1 Introduction

With the emergence of Bitcoin in 2008 [1] blockchain became a subject of great interest among researchers and practitioners. This decentralized ledger records every transaction on the network in a secure, transparent, and verifiable manner. By eliminating the need for third-party involvement, it significantly reduces the transactional costs while enhancing its efficiency and security [2]. Blockchain typically employs a linked data structure, wherein blocks of data are interconnected chronologically. The first block of the structure is termed as “genesis block”. The data within it is organized in a structure that captures the value reassigned via signature operations. Each block encompasses a set of data, a header, and a body. The subsequent elements of the header have been depicted in the Table 1.

Table 1 Elements in the header of blockchain
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In [3], the authors provided an inclusive summary of role of blockchain technology by addressing supply chain and logistics-related issues. They highlighted its potential in transforming the same to secure operations and accordingly, its benefits to ensure the traceability of vital products were emphasized. Likewise, the possible blockchain applications in future transportation systems were analyzed by Khoshavi et al. [4]. They provided a general review of the existing research work in this area, as well as discussed problems and prospects of implementing blockchain in this situation. A general idea about blockchain, including its structure and consensus mechanism has been discussed in Guru et al. [5]. They compared various algorithms and highlighted the significance of blockchain in smart healthcare, grids, and financial systems. A categorization that integrates technical and application information to aid the construction of a blockchain-based multimedia copyright protection scheme was proposed [6]. Accordingly, technical concerns and future research directions were highlighted. Similarly, Rawat et al. [7] provides a complete perceptive on potential applications of blockchain technology by providing a broad overview of its various applications in securing and instilling trust in smart systems. Furthermore, Hasan et al. [8] evaluated blockchain applications in smart grids, specifically focusing on perception of cybersecurity and energy data protection. The main focus was on integration of big data-blockchain technology for addressing security challenges in smart grids.

A comprehensive outline of blockchain usage and its concerns in Industry 4.0 were presented in Zuo [9]. Here the reference architecture for smart manufacturing supply chain applications has been proposed with a focus on limitations such as throughput, scalability, privacy, and security. Similarly, an examination of relevance of blockchain in Internet of Things (IoT) domain has been conducted by Xiao et al. [10], and accordingly, a taxonomy for categorizing blockchain applications in IoT was proposed. They also reviewed popular blockchain-IoT applications and highlighted the future direction of this integration. While previous survey articles focused on specific application domains, our work aims to cover several application domains and provide insights into the challenge faced in these domains. A brief overview of the recent literature in this domain has been depicted in Table 2.

Table 2 Overview of recent research work in the blockchain domain
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2 Blockchain architecture

Blockchain technology involves a comprehensive integration of progressive technologies, cryptography [11, 12], mathematical information, consensus protocols, and smart contracts [13]. It utilizes a peer system to connect all nodes that provide services to the network. Essentially, it is a distributed ledger wherein blocks are stored systematically and encrypted using cryptographic techniques to ensure tamper-proof verifiable data. The merkle tree structure is employed to process all transactional information within the block body where every operation is recorded in form of leaf nodes [14, 15]. These leaf nodes are used for generating hash values, which are propagated to obtain the root node. This allows the transactional data on the nodes to be inquired by all nodes in the system. Besides, a hash value is highly responsive to information stored across the network, and any malicious tampering with the transactional data would result in its modification [16]. So, the merkle tree structure provides a certain level of information security within it. A diagrammatic representation of blockchain architecture has been depicted in Fig. 1. Table 3 provides a comparative analysis of different types of blockchain highlighting their dissimilarities, as described by Lin and Liao [17].

Fig. 1
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Blockchain architecture

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Table 3 Comparison of public, private and federated blockchain
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Blockchain technologies possess several distinguishing features, reviewed as follows [18]:

  • Decentralization: Unlike centralized networks that rely on a central trusted group for transactional validation, Blockchain uses a decentralized peer-to-peer (P2P) architecture. This eradicates the requirement for authentication by a central authority and allows various consensus procedures to reduce trust concerns. Decentralization also lowers server costs and mitigates performance overheads compared to centralized systems. However, there may be trade-offs, like higher server energy costs, and lower performance in certain consensus protocols like Proof of Work.

