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The proliferation of Internet of Things (IoT) applications poses formidable challenges in managing data processing, privacy, and security. In response, technologies such as Fog Computing (FC), Blockchain (BC), and Federated Learning (FL) have emerged as promising solutions. Combining these technologies can broaden their scope, and impose novel challenges. This paper conducts a Systematic Literature Review (SLR) to investigate their integration within the IoT domain, systematically evaluating the current state-of-the-art by analyzing 40 papers against 38 extraction criteria, encompassing technical characteristics specific to FC, BC, FL, or their integration. The findings offer insights into the advantages, challenges, opportunities, and limitations of this integration, addressing data processing, privacy, and security concerns in IoT. By filling a research gap and directly examining FC, BC, and FL interoperability across architectural layers, this study contributes to knowledge expansion in the field. This paper proposes a novel framework for implementing FL and BC within FC environments for IoT applications, alongside a comprehensive synthesis of existing literature, distinguishing it from previous research efforts. Furthermore, it offers valuable insights into the current landscape, identifies research needs, and proposes future research directions. The framework and literature synthesis provided allow readers to access customized information on FC-BC-FL integration, aiding in designing and implementing robust IoT solutions.

Blockchain, a distributed and digital ledger technology, has the potential to transform several industries from cryptocurrencies to supply chains. However, the complexity of understanding the technology can be a challenge for most people, especially for newcomers. This study paper aims to provide an in-depth analysis and review of the different layers including the data, network, consensus, smart contract, and application layers. In this paper, we performed an in-depth analysis and review of the components of each layer. We also tried to simulate different consensus algorithms so a reader can understand which blockchain consensus algorithm can be chosen for a specific application. By reading this paper, a reader can understand the blockchain architecture and choose the right algorithms, languages and protocols for building their own blockchain network. The paper also addresses the challenges and difficulties of building a sustainable and secure blockchain. We believe that the choice of consensus algorithm is the most important thing for sustainability in a blockchain network. We show that some consensus algorithms use much more energy than others, and we suggest that developers choose consensus algorithms that use less energy. This paper is a great resource for anyone who wants to learn more about blockchain architecture and consensus algorithms. It gives a complete review of the subject and talks about the difficulties of making a blockchain that will be secure and sustainable. Researchers, developers, and anyone else interested in the future of blockchain technology will be interested in this study.

In modern cities, consumers with distributed energy resources (DERs) can trade energy by managing their consumption and supply. Blockchain is considered to provide technical support for establishing a distributed energy market, while the current mainstream blockchain technology cannot meet the requirement of efficiency and scalability under such a transaction scenario. In addition, the potential defaults of market players also hinder market implementation. Therefore, a reputation-based distributed energy trading mechanism and the corresponding blockchain consensus method considering reputation management are proposed in this paper. Firstly, a distributed reputation management mechanism is designed to systematically evaluate the user’s behavior in the market. Secondly, to address the limitations of traditional consensus methods in the distributed energy market distributed reputation control is introduced into the node model of blockchain, and a new energy blockchain consensus method named DPoR is proposed to solve the technical bottleneck under the distributed energy trading scenario. We also present a corresponding transaction mechanism to encourage market participants to maintain their reputations. Finally, the simulation results verify the effectiveness of the proposed transaction mechanism in this paper, and the presented blockchain consensus mechanism can meet the performance requirements under distributed energy trading scenarios in terms of high efficiency, low consumption, and openness.

The Metaverse platform offers 3D immersive experiences through virtual reality, artificial intelligence, and blockchain technologies. Blockchain-based Metaverse has garnered recent interest due to its decentralization, anonymity, and other security features. Integrating blockchain into Metaverse promotes the formation of a shared ecosystem and provides digital asset tracking, privacy protection, and security in both virtual and physical environments. This paper explores the role of blockchain in creating and managing the Metaverse platform. It is intended to provide a helpful reference for researchers and practitioners in the field of the blockchain-based Metaverse. The main topics covered include the concept and characteristics of the Metaverse; its different use cases, architectures, and technologies; Metaverse as a service provider; Metaverse management; Metaverse users and data; and blockchain-based Metaverse in terms of roles, technologies, applications, and challenges. In addition, recent advances in the blockchain-based Metaverse and challenges such as scalability, interoperability, and edge resource sharing will be discussed. The paper will conclude by highlighting open research issues and future directions, including improving immersion, scalability, security, and integration with existing systems.

Sixth-generation (6G) communication is emerging as a seamless and massive connection of almost all digital devices. Vehicles, which are extensively linked with human mobility, must keep up with a certain technological pace to maintain compatibility with the 6G era. 6G is also expected to potentially revolutionize Vehicle-to-Everything (V2X) communication. However, this modernization will surface several security challenges in the complex heterogeneous architecture of V2X communication in 6G. Similarly, the expansion of V2X is expected to introduce its own unconventional security risks and vulnerabilities. Therefore, the current paper aims to provide an overview of the security challenges associated with and solutions for V2X communication in the upcoming 6G era to visualize the future of this research domain. This paper discusses the architecture and standards utilized in 6G-enabled V2X communications and provisions a comprehensive analysis of V2X security in the Confidentiality, Integrity, Availability, Authentication, and Access Control (CIA3) domains. Through this process, we analyze the impact of the emerging technological concepts of Blockchain and Federated Learning (FL) in 6G-enabled V2X communication. Therefore, we propose a Blockchain-enabled FL-based generic security architecture for V2X communication in 6G networks. Ultimately, this review highlights the key lessons that have been learned and the future research directions in the domain of security of V2X communications in the 6G including Privacy in 3D Fog Computing, Privacy in Augmented Reality, Secure Software Defined Networking (SDN), Physical Layer Security in the THz Spectrum, SUMO (Simulation of Urban MObility), and Intrusion Detection using AI.

As the metaverse gains attraction, the importance of metaverse security research becomes increasingly evident. While there has been research on authenticating users in the metaverse, there is a notable gap in research concerning the authentication of specific spaces within the metaverse. This paper addresses this gap by proposing a novel user-centric blockchain-based authentication approach that incorporates space authentication. The proposed approach leverages blockchain smart contracts to authenticate users using cosine similarity metrics. A significant advantage of this approach its ability to establish user-centric authentication by seamlessly integrating metaverse and blockchain technologies, all without the need for a centralized authority. In this paper, we not only evaluate the security of our proposed approach but also conduct experiments to determine the cosine similarity threshold and assess its feasibility within a metaverse environment.

