Blockchain is characterized by privacy, traceability, and security features as a novel framework of distributed ledger technologies. Blockchain technology enables stakeholders to conduct trusted data sharing and exchange without a trusted centralized institution. These features make blockchain applications attractive to enhance trustworthiness in very different contexts. Due to unique design concepts and outstanding performance, blockchain has become a popular research topic in industry and academia in recent years. Every participant is anonymous in a permissionless blockchain represented by cryptocurrency applications such as Bitcoin. In this situation, some special incentive mechanisms are applied to the permissionless blockchain, such as âminedâ native cryptocurrency to solve the trust issues of the permissionless blockchain. In many use cases, permissionless blockchain has bottlenecks in transaction throughput performance, which restricts further application in the real world. A permissioned blockchain can reach a consensus among a group of entities that do not establish an entire trust relationship. Unlike permissionless blockchains, the participants must be identified in permissioned blockchains. By relying on the traditional crash faultâtolerant consensus protocols, permissioned blockchains can achieve high transaction throughput and low latency without sacrificing security. However, how to balance the security and consensus efficiency is still the issue that needs to be solved urgently in permissioned blockchains. As the core module of blockchain technology, the consensus algorithm plays a vital role in the performance of the blockchain system. Thus, this paper proposes a new consensus algorithm for permissioned blockchain, the Risk Assessmentâbased Consensus (RAC) protocol, combined with the decentralized design concept and the riskânode assessment mechanism to address the unbalance issues of performance in speed, scalability, and security.
Montassar Naghmouchi, Hella Kaffel Ben Ayed, Maryline Laurent
Nowadays, open standards for self-sovereign identity and access management enable portable solutions that are following the requirements of IoT systems. This paper proposes a blockchain-based identity and access management system for IoT -- specifically smart vehicles -- as an example of use-case, showing two interoperable blockchains, Ethereum and Hyperledger Indy, and a self-sovereign identity model.
In the blockchain network, the consensus algorithm is used to tolerate node faults with data consistency and integrity, so it is vital in all blockchain services. Previous studies on the consensus algorithm have the following limitations: 1) no resource consumption analysis was done, 2) performance analysis was not comprehensive in terms of blockchain parameters (e.g., number of orderer nodes, number of fault nodes, batch size, payload size), and 3) practical fault scenarios were not evaluated. In other words, the resource provisioning of consensus algorithms in clouds has not been addressed adequately. As many blockchain services are deployed in the form of blockchain-as-a-service (BaaS), how to provision consensus algorithms becomes a key question to be answered. This study presents a kernel-level analysis for the resource consumption and comprehensive performance evaluations of three major consensus algorithms (i.e., Kafka, Raft, and PBFT). Our experiments reveal that resource consumption differs up to seven times, which demonstrates the importance of proper resource provisioning for BaaS.
Ting Li, Mudassir Khan, Ashutosh Sharma, Mohd Dilshad Ansari
Abstract An intelligent climate and watering agriculture system is presented that is controlled with Android application for smart water consumption considering small and medium ruler agricultural fields. Data privacy and security as a big challenge in current Internet of Things (IoT) applications, as with the increase in number of connecting devices, these devices are now more vulnerable to security threats. An intelligent fuzzy logic and blockchain technology is implemented for timely analysis and securing the network. The proposed design consists of various sensors that collect real-time data from environment and field such as temperature, soil moisture, light intensity, and humidity. The sensed field information is stored in IoT cloud platform, and after the analysis of entries, watering is scheduled by implementing the intelligent fuzzy logic and blockchain. The intelligent fuzzy logic based on different set of rules for making smart decisions to meet the watering requirements of plant and blockchain technology provides necessary security to the IoT-enabled system. The implementation of blockchain technology allows access only to the trusted devices and manages the network. From the experimentation, it is observed that the proposed system is highly scalable and secure. Multiple users at the same time can monitor and interact with the system remotely by using the proposed intelligent agricultural system. The decisions are taken by applying intelligent fuzzy logic based on input variables, and an alert is transmitted about watering requirements of a field to the user. The proposed system is capable of notifying users for turning water motor on and off. The experimental outcomes of the proposed system also reveal that it is an efficient and highly secure application, which is capable of handling the process of watering the plants.