  • Persistency: Blockchain provides an infrastructure for quantifying genuineness and validating data of producers and consumers. All blocks are linked with one another through the hash of the previous block. Accordingly, whenever there is any modification in the previous block, hash value is changed making it difficult to tamper the data. Additionally, the users in the network also verify the transactions, making it harder to falsify data, resulting in an immutable distributed ledger.

  • Anonymity: Randomness is used to generate addresses via which users interact with a blockchain network. This is used to ensure anonymity thereby, guaranting privacy and avoiding disclosure of identity.

  • Auditability: Blockchain uses a digital distributed ledger and timestamp for validation of transactions, making it easy to audit and trace previous records [19]. For instance, in Bitcoin, transactions can be iteratively traced, making the data state in the network more transparent. Conversely, when money is passed via several accounts, it gets complicated to trace its origin.

3 Consensus protocols

In a centralized system, a single element holds all the power and can make changes without need for a complex consensus governance system. However, in a decentralized system, all participants must collectively decide what is best for the network as there is no chief authority. To achieve this, consensus protocols are used, that allow users to synchronize in a dispersed/decentralized environment. The rationale of consensus algorithms is to assure that the network as a whole agrees on one point regardless of certain entity failures, making the system fault-tolerant. Unlike voting, which might overlook the well-being of the minority, consensus algorithms aim to reach an agreement that benefits the entire network, not just the majority. Therefore, the consensus protocol agrees on a solution that benefits all the participants in the network, making it beneficial for the entire system [20]. For consensus to be successful, three elements must be in place. Firstly, the composition of blockchain, which includes laws, rules, transitions, and states, must be acknowledged and accepted. Secondly, the agent structure of the blockchain, which involves nodes, methods, and stakeholders applying legal structure, must also be accepted. Finally, in equality structure, all nodes must be equally recognized. When all three conditions are met, consensus algorithm is considered to be effective. Over time, multiple consensus protocols were developed for different applications. However, they must possess certain attributes to tolerate halting failures.

Consensus algorithms are crucial to secure distributed computing systems, especially for blockchain networks [21]. In a decentralized blockchain, all nodes have a dual role: a host and a server aspiring to communicate with other entities to achieve consensus for transactions. However, since any entity can become a node anonymously in a public blockchain, the possibility of altering transactions and causing forks exist. To prevent such situations, various consensus algorithms are used to ensure that every participant agrees to a single truth. Different types of blockchains have different requirements for consensus algorithms, and thus, an appropriate algorithm needs to be chosen based on the application. In the following sections, various consensus protocols and their suitability for blockchain applications were discussed [20].

3.1 Proof of work (PoW)

Proof of elapsed time (PoET) is a blockchain consensus protocol employed primarily for cryptocurrencies such as Bitcoin [22]. This mechanism requires a significant computational effort to mine a new block, which helps in the prevention of malicious attacks like denial-of-service (DoS). For the addition of new transactions, mining nodes in the network must prove their work with certain requirements. In PoW, nodes are chosen on the basis of their computing power, and they compete for the addition of a new block to the network [23]. Here next block is added by resolving an intricate mathematical problem through costly guessing. Accordingly, an adjustment in the network is done automatically based on the miners. However, mining using PoW requires a colossal amount of energy, thereby, incurring substantial costs for hardware and electricity.