Understanding the prospective of blockchain technology and its uses in the healthcare sector is essential so that its considerable implementation can support the industry’s much-needed digitization. Furthermore, blockchain can provide answers to the issues in the healthcare industry today. Blockchain’s features like security, traceability, transparency, cost efficiency etc. can help bring supply chain transparency, health record management and prevent drug counterfeiting. Blockchain has emerged as a promising technology with great ability to bring changes to the healthcare sector. Therefore, this study aims to comprehend the current state of blockchain technology research in the healthcare supply chains. Further, it presents potential repercussions and the potential routes it may open for future research initiatives in this area. A systematic literature (SLR) process has been used and conducted in two stages. In the first stage, articles were identified through literature search and were subjected to keyword selection, database search and screening process. Finally, 124 papers were categorized through bibliographic coupling. A detailed investigation of these included papers was performed in the second stage with descriptive and content analysis. The results reveal that research related to blockchain applications or implementation is at a nascent stage. The publications in this area have been rising steadily over the past few years. When it comes to publishing in this field, India is the most productive nation while IEEE Access is the most productive journal. Applications for blockchain technology in healthcare include medical insurance, remote patient monitoring, medication supply chain management, electronic health records (EHRs), and more. The most popular use case is EHR management. The analysis further conveys that findings are less generalizable due to more theoretical or less empirically designed studies published in this domain. This study will help stakeholders, policymakers, researchers, and managers in taking strategic decisions regarding the adoption of the technology in the healthcare industry. This study is done concerning the blockchain’s use in the healthcare sector context, so other emerging technologies and sectors not taken must be considered while generalizing the results. This study is among the few up-to-date consolidated attempts to present a systematic literature review and bibliometric analysis for assessing blockchain technology’s potential in the healthcare sector. It provides an overview of the published work with implications and proposed cluster-wise future research directions.

In recent times, Learning Management Systems (LMS) have gained significant popularity, particularly due to the COVID-19 pandemic, offering improved effectiveness and efficiency. Within LMS, online exams have emerged as a critical tool for assessing students’ performance and understanding of course material, playing a vital role in determining their progression. Ensuring the reliability and transparency of online exam results is imperative. Any vulnerability, such as hacking, can adversely impact students’ grades. Conventional online exam systems often store data centrally in databases like MySQL, making them susceptible to unauthorized access and manipulation. This paper presents a blockchain-based framework to enable secure and peer-to-peer conduction and evaluation of academic exams. The framework uses hashing techniques to ensure data integrity and employs proof of stake mechanisms for enhanced security. Blockchain’s decentralized data storage and cryptographic hashing for each block make it effective in safeguarding data integrity. The paper demonstrates the use of blockchain for developing online exams, storing each question and answer directly on the blockchain. To achieve this, we have created a module that integrates with the Moodle learning management system. Through a comparative analysis with Moodle’s default centralized storage, our module modifies the exam result storage, ensuring secure and tamper-proof data storage on the blockchain. By leveraging the blockchain, exam data is reliably secured, maintaining integrity, and resisting manipulation. Our results show that data stored on the blockchain is entirely accurate, with no discrepancies compared to Moodle’s standard approach. The blockchain network provides a reliable and immutable platform, preventing unauthorized changes to student data. In conclusion, our blockchain-based framework offers a robust solution for enhancing the security and reliability of online exam results. By harnessing blockchain’s decentralized and tamper-proof nature, we ensure data integrity and transparency, providing a more trustworthy assessment of academic performance.

Malicious assaults and information leakage have grown in importance in practically every area of information and communication technology (ICT) in recent years. Enterprise ledger organization, preservation, security, and protection are all greatly aided by information security (IS). To maintain their positions in the market, industries must safeguard their data and other vital assets. The main goals of this paper’s systematic review, which covers the entire process of privacy protection and security, are to introduce cryptographic IS for Industry 5.0 (the Fifth Industrial Revolution) as a comprehensive solution that provides regulatory compliance and IS policies in addition to the industrial goals. The review covers the four main areas: 1) recognizing the need for frameworks to be developed for a secure Industry 5.0 lifecycle; 2) emphasizing security guidelines, procedures, and countermeasures for Industry 5.0; 3) applying control, access, and availability in real-time; and 4) proposing a futuristic architecture for industrial information security. Furthermore, the analysis of previously published state-of-the-art techniques is presented in this paper. These techniques survive with various limitations and challenges, including intercommunication exchange, fine-grained control access, and interconnectivity-related issues, which affect the adoption of an IS in industrial programs. At the end of this systematic review, we investigated a few open research problems and mentioned those that are involved in the design of cryptographic re-encryption enabled IS for future Industry 5.0 developments.

Supply chain as an industry has gone through four-fold changes in the last century. Born as a bare-bones structure in 1.0 it grew to incorporate some form of record preservation in 2.0 and then integrated communication between two entities in 3.0. Supply chain 4.0, the current one, has total global integration of multiple entities with the records digitised. But increasing entities and pipelines, means increasing complexities, overhead and soft spots. In this paper, a systematic literature review is done with the objective of analysing existing Supply Chain 4.0. The focus of the paper is the usage of blockchain technology in the electronic industry to provide a decentralised architecture. Several papers were compared on the basis of different schemas like the type of blockchain network used, platform deployed on, security of frameworks, representation of unique identity, testing authenticity, working implementation, cost of implementation, etc. The pros and cons of various privacy and security methodologies are also explored and discussed. The paper also discusses the open issues and challenges in the same area of interest. Finally, the paper outlines the future scope to be delved into as a part of the future research.

Despite the increasing reliance on the Internet of Things (IoT) as a basic infrastructure for future applications. Integrating blockchain technology with IoT extensively helps provide basic security requirements owing to the built-in security structure of the blockchain. Healthcare IoT applications are one of the industries that will be revolutionized by using IoT-blockchain technology. This review aims to provide an integrated understanding of blockchain IoT healthcare applications. The methodology of our paper is to review the literature from 2018 to 2023, paying more attention to research that intersects and integrates IoT, Blockchain, and healthcare applications. This review addresses IoT-based blockchain types and technologies, healthcare applications, sensors, hardware tools, application databases, programming languages, software tools, challenges and open issues, and solutions with their advantages and limitations. We then compared our work with existing works on common metrics. The study in this paper includes 14 blockchain IOT healthcare applications: remote patient monitoring, patient tracking, disease prediction, tracking COVID-19, image retrieval, security of medical records, smart telemedicine, securing the Internet of Medical Things, big data, blockchain and sensors, accurate medical decisions, health monitoring, tracking soldiers, and solar energy.

