator is to produce, maintain,and configure decentralized applications for the blockchainnetwork.

d: OPERATOROperators have the control to monitor and manage theblockchain network and its applications.

e: AUDITORThe blockchain auditors maintain or review the history ofthe transactions over the blockchain network for business andlegal compliance point of view.

f: EDGE SERVICESThese services authorize the information that gets transferredvia the internet to the cloud, enterprise applications, and clientapplications. They maintain systems such as domain namesystems, content delivery networks, firewalls, and load bal-ancers. Domain name systems are used to correct the UniformResource Locator (URL) of the web sites that are linked to theTransmission Control Protocol-Internet Protocol (TCP-IP)address for the system which is to be used for the resources.The content delivery network carries user applications, whichgives the geolocation for the distributed systems which are

installed to minimize the response time for the distributedusers in the network. The firewall is responsible to maintainand give access control to the incoming and outgoing trafficin the network allowing or blocking the access. The loadbalancers are used for the distribution of the network trafficto maintain minimum response time, latency, and maximizethroughput across the resources such as computers, proces-sors, and storage systems. They are needed to balance the loadin local and global systems.

2) INTERACTION OPTIONIn the blockchain, there are various ways through which userscan interact with the blockchain network, they are shownbelow as:

a: SOFTWARE DEVELOPMENT KITThe SDK is useful for facilitating interaction between appli-cations and their platforms. Blockchain application develop-ment lifecycle has a number of phases such as developingphase, debugging phase, testing phase, and production phase.The blockchain applications need to interact and communi-cate with the network when the software development cycleexecutes.

b: CLIENT SOFTWARE DEVELOPMENT KITIt is a client-side programming library, which provides APImethods to be used by the end user program to give accessfunctionality within the blockchain network. The programs

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are written in Java, Python, and other languages and the kitalso supports development tools.

c: COMMAND LINE INTERFACEDevelopers and administrator usually need activities such asmonitoring, managing accounts of users, and importing &exporting some text commands formats. All these activitiescan be executed through the command line interface.

3) CLOUD NETWORKThe cloud network consists of a variety of running nodes,each with its own capability and functionality. The cloud net-work includes the blockchain applications, application pro-gramming interface, blockchain services, security services,and system integration.

a: BLOCKCHAIN APPLICATIONSThere are various types of applications such as web appli-cation, end-user applications and server-based applications.Users play different roles such as business users, adminis-trators, auditors, and operators. The blockchain applicationsuse the APIs for the post and get services of the resourceslike databases. A variety of applications such as healthcare,financial sector, insurance, energy domain, supply-chain, andIoT can be enabled with the blockchain to minimize the costand time [51]–[56].

b: APPLICATION PROGRAMMING INTERFACEAnAPI is useful for the developers and users to reuse the dataor information and its analytics with their services. It can becalled by different cross-platform technologies. Blockchaintechnology provides various APIs for the application inter-faces to use the components that can be handled in the busi-ness transactions.

c: BLOCKCHAIN SERVICESFor the performance and functional environment of theblockchain systems, there is a range of services such as:

d: MEMBERSThis service manages the user ids, credentials, and the his-tory of users transactions in a confidential manner overthe blockchain network. The permissioned network needsto validate the users of ongoing transactions and the usersidentification for the record of transaction and verification,so it requires membership in the network. In such networks,users have the access control to allow or block the transaction.In a non-permissioned network, it does not require the autho-rization by the user while submitting the transaction details.

e: CONSENSUSConsensus is a protocol in the blockchain network, whichmust be followed by each node in the network. This protocolspecifies time validity and rules that need to be followed

by all the nodes or users in the network to perform varioustasks or append transactions in the blockchain network. It alsomaintains a copy of the ledger in the network.

f: LEDGERAll the transactions are linked together with a cryptographichash in the blocks to form a ledger.

g: SMART CONTRACTIn general, a smart contract is a chain of the codes, which exe-cutes in the blockchain network environment. This code chaincommunicates the conditions or rules for different parties tofollow the terms between the nodes or users in the network.Smart contract can be developed in the blockchain platformwith the help of the supported programming languages.

h: SECURE RUNTIMEIn the secure runtime environment, blockchain transactionsare added in the ledger with the secured container such assecure OS, and library of the programming language runtimeused.

i: EVENT DISTRIBUTIONIn the blockchain network, the publisher notifies the sub-scribers for a specific event. The notification is sent in abroadcast manner within the network. Subscribers who sub-scribe to a specific publisher or events receive the notifica-tion.

j: SYSTEM INTEGRATIONThe blockchain services and the enterprise network are com-bined or integrated together via the application programminginterface and enterprise service bus.

k: CONNECTIVITYThe connectivity between the cloud network and the enter-prise network is established by the Virtual Private Net-work (VPN) or the gateway tunnel. It enables the secureconnectivity and standard data format and filters within theblockchain network.

4) ENTERPRISE NETWORKThe enterprise network consists of the enterprise directory, itsapplications, and the database.

a: ENTERPRISE USER DIRECTORYIn the enterprise applications, data or information regardinguser authentication, authorization, and personal data of usersare recorded. The gateway and virtual private network (VPN)maintain secured services for the access control of the users.

b: ENTERPRISE APPLICATIONSThese applications are used for the enterprise that communi-cates with the blockchain network. They also communicate

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FIGURE 7. Taxonomy of Blockchain for Industry 4.0.

with smart contracts in the network. Hence, smart contractcollect and store the enterprise data in the network andshare that information over the applications. They also makerequests for availing the services in the blockchain network.

c: ENTERPRISE DATAThe enterprise application in the blockchain records andmaintains the metadata of the system. It also maintains thefeedback of the system that contains the entire history ofthe blockchain network. Transactional data contains all therecords of the network which includes master repository,financial information, and business communication. All thedata is available via data repository and distributed datastorage. The second type of blockchain enterprise data isapplication data in which, data is collected and producedby enterprise applications and its operations. All the valuesare added for a better understanding of the application per-formance. The log data is recorded in log files for futureinspection for the security, governance, or compliance.

IV. BLOCKCHAIN DEPLOYMENT INSMART APPLICATIONSThe detailed taxonomy of blockchain deployment in real-time applications such as energy, healthcare, manufacturing,agriculture, business, digital content distribution, smart city,IoT [57], supply-chain & logistics, and tourism & hospital-ity [58] is shown in Fig. 7. Table 3 provides the detailedrelative comparison of the State-of-the-art proposals/Toolsused for blockchain-based security system. Parameters usedfor this comparison are objectives, techniques used, setuptype, programming languages or simulators, pros, and consof the existing tools/frameworks.

A. SUPPLYCHAIN AND LOGISTICSAgricultural applications need critical management inputs,such as supply-chain management (SCM) which plays a

prominent role in human lives. Traditional logistic systemsused in food-supply and agriculture simply store the ordersand delivered them to the destination. These conventionalsystems have a lacuna with respect to various features suchas auditability, traceability, and transparency [59]. However,in the modern digital era, these features can improve safetyand food quality, and hence, there is a huge demand ofgood quality of food by consumers [60]. Hence, most of theresearch & development(R&D) organizations adopt IoT tech-nologies such as wireless sensor networks (WSN), and radiofrequency identifications (RFIDs), which remotely observethe food supply-chain.

According to Caro et al. [61], most of the centralized cloudinfrastructures are being used as current IoT solutions inSCM. These infrastructures usually have open issues like dataintegrity, lack of transparency, tampering and single pointof failure. These issues can be handled in an efficient wayby using blockchains. Decentralized trustful systems can bedesigned for the same by using the blockchain. A decen-tralized, blockchain-based solution namedAgriBlockIoT, wasproposed in [61] for Agri-Food SPM. It integrated variousIoT sensor devices which produced and consumed data alongthe chain. The stored data can be accessed, and autonomousexecutable smart-contracts could be implemented throughAgriblockIoT, with the objective of achieving transparency,and inflexibility of the records in an environment, that usesmodern devices such as mini-PC and gateways. The perfor-mance and efficiency of AgriblockIoT are quantified in termsof CPU load, network traffic, and latency. The performancecan be improved by working on the constrained hardwarearchitectures.

Perboli et al. [62] suggested that the blockchain improvesthe reliability, efficiency, and transparency of supply-chain,and speedup inbound processes. Though many IoT technolo-gies are used for food safety and SCM, there are some issueswhich are not properly addressed. Themajor issue is to decide

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TABLE 3. State-of-the-art proposals/Tools used for Blockchain-based Security system.

whether the information or data shared among the membersof other supply-chain is trustworthy or not. To overcome thisissue, authors of [60] proposed a system called Hazard Anal-ysis and Critical Control Points (HACCP), which providedreal-time food tracing information to all SCM members andhas features like reliability, openness, neutrality, security, andtransparency.

Weber et al. [69] proposed a blockchain based decen-tralized solution to solve the problem of determining if theinformation or data shared among the members of the supply-chain is trustworthy in collaborative processes. They alsodiscussed various notations and process models for business.

The prototype model was implemented using blockchain andvalidated through business processes [70]. To execute busi-ness transactions securely, a model called business processmanagement(BPM) was proposed by Guerreiro [71]. Thismodel used the blockchain technology and an EnterpriseOperating System (EOS). The risk involved in the securedexecution of business transactions was eliminated in the pro-posed model by increasing trust, authenticity, robustness, andtraceability against fraud.

An Agricultural Supply Chain (ASC) system was pre-sented in [68] by Leng et al. This system was completelydependent on the double chain architecture which accelerated

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TABLE 4. Supply chain management with blockchain technology.

the efficiency of the blockchain in the ASC. The authors sug-gested solutions to provide adaptive rent-seeking and match-ing mechanisms for public service platform. These solutionsensured transparency, security and privacy of the enterpriseinformation. Moreover, the use of public service platform andthe efficiency of the system were also improved. The pro-posed system had drawbacks mainly in terms of performanceand increased size of the blockchain.

Mao [72] proposed a credit evaluation system which wasbased on public blockchains. This system helped in themanagement and supervision especially for the food-supplychain to improve the effectiveness. In particular, the authorsgathered the credit evaluation text from the traders by smartcontracts on the blockchain, and then analyzed the text usinga deep learning method named Long Short Term Memory(LSTM). Though the authors claimed the effectiveness oftheir method, but they did not consider the overall systemcosts and benefits. Due to these issues, they can not providea standard methodology to design, develop, and validate theoverall blockchain solution. Later on, the authors in [62]concentrated on one of the most critical issues, i.e, the imple-mentation of the blockchain in the supply-chain with the needof including all the different actors. Moreover, the sharing ofinformation along the entire blockchain could lead to inertiain adopting the solution. For this reason, a correct imple-mentation of the blockchain technology in the supply-chainmust starts from an analysis of the needs and the objectivesof the different actors involved. Keeping this objective inmind, the authors created a business model capable of high-lighting the returns in terms of both economic and customersatisfaction.