The rapid proliferation of renewable energy communities/ecosystems is an indication of their potential contribution to the ongoing energy transition. A common characteristic of these ecosystems is their complex composition, which often involves the interaction of multiple actors. Currently, the notions of "networking", "collaboration", "coordination", and "cooperation", although having different meanings, are often loosely used to describe these interactions, which creates a sense of ambiguity and confusion. To better characterize the nature of interactions in current and emerging ecosystems, this article uses the systematic literature review method to analyse 34 emerging cases. The objective is threefold (a) to study the interactions and engagements between the involved actors, aiming at identifying elements of collaboration. (b) Identify the adopted technological enablers, and (c) ascertain how the composition and functions of these ecosystems compare to virtual power plants. The outcome revealed that the interactions between the members of these ecosystems can be described as cooperation and not necessarily as collaboration, except in a few cases. Regarding technological enablers, a vast panoply of technologies, such as IoT devices, smart meters, intelligent software agents, peer-to-peer networks, distributed ledger systems/blockchain technology (including smart contracts, blockchain as a platform service, and cryptocurrencies) were found. In comparison with virtual power plants, these ecosystems have similar composition, thus, having multiple actors, comprised of decentralized and heterogeneous technologies, and are formed by aggregating various distributed energy resources. They are also supported by ICT and are characterized by the simultaneous flow of information and energy.
Blockchain is a promising technology that has received extensive attention from academia and industry in various subject domains. The significant potential of blockchain technology lies in its key characteristics of decentralization, persistency, anonymity, and auditability. However, the development of blockchain applications faces many technical difficulties because such applications are highly complex and heterogeneous, involving cooperation and interoperation between legacy systems and blockchain systems. These difficulties are further exacerbated by the lack of a common understanding of different blockchain solutions and components from a software engineering perspective. This study proposes a taxonomy to classify the eight fundamental components of blockchain systems. These components comprise a platform, network, distributed ledger, smart contract, consensus protocol, digital wallet, token, and node. Under the proposed taxonomy, each component is divided into several aspects (i.e., characteristics) that collectively describe the component. As a result of this elaboration, the taxonomy organizes the eight components into 83 dimensions and 199 characteristics. The taxonomy was validated using illustrative scenarios and a case study. The proposed taxonomy aims to provide a better understanding of the interrelationships among different blockchain components and aspects. Such an understanding can help blockchain application developers to design better blockchain architectures and systems.
Modern vehicles rely on data from a vast array of sensors such as radar and GPS equipment that can be shared with surrounding vehicles and other interested parties. Vehicle-to-Everything (V2X) is the collection of systems that enable such communication. Although this data sharing has the potential to improve both the safety and efficiency of vehicles, ensuring that what is shared has not been altered, deleted, forged, leaked, or otherwise tampered with remains a challenging problem. Today, blockchain technology allows a system's participants to come to an agreement (consensus) on the state of the system and its data in a decentralized, trustless manner. This new technology may be capable of securing V2X data, as well as enabling other useful V2X services such as payments. However, the V2X ecosystem poses several unique challenges that complicate the application of blockchain technology, not least of which is the vast number of communications that any proposed blockchain network will need to support. This paper gives an overview of V2X and blockchain technology, explores potential applications of blockchain within the V2X domain and justifies its importance. It also reviews, analyzes, and discusses various blockchain architectures that could support V2X applications.
Distributed ledger technology is becoming popular these days because of its high confidentiality, decentralization, and nontampering. It is suitable for replacing centralized security disadvantaged point transfer systems. Lowâpower wide area network (LPWAN) is capable for longârange communication with lowâpower consumption. The iconic features like wide area coverage and long batteryâpowered duration make it best to combine with largeâscale IoT application deployment. In both industry and academic field, such combination of LPWAN and point transfer system is highly attended. However, the ledger management system generates too much data that lowâbandwidth network such as LPWAN can hardly handle; meanwhile, the processing powerâs requirement for small IoT devices is challenging. Towards addressing these issues, we design a packet transmission optimizing mechanism for a ledgerâbased point transfer system (LPTS) in LPWAN to reduce overall data traffic and build a simulator to evaluate its performance. Moreover, we have implemented the system and evaluated in field experiment.