Metaverse is a virtual world platform that enables users to create and explore 3D environments. Recently, this technology has gained traction due to its potential to revolutionize the way people interact and share information. This paper provides an overview of the current state of Metaverse technologies. It begins by introducing their core components and surveys recent research and development activities in the area. Next, the paper examines the potential applications of Metaverse technology in different domains, such as gaming, social networking, training, education, healthcare, and marketing. It then outlines the challenges and opportunities associated with the development and deployment of Metaverse technologies, including scalability, privacy, and security issues. Finally, the paper concludes with a discussion of the implications of Metaverse technologies for the future of digital communication and information sharing.

The incorporation of Internet of Things (IoT) technology with agriculture has transformed several farming practices, bringing unparalleled simplicity and efficiency. This article explores the robust integration of IoT and blockchain technology(BIoT) in agricultural operations, offering insight into the resulting BIoT system’s design. This study investigates the potential benefits of merging the IoT and blockchain technologies in agriculture. A system for tracking plant growth using sensors and blockchain-integrated IoT has been developed and analyzed. Through empirical investigation, the report highlights greater efficiency, transparency, and security as significant benefits of BIoT architecture. A cost analysis is also conducted, showing that the system is cost-effective. The paper also proposes a mathematical formula for the calculation of infrastructure cost. It also looks at the problems of integrating BIoT in agricultural contexts, such as technological complications and the need for stakeholder participation. The findings indicate that the IoT can potentially revolutionize agricultural practices drastically, but its practical implementation would need careful consideration of technological, economic, and societal considerations. Empirical analysis is conducted to analyze the latency, throughput, and transaction scalability. The paper concludes with research suggestions, emphasizing the significance of interdisciplinary collaboration and the consequences of BIoT deployment in agriculture.

Healthcare credentialing plays a vital role in ensuring the competence and integrity of healthcare professionals. However, the current credentials verification process suffers from time-consuming procedures due to the large number of intermediaries, limited information access, data fragmentation and the persistent risk of fraudulent credentials, leading to delayed hiring, increased administrative burden, and loss of trust and reputation in the healthcare system. In this paper, we utilize blockchain technology to enhance the credentialing process by streamlining the verification steps, improving data security, and providing stakeholders with confidence through secure storage of credentials. In addition, we utilize advanced security techniques, such as proxy re-encryption and cryptographic algorithms, to ensure the protection of sensitive data, facilitate secure communication, and prevent unauthorized access. We develop smart contracts which eliminate the need for intermediaries, automate the verification process, and enhance transparency and data integrity. We present system architecture, sequence diagrams, entity relationship diagrams, and the underlying algorithms of our blockchain-based solution. We discuss how our proposed solution attains the objectives outlined in the paper. We conduct cost evaluation and security analysis to validate the effectiveness of our solution. Additionally, we compare our proposed system with existing blockchain-based solutions, highlighting its novelty. The code of our smart contracts is made publicly available on GitHub.

Cognitive Radio Ad-hoc Networks (CRAHNs) combines characteristics of ad-hoc networks with cognitive radios to facilitate a variety of communication scenarios. However, these networks are subject to persistent attacks from internal and external adversaries, such as Masquerading, Spoofing, Spying, and Distributed Denial of Service (DDoS). Existing deep learning models proposed to counter these attacks suffer from complexity, real-time processing limitations, and a lack of network scalability. In addition, their limited IP tracing capabilities make them unsuitable for real-time deployments. To address these issues, this paper proposes a novel blockchain-based model for deep traffic pattern analysis and mitigation of malicious attacks in CRAHNs. The proposed model employs a multi-step methodology. The collected traffic patterns are then used to train a deep Convolutional Neural Network (dCNN) model. This trained model permits the temporal classification of incoming real-time traffic packets. The packets are stored on a distributed network based on blockchain technology to ensure data integrity, transparency, and traceability. This blockchain implementation renders the packets immutable and easily accessible, while also facilitating the recommendation of improved mitigation strategies. The blockchain employs a Proof-of-Trust (PoT) consensus mechanism and is managed via a Genetic Algorithm (GA)-based sidechaining model, which significantly reduces access and writing delays for various packets. The proposed model achieves a significant reduction in communication delay in comparison to existing models, with decreases of 35.4%, 19.5%, and 23.5% for BIDS, BIST WM, and GAN, respectively. Additionally, energy consumption is reduced by 18.5%, 18.3%, and 24.5%, respectively. In addition, the model exhibits an increase in throughput of 14.5%, 16.4%, and 15.5%, respectively. Lastly, it improves the accuracy of attack detection during various communications by 8.3%, 23.2%, and 8.3%, respectively. This paper presents a promising solution for enhancing the security of CRAHNs by providing a robust defense against malicious attacks and real-time protection for dynamic ad hoc networks. The integration of deep learning, blockchain technology, and optimization techniques results in significant improvements in performance metrics, demonstrating the potential of the proposed model for ensuring the security and integrity of CRAHNs.

This paper presents an exhaustive investigation into the potential of integrating blockchain and Artificial Intelligence (AI) technologies within aerospace engineering, explicitly emphasizing supply chain management and operational efficiency. Given the decentralized nature of blockchain, it has the potential to enhance diverse facets of an aircraft’s lifecycle management significantly. At the same time, AI stands to revolutionize predictive supply chain models and structural fault detection. This paper provides a comprehensive overview of the current state, potential applications, challenges, and future research directions in this field based on an analysis of previous relevant literature. Further, it compares blockchain technology against traditional record management systems, underlining its data storage, security, transparency, and traceability advantages. Although these technologies promise significant advancements, many legal, regulatory, and technological readiness issues need addressing for broader acceptance within the industry. The findings highlight the importance of targeted research and development to unfold an array of new applications, driving innovation in aerospace engineering. This paper serves as a comprehensive survey for researchers, practitioners, policymakers, and industry stakeholders, illustrating the transformative potential of AI and blockchain in the aerospace sector.

The financial technology (FinTech) has promoted the wide application of FinTech with the help of artificial intelligence, blockchain, cloud computing, data science and other new technologies. Trust evaluation has become a forward-looking issue for the rapid development of FinTech. The existing trust evaluation methods of FinTech do not consider the impact of the timeliness, reliability and non-invasive factors of trust on trust evaluation, which results in low accuracy of trust evaluation and incapability of effectively identifying malicious behaviors of users. Firstly, this paper introduces the blockchain technology to construct a four-layer architecture structure and multiple trust evaluation indicators based on blockchain service data. Secondly, the paper proposes a blockchain based FinTech trust evaluation mechanism (BFTEM), which utilizes blockchain to record relevant data and multiple trust parameters during the transmission process of each block, and verify the trust degree issued by the trust holder through the comprehensive trust value of the user. Finally, the block generation time, throughput, delayed response time and comprehensive trust value are experimentally studied through simulation experiments. Simulation experiments show that BFTEM mechanism can better improve the security and reliability of FinTech data, and has advantages in improving the accuracy of trust evaluation and expanding potential applications.