Kshetri [65] presented an early evidence of linking theuse of the blockchain in supply-chain activities to increasetransparency and accountability. They also examined howthe blockchain is likely to affect the key SPM objectivessuch as cost, quality, speed, dependability, risk reduction,sustainability, and flexibility.

A public blockchain of the agricultural supply-chain sys-tem based on the double chain architecture was proposed byLeng et al. [68]. In this system, the authors mainly focused onthe dual chain structure and its storage mode, resource rent-seeking and matching mechanism, and consensus algorithm.The results exhibited that the double chain structure basedagricultural supply-chain could take care of the openness andsecurity of transaction information and the privacy of theenterprise information. It also had the ability to complete rent-seeking andmatching of resources self-adaptively. Therefore,the proposed architecture greatly enhanced the credibility ofthe public service platform and the overall efficiency of thesystem.

Table 4 provides the detailed relative comparison of theexisting blockchain based approaches for supply-chain &logistics systems using the parameters such as the trans-parency, reliability, security, architecture, consensus mecha-nism, traceability system, framework, pros, and cons of theexisting approaches.

B. ENERGY DOMAINEnergy is the actual base of our existence. It is essentialto the lives of humans and all other living organisms onearth. Humans and all the living creatures on the earth cannotsurvive in the absence of energy. We use energy for a vari-

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TABLE 5. Energy applications with blockchain technology.

ety of purposes like food, Communication, transportation,heating/cooling, and lighting. All conventional transportationmeans such as trains, buses, automobiles, and airplanes workon energy, which is derived from electricity, and fossil fuels.Our food is grown with considerable energy expenditure,and its storage and transportation also consume energy. Ourmodes of communication, such as internet and telephones runon electricity. Sun is the major source of all energies availableon the earth. It is very important to select the type of energyresources carefully, because it can lead to adverse effects onthe environment such as global warming, and pollution.

Energy resources are classified into two categories: non-renewable resources and renewable resources. The exponen-tial use of non-renewable resources may lead to rare existenceof these resources. So, it is very important to manage themwith intense care and proper management. Proper usage ofnon-renewable resources has become mandatory due to theirscarcity. The use of renewable energy sources such as solarpower or wind can leverage energy efficiency to maintainthe ecosystem [84]. Hence nowadays, most of the countriesencourage their people to use renewable energy resources forthe growth of their industries, agriculture, and transportation.

1) DISTRIBUTED ENERGY SYSTEMDistributed Energy System (DES) is one of the importantconcepts in the energy domain. DES generates power ondecentralized levels. It also enhances the overall throughputquality of the energy system by considering the parameterslike energy production, economics, and environment. DESovercomes the many challenges of the centralized energynetwork systems and maximizes the use of renewable sourcesfor a distributed generation of energy. With the use of IoT,Artificial Intelligence (AI) and Machine Learning (ML),DES has made it quite simple to monitor and maintain dataand records. With its due popularity, DES has brought a

significant improvement in the sector of electric utility whichgives the ambit for the expansion of renewables empowereddigital services.

Nowadays, there are many evolving technologies are avail-able which can simply convert energy into a digital. Usingsuch technologies, we can keep a closer watch on a DESwhich is placed at a remote location. Moreover, the IoT playsa vital role in energy transitions and hence is adopted by DES.The presence of the blockchain and IoT facilitates a widerange of services enabled by the DES. In fact, the blockchaintechnology and IoT get the credit of giving a digital look toDES for energy transitions. The application of the blockchainin DES helps it to have a trustworthy data flow among emis-sion traders, energy traders, energy producers, and operatingstaff. Digital DES offers a high level of security, and scope fordecision making and processing based on the real conditions.The blockchain also helps to generate energy efficiently.There are numerous scenarios where energy sharing DESis more appropriate and better than the conventional DES.The Blockchain technology provides a decentralized energytrading platform for the imports and exports of energy, whichcanmonitor electricity flows and aid tomaintain them by timestamping [77].

DES is a truly intelligent system that provides a broadrange of services in various stages such as the operatingstage, development phase, energy trading stage, and energymetering phase. Authors of [77] did not highlight the issueslike old grid infrastructure, reliability, energy loss, stability,environmental concerns, obsolete design, less efficiency intransmission, generation and distribution.

Truby [76] described how to improve environmentallysustainable development of the blockchain applications.Their study was based on the fiscal policy and regulatoryapproaches for the digital currencies [54]. This researchled them towards the proposal and establishment of some

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new policy tools and legal tools which are required for theconsumption of energy with the usage of blockchain tech-nologies. Authors [76] also came up with the fiscal policyfor the same purpose and suggested the use of the blockchaintechnology.

2) MICROGRIDSmall-scale power stations which have their own produc-tion as well as storage resources are known as microgrids.A microgrid always has definite boundaries. It can be per-ceived as a tiny cluster of electricity users who have a localsource of electricity supply. The clusters are connected to anational grid which operates independently. If a microgrid isconnected to the main grid, it is known as a hybrid microgrid.Decentralized Energy Resources (DER) such as diesel gen-erators, PV Panels and a group of loads are integrated withEnergy Storage Systems (ESS) like flywheels and batteriesto form a microgrid and provide electricity [73].

Decentralized flexibility created by renewable energysources can be easily reduced by approach, i.e, microgrids.Goranović et al. [85] suggested the two approaches forcontrolling electric grids, i.e, decentralized and centralizedmonitoring systems. In the centralized monitoring systems,an operator is accountable to execute the whole system. Theuse of centralized control devices needs expensive infrastruc-ture. Centralized systems measure and process the data andthen set proper proceeding in the circumstances. Multiplepoints can be made available in the system through whichinformation is sent and received by the communication chan-nels and centralized control devices. The major drawbackin this mechanism is that the use of multiple points in thecentralized system increases the probability of system failure.This limitation of the centralized system can be conquered bythe decentralized system where each device independentlycontrols itself. The decentralized system also improves thefault tolerance and communication speed of the system. Thedecentralized blockchain is precisely suitable to implementbusiness processes in microgrids using smart contracts [86].Authors of this paper also provided a few examples of theblockchain projects for microgrids with certain technicalparameters. The type of the blockchain, consensus mecha-nism and availability of parts required in the hardware devel-opment or open source were the technical parameters con-sidered by the authors for describing the example microgridprojects [85]. A brief summary of these projects is givenbelow.I) PowerLedger: It was a blockchain based market clear-

ing & trading mechanism [87]. It included the useof private Ethereum with Proof-of-Work (PoW) andpublic eco-chain that employed proof-of-Stack (PoS).This was an open source project.

II) Share&Charge: It was a group of Electric Based Vehi-cle (EBV) charging stations [88] which used publicEthereum and consensus algorithm as a PoW. Ownerscan register his or her station to fix charging tariffs.Any charging station could be integrated and combined

to Share&Charge network [73] through Share&Chargemodule.

III) NRGcoin: This framework was based on energy cryp-tocurrency developed through a smart contract. It oper-ated through gateways which simply calculated theflow of electricity and communicated through a smartcontract.

IV) GrunStromJeton: It was an Ethereum based conceptualframework developed to verify the actual use of elec-tricity. It used PoA as a consensus mechanism.

V) SolarCoin: It was developed to enhance the mass pro-duction of solar energy. Due to the lengthy setup pro-cess, customers usually do not go for solar installations.This project aimed at eliminating this problem by giv-ing rewards to buyers. One solarCoin was given as areward per producedMWh. It used PoW as a consensusmechanism and bitcoin as cryptocurrency.

VI) GridSingulartiy: It was a decentralized data exchangeframework specially designed for energy sector empha-sizing on electricity, water, gas, and heat. In this plat-form, PoA and PoW were the consensus algorithmswhich used public Ethereum.

VII) Electron: It is a Company which works in the energysector and provides Ethereum based better solutions.

Apart from the above projects, people are currently work-ing on numerous projects in the same domain. Table 5provides the detailed relative comparison of the existingblockchain-based approaches in the energy domain usingparameters such as the objective, transparency, reliability,security, architecture, consensus mechanism, traceability sys-tem, framework, pros, and cons of the existing approaches.

C. DIGITAL CONTENT DISTRIBUTIONSince the commercialization of the internet in 1994,delivery services of digital content has been increased expo-nentially. [89]. Delivery systems are mainly of two types:non-protected and protected delivery systems. Generally, dig-ital content is protected using the conventional encryptionmechanism. Different encryption mechanisms use differentways to generate, propagate, and maintain the keys anddecrypt the encrypted content with keys. Traditional systemssuch as Conditional Access System and Digital Rights Man-agement (DRM) are popular for protecting digital content, butface some major issues like network attacks, stealing of keys,and pirate attacking.

To overcome the drawbacks of the conventional centralizedsystem, the authors of [89] proposed a decentralized digitalcontent distribution system based on the blockchain. In thisdigital content system, the owner of the actual content couldsupervise and control the security as well as simplicity. Theuse of the mining techniques ensured that the addition of eachtype of transaction to the blockchain. PoW was used as theconsensus mechanism to guarantee the security and privacyof the transactions stored in the blockchain. Due to some openissues such as pirate attacking, it was not possible to entirelycontrol this mechanism.

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TABLE 6. Distribution with blockchain technology.

Table 6 provides the detailed relative comparison of theexisting blockchain-based approaches in the digital contentdistribution domain using parameters such as the objective,transparency, reliability, security, architecture, consensusmechanism, traceability system, framework, immutability ofthe blockchain, advantages, and drawbacks of the existingapproaches.

D. TOURSISM AND HOSPITALITY INDUSTRYTourism is the process of spending time to outside station, i.e,away from our home for purposes such as business purpose,personal purpose, relaxation and pleasure. Serving travelersis the major functionality of the tourism Industry. Nowadays,most of the people search and book their traveling tickets,food, and lodging online with the use of the internet. There-fore, the worldwide usage of the internet, the tourism and hos-pitality industry has witnessed rapid changes. In this digitalworld, many tourism companies like Expedia Group, BCDTravel, Uber, Ola, and AirBnb have replaced their traditionalbusiness models by Consumer-to-Consumer (C2C) models toachieve transparency and security in transactions. There is ahuge demand for innovative platforms in the tourism industry,which can integrate technology, money, and knowledge.