Sometimes, two mining nodes can produce blocks simultaneously due to time lag in accepting blocks in the network. This can lead to a short-term fork, the nodes must then agree on which of the two to consider. Proof of Work (PoW) offers an efficient solution to combat this issue. For instance, if there are two simultaneous transactions to spend a particular coin and both are added to the unconfirmed pool of transactions, the miners will only validate the block having the initial transaction, rendering the second one invalid and removing it from the system. Nonetheless, if transactions are validated simultaneously, a fork is created in the blockchain. This fraudulent fork becomes impractical over time in a completely decentralized network since the adversaries have a minute chance of continuously winning the subsequent block and including it in a falsified network. Moreover, attempting to get sufficient confirmations would require reversal of blocks included after the fraudulent block, which is computationally and financially infeasible.

According to Xiao et al. [10], PoW consensus has several significant limitations, including a trade-off between performance and security. While PoW has low transaction throughput, large block sizes possess a higher risk which can undermine network security thereby, increasing the likelihood of fork incidents. Another major limitation of PoW is its huge energy consumption, which stems from the block generation scheme. Additionally, PoW is vulnerable to attacks such as the Eclipse attack [24] and selfish mining [25]. In the former, a target is denied access to interested transactions after an attacker seizes the control of Internet Protocol (IP) addresse. In selfish mining, a malicious user keeps all mined blocks for itself and only broadcasts them when its chain outnumbers the primary chain of blocks.

3.2 Proof of stake (PoS)

Proof of elapsed time (PoET) is more energy-efficient compared to PoW. Unlike PoW, a pseudorandom selection process is employed in PoS that selects the validator for the next block depending on several factors such as randomization and staking age, together with the node’s wealth. In PoS, blocks are "forged" rather than mined and the node which generates a new block is selected based on its stakes [26]. This stake usually varies depending on how many coins a node owns for a specific block it is trying to mine. However, this selection process can lead to bias and centralization if a single node dominates with a maximum number of stakes. This issue can be addressed using additional methods like “randomized block selection” and “coin age selection” which are employed for selection method. In the former technique, the next forger is chosen by combining the lowest hash value and highest stake. In the latter, the next forger is chosen based on the duration for which the stake has been held and its size, which is known as coinage. The value of coinage is measured by multiplying staked coins with the total days they were held as stakes. After forging process, the node's coinage is reset to zero, thereby preventing dominance by large stake nodes [27].

After being selected to form the next block, a node must authenticate the transactions within the block. If the transactions are legitimate, the node signs and commits the block to the network. The node receives transaction fees related to the validated transactions as a reward. If a node decides to stop being a forger, it must wait for a specific time before releasing its stake and accumulated rewards. This waiting time allows the network to ensure that no fraudulent blocks were added to the blockchain. Fraudulent behavior by a forger is discouraged as any detected fraudulent transactions could result in the node losing a portion of its stake and being disqualified for the future. Given that the stakes are more valuable than the potential reward from fraud, the validator incurs a net loss from engaging in fraudulent activities.

PoS consensus has several limitations including the costless simulation problem, which arises due to the absence of intensive computation, allowing attackers to produce a substitute blockchain. Another issue associated with it is nothing-at-stake which arises when users have no risk of losing anything; they are more likely to participate in multiple blockchains simultaneously, leading to forks in the network. Moreover, PoS is vulnerable to posterior corruption, where attackers bribe nodes to support a substitute chain comprising of forged transactions. Additionally, long-range and stake-grinding [28] attacks are also possible vulnerabilities in PoS.

3.3 Delegated proof of stake (DPoS)

Proof of elapsed time (PoET) is a modified version of the PoS protocol which offers better scalability and productivity [29,30,31] but reduces validators to a certain number on the network. It was proposed by Daniel Larimer in April 2014 [32] to speed up transactions thereby, addressing the security concern of offline nodes accumulating coin age in PoS. DPoS is presently used for BitShares [33] and Crypti [34] platforms. It was created to resolve scalability trilemma, which suggests that a blockchain can only have a pair out of three features: decentralized block production, security, and scalability. Compared to PoW-based systems, DPoS has a shorter block generation time, higher throughput, and peak throughput of thousands of transactions per second, as seen in BitShares. Additionally, DPoS reduces confirmation time to seconds, elevating cryptocurrency technology to a new level.