With the frequent occurrence of private data breaches, it is now more necessary than ever to address how to protect private data. The combination of Ciphertext-Policy Attribute-Based Encryption (CP-ABE) and blockchain typically enables secure storage and sharing of data. However, in high-dimensional attribute domains, that is, the number of attributes is large, these schemes have issues such as low security of data protection, high computational overhead, and high cost of attribute revocation. This paper proposes a personal privacy data protection scheme for encryption and revocation of high-dimensional attribute domains to address these issues. The proposed scheme is made up of three components. Firstly, Fast High-dimensional Attribute Domain-based Message Encryption (HAD-FME) is proposed to improve data security and reduce computational cost. Secondly, an Attribute Revocation Mechanism Based on Sentry Mode (SM-ARM) is designed in combination with smart contracts. Lastly, a Blockchain-based Model for Personal Privacy Data Protection (BC-PPDP) is proposed by integrating HAD-FME with SM-ARM. The security analysis results show that HAD-FME proposed in this paper is secure under the DLIN assumption, and the attribute revocation satisfies both forward and backward security. Experiments show that HAD-FME has higher computational efficiency than existing schemes in the high-dimensional attribute domains, SM-ARM has lower revocation cost than existing attribute revocation mechanisms, and smart contracts and blockchain work well.

Blockchain and machine learning (ML) has garnered growing interest as cutting-edge technologies that have witnessed tremendous strides in their respective domains. Blockchain technology provides a decentralized and immutable ledger, enabling secure and transparent transactions without intermediaries. Alternatively, ML is a sub-field of artificial intelligence (AI) that empowers systems to enhance their performance by learning from data. The integration of these data-driven paradigms holds the potential to reinforce data privacy and security, improve data analysis accuracy, and automate complex processes. The confluence of blockchain and ML has sparked increasing interest among scholars and researchers. Therefore, a bibliometric analysis is carried out to investigate the key focus areas, hotspots, potential prospects, and dynamical aspects of the field. This paper evaluates 700 manuscripts drawn from the Web of Science (WoS) core collection database, spanning from 2017 to 2022. The analysis is conducted using advanced bibliometric tools (e.g., Bibliometrix R, VOSviewer, and CiteSpace) to assess various aspects of the research area regarding publication productivity, influential articles, prolific authors, the productivity of academic countries and institutions, as well as the intellectual structure in terms of hot topics and emerging trends. The findings suggest that upcoming research should focus on blockchain technology, AI-powered 5G networks, industrial cyber-physical systems, IoT environments, and autonomous vehicles. This paper provides a valuable foundation for both academic scholars and practitioners as they contemplate future projects on the integration of blockchain and ML.

Blockchain technology is a distributed ledger that guarantees the immutability of data and asset tracking. Its characteristics can result in an improvement to traditional agri-food Supply Chains. Blockchain-based traceability systems let producers improve their visibility and consumers trust the products they buy and where they come from. Actual literature lacks an exhaustive analysis of the benefits and drawbacks of Blockchain applied to the agri-food domain. This paper aims to overcome this issue: to understand the state-of-the-art related to the application of Blockchain in the agri-food sector, we screened 183 papers and performed a literature review answering six Research Questions. The work takes into consideration the advantages and disadvantages of implementing such paradigm, with an analysis on the role of industries. The main findings are related to research directions: they regard the lack of training both for industries and stakeholders, the involvement of additional technologies (i.e., Big Data, Edge Computing), and the absence of supporting tools for developers.

The inherent security and computational demands of classical consensus protocols are often presumed impervious to various forms of attack. However, quantum computing advancements present considerable threats to the assumed attack resistance of classical security strategies currently deployed within blockchain systems. Adopting consensus algorithms fortified with post-quantum security measures can significantly enhance traditional blockchains’ privacy and security dimensions. Notable advantages of such post-quantum solutions in blockchain consensus include accelerated transaction verification, clarified mining authorship, and resilience against quantum attacks. Yet, a comprehensive analysis of the implications of post-quantum solutions for blockchain consensus is notably absent in the existing scholarly discourse. This paper aims to bridge this gap by systematically reviewing Post-Quantum Blockchain Consensus (PQBC). The four primary contributions of this study are (i) a systematic approach to presenting a comprehensive overview of PQBC, (ii) the systematic selection and analysis of 29 key studies from an initial pool of 1192 papers, (iii) a critical review of methods, enhancements to security, scalability, trust, and privacy, as well as the evaluation employed for PQBC, and (iv) a discussion of primary gaps and prospective directions for future PQBC research.

With the continuous development of blockchain technology, many blockchain applications, such as digital currencies in the form of tokens, are deployed. However, due to the lack of data and value inter-blockchain transmission methods, these chain applications form many data islands. Therefore, cross-chain technology is proposed and applied in distributed transaction platforms, digital finance, e-government and many other different fields. Although cross-chain technology just started, the cross-chain technology and its applications are gradually improving to meet the development needs of blockchain system. At the same time, they have already realized asset transfers across heterogeneous blockchains and platforms, and some projects have realized cross-chain information exchange. At present, cross-chain technology includes the following typical methods: Hash-locking, Notary scheme, Distributed private key control, Sidechains/Relays and Tight coupling. This paper analyzes the above methods from the aspect of techniques, security requirements, and technical limitation, and compares their applicability. With public blockchains and consortium blockchains, this paper analyzes their problems and challenges in cross-chain technology and introduces the main approaches of existing solutions. By analyzing the existing cross-chain technologies and problems, this paper further introduces eight popular cross-chain projects and their application prospects. Finally, this paper summarizes and proposes the future research topics and development trends of cross-chain technology.

The state of computer network technologies has continually advanced at a rapid pace. Software Defined Networking (SDN) and Blockchain (BC) have emerged as complementary technologies providing support that facilitates greater security and greater network performance for many domains of application, including the Internet of Things (IoT) ecosystem, ideally resulting in an improvement to our collective quality of life. The proliferation of IoT devices is driven by a wide variety of use cases and by their ubiquitous availability. When combined with the emergence of SDN and BC, this environment presents rich opportunities for various emerging research efforts and provides a motivation for this paper. Here, we present a comprehensive survey of the studies in which BC and SDN have been integrated into the IoT ecosystem, referred to hereafter as BC-enabled Software-Defined IoT (BC-SDIoT). The paper first discusses the motivations and drivers for integrating BC-enabled SDN and BC-SDIoT, as well as their benefits and drawbacks. Second, we categorize the relevant studies according to six key implementation objectives and ideas that combine BC, SDN, and IoT technologies to create smart, secure, and effective frameworks: Security, computing paradigms (edge and fog computing), trust management, access control & authentication, privacy, and networking. In the corresponding sections, we present the categories (i.e., problem domains) of the aforementioned novel taxonomy and discuss related studies (i.e., solutions) in depth. Finally, we outline potential major challenges, open issues, and future prospects that require further research attention and intensive endeavors for complete and ground-breaking frameworks to broaden newer research domains in BC-SDIoT. This survey paper may serve as a fruitful primer for the reader investigating the exploitation of BC in SDN and IoT ecosystems.