As a decentralized distributed ledger, blockchain is endowed with immutability, traceability, anonymity, and transparency, which has got rapid development in cryptocurrency and production as a new trend. In the meantime, the occurrence of Blockchain-as-a-Service (BaaS) helps in mitigation of the complexity and difficulty in deployment and management of blockchain systems and makes it easier to concentrate on business logic implementation for developers. However, most existing BaaS systems are hosted in the environment of cloud vendors, which has also incurred vendor lock-in risk and impairs the inherent trustless characteristic of blockchain. Though present BaaS systems own a level of availability by using cloud computing or edge computing as infrastructure, the availability is limited, considering the availability of network connections and the data center itself. In this article, a novel cloud-edge collaborative BaaS paradigm is proposed. With the assistance of redundant blockchain node candidates, leader election, and edge network self-healing components, the proposed BaaS system is equipped to extend BaaS to the on-premises edge or private cloud, and realize high availability of blockchain systems in edge-autonomy and cross-data-center scenarios. Through testing a simplified system in a simulated environment in cloud servers, this proposed BaaS system has an acceptable throughput under specific transaction sending rates without much performance degradation due to containerization and data synchronization compared with the original blockchain on-premises deployment method.
Manuel Pereira Lamela, JesĂșs RodrĂguez-Molina, Margarita MartĂnez, Juan Garbajosa
The possibilities that Distributed Ledger Technologies (DLTs) offer for cooperation, development, and achievement of the Sustainable Development Goals (SDGs) are remarkable. This is because DLTs enable several key features, such as sharing complete information about every data transaction in the distributed system that participants belong to, the immutability of the recorded data transactions, or consensus among what data can be regarded as true, of great usefulness for the implementation of the SDGs. As far as developing countries are concerned, this information could be useful in trading locally produced goods, as it could enhance the reputation and profitability of Small-Scale Producers (SSPs). Unfortunately, it is rare to find a digitalized marketplace that has been specifically implemented for this application domain. This paper puts forward a blockchain-based marketplace that makes use of Smart Contracts and offers information about how the sold goods were produced and can be traced to their very origin. Besides, cloud computing has been conceived to be used in this development from the beginning to reduce the computational resources required by end user operations. An implementation with cloud computing facilities, software components running on the Ethereum blockchain and a web front end have been tested with satisfactory performance results.
Edge computing offloads the data processing capacity to the user side, provides flexible and efficient computing services for the development of smart city, and brings many security challenges. Aiming at the problems of fuzzy boundary security protection and dynamic identity authentication in the edge computing environment in smart city, the zero trust architecture based on blockchain is studied, and a digital identity model and dynamic authentication scheme of edge computing nodes based on distributed ledger are proposed. Firstly, a digital identity model of two-way authentication between edge computing node and sensing terminal is established to realize fine-grained authorization and access control in edge computing. Secondly, based on the identity data and behavior log bookkeeping on the chain, the quantification of trust value, trust transmission and update are realized, and the traceability of security events is improved. Finally, based on the improved RAFT consensus algorithm, the multi-party consensus and consistency accounting in the authentication process are realized. Simulation results show that this scheme can meet the requirements of zero trust verification in edge computing environment, and has good efficiency and robustness.
Bitcoin is a decentralized cryptocurrency where all the transactions are saved in a ledger. Blockchains have good features to be used in different finance applications by using smart contract. Also, blockchains are attractive platform for many industrial domains, including the logistics and supply chain industries. Supply chain technology contributes to record every single asset through its flow, tracking orders, receipts, and payments. There are several relay protocols proposed in previous research; these relay protocols are used to connect different types of blockchains. In this paper, we present a Secure Organizational Transactions Framework (SOTF) based on bridge chain to connect private chain or consortium with public chain which reduces interaction with public blockchain and saves the organization details privately in private chain or consortium. The proposed framework makes it possible for smart contract services to acquire means of payment in the consortium and private chain. Moreover, the proposed framework automates the process of updating the payment non-interactively. In this paper, we validate the communication between organizations blockchain and bitcoin, and find out the development cost of the proposed framework which ensures the efficiency and feasibility of the proposed framework. The code of framework implementation is publicly available at GitHub.