TUI and many other companies have already started usingthe blockchain for implementing the functionalities likebooking tickets and making payments. Many companies likeExpedia, CheapAir,Webjet, and One Shot Hotels use bitcoinsfor the travel purpose, i.e, to book and reserve tickets. Digitalcurrencies simply integrate with smart contracts which haveenough potential to develop highly disruptive technologiesfor the tourism industry. Authors of [99] suggested threeprepositions which helped to highlight some open issues inthe tourism industry. These prepositions mainly focus on thecustomer’s point of view and market implementation’s pointof view. The prepositions include: I) New Type of evaluationas well as review techniques which can build trustworthy

systems for rating purpose. II) The extensive adoption of dig-ital cryptocurrencies for C2C markets. III) Use of blockchainleads to increase of disintermediation in the tourism industry.In the case study part of our paper, we try to highlight theabove issues in the tourism industry. The detailed explanationof the same is available in the case studies section.

E. SMART HEALTHCAREHealth is the most valuable asset of any nation. In traditionalhealthcare, all patient related data is stored in a centralizedway and therefore, it is not advisable to give access of data toany untrusted third party. Moreover, the privacy and securityof patient information must be maintained as it is vulnerableto a variety of attacks [121]. A centralized architecture cannotfulfill these requirements completely. Hence, smart health-care is introduced to deal with the above mention issues inconventional healthcare systems. Smart healthcare focuses onmonitoring and diagnosing patients’ health remotely throughwireless communication channels. It collects the necessaryinformation of various patients through heterogeneous wear-able devices and sensors. Enormous data is collected for alarge number of patients. It is a big issue to analyze andstore this data in a secured manner. These data should alsobe shared securely among trusted parties such as hospitals,patients, doctors, and medical stores. Secure communicationof these data is pivotal as it affects important decisions suchas planning of new services in the hospital, recommend-ing doctors, analyzing symptoms of different diseases orhealth issues, and improving the overall system to make itintelligent.

Table 7 provides a detailed relative comparison of the state-of-the-art healthcare security standards used for smart health-care. These standards are compared using the parameterssuch as access management, security maturity, reduction incost and complexity, and improvement in healthcare compli-ance. For the various medical research activities, deciding

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TABLE 7. Worldwide State-of-the-art Healthcare Security Standards.

treatments, and analyzing symptoms of diseases, patients’data is required to be shared periodically. Traditional accesscontrol policies are not secured enough to share highly sen-sitive patient records from one party to another. Moreover,in most of the cases, patients do not share their medicalhistory with the doctors. In case of a medical emergency,medical records of the patient are necessary, but the same isnot available due to poor record maintenance. All the above-mentioned issues can be solved by smart healthcare usingElectronic Health Records (EHR). Though smart healthcareis capable of solving the major issues in the healthcare indus-try, there are some challenges to be addressed. Access controlpolicy for EHR, privacy, security, and availability, are openissues in smart healthcare. The blockchain technology can beused to get solutions to these issues. In fact, the blockchainhas the potential to support smart healthcare through the dis-tributed ledger among various users such as patients, doctors,medical stores, and insurance agencies.

Authors of [100] proposed a blockchain-based intelligentapplication commonly known as Healthcare Data Gateway(HDG). Patients can securely share and control their datathrough a secured data gateway. It processes and managespatients’ data without any concern about the third party. HDGconsists of three layers namely Data Usage, Data Manage-ment, and Storage. Entities that use healthcare data suchas physicians, companies, government, and researchers areassociated with the data usage layer. In the data managementlayer, HDGs independently connected to each other. Thislayer also manages all types of metadata such as patients’data, schemas, and indices information. The storage layer pre-vents the attacks on integrity and confidentiality by providingsecure and scalable storage for the healthcare system.

Azaria et al. [101] developed a decentralized MedRecmodel which was a novel data management system for largescale EHR. In this proposal, confidentiality, authentication,and accountability of health records were maintained via acomprehensive log using blockchain-based MedRec model.

Authors of [102] developed a new architecture for the med-ical field especially for precision medicine and clinical trial.This architecture had four new components: I) Blockchain-based parallel and distributed computing component to

examine parallel computing using data analytics, II) Trust-worthy information sharing component to enable a trust-worthy medical data system for collaborative research, III)Application data management component to maintain theintegrity of data, and to integrate dissimilarity of medicaldata, IV) Verifiable unknown identity management compo-nent for maintaining identity privacy for IoT, person anddevices as well as secured access to patient-centric medicinedata.

Authors of [103] developed a reliable healthcare systemon the basis of Pervasive Social Network (PSN) using dif-ferent protocols. The first protocol was an extended versionof IEEE 802.15.6 display authenticated association. It wasused to establish secured links by means of unbalancedcomputational requirements for mobile devices and resource-restricted sensor nodes. Health data was shared between PSNnodes with the help of the second protocol which was basedon the help blockchain technique. The authors examined theproposed protocols and other factors for evaluating the per-formance. The proposed system demonstrated the possibilityof using the blockchain technology, especially for PSN-basedapplications. Though the performance of the proposed systemwas not measured on a mass-scale healthcare system, i.e,PSN-based system, as stated by the authors, the performanceof the proposed system could be improved in terms of trans-port and monitoring of the environment.

Authors of [104] discussed a viewpoint on the blockchainfounded healthcare data management system. They alsobestowed a framework for sharing, managing EMR, espe-cially for the patients suffering from cancer. The proposedarchitecture included a user interface as well as the backend.The backend comprised of the components such as member-ship services, certification authority, clusters of nodes, loadbalancer, and distinct cloud storages for patients’ certificatesand data. This work substantially reduced turnaround timefor EMR sharing, increased the power of decision making forthe sake of medical care, and also reduced the overall systemcost. The proposed system also guaranteed the availability,security, privacy, and access control across the EMR data.

Xia et al. [105] developed a trustworthy blockchain-based system called ‘‘MeDShare’’ especially to handle the

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TABLE 8. State-of-the-art blockchain based approaches to secure healthcare 4.0.

challenges of maintaining voluminous medical informationon a cloud using big data for data provenance. Activities suchas sharing and transition of information were recorded andstored in a tamper-proof manner. The authors also comparedthe performance of ‘‘MeDShare’’ with the existing methodsof data sharing and came up with the conclusion that auditingand data provenance could be achieved by cloud serviceproviders through theMeDShare. Risk factors of data privacywere also minimized through the proposed system, but issuessuch as scalability, data interoperability and key manage-ment were not highlighted in the paper. Rifi et al. [106]discussed the important problems such as scalability andinteroperability, and highlighted the advantages of includ-ing the blockchain technology for medical data exchange toachieve the best performance.

Liang et al. [107] developed a user-driven health infor-mation sharing solution to handle the issues of privacy andidentity management. To address these issues, they suggestedthe use of the channel formation scheme andmembership ser-vice of the blockchain. The authors also proposed a mobile-controlled system based on hyperledger fabric with the useof permissioned blockchains. The proposed work majorlyfocused on the validation of the network nodes, and thepreservation of healthcare-related data.

A new blockchain-based information model was proposedby Magyar et al. [108]. This model basically integrated com-plex Electronic Healthcare Data (EHD). The implementationof a decentralized and purely expendable network was possi-ble due to the use of cryptographic tools and the blockchain.The model was developed by considering the basic beliefs

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of the HIPAA regulation existing in America. The proposedwork ensured information availability and resolved the issueof data privacy at the same time, although the authors did notprovide any algorithm or method to handle the EHD relatedissues such as integrity, security, portable user-owned data,and interoperability.

Jiang et al. [110] focused on the fact that everyday hugenumber of healthcare-related data are produced by individ-uals and hospitals. This data is very beneficial in the med-ical industry for various purposes. It is quite challengingand important to store this data securely. It is must to havemechanisms to maintain confidentiality, privacy and integrityof data. By keeping these requirements in mind, the authorsdeveloped a BLOCkchain-based model for Healthcare Infor-mation Exchange(BlocHIE), which resolved the above-listedissues. In this mechanism, they considered two types ofhealthcare-related data - personal healthcare related data andelectronic medical records. They performed analysis of vari-ous ways and requirements to share and store the healthcarerelated data. The framework was based on two blockchainswhich were loosely-coupled and one was an EMR-chain andthe other was a data-chain. Different methods and techniquesof chain verification, as well as storage, were integrated toensure authentication and privacy. The authors also devel-oped two transaction packaging algorithms such as TP&FAIRand FAIR-FIRST for PHRD-Chain and EMRChain respec-tively, which increased the fairness, efficiency, and systemthroughput among the users. These two packaging algorithmswere evaluated in terms of throughput and fairness using theBlocHIE mechanism. As claimed by the authors, the FAIR-FIRST algorithm increased the fairness and the TP&FAIRalgorithm increased the throughput.

Nowadays the blockchain is being used worldwide in themedical field to maintain and store the healthcare related datasecurely. Theodouli et al. [111] said that this data could beused for further innovation and research in the healthcareindustry. By considering the needs of the healthcare industry,the authors of [111] proposed a design architecture for asystem which can easily secure permission management anddata sharing for the healthcare with the help of the blockchainfeatures. The proposed infrastructure consisted of three lay-ers: Web/cloud platform layer, Cloud middleware layer, andBlockchain network layer. As shown in the paper, this modelcould help to enhance security and integrity to a good extent.This model was also used in the KONFIDO project to verifythe parameters such as interoperability and data exchange.According to the authors, and the proposed model gave addi-tional benefit with respect to workflow automation, patientpseudonymity, accountability, auditing, and data integrity.

Fig 8, gives an idea about the use of blockchain technol-ogy in smart healthcare. Table 8 provides a detailed relativecomparison of the existing blockchain-based approaches forsmart healthcare. Parameters used for this comparison arethe objective, security, architecture, simulation tool or frame-work, hardware, and physical design, benefits and drawbacksof the existing approaches.

FIGURE 8. Blockchain in smart healthcare.

