Smart contract applications within blockchain technology: A systematic mapping study

With the advent of blockchain, smart contracts have become one of the most sought-after technologies because of the high customisability they add to transactions. This has given rise to many smart contract applications in areas ranging from financial services, life sciences and healthcare to energy resources and voting. However, due to their infancy, smart contracts still pose many challenges that encumber the stakeholders who interact with them: users, developers and the organisations that are built on top of smart contracts. This study aims to contribute to the body of knowledge of smart contracts within blockchain technology. Based on a systematic mapping study, we offer a broad perspective on their problems and corresponding solutions, present the research trends within the area and compile the 64 papers identified, grouped by top publication sources, channels, methods and approaches. We conclude that, since 2016, there has been an increasing trend towards the publication of blockchain-based smart contract articles at conferences and journals, mainly reflecting experiments and presenting methods, tools and models. According to the results, the most commonly discussed problems and solutions in the literature are related to the security, privacy and scalability of blockchain and the programmability of smart contracts.     

A blockchain future for internet of things security: a position paper

Internet of Things (IoT) devices are increasingly being found in civilian and military contexts, ranging from smart cities and smart grids to Internet-of-Medical-Things, Internet-of-Vehicles, Internet-of-Military-Things, Internet-of-Battlefield-Things, etc. In this paper, we survey articles presenting IoT security solutions published in English since January 2016. We make a number of observations, including the lack of publicly available IoT datasets that can be used by the research and practitioner communities. Given the potentially sensitive nature of IoT datasets, there is a need to develop a standard for sharing IoT datasets among the research and practitioner communities and other relevant stakeholders. Thus, we posit the potential for blockchain technology in facilitating secure sharing of IoT datasets (e.g., using blockchain to ensure the integrity of shared datasets) and securing IoT systems, before presenting two conceptual blockchain-based approaches. We then conclude this paper with nine potential research questions.     

Blockchain-inspired lightweight trust-based system in vehicular networks

A decentralized application runs on the blockchain network without the intervention of a central authority. Transparency in transactions and security in vehicular networks are the issues for central systems. The proposed system uses blockchain-based smart contracts, which eliminate the requirement for any third-party verification. Additionally, with signature verification and reduced overhead, smart contracts also help in a fast and secure transaction. This study suggests a trust-based system paradigm where certificate authority (CA) is employed for vehicle registration. We also propose a blockchain-based system that provides efficient two-way authentication and key agreement through encryption and digital signatures. The analysis of the proposed model reveals that it is an efficient way of establishing distributed trust management, which helps in preserving vehicle privacy. The proposed scheme is tested in Automated Validation of Internet Security-sensitive Protocols (AVISPA), and security parameters verification in Network Simulator 2(NS2) also shows that the proposed scheme is more effective in comparison with existing schemes in terms of authentication cost, storage cost, and overhead.     

Secure large-scale E-voting system based on blockchain contract using a hybrid consensus model combined with sharding

The evolution of blockchain-based systems has enabled researchers to develop next-generation e-voting systems. However, the classical consensus method of blockchain, that is, Proof-of-Work, as implemented in Bitcoin, has a significant impact on energy consumption and compromises the scalability, efficiency, and latency of the system. In this paper, we propose a hybrid consensus model (PSC-Bchain) composed of Proof of Credibility and Proof of Stake that work mutually to address the aforementioned problems to secure e-voting systems. Smart contracts are used to provide a trustworthy public bulletin board and a secure computing environment to ensure the accuracy of the ballot outcome. We combine a sharding mechanism with the PSC-Bchain hybrid approach to emphasize security, thus enhancing the scalability and performance of the blockchain-based e-voting system. Furthermore, we compare and discuss the execution of attacks on the classical blockchain and our proposed hybrid blockchain, and analyze the security. Our experiments yielded new observations on the overall security, performance, and scalability of blockchain-based e-voting systems.     

基于区块链的SDN物联网部署安全

与传统互联网相比,由于基于SDN的物联网覆盖面更广、连接的设备更多、传输的数据更复杂等原因,还存在很多安全方面的技术挑战。提出了在SDN物联网中加入一个基于区块链的安全层作为安全网关,对进入物联网的数据进行一次性的精确验证,各安全网关作为平等的区块链节点加入区块链系统,结合区块链系统的可追踪和不可篡改性,提高了SDN物联网部署的安全性能和效率。     

6G oriented blockchain based Internet of things data sharing and storage mechanism

Considering the heterogeneity of various IoT system and the single point failure of centralized data-processing platform,a decentralized IoT data sharing and storage method based on blockchain technology was proposed.The block consensus and decentralized storage of shared data were realized through the PoS consensus mechanism.A block layered propagation mechanism between consensus node and verified node was proposed based on the Gossip protocol.The block propagation delay model and decentralization evaluation model of blockchain networks were derived.The trade-off between the block propagation delay and the decentralization degree of networks was analyzed.The simulation results demonstrate that the block propagation delay and degree of network decentralization decrease with the increase of minimal capabilities of consensus nodes.As an application example,in the trajectory data sharing scenario of confirmed patients,the data sharing smart contract is implemented and tested based on the Ethereum development platform.     