DPoS has a specific mechanism for block construction and preset block producers, known as witnesses, who are responsible for producing new blocks and validating transactions. To become a witness, the system users i.e., token holders must vote for a block producer candidate. Token holders choose a preferred block producer, and their vote value depends on the stakes. They can also delegate their stakes to other voters to cast votes on their behalf [35]. Additionally, each DPoS system sets a limit on the witness number accountable for proposed blocks. After the election of all witnesses, they can produce blocks in order of their selection, after verifying all transactions. A reward is received when all transactions are confirmed and signed by the witnesses, which is typically shared among users that nominated them. However, if a witness is unsuccessful in the timely production of a block, the transaction remains unverified and no block is formed. In DPoS, voters can also choose on behalf of other candidates they believe are more effective for the task, providing continuous elections. Voters also choose the "delegates," who are accountable for supervising the blockchain’s performance.

For a network to operate and make decisions effectively, delegators must be knowledgeable and select trustworthy witnesses. However, having a limited number of witnesses can result in the centralization of the network. In DPoS blockchain, there is a risk of weighted voting issues where users with smaller stakes may choose not to participate in voting because they feel their vote holds little significance.

3.4 Proof of elapsed time (PoET)

Proof of elapsed time (PoET) is a block-chaining consensus mechanism that operates in the same way as PoW but with significantly reduced computational resources. This eliminates the need for energy-intensive mining processes, resulting in lowering energy consumption and resource utilization. In PoET, each node in the distributed ledger is equipped with a separate random timer that operates independently. This timer determines whether the node will create a new block and receives a reward, giving the same probability to every node, thereby, making the system more efficient. The notion of PoET was developed by Intel in early 2016 to address computational problems of “Random Leader Election”. In PoET, the participating nodes must wait for an arbitrary amount of time assigned by a random timer. The next block generator is determined by identifying the node with the shortest waiting time, which then proceeds by creating and sharing a subsequent block with the network. This method of selecting the block generator is repeated for the detection of succeeding blocks.

Before delving into the workings of the PoET mechanism, it is crucial to realize the role of an advanced technology, Software Guard Extension (SGX) necessary for this protocol. SGX can produce a signed attestation from the platform/ application, rooted in the CPU, which authenticates the correction of the code. SGX ensures that the participant nodes confirm that they are running a reliable code required for PoET’s implementation. The functioning of the PoET algorithm is divided into two stages. The initial phase is Verification and Network Joining, where SGX plays a crucial role. SGX which is a security-related instruction code runs on the CPU and is used by applications to segregate trusted code sections and data, known as enclaves. It provides a secure execution environment (TEE) where trusted code and data can run independently protecting insightful data and code from external interference [36]. The permission network joining process involves two stages. In the first stage, a node downloads the trusted PoET code and executes it on SGX, generating a new private/public key pair and an attestation which is signed by the node. The existing network elements then verify the attestation by accepting or rejecting it and in case of acceptance, the node can participate in the randomized selection process of subsequently block. The second stage is Participation in the Actual Mining Lottery Elapsed Time Round, where each participant receives a signed timer object from a trusted code. The participants wait for the expiry of their chosen timer, and the winner becomes the one whose timer expires initially. A certificate signed via private key is obtained by the winner which is subsequently broadcasted in the network so that it holds back for a certain time before mining the next block. The winner after creating and committing the next block broadcasts the essential information to the peer network [37]. This randomization prevents malicious nodes from acquiring the shortest-timer object and receiving more rewards by continuously generating more blocks.