F. SMARTCITYIn smart city implementations, heterogeneous sensors areused by various smart devices and users to collect the requireddata. These data are processed and used in traffic manage-ment, transportation systems, waste management, schools,libraries, water supply networks, community services, andpower plants to improve the performance. There is a grad-ual increase in the number of people living in city areas.Due to increased use of the Internet, big data [129], andIoT, the concept of a smart city has become very popular.To strengthen the development of the smart cities, we needeffectivemechanisms to solve the existing problems related toenergy, transportation, governance, and environment. Someopen issues such as deficient security in IoT, difficulty inmaintenance and upgradation of equipment, maintaining thetrust among the internet users, optimizing the cost of runningdata centers, damage resistance, privacy, and security needto be addressed to deploy smart city projects effectively andefficiently. According to the authors of [128], the blockchaintechnology is the potential of solving all these problems andhence, it is best suited for developing smart city solutions.

As we know, the consumption of energy increases due tourban development. The purpose of the internet is to developan intelligent energy system. Authors in [128]mainly focusedon how the blockchain could help to solve the problems inthe internet, big data, and IoT [15], [16]. In this research,issues such as user’s creditability, the creditability of thedata in the central database, data privacy protection, andprivacy protection of data were addressed. In the proposedwork, the blockchain identified valid IoT nodes and deniedthe system access by malicious nodes. It also maintaineddata privacy in IoT and improved storage and computingabilities with the help of decentralized databases. As shownin the paper, the proposed work effectively prevented variousattacks on the network infrastructure with improved recoverymechanism in big data [130].

Various architectural issues in the network infrastructureof the smart city were discussed by Sharma and Park [126].Due to the exponential rise in information volume as well asthe increase in the count of connected IoT devices, differentissues such as bandwidth, security, latency, and scalabilityemerge in the existing smart city frameworks. To addressthese issues, authors in [126] proposed a hybrid architecture

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FIGURE 9. Framework for smart city.

for a smart city. It was divided into two partitions: edgeand core network through the hybrid architecture scheme.Moreover, this architecture was developed by considering allthe strengths of the distributed as well as centralized archi-tectures. In this paper, the authors also suggested the PoWscheme to strengthen privacy and security. They simulatedthe proposedmodel by evaluating feasibility and performancebased on different performance metrics such as latency, andthroughput. Authors also came up with a software-definednetworking (SDN) and blockchain-based hybrid networkarchitecture, although they did not focus on important param-eters like how to deploy edge nodes, how to enable thecaching technique at edge nodes etc. Due to this research gap,there is a tremendous scope of work in this domain in the nearfuture.

Biswas and Muthukkumarasamy [122] proposed a four-layer security based framework which was developed usingthe decentralized blockchain technology. It was integratedwith smart devices that provided a secure and trustworthycommunication model for a smart city. The proposed frame-work comprised of four layers- the physical layer, commu-nication layer, database layer, and interface layer. In thephysical layer, multiple standards were defined for smartdevices using which data collected could be shared and inte-grated. The blockchain protocols were used to integrate withthe communication layer to provide privacy and security ofthe transmitted data. The authors also suggested that theextensive use of the private ledger could lead to the improve-ment in performance, efficiency, and security for various real-time applications such as smart parking of vehicles, smartcleaning, smart home, and traffic control system in a smartcity [131]. Scalability achieved by this framework was alsoup to the mark. As shown in Fig. 9, the proposed modelhad good features like fault tolerance, reliability, capability,and faster execution of the operation. Due to the use of theblockchain, various smart devices were able to communicatein a distributed environment. The major gap found in thispaper is that the proposed model not missed to focus on someof the important issues like scalability and interoperability ofthe heterogeneous platforms.

Rivera et al. [123] defined a smart city as the use ofinformation technology (IT) to make the life of citizensmore better and comfortable [125]. A smart city is a digitalworld which interconnects various areas such as govern-ment offices, schools, healthcare, colleges, and the economy.Nowadays, the unique identity of users is the biggest concernin business and smart city environments. Many researchersand developers have attempted to develop a reliable tech-nology which can accurately determine the users’ identities.These attempts have used various attributes such as name,address, health status, hobbies, and credit record of the users.The digital identity is significantly important as it plays avital role in security measures for interconnected devices ina smart city. The authors of [125] failed to highlight some ofthe important issues like smart energy, architecture, and SDNbased security in the development of a smart city.

In [124], Liao et al. focused on some important issues ofsmart cities like interoperability and transparency of variousservices. Due to the advancement in technology, fair andtransparent services are demanded by the citizens in a smartcity. Lottery game is an important segment in a smart cityapplication, but it has a deficiency in terms of fairness andtransparency. Therefore, the authors of [124] came up with anoptimal solution to improve the transparency and fairness of alottery system. They designed a blockchain-based transparentlottery system for a smart city. The authors proposed a three-layered blockchain-based lottery system known as FairLottowhich used four lightweight protocols. Closing time, lotterypurchase, initialization, and verifying winning numbers werethe four different lottery stages in the proposed system. Equalpossibility of winning the prize for each and every participantwas guaranteed by this four-layered architecture. FairLottoeffectively ensured transparency and did not store any finan-cial transactions in the blockchain. Due to this, the transac-tional privacy was preserved and fairness and transparencywere achieved in the lottery system. However, there was alack of connectivity and service integration in the lotterysystem. Moreover, the authors also implemented Fairlottosystem in Ethereum, but the results of the numerical analysison the performance were not provided. These two were themajor research gaps in the proposed work.

Table 9 provides a detailed relative comparison of theexisting blockchain-based approaches for smart city applica-tions. We use parameters such as the objective, digital iden-tity, security, architecture, smart energy, smart parking andautomation, smart traffic, green environment, advantages,and drawbacks of the existing approaches for making thiscomparison.

G. BUSINESSThe Blockchain is a decentralized technique used for thesecured exchange of cryptocurrency and financial transac-tions. Each user maintains its distributed ledger which isuseful for validating a new transaction. Bitcoin is amedium ofdigital cryptocurrency that provides transactions in a securedand distributed environment. The group of all executed

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TABLE 9. Smart city development with blockchain technology.

bitcoin transactions performed in the past is called a dis-tributed ledger. After every successful transaction, an authen-tic user has to make changes in the distributed ledger whichis distributed over the network and shared by all users inthe network. As hash functions are used in the formation ofthe blockchain, data integrity, confidentiality, and privacy aremaintained across all the transactions.

Singh and Singh [73] discussed the importance ofblockchain in business, banking, and financial applications.It has enough potential to reorganize the business marketindustry. Use of block-chain reduces the risks, cost, proba-bility of cyber attacks in financial organizations, and preciseauditing of organizations can be achieved. Authors simplydiscussed the use of blockchain in the business applicationis highly desirable and convenient, due to its characteristics.They did not suggest any basic architecture for a businessapplication to overcome the problems of blockchain likeinteroperability and scalability.

Nguyen [132] discussed that sustainable development infinance can be achieved through the inclusion of the securedblockchain. This technology could bring various benefitsfor the existing banking system as well as society. It couldincrease the speed and efficiency of execution, optimize thetransaction time and networks of record keeping, reducethe cost of financial transactions, and improve the probablechances of accessing the financial market. Nowadays, stillthere are no complete legal rules and regulations for cryp-tocurrencies and bitcoins. Hence, the use of the blockchain isa big challenge in the payment industry.

Rimba et al. [133] provided a comparison of cloud ser-vices and blockchains for Business Process Execution (BPE).Based on the experimental results, the authors showed thatthe cost of Ethereum based process execution is higher ascompared to the cost for business process execution on Ama-zon SWF, but authors ignored to formulate a method whichcould estimate the execution cost depending on the model aswell as data collected in the past. Moreover, this paper did notdescribe how to minimize latency and execution cost.

Lundbak and Huth [134] discussed that consensus andtrust could be achieved in a distributed network throughthe blockchain. Thus, many private and governmental sec-tors, central banks, insurance and finance agencies, academic

institutions, and especially some startups in Europe focuson the implementation of the blockchain in their routineoperations. Improper implementation of the blockchain maylead the industrial standards and agendas to non-secured oper-ations. The authors of [134] devised an oligarchic approachto authenticate and secure business processes and data. Theirapproach shared the business data without exposing the sen-sible information and resolved numerous issues of game-theoretic mining but it was not able to prevent uncertainbehavior such as cheating.

The authors of [135] described an algorithm to ensuredata confidentiality in an untrustworthy environment. Thisalgorithm translated the Business Process Execution Lan-guage (BPEL) into a highly confidential smart contract, butthis algorithm did not meet the basic security pillars suchas data integrity, correctness, and authenticity. The imple-mentation of the blockchain may help to resolve the above-mentioned issues.

Johng et al. [136] presented a framework to improvethe trust in business processes using the blockchain. Thisframework mainly focused on issues like transparency andimmutability. It also improved the trust among differentstakeholders. Though the framework was not capable ofresolving issues like traceability, the authors tried to builda process meta-model for supply-chain through the samemechanism.

An end-to-end model for Real Time Gross Settle-ment (RTGS) through hyperledger fabric blockchain platformwas designed by the authors of [137]. The proposed systemmade the payment service more secure and efficient. It used atimestamp algorithm which resolved the problem of gridlockand the risk of privacy. This framework was not generic fordiverse payment services. A more generic platform can bedeveloped through the blockchain technology [138].

Mendling et al. [139] discussed the execution of busi-ness processes beyond organizational boundaries through theblockchain without the inclusion of any trusted third party,although the authors did not explain how to resolve the exist-ing issues such as latency, bandwidth, throughput, and size inthe proposed work.

Table 10 provides a detailed relative comparison ofthe existing blockchain-based approaches for the business

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TABLE 10. Business in blockchain technology.

domain. Parameters used for this comparison are BusinessProcess Service(BPS), trust management, security, architec-ture, consensus mechanism, cost model, monetary policy,pros, and cons of the existing approaches.

H. INTERNET OF THINGSIn the Internet of Things (IoT), various devices are connectedthrough the internet to share useful information via servers forperforming specific tasks or actions in the external environ-ment such as measuring temperature or humidity and movingof shaft. Delivering the right information to the right peopleat the right time is possible through the use of IoT. Varioussensors continuously sense the data and these collected datacan be used for effective decision making. Things connectedto the internet are expected to cross 50 billion in the nearfuture, which is basically an approach of how these variousdevices should be designed and integrated with each other,so as to deliver a service delivery network, which can servethe needs in the future. The architecture of IoT is basicallythe backbone of any application and thus, it should be craftedcarefully considering the needs of the evolution of function-ality, scalability, availability, and maintainability. From thisIoT architecture model, it is very clear to know that securityis an essential factor in all IoT layers as shown in Fig. 10.Nowadays, most of the IoT devices are not fully secured

and can be easily hacked. These devices have restrictednetwork capacity, limited computation power, and smallstorage capacity. Due to these characteristics, such devicesare vulnerable to a variety of attacks as compared tocomputer systems. Samaniego and Deters [141] observedthat the issues of network latency occurred due to cloud-centric IoT systems. To overcome these problems, theydeveloped a software-defined IoT management constructknown as Virtual Resources (VR). Tamper-proof, decentral-ized blockchains have the potential to solve security issues inany IoT Implementation. To use the blockchain as a servicefor the IoT, hosting environment is one of the challenges.