Although blockchain is an emerging technology, it has been applied in a lot of domains by leveraging its features. Traditional identity management systems have many issues regarding security and privacy of personal data. Blockchain has the potential to mitigate and avoid such issues by creating trust among the parties involved in the system while reducing reliance on third-party authorities. The first blockchain-based identity management solutions were launched in 2016. Since then, due to high demand, numerous primary and experimental studies, and intatives have been carried out to provide solutions to this research topic. Along with that, there are also a lot of secondary studies to overview the current state of research on this topic. However, the number of systematic research articles is still limited and each research has its limitation. Through this study, we provide a novel systematic literature including categorization of studies into predefined categories (domain, research type, place of publication), analysis of publication frequency, co-authorship, number of papers citing each paper of all studied papers. Comparing to other systematic literature mapping studies, our paper provides a more comprehensive view of the studied articles. In particular, we analyze the number of citations, which no study has ever done. In this research, we studied 361 papers published from January 2009 to April 2022 in four big databases (IEEE Explore, ACM Digital Library, ScienceDirect, Springer Link), the largest number of articles studied compared to previous researches. The obtained results show that most of the articles under validation research type (providing solution and implementing that solution but not in real-world scenarios) propose solutions/systems, models/schemes and architectures to address general problems. We also find that the majority of authors works alone or collaborate in a separate group and co-work in only one paper. This shows that there is no long term collaboration in blockchain-based identity management, and thus subsequent publications presenting real-world blockchain-based identity management products do not exist.

Given the challenge of manufacturing data silos and information credibility issues in traditional aviation suppliers’ result-oriented management approach, this paper proposes a blockchain-based aviation supplier manufacturing process quality data-sharing platform. Firstly, the paper introduces the possibility of integrating manufacturing supply chain quality management with blockchain technology. Secondly, the quality and data sharing platform architecture of the production process of new aviation suppliers is presented based on quality state and island kinds of aviation suppliers. Then, a detailed method for the implementation of quality and data security sharing is proposed to support the sharing platform’s real-time and orderly operation. Build critical technologies such as manufacturing quality data block packaging models, data storage security sharing, and supplier assessment models on this foundation. Finally, depending on data collection of supplier product production processes to shared application practices based on a specific aircraft industrial park under the supervision of the platform architecture and technology. The application platform integrates the data supply and request components, providing practical and intelligent sharing solutions for airlines’ product quality data.

The term Metaverse is emerging as a result of the late push by multinational technology conglomerates and a recent surge of interest in Web 3.0, Blockchain, NFT, and Cryptocurrencies. From a scientific point of view, there is no definite consensus on what the Metaverse will be like. This paper collects, analyzes, and synthesizes scientific definitions and the accompanying major characteristics of the Metaverse using the methodology of a Systematic Literature Review (SLR). Two revised definitions for the Metaverse are presented, both condensing the key attributes, where the first one is rather simplistic holistic describing “a three-dimensional online environment in which users represented by avatars interact with each other in virtual spaces decoupled from the real physical world”. In contrast, the second definition is specified in a more detailed manner in the paper and further discussed. These comprehensive definitions offer specialized and general scholars an application within and beyond the scientific context of the system science, information system science, computer science, and business informatics, by also introducing open research challenges. Furthermore, an outlook on the social, economic, and technical implications is given, and the preconditions that are necessary for a successful implementation are discussed.

This paper uses blockchain technology to conduct in-depth research and analysis on enterprise cost optimization control. Based on the analysis of the cost control status in enterprises, the concept of target cost optimization control and specific control ideas are proposed. And the study of optimization control under target cost based on genetic algorithm is carried out in combination with the current three major controls of quality, schedule, and cost. It provides the technical basis for the realization of the target profit of the enterprise. The Optimized Scalable Byzantine Fault Tolerance (OSBFT) algorithm, which is suitable for spectrum sharing, is proposed based on PBFT (Practical Byzantine Fault Tolerance) algorithm. So, in this paper, an improved consensus algorithm OSBFT (Optimized Scalable Byzantine Fault Tolerance) is proposed based on it. The improved genetic algorithm is used to solve the objective function and verify the validity, reasonableness and applicability of the model and algorithm. It is shown that the introduction of delay cost in the multilevel inventory model reduces the total cost of the optimized model by 16.87% compared to previous studies. The algorithm reduces the consensus steps, incorporates a data synchronization mechanism, and enables nodes to join and exit consensus.

Existing network service provisioning and lifecycle management (LCM) workflows rely on heterogeneous devices from multiple vendors and collaboration between multiple network actors, which can lead to numerous trust management and interoperability issues. Blockchain networks (BCNs) are a revolutionary way to establish trust in untrusted environments. In this complex environment, BCNs can help ensure transparency and security for network service LCM. However, BCNs are also vulnerable to quantum attacks. Advances in quantum computing will challenge the security of existing blockchain technology based on Public Key Infrastructure (PKI) technologies. In this paper, we explore how network services can be managed in a multiple administrative scenario. Our approach uses BCNs to track the operational steps of network service instantiation metrics while benefiting from the security features of post-quantum cryptography (PQC). Together with the use of N-th degree Truncated polynomial Ring Units (NTRU) as an example of a PQC algorithm that relies on the parallelization power of the Toom-Cook computation method with different security levels, we have shown that Quorum can provide a lower average time-to-write value compared to other BCNs considered (Ethereum and Hyperledger). At the end of the paper, we discuss the evaluation results and future directions regarding the coexistence of PQC algorithms and BCNs for network service orchestration and service federation between multiple administrative domains.

Healthcare supply chains have evolved drastically over time, with complex domestic and global networks and interactions spanning across various organizations and entities. This gives rise to numerous challenges related to information and data pertaining to medical devices used within healthcare supply chain, including data integrity, provenance, traceability, and transparency. Counterfeit medical devices are a major obstacle that the healthcare industry is trying to resolve as it poses a huge risk to the safety of its users. Therefore, it is paramount to have an end-to-end system in place that tracks medical devices not only as they move across the supply chain but also as they are purchased and sold online in digital marketplaces. Unfortunately, existing systems follow a centralized architecture, which leads to being a single point of failure and eradicating transparency and authentication. In this paper, we propose a non-fungible token (NFT) based solution that exploits blockchain smart contracts, integrates tokenization protocols, and utilizes a decentralized storage system for a reliable and efficient medical devices traceability system and ownership management solution. In our proposed system, NFTs are used to represent the digital twin of the medical device. This digital twin captures the medical device attributes and its relevant metadata during its life cycle from production, manufacturing, distribution and movement, to current use and ownership. We present the system architecture and implementation details, along with tested algorithms that define the various functions of our smart contracts. The paper also presents testing details and analyses the solution’s feasibility through a cost and security analysis.