Open access
Blockchain Technology Applications and Security
IoT and Edge/Fog Computing
Advanced Steganography and Watermarking Techniques
Priyanka Gaba, Ram Shringar Raw, Mazin Abed Mohammed, Jan Nedoma · 5 authors
Blockchain, a vital technology in today’s era, changed the way we share, manage and exchange our data in a centralized way to decentralized architecture. With the increasing demand for Blockchain, various platforms are available to implement public, private, consortium, or permissioned, permissionless Blockchain. Hyperledger, an open-source, permissioned, distributed ledger-based Blockchain, was hosted by Linux. This paper explores Hyperledger Fabric Private Blockchain Network (HFPBN). The architecture of HFPBN with its components and transaction flow is explored in detail. The Blockchain in HFPBN comprises multiple blocks that are linked to each other. The block elements are discussed in detail with their type and size, and after that, the total size of the block depending upon various parameters is calculated. Further, one application of Blockchain, i.e., Vehicular Ad-hoc Networks (VANETs), is discussed in this paper as a case study. The VANET application is being implemented on the Hyperledger Fabric platform. Formulas showing the dependency of various parameters like endorsement policy, number of transactions, and number of reads and writes on block size are derived and shown in their relationship through the graph for the VANET system. The impact of block size on various performance parameters like throughput, latency, memory, and CPU utilization for the VANET system is then analyzed using Hyperledger Caliper. An optimal required value of throughput and latency is achieved for Blockchain-based VANET. Also, the Hyperledger Fabric platform seems suitable for many applications as it creates separate Blockchain for different applications.
With the rapid development of the social economy, the problem of environmental pollution has been widely concerned. The existing environmental monitoring system adopts a hierarchical centralized management structure, which has some problems, such as data silos and the risk of data falsification. Thus, this paper proposes an environmental monitoring data security model based on the blockchain, which uses the blockchain distributed storage mode to realize the secure sharing of monitoring data and curb the behavior of data forgery. A practical Byzantine fault tolerant mechanism based on credit grouping supervision is adopted to reduce the computation and communication overhead caused by data consensus. Through the cloud chain fusion technology, the encrypted monitoring data is stored on the cloud storage server, and the monitoring data credentials are stored on the blockchain to reduce the storage pressure. And AES(Advanced Encryption Standard) combined with the RSA (Rivest-Shamir-Adleman) encryption algorithm to ensure the security of data transmission and storage. Security analysis and experiments demonstrate that our proposed scheme achieves authenticity, integrity, and security for monitored data. In addition, it effectively reduces the computation, communication, and storage overhead of the block nodes.
Amila Saputhanthri, Chamitha de Alwis, Madhusanka Liyanage
The ever-growing smart applications will expand the Internet of Things (IoT) ecosystem to connect over 75 billion devices by 2025. IoT ecosystems comprise sensors that act as data suppliers and applications where monetary transactions are required to compensate the data producers. This signifies the importance of IoT payments and marketplaces to facilitate micro-transactions of billions of connected devices in the IoT ecosystem, which is heterogeneous, decentralized, and diverse. However, realizing such an ecosystem raises multiple challenges such as overcoming poor inter-operability, resource constraints, and security and privacy vulnerabilities of IoT devices and platforms. Blockchain is a Distributed Ledger Technology (DLT) that can be identified as a potential solution to overcome the challenges in realizing IoT payments and marketplaces. This is due to the characteristics of blockchain such as decentralization, traceability, immutability, and non-repudiation. This paper presents a comprehensive survey on blockchain-based IoT payments and marketplaces. This paper provides a brief introduction to the concepts of IoT payments and IoT marketplaces. Then the technical challenges involved in realizing IoT payment and marketplaces are discussed by highlighting the blockchain-based solutions. Furthermore, blockchain-based smart applications which use IoT marketplace and IoT payment concepts are presented marking the role of blockchain in each of the application. Subsequently, the paper discussed the integration challenges while also highlighting possible solutions. It is envisaged that this paper would shed light on the development of blockchain-based solutions to realize IoT payments and marketplaces.
Ahmad N. Gohar, Sayed AbdelGaber AbdelMawgoud, Marwa Salah Farhan
Due to the distributed and non-integrated nature of the healthcare systems which results from the application-centric view it leads to a challenging task to manage healthcare data exchange (heterogeneity problem). On the other hand, Blockchain technologies are emerging as promising and cost-effective means to meet some of these requirements due to their inherent design properties, such as secure cryptography and a resilient peer-to-peer network. Likewise, Blockchain-based applications can benefit the healthcare domain via their properties of asset sharing, and audit trails of data access. Existing work mainly pays attention to centralized and blockchain-based mechanisms. But it doesn’t realize the increase need for better data interoperability amount multiple healthcare systems and services. This requires shifting from the application-centric solutions toward the patient-centric solutions. This paper presents A secure and efficient framework based on Blockchain, Cloud, and IoT named Patient-Centric Healthcare Framework (PCH) for better healthcare systems interoperability. A tiered-based architecture (5 tiers) with collaboration is designed for the feasible realization of PCH. Also, the design and implementation aspects start from the layering diagram, system context, and detailed reference architecture that emphasizes the detailed component topology and interactions within the framework. An electronic medical record is used to show how healthcare data is processed with the required security considerations. Then, an evaluation of PCH against the existing Blockchain-based healthcare frameworks is conducted. The results analysis demonstrates that PCH offers practical solutions to protect healthcare data and support efficient data sharing with better interoperability.