FIGURE 10. IoT architecture model.

Edge devices have limited computational resources as well asbandwidth, thus making fog or cloud as the potential hosts.

The authors of [142] surveyed and categorized someimportant IoT related security challenges and requirements.The same were tabulated and mapped against the existingstate-of-the-art solutions. The authors suggested the integra-tion of the blockchain as a key solver for such challenges andalso outlined the research issues which must be addressedin future, that could provide scalable, reliable, and efficientsecurity solutions for the IoT.

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Singh et al. [143] observed that the current security tech-nologies do not have the potential to secure IoT applicationsfrom various cyber-attacks in the business domain. They alsosuggested three different patterns of the blockchain-basedsecurity model for the IoT. There are various distributedledger protocols suitable for the IoT Implementation such ashyperledger fabric, Ethereum, and Internet of Things Appli-cation (IOTA) [144]. In this paper, the performance of theseprotocols was compared for the development of IoT applica-tions. The authors also presented three different architecturesfor the same. The architectures differ in the position of keystorage and Ethereum blockchain which enhanced the secu-rity and reduced the network traffic. The problem with thesearchitectures was that they were not capable of monitoringthe IoT devices’ transactions automatically.

Huh et al. [145] developed a new way to manage a fewnumbers of IoT devices with the use of Ethereum and com-puting platform. They used three Raspberry Pis, and smart-phones and proposed three smart contracts which used publickeys and signatures to track meter values and save the valuesof light bulbs and air conditioners. Malicious attacks onsmart contracts could be detected and ignored by the com-puting systems of light bulbs and air conditioners. However,the proposed work failed to resolve issues such as Denial ofService (DoS) and synchronization. Moreover, the proposedmechanism considered a small number of IoT devices andthus was unable to implement a full-fledged IoT system formultiple devices.

Liao et al. [146] presented various design issues and anarchitectural approach for the blockchain-based IoT services.Design decisions could be carried out by developers with thehelp of this architecture. Unfortunately, the proposed workfailed to show the adverse effects on architectural attributeslike robustness, efficiency, and security.

Reyna et al. [147] analyzed the major challenges of IoTIntegration such as scalability and storage capacity, dataprivacy and anonymity, and consensus mechanisms. Theyidentified the potential benefits of the blockchain for the IoTand also suggested different topologies for the integration.Some key points to enhance the performance and feasibilityof IoT applications with the help of the blockchain was alsodiscussed in the paper.

Table 11 provides the detailed relative comparison of theexisting blockchain-based approaches for the IoT. This com-parison has been done using parameters such as reliability,encryption, security management, edge computing, architec-ture, consensus mechanism, threat model, framework imple-mentation, advantages, and disadvantages of the existingapproaches.

I. MANUFACTURINGThe process of manufacturing includes several elementssuch as operations management, asset management, intelli-gent manufacturing, planning, the interaction of humans andmachines, performance optimization, performance monitor-ing, and end-to-end operational visibility.

Li et al. [157] stated that the IoT has converted the conven-tional manufacturing processes into a smart manufacturingprocess. The IoT enabled manufacturing is far smarter andefficient than cloud manufacturing, as it speeds up the flowof production especially in the manufacturing plant, man-agement of inventories & warehouses, and observation ofdevelopment cycles by using IoT devices. Due to this, most ofthe manufacturing companies have invested crores of fundsin the implementation of the IoT applications. The use ofthe IoT in the field of manufacturing and logistics will riseto 40 Billion by 2020 [162]. Due to the characteristics ofthe IoT such as greater energy efficiency, predictive main-tenance, higher product quality, reduced downtime, speed,and more informed decisions, it has various applications inthe manufacturing plants [163]. As we know, energy is oneof the largest expenses for manufacturing Industry, energyefficiency must be achieved which can be done through IoTbased smart manufacturing.

The authors of [159] proposed a trusted FabRec prototype,which linked physical devices and various computing nodesthrough a decentralized platform. In this prototype, trans-parency was ensured through audit trails. In the decentral-ized network, the authors developed smart contracts for theautonomous interaction of nodes in the absence of humaninvolvement. The proposed architecture used a proof of con-cept linked with the nodes and physical devices and enabledsmart manufacturing. Cloud-based manufacturing basicallyuse the centralized networks which have problems such assecurity, flexibility, availability, and efficiency.

To resolve such issues, the authors of [157] discussed anddeveloped a blockchain-based distributed network architec-ture known as BVmfg. This architecture had a total five layerswhich improved the trust between the service providers andusers for secured service sharing. The authors evaluated theperformance of BCmfg a case study in which for fifteenend users and five service providers, scalability, and securitywere improved. Later, the authors revised their prototypeand developed a shop floor and machine level data sharingprototype [160]. Authors used a public blockchain for shoplevel and a private blockchain for service providers throughwhich important data is collected and gathered. The new pro-totype was level 2 Point-to-point (P2P) network implementedthrough the blockchain. It handled cloud manufacturing chal-lenges like security and centralization effectively.

The authors of [158] proposed a blockchain and privatecloud based manufacturing four-layer knowledge sharingsystem for Injection Mould Redesign (IMR). This work pro-vided the rules and standards for the secured implementationof the system in a trusted environment. It also provided aknowledge sharing mechanism for the owners through whichtheir data, as well as assets, could be shared securely amongthem. The system used the k- nearest neighbor retrievalmethod which improved the efficiency of the search pro-cess. The proposed model was limited to only some appli-cations and not fully developed for many applications. Theauthors of [161] investigated various industrial requirements

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TABLE 11. Internet of things in blockchain technology.

TABLE 12. Manufacturing with blockchain technology.

such as scalability and adaptability of the network with theimplementation using OMNeT++ network simulator. Theirapproach was efficient up to the first fourteen participatinglines and no uncertainty was identified.

Table 12 provides the detailed relative comparison ofthe existing blockchain-based approaches for manufacturingusing the parameters such as scalability, architecture, secu-rity, simulation/framework, smart contract, pros, and cons ofthe existing approaches.

J. AGRICULTUREIn recent times, various issues related to food safety have beenobserved. Higher use of fertilizers and pesticides on agricul-tural products is the major concern in food safety. Pesticides

and fertilizers residues on various agricultural products havecaused world-wide concern [165]. Due to this, there is a hugedemand for safe agricultural products in the market. To fulfillthis demand, we need secured solutions for handling theperfect tracing andmanagement of the production, wholesale,logistics to retail, production standards, certifications, andbusiness reputation [166].

Hua et al. [164] proposed a blockchain-based agriculturaltracking system, which was basically a decentralized systemin order to solve the trust crisis in the domain of supply-chain. This blockchain-based agriculture platform recordedthe information about the production, storage, transporta-tion, processing, distribution and supply-chain of agriculturalproducts for the third parties like government, insurance

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TABLE 13. Agriculture with blockchain.

companies, customers, and banks. The platform recorded allthe agriculture product related information on the blockchainstructures, as it could involve different users such as com-panies, agencies, banks, or government to work together.By considering the requirements, the authors developed anagricultural traceability system for the same. This systemconsidered the fertilizers, pesticides, companies, seeds, agri-cultural operations, time, and residue testing. According tothe authors, it was a very tedious task to build a platformhaving a uniform structure, which considered all the complexinformation and eliminated the possibility of the redundancyin data. Hence, the authors designed two related structuresespecially for the basic planting information as well as forprovenance records. Planting information included the sourceproduction information in terms of identity, species name,planting-time, company-name, greenhouse number, and geo-graphical location. Provenance records include the detailsabout the agricultural operations in terms of identity, date& time, person, digital-signature, location, operation-type,inputs & memo, and company. The agriculture tracking plat-form consisted of three components- data node, clients andregistration center. The issues in the agriculture system suchas creditability of data and integration the subsystems wereeasily handled by this open data-sharing platform. Due tothis, any participant could view the data uploaded by anyparticipating companies, which was also one of the majoradvantages of this platform.

According to Tian et al. [63], food safety is the major con-cern, especially in China. As China is an agricultural country,the annual demand for vegetables and fruits is approximately730million tons [167]. Due to the huge demand of themarket,traditional agri-food logistics are not capable of handlingthis situation. There are some open challenges in traditionalagri-food logistic systems such as deficiency of funds andmodern equipment, shortfall of a monitorable traceabilitysystem, moderate level of information, and unordered reg-ulatory systems. Therefore, there are massive and frequentbrokedown events of food safety in China. To overcomethe limitations of the traditional agri-food logistic systems,the authors of [63] proposed a blockchain and RFID-basedagri-food supply chain traceability system. This system sig-nificantly improved the quality and safety of food, and alsoreduced the probability of different losses in the conven-tional logistics process. The building process of the systemincluded various stages such as production link, processinglink, warehouse management link, distribution of cold chainlink and sales link. The authors compared and analyzed theproposed traceability system with the traditional traceability

FIGURE 11. A conceptual food traceability systems [167].

systems using various parameters. The authors also discussedthe advantages of using the blockchain and RFID technologyin the proposed system. As stated by the authors, the majoradvantage was that the traceability system totally removedthe necessity of the trusted centralized agencies and provideda data sharing decentralized platform through which all theusers could carry out their respective operations with open-ness, neutrality, transparency, security, and reliability.

Lin et al. [167] developed a blockchain-based traceabilitysystem, especially for food supply-chain. It stored the dataof every node in the food supply-chain and combined allthe information using blockchains. The authors proposed aconceptual framework for agri-food traceability system usingEthereum and blockchain as shown in Fig. 11. In this fig-ure, a user can register with the help of the cryptographickeys and can get the information of the products stored onBigchainDB.