One drawback of PoET is its reliability on TEE-facilitated hardware systems. While the protocol maintains a monotonic counter to safeguard against malicious attacks and ensure the blockchain runs on a single processor, its usage is restricted [37]. Furthermore, SGX, a crucial component of PoET, goes against one of the three fundamental principles of the blockchain model, which aims to eliminate the need for third-party trust. As SGX was developed by Intel, the consensus protocol is dependent on it. Besides, the reliability of the protocol is doubtful as it is moderately new and not much tested when compared to other consensus mechanisms. Hence, the prediction of its fault-tolerant failures is a difficult task. Additionally, the PoET is susceptible to Sybil attacks, where a malicious user influences the network by generating numerous fake identities to exploit the network [38].

3.5 Practical byzantine fault tolerance (PBFT)

Practical byzantine fault tolerance (PBFT), presented by Castro et al. in 1999 [39]. Here communication between nodes takes place to achieve consensus with the assumption that every honest node possesses identical ledgers. PBFT consensus mechanism offers higher energy efficiency compared to other protocols since it does not always need energy-intensive calculations to reach consensus, reducing the environmental impact for the miners. Moreover, the PBFT protocol allows for collective decision-making through a general record agreement marked by messages, unlike PoW where a single leader can propose the next block. This allows for incentivizing every active node, resulting in all nodes being rewarded and decreasing reward variations for miners.

To ensure the proper functioning of the PBFT protocol, the malicious nodes must be fewer than x/3(where × represents the network's node count). As node number increases, the network becomes more secure since it becomes less likely to have x/3 malicious nodes. The block generation phase in PBFT is referred to as a view and is subsequently categorized into four phases. Firstly, a transaction request is sent by the client to head node. Secondly, these transaction requests are grouped by the organizer node into a block and broadcasted to the backup nodes. Thirdly, the verification of the transactions is carried out by all backup nodes resulting in the formation of a legitimate transaction block. The node calculates the block hash and transmits it to the subsequent nodes. Finally, the node will hold off until it receives a response from either r + 1 nodes or two-thirds of total nodes number to respond with an identical hash, where r symbolizes defective node count. If a node successfully obtains consistent responses, the block is then appended to that node’s ledger.

Compared to PoW, PBFT offers higher transaction throughput [40]. While PBFT requires an authoritative service for backup node selection, its leader node election process is decentralized. PBFT performs well for private networks having selected backup nodes and addressing the computational intensive problems. Nevertheless, when employed for public networks, scalability becomes a concern due to communication overhead, which can also result in possible deadlock of the protocol. Additionally, PBFT is vulnerable to Sybil attacks in public networks, where multiple faulty identities can be created by a single entity without certified authorization, thereby gaining access over a significant portion of the network [38].

3.6 Proof of authority (PoA)

Proof of authority (PoA) algorithm empowers small designated blockchain actors to update the distributed registry and authenticate the transactions in the system. In PoA, new blocks are generated by one or more validating machines, and blocks can be accepted without extensive verification or majority consensus, depending on the blockchain’s configuration [41]. Unlike Proof of Stake (PoS), where validator's stake coins are used, PoA leverages the reputation of validators as their stake. Thus, trusted entities, known as validating nodes, secure the blockchain in PoA-based models, which are highly scalable due to their minimal dependence on block validators. PoA also enables organizations to maintain privacy while benefiting from blockchain technology. In PoA, validators assert their legitimate identities and register in the open public accountant database with matching identities used on the platform. This involves validating their identity through smart contracts,that generate a code that must be submitted as confirmation. Only the true owner of the identity can obtain this code, making it difficult for malicious actors to impersonate others. This increases transparency making it challenging to conceal one’s identity, as concerned parties can easily cross-confirm identity in publicly accessible databases.

PoA consensus is designed to be more resistant to 51% of attacks compared to PoW. In PoA, an attacker would need to control 51% of network nodes, which differs from PoW where an attacker has to acquire 51% of computational power [41]. Acquiring access to the authorized nodes in a PoA network is more tricky as the nodes are already verified, and if any of them becomes unavailable, they can be excluded from the approval process by the network. An attacker may try to disrupt the activity of a targeted network node by transmitting several transactions and blocks, but this is difficult to achieve. Similarly, PoA mechanism provides defense against DoS attacks via two means. Firstly, block creation authority is granted only to nodes that can resist DoS attack, i.e., network nodes that are verified. Secondly, to mitigate the risk of DoS attacks, the node is often eliminated from the group of approving nodes if it becomes inaccessible for a particular period.