Privacy is playing a crucial role in the smart health industry, where health service providers and their customers use the internet of things (IoT) to provide and consume health services. Preserving privacy for legitimate users and preventing illegitimate users from accessing services are difficult to implement simultaneously. In this study, we addressed this issue by proposing a new healthcare system for IoT based on the blockchain and zero-knowledge succinct noninteractive argument of knowledge (zk-SNARK). We employ the anonymity property of the public blockchain to protect users’ privacy. The zk-SNARK scheme works as an anonymous authenticator to prevent unauthorized users from using services. We also analyze the security of the proposed system by showing that it can resist various types of attacks, such as impersonation, collusion, and man-in-the-middle attacks. Finally, we evaluate the performance of the zk-SNARK scheme with respect to computational costs and the interactions with the Ethereum blockchain smart contract with respect to transaction fees.
Interoperability is identified as one of the major design constraints for blockchain technology. Cross-blockchain technology is fast evolving as the demand for value transfer among different blockchain systems is growing. A generic cross-blockchain design methodology for interoperability requires a set of suitable components to facilitate the integration process. One of the main challenges in the integration is to protect the integrity of the shared data. Various integration systems and their components may operate with different underlying security assumptions and this may lead to compromise of the overall security. In this paper we review the latest advancement in blockchain integration systems and provide a comprehensive analysis of integration characteristics for cross-blockchain technology and then define the essential components and modes of integration. Based on the outcome of our review, we propose a novel integration design decision framework that identifies key assumptions and critical characteristics of the cross-blockchain technology. The proposed framework facilitates the best-practice decision-making process. This reduces the potential for design errors and the associated security risks and performance degradation of the overall system.
Marah R. Bataineh, Wail Mardini, Yaser Khamayseh, Muneer Bani Yassein
Internet of Things (IoT) has grown increasingly in the past decade. This growth brings up several challenging issues for a successful continuous operation of IoT applications. Some of these challenges that need to be taken care of are resource constraints, central server overload, and the risk of illegal use of private data. On the other side, Blockchain technology is increasingly popular and has gained huge success in cryptocurrencies. It offers numerous vital qualities such as a technique for consensus, peer communications, confidence-building without a trustworthy third party, and a transaction controlled by conditions and functions using the intelligent contract technique. Blockchain is an excellent candidate to establish a decentralized, autonomous IoT system addressing the above issues. This study proposes an IoT-Blockchain integration architecture using an Ethereum Blockchain infrastructure within a rich-thin client IoT approach to address the challenges created by the limited IoT resources while implementing the Blockchain mining technique in IoT systems. The architecture depends on load distribution between the resources. Limited resource devices are the thin-clients, while the higher resource devices are assigned as rich-clients. Both clients can access the blockchain and collect the data, but rich-client can only execute the mining process. In addition, we implement a healthcare system based on the proposed architecture in which surgical process management is carried out. We also prove our solutionâs efficiency by testing and comparing the architecture against other well-known IoT-based blockchain architectures. The obtained results show that proposed blockchain-IoT architecture is suited for many IoT applications while avoiding difficulties created by IoT devicesâ limitations.
Blockchain and big data are the emerging technologies that are on the highest agendas of the firms. These are significantly expected to transform the ways in which the business as well as the firm run. These are on the verge of increasing the expectation of the distributed ledgers, which would keep the firms away from struggling challenges. The concept of big data and Blockchain has been used up by various other concepts that would help secure and interpret the information. The ideal solutions offered by these technologies shall address the challenges of big data management as well as for analytics. In addition to that, Blockchain provides its own consensus method, which is the primary means to create an audit trail. This enables users to verify all transactions. The audit trail is a means of verifying the correctness and integrity of every transaction, regardless of who owns the asset. The Blockchain can also verify that different parties of a transaction are following an agreement and not breaking the agreement. Moreover, there have been continuous arguments in the concept of Blockchain at which the bitcoin is fundamental and there are several popular blockchain approaches developed which would deliver performance, security as well as privacy. Apart from this, the use of Blockchain plays a major role in adding an extra data layer for the big data analytics process. Big data is considered secure which cannot be further forged with the network architecture. The current paper shall be discussing the emerging concepts that are using Blockchain as well as big data.