Storage and management of data performed with the helpof BigchainDB. All the users in a system such as producers,retailers, distributors, consumers, processors, and regulatorycould check the information and modify or add the productfromBigchainDB if they are the authentic users of the system.As per the authors, this RFID and blockchain-based modelhad a few limitations such as it did not have any mechanismto ensure whether the raw data collected from sensors wascorrect, whether the data scanned by the RFID tags and

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FIGURE 12. Taxonomy of open issues in Blockchain Applications.

barcodes to scan food tracking is correct, i.e, anyone cantamper the sensor’s data and the absence of the blockchainmethods to detect the same.

Table 13 provides a detailed relative comparison of theexisting blockchain-based approaches for the agriculturedomain. The parameters used for this comparison are trans-parency, reliability, security, architecture, consensus mech-anism, traceability system, framework, advantages, anddisadvantages of the existing approaches.

V. OPEN ISSUES AND CHALLENGESIn this section, we highlight the open issues and challengesin some application domains such as healthcare, IoT, energy,business, smart city, agriculture, energy, and supply-chain &logistics. Fig. 12 gives a detailed taxonomy of the open issuesin the blockchain applications.

A. BLOCKCHAIN DESIGN AND IMPLEMENTATIONCHALLENGESThe future of the blockchain can be decided by its safety,robustness, smart contract, database technology, securitytokens, and changing regulatory environment. However,to achieve the goals, the design and implementation ofthe blockchain need to provide extreme reliability, safety,and scalability which rely on major technologies such asshared ledger, consensus, provenance, immutability, andsmart contract. In this section, we outline the design andimplementation issues faced by the traditional systems andthe possible solutions by the blockchain technology, asshown in Fig. 13.

1) CENTRALIZATIONOne of the major hurdles in the traditional system is itscentralized mechanism. Such systems are larger, more com-plex for organizations in particular. If the centralized systemis getting attacked or compromised, all the data can leadsto a different direction. In this more network delay andhigher computing power required, so the cost is more for

FIGURE 13. Design and Implementation issues of Blockchain.

the server. The central authority having all privileges in thesystem that clears the transactionsmade by the users. It can beeliminated or replaced with the decentralized system, in thatverification is done by the consensus of the different users inthe network.

2) SCALABILITYNowadays, we store all the transactions in the decentralizedblockchain network to validate them. As a result of this,the blockchain becomes heavy and slow. There is a restrictionon the size of each block and time interval required to createa new block. The blockchain can process only 7 to 8 trans-actions in one second, but in real time scenarios, millions oftransactions execute and hence it is impossible to implementa blockchain for a real-time scenario which imposes a chal-lenge of scalability.

3) ESTABLISHING TRUSTIn today’s era, how to establish the trust is the major problemfor everyone because any third party creates major issueswith the ongoing situation or breaches the data and increasesthe redundancy which makes more difficult to trust anyone.In such scenarios, the blockchain can be used to prevent ham-pering and establishing the trust as it uses the cryptographichash for building the blocks and immutable nature of theledger.

4) SECURITYSecurity of important data is the major concern in everyorganization. The security challenges include monitoringthe cloud configuration, impact of attacks, vulnerability ofmobile carriers, unauthorized access, and modification ofdata by intruders. The blockchain technology records thetransactions using blocks which are linked together with thehelp of the cryptographic keys and immutable ledger and

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TABLE 14. Design and implementation challenges of existing system and possible solutions by blockchain.

TABLE 15. Open challenges in Healthcare.

thus, makes it very difficult for attackers to modify or deleteinformation or transactions.

5) COSTUse of different agencies, intermediaries mostly includes var-ious frauds, commission charges, and duplication of product.The blockchain eliminates the need of a third party and there-fore, the transactions can be completed resulting in fewerfees [168]. Smart contracts, a component of the blockchaintechnology are self-executing and stored on the blockchains.Due to the decentralized nature of the system, no one cancontrol these contracts and therefore each involved party cantrust their validity. Because of the high level of automa-tion in this technology, the companies who have adoptedthe blockchain technology, have experienced huge costsavings.

6) TRANSPARENCYDifferent companies have their own policies, regulations,and tracking systems. This leads to a poor connection andless visibility among the customers and business. The dis-tributed nature of the blockchain transactions make thempublic and verifiable by every user in the network with trans-parency [169].

Table 14 provides the detailed relative comparison of thedesign and implementation challenges associated with thetraditional systems and the possible solutions by using theblockchain technology.

B. OPEN CHALLENGES IN HEALTHCARETable 15 provides a detailed relative comparison of the designand implementation challenges in the healthcare domain andthe possible solutions using blockchains.

1) MASTER PATIENT INDICESEvery year the volume of the healthcare related data increasesand often when dealing with the healthcare data, records getmismatched or duplicated. Also, different electronic healthrecords systems have their own data format and data set toenter and execute the data, which raises a need for having astandardized data format. Due to the use of blockchain tech-nology, the data are cryptographically hashed in the ledger.The user could look for the recorded transactions which canhave multiple records or the keys, but with the use of theblockchain technology, all information is linked with singlepatient Ids.

2) PATIENT DATA MANAGEMENTThe Health Insurance Portability and Accountability Act isknown as (HIPAA) controls the patients’ data privacy andmakes the data PHI secured, but the patients need to givetheir medical data to the third parties such as pharmacists,imposing the need of protecting the data. With the use ofthe blockchain, a hash for each patient’s health informa-tion in blocks which contains the patient ids is created.Using the blockchain network API, the disease-related datacan be viewed with respect to the affected patient without

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revealing the patient’s personal information. In the samemanner, a patient can have the privilege to decide who canview or access his data with a specific third party [170].

3) DATA PROVENANCE AND INTEGRITYPatients’ health information, electronic health records, datacollected from IoT, and monitoring systems are maintainedby the medical facilities. Here, the main target is to securethe information and its sharing techniques, authorize health-care facilities and its entities to confirm the correct infor-mation and ensure the proper services. The blockchain ismore useful in such scenarios because of its ability to providedata integrity. The approach of the blockchain is to shareand distribute data publicly with the secured transactions.The technique used by this technology is PoW with timestamping.

4) CLINICAL TRIALSResearchers working in various domains always want theirconfidential information to be stored privately and securelyso that no unauthorized person can breach or modify or stealtheir data. In the blockchain technology, data modificationis impossible with the SHA256 algorithm that creates theunique hash values which are linked together into a chain.The healthcare industry needs to maintain and share theinformation related to clinical trials securely which can onlybe shared with authorized parties such as research sponsorsor regulatory committees. With the blockchains, the data canbe managed or traced with consent within multiple sites, pro-tocols, and systems. Patients having proper access privilegescan also access this information regarding their health issuesand related research.

5) DRUG TRACEABILITYCurrently, the main hurdle in pharmacology is the drug coun-terfeiting. By the survey of the health researchers, it has beenobserved that about 10 to 30 percentage of the drugs in thedeveloping countries are duplicate. The adverse effect of thisis the loss of business and improper usage of fake drugswhich can lead to severe damages to a person’s health. Theuse of the blockchain network across the drug facilities candetect frauds from the drug dealer. All the operations from themanufactures to the suppliers are contained in the blockchainnetwork that enables to trace the whole route of drugs.

6) DATA ENRICHMENTStoring unstructured data can lead to variability, time con-sumption in the search process, the lack of reliability. Dataenrichment is an operation for adding values to increasequality. Health records must be structured, secured, accurate,time-stamped, and easy to read. Following steps are requiredto be executed to organize the data before adding it to theblockchain: Replacing the patient’s identity with the publichash key, making it compliance-ready, adding meta infor-mation and structuring it for computation. Organized dataenables all healthcare providers to access the data efficiently.

C. OPEN CHALLENGES IN INTERNET OF THINGSTable 16 provides the detailed relative comparison of thedesign and implementation challenges in the IoT and possiblesolutions by using blockchains.

1) ARCHITECTUREIoT ecosystems depend upon the centralized network inwhich all the devices are connected in a client-server modelthrough the brokered communication. It uses the cloudserver to authenticate and identify devices. It needs higherprocessing time, computation power and bandwidth. Theblockchain decentralized architecture creates a P2P networkthrough which messaging, file sharing and device coordina-tion becomes easier.

2) SENSORS’ MAINTAINING ISSUESWith the increase in the number of devices used in IoT eachyear, it becomes a very problematic and challenging taskfor the manufacturers or service provides to maintain thesedevices on a daily basis. Moreover, this is a time consumingand high maintenance cost task. The use of blockchain tech-nology in this domain can reduce the cost as well as time.

3) CENTRALIZED DATABASESA centralized database has a restricted computing power andstorage capacity. There is always a large number of nodes toconnect to the server which is a time-consuming task. It isalso difficult to find faulty nodes in this structure. Most ofthe IoT devices connect with the centralized database andcloud network which increases the cost and computationalrequirements. In the distributed blockchain technology, nodeshave minimum connectivity and still, the network remainsreliable and safe. With distributed computing, the utilizationof available computing power is increased for billions oftransactions irrespective of the location of the devices. Thismakes the IoT more reliable and cost-effective.

4) DATA PRIVACY AND SECURITY ISSUESIf the users’ data are stored in a centralized database thenprivacy & security becomes the major concern. Nowadays,to earn profit, various companies store, use and sell user’s datato third parties without the consent of the users. Such actionscompromise the privacy of users’ data. The blockchain tech-nology uses a distributed database structure which storesdata in the encrypted form and thus reduces the risk of datastealing and breach of privacy.

5) DEVICE LEGAL IDENTIFICATINIn the current era, sensor devices used in the IoT applicationsare small in size and have limited computing and storagecapacity. Hence, such devices are vulnerable to physicalattacks such as impersonation or spoofing. The blockchaintechnology uses smart contracts and consensus mechanismwhich boost the proper identity verification of the IoT nodes,

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TABLE 16. Open challenges in IoT.

and eliminates the unauthorized access of the active devicesby unknown users.

D. OPEN CHALLENGES IN BUSINESS1) DATA PRIVACYIn today’s era, data privacy is one of the key challenges inthe business domain, where many systems encounter databreaches, leak of personal information, unauthorized mon-itoring and eavesdropping, breach of access control rights,data stealing and leaking. With the distributed blockchaintechnology, data are stored in an immutable manner havingsecured time-stamping, public audit and consensus, makingthe system robust against privacy issues.

2) BACKUP AND DISASTER RECOVERYStorage and backup of data are very important in any businessapplication. For storing and maintaining large a volume ofdata, more computing power is needed which results in theincrease of the overall cost. Moreover, if data is maintainedon a centralized system, the risk of a single point of failurealso increases. The blockchain mechanism uses decentralizedsystems for the distributed handling of data. A clusteredhierarchy is used for data storage and backup that eliminatesthe probability of losing the data.