The general perception of PoA is that it sacrifices decentralization in favor of efficiency, making it an ideal solution for large corporations with logistical needs. However, this approach raises concern within the cryptocurrency community, as PoA networks may be susceptible to censorship and blacklisting, compromising immutability. PoA, therefore, prioritizes high throughput and scalability over decentralization [42]. Although validator specifications in PoA networks are available to all, there is a conflict that the setup players capable of holding this position may try to become validators by revealing their identities. This may lead to outsider interference with a contender, disturbing the network and influencing the validator to act deceitfully. Additionally, reputational damage threat does not necessarily deter individuals from engaging in malicious activities. The potential gains from such actions often outweigh the risks to their reputation within the network. This can lead to third-party participation and increases the probability of malicious activities. Table 4 briefly summarizes consensus protocols.

Table 4 Summary of consensus protocols
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4 Applications of blockchain

The current work explores the usage of blockchain technology for various applications as depicted in Fig. 2. The benefits and challenges associated with these applications have been discussed.

Fig. 2
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Applications of blockchain

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4.1 Finance sector

Blockchain technology has found significant utilization in financial sectors, including applications such as settling trade finance, insurance, real-time money transfers, and cross-border payments [36, 37]. Bitcoin, the primary decentralized cryptocurrency is not reliant on a central bank, enabling direct transactions between users devoid of any intermediaries [32]. Other cryptocurrencies like Ethereum [43], Ripple, and Dash [44] have also emerged. Traditional cross-border payment banking system suffers from drawbacks such as high costs, time-consuming processes, and lower security. However, leveraging blockchain to reconstruct the payment system can efficiently address these limitations [33]. It can also be used to record, transfer, and verify ownership of assets such as cars, houses, and stocks, and ensure the veracity and legitimacy of sensitive data. Similarly, blockchain technology has played a significant role in enabling a decentralized marketplace that supports safe real-time payments, reducing fraudulent activities [45]. For instance, [46] suggests a blockchain-based decentralized reputation system to store and manage reputation scores of buyers and sellers in an e-commerce environment. Also a blockchain-powered logistics financial platform for e-commerce retailers has been proposed [47].

4.2 Healthcare

It is another important service sector where blockchain has the potential to offer its services. Although medical data sharing is vital, current healthcare systems often require patients to manually exchange their health-related data with medical staff, either in printed or electronic form using storage devices. This information-sharing procedure is incompetent as it is time-consuming, insecure, and provider-centric rather than patient-centric. The inefficiencies arise due to lack of credibility among various IT platforms employed by healthcare organizations. As specified by Lumpkin et al. [48], medical interoperability needs to address three chief stages: foundational, structural, and semantic. Blockchain systems can solve this interoperability issue [49]. By implementing blockchain, patient medical information can be securely shared using smart contracts that control operations like changes in viewership authority or the creation of new records.

4.3 Agriculture

Blockchain can facilitate data sharing in agriculture, enabling independent and smart agricultural management. Smart Agriculture requires food traceability, which ensures the quality and shelf life of agricultural goods [50]. However, conventional food supply chains face challenges in meeting customer demands due to their centralized management, lack of transparency, and unreliable data in their traceability systems [51,52,53]. This enhances the effectiveness and quality management of agri-food supply chain while ensuring food safety [54,55,56].