Many security standards and cryptographic solutions exist for different applications such as agriculture, aircraft, banking systems and etc. but a more effective and efficient solution can be given by combining existing technologies with blockchain. This work addresses the problems of previous works such as scalability, immutability, robustness, network latency, auditability, and traceability. Satoshi Nakamoto introduced Blockchain (BC) to tackle the Address Resolution Protocol (ARP) spoofing attacks, Distributed Denial of Service (DDoS), phishing problems and various security issues. Blockchain is a technology that stores the data using a chain of blocks in an encrypted form with hashing algorithms. It uses the decentralized architecture to store the information that helps users and customers to have transparency on records. The data is stored in a distributed ledger that is tamperproof and immutable. To amalgamate the research done so far, this paper presents a systematic review of ten different applications and tools used in blockchain. The applications include academics and education, agriculture, aircraft, banking, car sharing, e-voting, healthcare, Internet of Things (IoT), Intellectual Property Rights (IPR), and Supplychain (SC). Moreover, this paper presented a taxonomy for these applications and analyzed the implementation of tools used in different domains. Different open issues and challenges and key takeaways of blockchain technology were also highlighted. Hence, this paper helps give a new insight into working with blockchain and deciding on appropriate tools and approaches for a particular application.

With the rapid transformation of the energy sector towards modern power systems represented by smart grids (SGs), microgrids (MG), and distributed generation, blockchain (BC) technology has shown the capability for solving security, privacy, and reliability challenges that hinder progress. Currently, the energy structure is forming a decentralized system that prioritizes customer satisfaction. BC technology undertakes power network stockholders in a secure energy market, transparent transactions, and fair competition and offers promising energy solutions. This paper is a comprehensive review of energy applications using BC integration. Firstly, we introduce the drivers of BC leverage that make it a potentially important component of the power network. Following that, we provide background information on BC and its application in areas other than the energy sector. Subsequently, we discuss studies and sort potential energy applications from various recent papers and surveys that have already adopted BC technology in the energy sector. Then, we summarize the pricing infrastructure for applying BC in the energy sector and identify the requirements to build it. Finally, energy security and privacy challenges based on BC are highlighted, along with potential drawbacks and concerns related to the pricing infrastructure.

The digitization of the national economy and the development of the national network have rapidly increased the amount of data, and research in content storage and forwarding is significant. The existing methods of storing certificates and distributing file content entirely rely on the judgment made by the router, and the forwarding process does not consider the security and legality of the data; at the same time, the traditional peer-to-peer (P2P) forwarding network files cannot be effectively reused, and additional security mechanisms are introduced. It affects the performance of the network itself. To improve the overall network performance, optimize the file forwarding process, and ensure the security of content and the verification of historical information, this paper proposes a method for document content storage and distribution that integrates blockchain technology and Named Data Network (NDN). The advantages of data signature encryption, reverse path forwarding of content, and flexible routing improves the overall performance of the forwarding network. Combined with blockchain decentralization technology, the documents and transaction processes can be stored on the chain to ensure the actual security of the forwarding process. In addition, this paper restricts the forwarding process in the NDN network without making any judgments through smart contract rules to ensure the security of confidential files during the forwarding process and, at the same time, limit the forwarding scope of irrelevant junk files in the private network. Finally, experiments prove that the method proposed in this paper can effectively improve the network’s overall performance, optimize the forwarding process, and make rule judgments on the forwarding process of specific files to ensure the security of files.

In the last few years, the technological future becoming apparent by the introduction of smart contracts into mainstream technology, specifically in the development of Web3 and the metaverse. Smart contracts will play a vital role in the decentralization and autonomy of the day-to-day tasks that must be completed. Several literature reviews, considered secondary sources, highlight the current state of testing methods for smart contracts made for Blockchain applications. In this paper, we present the results from a systematic mapping study to give structure to the information found from primary sources. Systematic mapping is a well-known method to identify and categorize research papers in a field with an increasing amount of literature. For this systematic mapping, we searched for studies between 2017 and present-day (March 2022) and were able to find 303 results, from which 47 were selected, by specific inclusion and exclusion criteria, to be relevant to this study. A concept map was created from the information gathered from primary sources to the attributes such as research type, contribution type, blockchain network, smart contract language, development process, testing methods, and testing environment. We also categorized the trends and demographics found in the selected papers based on publication year, author’s country, and more. The results of this systematic mapping showed that this field is very new and quickly increasing with new research. The researchers that are interested in this field could use the results found to create opportunities for their future work.

As the Internet of Things (IoT) ecosystem evolves, innovative applications with stringent demands with respect to latency will emerge. To handle computation-intensive tasks in a timely manner, data offloading to Mobile Edge Computing (MEC) servers has been suggested. On the other hand, prospective IoT networks are expected to include Unmanned Aerial Vehicles (UAVs) to enhance coverage and connectivity, while retaining reliable communication links with ground nodes in urban, suburban, and rural terrain. Nevertheless, the evolution of UAV-aided MEC-enabled IoT presupposes the mitigation of security threats through the implementation of efficient and robust countermeasures. As UAVs inherently have certain limitations in terms of energy, computational, and memory resources, designing lightweight security solutions is required. This paper provides an overview of the UAV-aided MEC-enabled IoT and a detailed presentation of use cases and application scenarios, where security is of utmost importance. Subsequently, up-to-date research works on security solutions for the UAV-aided MEC-enabled IoT are comprehensively presented. To this end, the adoption of information-theoretic techniques that ensure adequate Physical-Layer Security (PLS) is discussed along with sophisticated security approaches based on emerging technologies, such as Blockchain and Machine Learning (ML). In addition, research studies on software- and hardware-based methods for the identification and authentication of network nodes are presented. Finally, this paper provides future perspectives in this research domain, stimulating further work.