3) SMART CONTRACTSThe process of contracting includes bidding, validation, andapproval for enabling the next steps. Execution of a tradi-tional contract may require human intervention which makesthe involvement of a third party as a service. The same isrequired even during disputes and leads to take higher timefor resources consumption, and the high cost of the con-tract. Using blockchains, smart automation is created withouthuman intervention, which eliminates the involvement ofthird party transactions and unnecessary time delays.

4) LETTER OF CREDIT (LC) PAYMENTAn international letter of credit payment requires a purchaserand dealer and they use paper-based letter of credits tomake transactions. In this scenario, each party needs to sendthe necessary documents via post or courier services. Dueto requirement, time and cost involved in the process aremuch higher and not convenient for the exporters. If usedin this domain, the blockchain technology has the poten-tial to eliminate the time delay by providing cost-effective

faster services. The blockchain makes the transactions trans-parent and integrated with the electronic bill of the ledger.

Table 17 provides a detailed relative comparison of thedesign and implementation challenges for business applica-tions and possible solutions by using blockchains.

E. OPEN CHALLENGES IN SMART CITYTable 18 provides a detailed relative comparison of the designand implementation challenges in the smart city domain andthe possible solutions with the blockchain technology.

1) DIGITAL IDENTITYIn the current era, online services need users or clients toprovide personal identification information before availingthe services. All these data are stored without the knowledgeof the owners and can be accessed by third parties. Whenthe decentralized blockchain technology is used to imple-ment online services, digital ids are created for all the users.These ids along with digital watermarking techniques areused while executing user transactions. This is how users’data can be stored, maintained and controlled in the permis-sioned network having access rights only with the individualusers.

2) TRANSPORTATION MANAGEMENTThe transportation business is very popular these days toprovide routine services to a large number of customers.Providing necessary services to the customers is quite costly.The involvement of third parties in providing services maylead to the breach of privacy of users’ personal data as wellas an increase in the cost of availing services. A decentralizedblockchain network can handle all these issues effectivelyand efficiently by enabling a P2P platform for transportationservices.

3) EDUCATIONIn today’s world, education institutes either private or public,do not provide the exact records to the government. That iswhy the government cannot check or help for literacy targets.With the inclusion of blockchain technology, educationalrecords can be made available via an automated consentmechanism. This solution makes the information redundantand the same can be integrated with the government popu-lation registry so that it can handle all the literacy targets incountry’s population.

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TABLE 17. Open challenges in business.

TABLE 18. Open challenges in smart city.

TABLE 19. Open challenges in Agriculture.

4) LAND USETraditional registration of land or property is a very timeconsuming and costly process. The blockchain technologycan eliminate the hurdles associated with this conventionalprocess by creating a digital process of automated propertyregistration. This solution increases the transparency and trustwithin the system and improves the economy. The newerdevelopment of smart cities combines the blockchain basedtechnology for a number of processes such as land and prop-erty registry, getting approvals, generating inspection reportsand recording the certificates.

F. OPEN CHALLANGES IN AGRICULTURETable 19 provides the detailed relative comparison of thedesign and implementation challenges in the agriculturedomain and the possible solutions using blockchains.

1) OUTDATED RECORD-KEEPINGIn agriculture, all the information regarding foods, farmers,seller-buyer information are very outdated and not availableto all the users. So, its very difficult to process the dataand conduct market analysis. With the usage of blockchainnetwork all the participants have the access of all record andtransactions in trustworthy and secure manner.

2) TRACEABILITY / TRANSPARENCYThe second open challenge in agriculture is traceability,which focus on the origin of the foods and its quality. But, itsvery difficult to find original and genuine products or foods

in supply chain. Blockchain based sensor tracking system isa viable possible solution to eliminate the aforementionedissue.

3) TRANSACTION COST AND MARKET ACCESSSome times small scale farmers are not getting the wholemarket access in agriculture. Thus, the farmers compromisedwith higher cost with limited access to the market. With thehelp of distributed ledger technology of blockchain network,all the data are available and easily access to the every marketon the network, which helps the all the farmers to connectswith market and also to built trust.

G. OPEN CHALLENGES IN ENERGYTable 20 provides the detailed relative comparison of thedesign and implementation challenges in the energy domainand the possible solutions based on the blockchains.

1) ENERGY AND ENVIRONMENTIn today’s scenario, we don’t have a smart grid like infras-tructure, and the use of the normal infrastructures makesthe third party intermediary problems such as VAT frauds,security issues, high cost, and carbon emission which canlead the environment to a very worse condition. With theuse of blockchain technology, the development of the smartgrid energy infrastructure is possible through which eachcustomer can get emission allowance criteria for the safetyof the environment. All kind of tracking and monitoring of

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TABLE 20. Open challenges in energy.

energymakes it easier to build and sustain a healthy and greenenvironment on the earth.

2) INEQUALITYIn the current scenario, retailers don’t have the grid infrastruc-ture. So, the energy providers enable middlemen to monitorthe electric meters and put extra burden on the customersto cover the cost of the middlemen and earn high profits.The blockchain technology helps to eliminate the middlemenenergy retailers so that the consumers can trade the energyand also buy it, directly from the smart grid. It has beenobserved that the consumers can reduce the energy bill by38%.

3) PEER-TO-PEER TRADINGEnergy trading has involved intermediaries or brokers so far.They charge their fees for every trading process and act asa link between energy generators and consumers. Energytrading takes place at the power exchanges and over thecounters. The blockchain P2P network created in the smartgrid infrastructure helps directly exchange the energy to oneanother without involving brokers and paying them unnec-essary costs. The overall process becomes cost-effective andeasy for customers.

4) ENERGY METERSCurrently, the use on energy meters creates dependency onmiddlemenmonitoring. It also increases the amount of billingand makes the overall process tedious. Smart meters can beused for quick implementation of the process and monitorthe correct energy usage. This eliminates the dependencyof meter monitoring by middlemen at a great extent. Theusers can avail the required load and power with the use ofblockchain-based microgrids energy.

H. OPEN CHALLENGES IN SUPPLY-CHAIN & LOGISTICS1) COUNTERFEITINGIn today’s world, every industry has issues of counterfeitingof products and drugs. This creates issues like poor customersatisfaction with quality, unverifiable products or fake prod-ucts. All thesemake the overall trust and reputation of compa-nies or manufactures to go down. The blockchain technologylessens the distance between customers and companies andmakes the processes more transparent. It stores tamper proof

tracking history of the products which makes it difficult tocounterfeit the products.

2) AUTHENTICITYIn today’s world, users rely on the documents to check prod-ucts’ or services’ validity and originality. But such documentscan easily be tempered. The blockchain technology providesa secure way to maintain the information about the supplychain to avoid any kind of modification or breaching of data.This technology enables the clients and suppliers to trace theorigin as well as movements of the products. With the useof RFID tags attached to the vehicles, it becomes possible totrace the products along with timestamps.

3) PROVENANCE TRACKINGEvery industry and company has dependencies on the supplychains. It is very difficult to track every record in transiteven in multinational companies. The need for transparencyleads to the increased cost and clients’ relational issues whichcan weaken the brand or company value. A blockchain-basedsupply chain can maintain all the necessary records and theirtracking details easily with the help of the embedded sensors.This kind of precise tracking can help to identify any fraudthat occurs anywhere in the supply-chain.

4) INEFFICIENCYAlthough contemporary supply-chains can handle the com-plexities of manufacturing processes, they are still extremelyslow, expensive, and inefficient. When each supplier andmanufacturer have their own infrastructure, tracking productsin real time is difficult in a fragmented system. Productdelivery delays are usually caused by the lack of access to up-to-date data. This can be mitigated using the blockchain tech-nology, which increases the supply-chain efficiency whilespeeding up the time to market. Table 21 provides the detailedrelative comparison of the design and implementation chal-lenges in the supply chain and logistics and the possiblesolutions based on the blockchain.

VI. CASE STUDIESIn order to demonstrate the use of blockchains, we havetried to implement the blockchain technology for two dif-ferent applications: smart farming and tourism & hospi-tality. The blockchain is one of the greatest inventions ofthis decade and it has taken the whole world by a storm.Nowadays, the blockchain has become a popular technol-

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TABLE 21. Open challenges in supply-chain & logistics.

FIGURE 14. A blockchain based smart farming.

ogy due to its properties such as decentralization, improvedsecurity, replication, irreversibility, time-stamping and cryp-tography. In this paper, we have discussed the use of theblockchain technology for a variety of applications such assmart farming, smart healthcare, supply chain & logistics,energy sector, IoT, smart city, business, manufacturing, agri-culture, and tourism & hospitality. We have also discussedvarious open issues and challenges associated with differentapplications.

A. SMART FARMINGIn this case study, we provide insights into the currentissues associated with smart farming and how they can beresolved by implementing the blockchain mechanism. Here,we present blockchain-based smart farming and mentionedrole & functionality of different users in smart farming.

In smart farming, various issues related to food safety, foodintegrity, transaction cost, and food traceability need to beconsidered. Extensive use of fertilizers and pesticides on agri-cultural products is the major concern in food safety. Pesti-cides and fertilizers residues on various agricultural productshave drawn the attention of many countries. [165]. This hasleveraged the demand for safe agricultural products in themarket. To handle this demand, we need a perfect tracingand management system for ensuring food safety during eachprocess of production and supply [166].

All these issues in smart farming can be handled withthe help of the proposed architecture shown in Fig. 14.In this architecture, different stakeholders such as farmers,crop insurance agencies, feed manufacturers, food producers,

FIGURE 15. A blockchain based tourism framework

food manufacturers, retailers, and consumers are considered.Farmers have various functionalities such as farm manage-ment through the analysis of soil/crop health, crop-livestockmanagement through agricultural robots, financial servicesmanagement based on the entities like transaction costs,the safety of crops by sensors and insurance agencies. Feedmanufacturers take the raw data from the oil-seed-crusher andmineral suppliers. They provide inputs to the food processor,through which the food is manufactured, and then sent to thecustomer across the chain of the food distributors & retailers.To maintain the food safety, transparency & food traceabilityand minimum transaction cost, our proposed blockchain-based architecture uses a distributed network which estab-lishes and maintains all the transactions in a secured manner.