4.4 Industry 4.0

Conventional manufacturing systems typically have a centralized architecture that leads to high costs in resource usage, a deficit of transparency, delays, inflexibility in handling manufacturing disturbances, and increased security risks. To tackle these issues, blockchain is increasingly used to develop a decentralized and automatic smart manufacturing system that is highly efficient and productive. Smart manufacturing combines physical-cyber technologies and involves multiple agents, including task-driven smart tools having autonomy, heterogeneity, and decentralization. It requires cooperation between manufacturers and product management so that manufacturers are enabled to achieve self-adaptability, reliability, and flexibility, while quickly responding to new customer demands. For effective management of these manufacturing and business organizations in the era of Industry 4.0, it is necessary to strategically interact with partners, assess their importance, and determine the appropriate approach to engage with them. Industry 4.0 facilitates sustainable supply chain proposals that boost financial gain, mitigate environmental impact, and add to social progress. With Industry 4.0, supply chains are becoming smarter, enabling complete product traceability. Industry 4.0 can leverage smart intelligent devices to minimize surplus production, material movement, and energy usage [57]. Blockchain technology can support smart automation by providing a decentralized control and connectivity framework for enhancing sustainability and prospective competitiveness [58]. The integration of Artificial Intelligence (AI), Industrial Internet of Things (IIoT), machine learning, and blockchain is driving the transformation to data-driven smart manufacturing and better decision-making [59].

4.5 Military and defence

Years of cyber-attacks and exploitation of cyber-security systems have demonstrated how determined attackers can compromise both military and civilian networks, posing threats to military systems [60]. To address this challenge, there is a need to seek long-lasting and cost-efficient defense strategies. Blockchain technology, although untested in military applications, is likely to address the security flaws of cyber systems from a single-point-of-failure paradigm. Additionally, its adoption in the military field can have potential applications in areas such as intrusion detection, battles management, UAV (unmanned aerial vehicle) management, and encrypted communications. Although military applications of blockchain are not yet fully matured, it is expected that defence logistics and security will be among the first concrete implementations of military blockchain in the near future. Likewise, smart Transportation has adopted UAVs, or drones, for traffic surveillance, packaged delivery, and instantaneous object detection. These applications require massive data collection and dissemination from drones to remote data centres, which necessitates elevated computational resources, reliable connections, and high transmission rates. However, an increase in drone numbers also leads to security risks, increased air traffic, and potential crashes of drones. To ensure secure communication among UAVs, privacy, and authentication must be of utmost significance. The current solution for drone communication encounters problems with high storage costs, communication dependability, delay, and bandwidth issues. The usage of drones in various applications like surveillance, package delivery, and object detection requires reliable communication and high information security, which can be provided by blockchain technology [61]. By incorporating blockchain, drones can offer improved authentication services and data availability sustained through fog and cloud computing devices [62]. For instance, blockchain has the potential to secure unidentified authentication mechanisms for the speedy reauthentication of vehicles in Vehicular Ad Hoc Networks (VANETs) that provide safe road information and instant vehicle communication [63]. Additionally, storage and transmission of application data in VANETs can be employed securely via Blockchain without a need for central authority [64].

4.6 Goverance

Smart government has the potential to improve government management and decision-making ability thereby, enhancing public services [65]. Blockchain plays a critical role in this regard by providing an immutable data structure for storing government reports vulnerable to security breaches. It can also upgrade processes, and integrate hyper-connected services, thereby, preventing tampering and bribery [66, 67]. For instance, the development of Mattereum leads to the management of legal property rights, objects, and information by tokenizing assets and introducing the notion of automatic custodians [66]. Additionally, [68] proposed a consortium blockchain-based electronic certificate-sharing method for addressing the issues of cross-border government services. Besides, the existing certification schemes in higher education are slow, complex, costly, and susceptible to forgery, which affects the legitimacy and authenticity of academic achievements [69, 70]. However, the implementation of blockchain in education can improve the management of digital libraries, student records, and credentials [71]. Blockchain technology can assure the legitimacy of certifications, providing students with tamper-proof data rapidly [70]. Moreover, blockchain can enhance the openness and decentralization of online education and lifelong learning, enabling learners to manage their learning process in an effective way [72]. Finally, it can enhance privacy, data sharing, and information tracing in e-Portfolios [73, 74].