Supply chain management (SCM) is a core corporate activity responsible for moving commodities and services from one point to another through a variety of stakeholders. The traditional SCM is based on a centralized approach managed at the central headquarter, and all other sub-offices get instructions from the main office. Some major issues with present SCM systems are security, transactional transparency, traceability, stakeholder involvement, product counterfeiting, additional delays, fraud, and instabilities. Blockchain (BC) emerges as a technology that can manage the data and build trust efficiently and transparently. It can also aid in transaction authorization and verification in the supply chain or payments without a third party. To address the present SCM issues, BC technology is a feasible solution. Motivated by the aforementioned considerations, in this paper, we present a survey on the adoption of BC in SCM. This paper undertakes a comprehensive analysis of the literature on BC characteristics, implementations, and business consequences in various SCM. This Blockchain-centered study, in particular, discloses the research state and delineates future research directions by studying and analyzing 97 up-to-date publications highlighting BC’s supply chain uses. Transparency and traceability, information sharing, product anti-counterfeiting, and building trust are the major aspects propelling BC’s implementation in SCM. Further, we analyzed various applications of SCM in which BC can be used as a probable technology to secure all transactions. Then, we have highlighted open issues and research challenges for adopting BC technology in SCM that open the doors for beginners eager to start work in this amazing area.

This paper proposes a blockchain-based supply chain information operation method to solve the current shortage of business information sharing in the supply chain. These approaches include the idea of blockchain application to realize the sharing of supply chain information, the supply chain architecture of production enterprises based on blockchain, and the hierarchical model of supply chain information flow based on blockchain. This paper proposes the information block recording method of internal and external data sources in the supply chain, including the composition structure and the analysis of the multisource data inside and outside the supply chain. In addition, the multisource data information block recording method is also proposed. Building a blockchain-based supply chain system can improve the integration and reconstruction capabilities of the supply chain. The information recording of the internal data of the supply chain and the external related multisource data in the block can improve the learnability of the supply chain. The internal and external information block connection of the supply chain system is the further integration and reconstruction of the supply chain information resources in the blockchain system. The information storage and access control of the blockchain-based supply chain is an information security guarantee system in the supply chain information sharing environment. Through the method of this study, the system can form a business architecture system based on blockchain-based supply chain information sharing.

Nowadays, health insurance has become an essential part of people’s lives as the number of health issues increases. Healthcare emergencies can be troublesome for people who can’t afford huge expenses. Health insurance helps people cover healthcare services expenses in case of a medical emergency and provides financial backup against indebtedness risk. Health insurance and its several benefits can face many security, privacy, and fraud issues. For the past few years, fraud has been a sensitive issue in the health insurance domain as it incurs high losses for individuals, private firms, and governments. So, it is essential for national authorities and private firms to develop systems to detect fraudulent cases and payments. A high volume of health insurance data in electronic form is generated, which is highly sensitive and attracts malicious users. Motivated by these facts, we present a systematic survey for Artificial Intelligence (AI) and blockchain-enabled secure health insurance fraud detection in this paper. This paper presents a taxonomy of various security issues in health insurance. We proposed a blockchain and AI-based secure and intelligent system to detect health insurance fraud. Then, a case study related to health insurance fraud is presented. Finally, the open issues and research challenges in implementing the blockchain and an AI-empowered health insurance fraud detection system is presented.

One of the features of the Bitcoin network today is that its participating nodes are located in different regions of the world. Generally, inter-region data transmission is relatively time-consuming compared with intra-region data transmission. Thus, an important challenge for a blockchain network is shortening the block propagation time in order to reduce forks and maintain fairness, i.e., similar mining durations, for all miners. Previous methods have tried to increase the block propagation speed at the expense of imposing a higher burden on each node and a higher risk of eclipse attack. This paper proposes a new neighbor selection method that is based on only the neighbor’s regional information and assumes that a node has a relatively small number of neighbors located outside its region. By using this simple method, the distribution of blocks throughout the network becomes faster and the random neighbor-selection nature of the blockchain network is kept intact; thus, risk of an eclipse attack is low. This paper also proposes a block propagation model over multiple regions for exploring the theoretical reasons for the effectiveness of the proposed neighbor selection method. Finally, it examines a migration scenario to the proposed method from the default neighbor selection method implemented in Bitcoin nodes, and evaluates the migration effects in various sizes of networks.

The cloud storage service provides the storage and access function for massive data, reducing the management cost for large amounts of data. The data integrity verification scheme in cloud storage can be employed to help users confirm the integrity of outsourced data. Although public data integrity verification schemes allow users to outsource data integrity verification to third-party auditor (TPA), there are still many problems with centralized TPA in terms of security and efficiency. In recent years, researchers have tried to apply blockchain technology to solve the centralization problem of traditional methods, but these schemes do not pay attention to the problem of efficiency degradation caused by the use of blockchain technology. This paper proposes an efficient data integrity verification scheme for multi-cloud storage services by using blockchain technology. The overall verification can verify the integrity of multiple CSPs, which solves the problems of low computational efficiency. Local verification can trace the source to the specific damaged CSP, which is more secure and reliable. In addition, this paper puts the data verification process directly in the blockchain for public execution and provides data integrity verification services without the assistance of any third-party audit platform, avoiding the security problems caused by untrusted TPA. Theoretical analysis and experiments verify the safety and effectiveness of the scheme.

The sudden demand rises in security made researchers come up with solutions that provide instantaneous safety better than the state of the art solutions. The quest for securing data began in the Spartan era. People are now looking to expand this field of research by attacking the existing paradigms and inventing new algorithms that prove to be better than their vulnerable counterparts. Unmanned aerial vehicles (UAVs) are very much prevailing due to their sleek design and flexible mobility in many sectors such as agriculture, army, healthcare, monitoring and surveillance, and many more. We discuss the growth and demand of drone technology along with its importance in this article. The paper also throws some light on the ongoing security issues in real-time scenarios and the role of quantum cryptography in securing the information over the traditional solutions. Motivated by this, we present a survey on quantum cryptography’s importance, role, and benefits in securing UAV communications underlying beyond 5G networks. A novel quantum cryptography-based layered architectural solution is also proposed to achieve high data security and efficient transmission. This paper also present a case study on the battlefield application on the Internet of military things. The performance of the proposed case study system is evaluated by considering the latency, security, and reliability.

Targets of cyber crime are not exclusive to the private sector. Successful cyber attacks on nation-states have proved that cyber threats can jeopardize significant national interests. In response, nation-states have begun to handle cyber threats at the national defense level, which is titled ‘cyber defense.’ The cyber defense sector is related to national security, therefore requires robust security technology. Contrary to normal systems, blockchain provides strong security properties without a centralized control entity, and as such its application in the cyber defense field is under the spotlight. In this paper, we present opportunities blockchain provides for cyber defense, research and national projects, and limitations. We constructed a survey of government documents, interviews, related news, technical reports, and research papers from 2016 to 2021. As a result, our research contributes to reducing the gap in blockchain for cyber defense by systematically conducting research and analysis. In our research, we found that not only research but also government-led plans are actively promoting blockchain, which demonstrates that blockchain will play a remarkable role in cyber defense. This paper concludes with suggestions for future research in aspects of the blockchain technology, evaluation, and survey.