B. TOURISM & HOSPITALITYIn this case study, we highlight the current issues inthe tourism industry and show how they can be resolvedby implementing the blockchain mechanism. We presenta case study that follows the process model shownin Fig. 15 Recently, many tourism companies like ExpediaGroup, BCD Travel, Uber, Ola, and AirBnb have replacedtheir conventional business models by C2Cmodels to achievetransparency and security in transactions. There is a hugedemand for innovative platforms in the tourism industryto integrate technology, money, and knowledge. There aremany companies like TUI which has already started usingblockchains for ticket booking transactions. Many companieslike Expedia, CheapAir, Webjet, and One Shot Hotels havestarted using bitcoins for their transactions. Digital currenciessimply integrate with the smart contracts which have enoughpotential to develop highly disruptive technologies for the

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tourism industry. Generally, customers take the help of onlinereviews of different tourism products to make a decision.They think that all the reviews of real travelers are honestand true, but actually, most of the tourism & hospitalityindustry players, (i.e. Hotels, Travel agencies, or restaurants)use centralized platforms to store and maintain these reviews.Through such centralized storage platforms, user reviewscan be manipulated and modified very easily by differentagencies for their own profit.

There is a frequent involvement in the exchange of moneyin the tourism industry across the country to another partywhere they do not have any past business relationship. Forsuch exchanges, customers generally take the help of thetrusted third parties. Every time, a trusted third party triesto maintain a secured exchange of money. For providing thisservice, the trusted third party takes a commission. The needof involving third parties in the transactions can be avoided bythe inclusion of cryptocurrencies in the blockchain technol-ogy for the exchange of money. We can create a new platformfor C2C transactions in markets for tourism products. So,in our case study, we have suggested the use of a blockchain-based decentralized online customer review system to resolvethe above issues. All the current issues in the tourism industrycould be resolved with the help of our proposed architecture.In this architecture, users, travel agencies and hotels are thedifferent categories of tourism industry users. Here, we usethe blockchain decentralized network and cryptocurrenciesthrough which the users can book tickets. Thus, the trustedthird parties and commission charges by them can be avoided.All the transactions are maintained through blocks withunique identities which eliminates the creation of duplicateor fake online reviews.

VII. CONCLUSIONIn this paper, we provide insights to the readers about theimportance of the blockchain technology for various smartapplications, where security remains paramount. This sur-vey is divided into five parts. The first part discusses thetraditional security systems, background, and history of theblockchains. The second part describes the basic architec-ture of the blockchain technology, including the verificationof each transaction in the distributed network which makesa permanent, verified and unalterable nature of ledger forthe information or data. Moreover, the blockchain referencearchitecture which consists of three different networks suchas public network, cloud network and enterprise network. TheThird part of our paper focuses on the real-time deploymentof the blockchain for various applications such as smarthealthcare, smart farming, supply-chain& logistics, business,tourism& hospitality, energy, agriculture, digital content dis-tribution, smart city, IoT, and manufacturing which are alsoconsidered in the survey part of the paper. The fourth partemphasizes on the open issues and challenges in Industry4.0-based smart applications and suggests some blockchainbased solutions for those applications. Finally, to demon-strate the suitability of the blockchain technology for smart

applications, the last part of our paper illustrates case studieson two application domains: smart farming, and tourism &hospitality. We plan to explore the feasibility of developinga blockchain-based infrastructure for precision agriculture infuture.

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UMESH BODKHE is currently pursuing the Ph.D.degree with Nirma University, Ahmedabad, India.He is also working as an Assistant Professor withthe Computer Science and Engineering Depart-ment, Institute of Technology, Nirma University.His current research interests include networksecurity and blockchain technology. He is a Life-time Member of ISTE.

SUDEEP TANWAR (Member, IEEE) receivedthe B.Tech. degree from Kurukshetra Univer-sity, India, in 2002, the M.Tech. degree (Hons.)from Guru Gobind Singh Indraprastha Univer-sity, Delhi, India, in 2009, and the Ph.D. degreewith specialization in wireless sensor network,in 2016. He is currently an Associate Profes-sor with the Computer Science and EngineeringDepartment, Institute of Technology, Nirma Uni-versity, Ahmedabad, Gujarat, India. He is also a

Visiting Professor with Jan Wyzykowski University, Polkowice, Poland,and the University of Pitesti, Pitesti, Romania. He has authored or coau-thored more than 130 technical research articles published in leading jour-nals and conferences from the IEEE, Elsevier, Springer, and Wiley. Someof his research findings are published in top cited journals, such as theIEEE TRANSACTIONS ON NETWORK SCIENCE AND ENGINEERING (TNSE), the IEEETRANSACTIONS ON VEHICULAR TECHNOLOGY (TVT), the IEEE TRANSACTIONS

ON INDUSTRIAL INFORMATICS, Computer Communications, Applied Soft Com-puting, the Journal of Network and Computer Application, Pervasive andMobile Computing, the International Journal of Communication Systems,Telecommunication Systems,Computers and Electrical Engineering, and theIEEE SYSTEMS JOURNAL. He has also published six edited/authored bookswith International/National Publishers, such as IET and Springer. His cur-rent interests include wireless sensor networks, fog computing, smart grid,the IoT, and Blockchain technology. He has guided many students leadingto M.E./M.Tech., and guiding students leading to Ph.D. He was invited as aGuest Editor/Editorial BoardMember of many international journals, invitedfor keynote Speaker in many international conferences held in Asia andinvited as the Program Chair, the Publications Chair, the Publicity Chair, andthe Session Chair in many international conferences held in North America,Europe, Asia, and Africa. He has been awarded best research paper awardsfrom the IEEEGLOBECOM2018, the IEEE ICC 2019, and Springer ICRIC-2019. He is an Associate Editor of IJCS, Wiley and Security and PrivacyJournal, Wiley.

KARAN PAREKH is currently pursuing the mas-ter’s degree with Nirma University, Ahmedabad,India. His research interests include blockchaintechnology, big data analytics, and computersecurity.

PIMAL KHANPARA received the B.E. degreein Information technology from Dharmsinh DesaiUniversity, Nadiad, the M.Tech. degree in com-puter science and engineering from Nirma Univer-sity, and the Ph.D. degree in survivable mobile adhoc networks from Gujarat Technological Univer-sity, in 2018. She has been an Assistant Profes-sor with the Computer Science and EngineeringDepartment, Institute of Technology, Nirma Uni-versity, since 2012. Her research interests are wire-

less network communication, network security, and computer architecture.She has been actively contributing to the domain of ad hoc networks throughresearch articles and projects.

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http://dx.doi.org/10.1109/ICASI.2018.8394531

http://dx.doi.org/10.1109/EEEIC.2018.8494395


SUDHANSHU TYAGI (Senior Member, IEEE)received the Ph.D. degree from Mewar University,Chittorgarh, Rajasthan, India, in 2016. He is cur-rently working as an Assistant Professor with theDepartment of Electronics and CommunicationEngineering, Thapar Institute of Engineering andTechnology, Deemed University, Patiala, India.He has published 40 research articles in peer-reviewed international journal and conferences.His research area includes lifetime enhancement

of homogeneous and/or heterogeneous WSNs. He is a member of IAENG.

NEERAJ KUMAR (Senior Member, IEEE)received the Ph.D. degree in CSE from Shri MataVaishno Devi University, Katra (J&K), India.He was a Postdoctoral Research Fellow withCoventry University, Coventry, U.K. He is cur-rently as a Full Professor with the Departmentof Computer Science and Engineering, ThaparUniversity, Patiala, India. He is also a VisitingProfessor with Coventry University, Coventry,U.K. He has published more than 300 techni-

cal research articles in leading journals and conferences from the IEEE,Elsevier, Springer, and John Wiley. Some of his research findings arepublished in top cited journals, such as the IEEE TRANSACTIONS ON INDUSTRIALELECTRONICS (TIE), the IEEE TRANSACTIONS ON DEPENDABLE AND SECURE

COMPUTING (TDSC), the IEEE TRANSACTIONS ON INTELLIGENT TRANSPORTATION

SYSTEMS (TITS), the IEEE TRANSACTIONS ON CLOUD COMPUTING (TCC),the IEEE TRANSACTIONS ON KNOWLEDGE AND DATA ENGINEERING (TKDE),the IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY (TVT), the IEEETRANSACTIONSONCONSUMERELECTRONICS (TCE), the IEEENETWORK, the IEEECOMMUNICATIONS, the IEEE WIRELESS COMMUNICATIONS (WC), the IEEEINTERNET OF THINGS JOURNAL (IoTJ), the IEEE SYSTEMS JOURNAL (SJ), FGCS,JNCA, and ComCom. He has guided many Ph.D. and M.E./M.Tech. Hisresearch is supported by fundings from Tata Consultancy Service, Councilof Scientific and Industrial Research (CSIR), and Department of Scienceand Technology. He has awarded best research paper awards from the IEEEICC 2018 and the IEEE SYSTEMS JOURNAL 2018. He is also leading theresearch group Sustainable Practices for the Internet of Energy and Security(SPINES), where group members are working on the latest cutting edgetechnologies. He is a TPC Member and a Reviewer of many internationalconferences across the globe.

MAMOUN ALAZAB (Senior Member, IEEE)received the Ph.D. degree in computer sciencefrom the School of Science, Information Tech-nology and Engineering, Federation University ofAustralia. He is currently an Associate Professorwith the College of Engineering, IT and Envi-ronment, Charles Darwin University, Australia.He is also a Cyber Security Researcher and aPractitioner with industry and academic experi-ence. His research is multidisciplinary that focuses

on cyber security and digital forensics of computer systems with a focuson cybercrime detection and prevention. He has more than 150 researcharticles in many international journals and conferences, such as the IEEETRANSACTIONSON INDUSTRIAL INFORMATICS, the IEEE TRANSACTIONSON INDUSTRYAPPLICATIONS, the IEEE TRANSACTIONS ON BIG DATA, the IEEE TRANSACTIONS

ON VEHICULAR TECHNOLOGY, Computers & Security, and Future Genera-tion Computing Systems. He delivered many invited and keynote speeches,24 events in 2019 alone. He convened and chaired more than 50 conferencesand workshops. He works closely with government and industry on manyprojects, including Northern Territory (NT) Department of Information andCorporate Services, IBM, TrendMicro, the Australian Federal Police (AFP),Westpac, and the Attorney Generals Department. He is the Founding Chairof the IEEE Northern Territory (NT) Subsection.

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blockchain for industry 4.0: a comprehensive review · sudhanshu tyagi 2, (senior member, ieee),...

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