5 Challenges

Blockchain technology is capable of enhancing data-sharing computations. However, numerous issues need to be tackled in the field of interoperability, survivability, and manageability [75]. Additionally, there are limitations such as high power computations, inefficient consensus mechanisms, the significant overhead of networks, and a small number of transactions per second [76,77,78]. Moreover, a higher delay in transactions leads to ambiguity for participants [76]. Additionally, blockchain requires substantial energy, a colossal amount of space for block storage, and higher processing power for implementing consensus protocol [79,80,81]. As a result, its current state might be infeasible for IoT devices. The high processing and space requirement of wireless devices also hampers blockchain applications in mobile systems [82]. Furthermore, the structured blockchain makes the recent block susceptible to attacks, as malicious nodes might try to alter the recent block, creating a new block and broadcasting the same, thereby, owning the longest network chain [83]. As a result of which, it cannot resist security and privacy breaches [84,85,86]. So, several barriers have been identified that hinder the adoption of blockchain, these include issues related to information systems, absence of business understanding, and awareness of the technology. Furthermore, the absence of effortless usage, technical competency, and transparency hampers its adoption.

Blockchain, with its features of decentralization, transparency, interoperability, traceability, and privacy protection, has the potential to be a solution for financially independent machines involved in Industry 4.0 [87]. The assimilation of blockchain-IoT has resulted in a remarkable boost of possible applications, including smart healthcare, finance, supply chain, agriculture, transportation, education, and e-commerce [76]. Moreover, the advent of 5G networks has improved data processing and data transferring time. Edge computing, which balances computational workload and offers a suitable response to devices, has emerged as a replacement for traditional cloud computing [88, 89]. The flexibility of 5G via the introduction of network slicing and mobile edge computing has paved the way for additional blockchain-based applications on mobile platforms [90].

Additionally, AI which is a crucial technology for Industry 4.0, gives businesses the ability to self-optimize, be self-aware, and self-monitor [60]. AI completely redefines manufacturing processes and business models by empowering businesses to observe their environment, analyze the acquired data, solve complicated challenges, and learn from the experience. The assimilation of AI-blockchain results in formation of a secure, irreversible, and decentralized system for extremely susceptible data, thereby, offering potential benefits for addressing digital transformation issues of Industry 4.0 [76]. The challenges of blockchain technology have been briefly summarized in Table 5.

Table 5 Challenges in blockchain
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6 Conclusion and future scope

The rationale of the current review is to comprehensively investigate the working, advantages, applications, and challenges of blockchain. Furthermore, considering its integration and collaboration with evolving technologies like IoT, cloud computing, and AI, the research scope extends beyond individual enterprises to encompass the complete network and the broader business ecosystem. Blockchain represents a revolutionary advancement in information and communication technology (ICT), offering alertness, capability, interoperability, and scalability, and serving as a promising base for advanced research.

In this work, numerous technological challenges were discussed and the areas which need further research to fully unlock prospective of blockchain were highlighted. Our concluding remarks and key recommendations are as follows:

  • The blockchain’s data integrity, immutability, and traceability capabilities can assist in determining the amount and kind of data for a variety of applications. Nevertheless, current blockchain-based solutions struggle to handle data quality problems effectively, especially in sectors like healthcare and transportation.

  • Crucial performance factors like throughput, execution latency, propagation time, data quantity, participant competing interests, and smart contract vulnerabilities can have a significant impact on contemporary blockchain systems.

  • Private blockchain networks can provide data privacy via private channels and access control procedures. However, because of its zero-access control approach, public blockchain networks may experience issues with data privacy leakage though they can efficiently record the state of the model during its creation, updating, or usage phases.

  • The success of blockchain-based applications is dependent on the network size. Several methods can be used to compress the data and minimize redundancies, thus addressing the challenges related to blockchain network size. Further research is required to address these drawbacks and develop innovative solutions to fully leverage the potential of blockchain.