A smart contract is known to be useful for automating business processes triggered by specific events caused by IoT sensors, data feeds, or other applications. A blockchain-based smart contract management system is an innovative technology that is foreseen to automate future business-to-business (B2B) processes. Blockchain is well-known to play a central role in business process re-engineering by optimizing business workflow operations, especially in multi-party arrangements. This paper presents a multi-organizational smart contract management system in which a user can create, deploy, and execute smart contracts. This paper consists of two parts; in the first part, we have compared existing smart contract management systems based on different characteristics that can play a vital role in selecting a particular system for a specific business need. In the second part, while utilizing and building upon the state-of-the-art techniques, we have built a framework for a blockchain-based smart contract and transaction management system. It is a unified architecture supporting DAO (Decentralized Autonomous Organizations) and organizational level blockchain-based smart contract execution. There are two types of separate blockchains utilized in the proposed framework, i.e., SBlockchain and TBlockchain. SBlockchain is used to store smart contracts, whereas all the data generated by the smart contracts is stored inside the TBlockchain. In addition, each smart contract has some terms and clauses necessary for some event execution. Various components of the framework and their implementation have been described in detail with the help of relevant use-cases.

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.

Collaborative and Federated Leaning are emerging approaches to manage cooperation between a group of agents for the solution of Machine Learning tasks, with the goal of improving each agent’s performance without disclosing any data. In this paper we present a novel algorithmic architecture that tackle this problem in the particular case of Anomaly Detection (or classification of rare events), a setting where typical applications often comprise data with sensible information, but where the scarcity of anomalous examples encourages collaboration. We show how Random Forests can be used as a tool for the development of accurate classifiers with an effective insight-sharing mechanism that does not break the data integrity. Moreover, we explain how the new architecture can be readily integrated in a blockchain infrastructure to ensure the verifiable and auditable execution of the algorithm. Furthermore, we discuss how this work may set the basis for a more general approach for the design of collaborative ensemble-learning methods beyond the specific task and architecture discussed in this paper.

For the development of blockchain smart contracts, a structured approach based on the principles of the Model Driven Architecture can be beneficial and facilitate the implementation of smart contracts. This paper presents such an approach, which, in combination with Unified Modeling Language (UML) Class and State machine diagrams, allows the smart contract structure and behavior logic to be modeled in several abstraction layers. This paper delves into details on how the model-to-model transformations from the specified Blockchain Platform Independent Model (PIM) with specified state-like behavior can be used to produce a Solidity Platform Specific Model (PSM). Subsequently, we elaborate on how the Solidity PSM is used for Solidity smart contract code generation by employing model-to-text transformations. The paper also demonstrates the process of our proposed transformations and code generation using smart contract code examples from Solidity documentation. Based on the examples, a Blockchain PIM is specified and transformed to Solidity PSM, which is then used for Solidity smart contract code generation. The generated smart contract code is then compiled, deployed on the Ethereum blockchain JavaScript virtual machine, and compared to the original smart contract code in terms of Solidity code metrics, similarity scores, and execution costs. The evaluation results indicate that our approach could be successfully used to model and later generate smart contract code.

To this day, abstention rates continue to rise, largely due to the need to travel to vote. This is why remote e-voting will increase the turnout by allowing everyone to vote without the need to travel. It will also minimize the risks and obtain results in a faster way compared to a traditional vote with paper ballots. In fact, given the high stakes of an election, a remote e-voting solution must meet the highest standards of security, reliability, and transparency to gain the trust of citizens. In literature, several remote e-voting solutions based on blockchain technology have been proposed. Indeed, the blockchain technology is proposed today as a new technical infrastructure for several types of IT applications because it allows to remove the TTP and decentralize transactions while offering a transparent and fully protected data storage. In addition, it allows to implement in its environment the smart-contracts technology which is used to automate and execute agreements between users. In this paper, we are interested in reviewing the most revealing e-voting solutions based on blockchain technology.

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 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.

Blockchain technology and its applications are gaining popularity day by day. It is a ground-breaking technology that allows users to communicate without the need of a trusted middleman. A smart contract (self-executable code) is deployed on the blockchain and auto executes due to a triggering condition. In a no-trust contracting environment, smart contracts can establish trust among parties. Terms and conditions embedded in smart contracts will be imposed immediately when specified criteria have been fulfilled. Due to this, the malicious assailants have a special interest in smart contracts. Blockchains are immutable means if some transaction is deployed or recorded on the blockchain, it becomes unalterable. Thus, smart contracts must be analyzed to ensure zero security vulnerabilities or flaws before deploying the same on the blockchain because a single vulnerability can lead to the loss of millions. For analyzing the security vulnerabilities of smart contracts, various analysis tools have been developed to create safe and secure smart contracts. This paper presents a systematic review on Ethereum smart contracts analysis tools. Initially, these tools are categorized into static and dynamic analysis tools. Thereafter, different sources code analysis techniques are studied such as taint analysis, symbolic execution, and fuzzing techniques. In total, 86 security analysis tools developed for Ethereum blockchain smart contract are analyzed regardless of tool type and analysis approach. Finally, the paper highlights some challenges and future recommendations in the field of Ethereum smart contracts.

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 discuss 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.

A smart electric vehicle (EV) charging station energy management system (CSMS) based on blockchain technology, which aims to protect privacy of EV users, ensure fairness of power transactions, and meet charging demands for large numbers of EVs, is proposed in this study. EV charging pile is designed as a local blockchain distributed ledger node, which operates synchronously with blockchain system and blockchain distributed ledger in cloud server. This paper integrates CSMS through smart contracts, providing EV users that ability to conduct power transactions and perform optimal charging and discharging control in real-time. The distributed ledger is in charge of recording all the EV charging and discharging data to maintain fairness of power transactions, protects data from being maliciously tampered, and enables the EV user to monitor status of the EV participating in power transactions and dispatching. The intelligent CSMS consists of an artificial intelligence (AI) module, centralized optimal scheduling module, and decentralized optimal control module. The AI module is responsible for forecasting renewable energy generation and load consumption. There is a two-layer architecture consisting of centralized and decentralized optimal control modules; the upper layer performs optimal charging and discharging scheduling of the entire EV charging station at time 15-min time segments, the bottom layer performs distributed optimal scheduling control in each EV charging pile at 5 min time interval. Proposed system in this paper can deal with feeder congestion and real-time power supply and grid demand imbalance, which are caused by high numbers of EVs.