Internet of Things (IoT) is a system of interconnected devices that have the ability to monitor and transfer data to peers without human intervention. Authentication, Authorization and Audit Logs (AAA) are prime features of Network Security and easily attained in legacy systems, however, remains unachieved in IoT. The IoTs require due security considerations as the conventional security mechanisms are not optimized for such devices due to various aspects such as heterogeneity, resource constrained processing, storage and multiple factors. Additionally, the legacy systems are mostly centralized and thus introduce a single point of failure. In this research, a novel framework, FBASHI is presented that is based on fuzzy logic and blockchain technology to achieve AAA services. The proposed system is developed using Hyperledger that is a blockchain platform providing privacy and fast response capability, therefore, it is best suited for the healthcare IoT environments. This work proposes behavior driven adaptive security mechanism for healthcare IoTs and networks based on blockchain by utilizing fuzzy logic and presents a heuristic approach towards behavior driven adaptive security providing AAA services. FBASHI is implemented to analyze its security and practicality. Furthermore, a comparison is drawn with other blockchain-based solutions.
Abstract To overcome boundaries in the cross-company data exchange, a new solution to use Distributed Ledger Technology (DLT) for the transfer of data between asset supplier and the Asset Administration Shell (AAS) in a remote repository is proposed in this paper. A short introduction to the AAS and an analysis of DLT in industrial context is given and showing useful properties for industrial usage as well as challenges to solve. The status of the exchange of AASs and possibilities to use DLT in supply chain tracking are described. The new solution combines both concepts by sending data through the distributed ledger from the supplier to the AAS. This is also shown in a proof-of-concept implementation of the solution using IOTA as a DLT and BaSyx as a framework for the AAS. The evaluation and discussion shows challenges and advantages from using the presented approach.
Haya R. Hasan, Khaled Salah, Ibrar Yaqoob, Raja Jayaraman · 6 authors
Todayâs resource-constrained IoT streaming devices generate large amounts of data which is stored, processed, analyzed for value creation, and accessed using centralized systems, technologies, platforms, and services. Most existing systems leveraged for storing and accessing IoT streaming data fall short in providing transparency, traceability, reliability, trustworthiness, and security features. Also, they are vulnerable to the single point of failure problem due to centralization. In this paper, we propose a blockchain-based solution for resource-constrained IoT streaming devices that allows data chunks to be transferred in a decentralized, transparent, traceable, reliable, secure, and trustful manner. We preserve the privacy and confidentiality of the IoT streamed data through a proxy re-encryption network. We use the decentralized storage of the Interplanetary File System (IPFS) to store and share the IoT streaming data, thereby dealing with the large-size data storage problem. We present system diagrams and eleven algorithms along with their full implementation details. We perform security analysis to show our smart contract code is secure enough against well-known security threats and vulnerabilities. We compare our proposed approach with the existing solutions to show its novelty and effectiveness. We make our smart contract code publicly available on the GitHub repository.
Electronic Health Records (EHRs) are electronically-stored health information in a digital format. EHRs are typically shared among healthcare stakeholders and face power failure, data misuse, lack of privacy, security, and audit trail. On the other hand, blockchain is the revolutionary invention of the twentieth century that offers a distributed and decentralized setting to communicate among nodes in a list of networks without a central authority. It can address the limitations of EHRs management and provide a safer, secured, and decentralized environment for exchanging EHRs data. Three categories of blockchain-based potential solutions have been proposed by researchers to handle EHRs: conceptual, prototype, and implemented. This study focused on a Systematic Literature Review (SLR) to find and analyze articles submitted either conceptual or implemented to manage EHRs using blockchain. The study examined 99 papers that were collected from various publication categories. The deep technical analysis focused on evaluating articles based on privacy, security, scalability, accessibility, cost, consensus algorithms, and the type of blockchain used. The SLR found that blockchain technology promises to provide decentralization, security, and privacy that traditional EHRs often lack. Moreover, results obtained from the detailed studies would provide potential researchers with the type of blockchain for future research. Finally, future research directions, in the end, would direct enthusiasm to combine new blockchain-based systems to manage EHRs properly.