基于区块链的电子政务数据共享设计研究

区块链技术提供了链上数据不可篡改、共享可查的链上记录等能力,提供了多方信任和数据共享机制。因此,区块链技术可以实现各个政府部门之间的数据共享访问验证。为此,针对“一网通办”电子政务数据共享的需求,深入的对区块链技术进行研究,将电子政务数据存储在区块链上,采用主链和子链的分层架构来增强了权限管理、安全控制等机制,基于Hyperledger Fabric1.4来设计的,并对智能合约和区块链的存储的核心模块的开发进行阐述。     

A systematic literature review of machine learning applications in IoT

The Internet of Things (IoT) is a network of interconnected smart objects having capabilities that collectively form an ecosystem and enable the delivery of smart services to users. The IoT is providing several benefits into people's lives through the environment. The various applications that are run in the IoT environment offer facilities and services. The most crucial services provided by IoT applications are quick decision for efficient management. Recently, machine learning (ML) techniques have been successfully used to maximize the potential of IoT systems. This paper presents a systematic review of the literature on the integration of ML methods in the IoT. The challenges of IoT systems are split into two categories: fundamental operation and performance. We also look at how ML is assisting in the resolution of fundamental system operation challenges such as security, big data, clustering, routing, and data aggregation.     

A blockchain-based trustworthy collaborative power trading scheme for 5G-enabled social internet of vehicles

Social Internet of Vehicles (SIoV) falls under the umbrella of social Internet of Things (IoT), where vehicles are socially connected to other vehicles and roadside units that can reliably share information and services with other social entities by leveraging the capabilities of 5G technology, which brings new opportunities and challenges, e.g., collaborative power trading can address the mileage anxiety of electric vehicles. However, it relies on a trusted central party for scheduling, which introduces performance bottlenecks and cannot be set up in a distributed network, in addition, the lack of transparency in state-of-the-art Vehicle-to-Vehicle (V2V) power trading schemes can introduce further trust issues. In this paper, we propose a blockchain-based trustworthy collaborative power trading scheme for 5G-enabled social vehicular networks that uses a distributed market mechanism to introduce trusted power trading and avoids the dependence on a centralized dispatch center. Based on the game theory, we design the pricing and trading matching mechanism for V2V power trading to obtain maximum social welfare. We use blockchain to record power trading data for trusted pricing and use smart contracts for transaction matching. The simulation results verify the effectiveness of the proposed scheme in improving social welfare and reducing the load on the grid.     

Fog-Sec: Secure end-to-end communication in fog-enabled IoT network using permissioned blockchain system

The technological integration of the Internet of Things (IoT)-Cloud paradigm has enabled intelligent linkages of things, data, processes, and people for efficient decision making without human intervention. However, it poses various challenges for IoT networks that cannot handle large amounts of operation technology (OT) data due to physical storage shortages, excessive latency, higher transfer costs, a lack of context awareness, impractical resiliency, and so on. As a result, the fog network emerged as a new computing model for providing computing capacity closer to IoT edge devices. The IoT-Fog-Cloud network, on the other hand, is more vulnerable to multiple security flaws, such as missing key management problems, inappropriate access control, inadequate software update mechanism, insecure configuration files and default passwords, missing communication security, and secure key exchange algorithms over unsecured channels. Therefore, these networks cannot make good security decisions, which are significantly easier to hack than to defend the fog-enabled IoT environment. This paper proposes the cooperative flow for securing edge devices in fog-enabled IoT networks using a permissioned blockchain system (pBCS). The proposed fog-enabled IoT network provides efficient security solutions for key management issues, communication security, and secure key exchange mechanism using a blockchain system. To secure the fog-based IoT network, we proposed a mechanism for identification and authentication among fog, gateway, and edge nodes that should register with the blockchain network. The fog nodes maintain the blockchain system and hold a shared smart contract for validating edge devices. The participating fog nodes serve as validators and maintain a distributed ledger/blockchain to authenticate and validate the request of the edge nodes. The network services can only be accessed by nodes that have been authenticated against the blockchain system. We implemented the proposed pBCS network using the private Ethereum 2.0 that enables secure device-to-device communication and demonstrated performance metrics such as throughput, transaction delay, block creation response time, communication, and computation overhead using state-of-the-art techniques. Finally, we conducted a security analysis of the communication network to protect the IoT edge devices from unauthorized malicious nodes without data loss.     

Energy aware cloud-edge service placement approaches in the Internet of Things communications

In recent years, applying Internet of Things (IoT) applications has significantly increased to facilitate and improve quality of human life activities in various fields such as healthcare, education, industry, economics, etc. The energy aware cloud-edge computing paradigm has developed as a hybrid computing solution to provide IoT applications using available cloud service providers and fog nodes for the smart devices and mobile applications. Since the IoT applications are developed in the form of several IoT services with various quality of service (QoS) metrics which can deploy on the cloud-edge providers with different resource capabilities, finding an efficient placement solution as one of challenging topics to be measured for IoT applications. The service placement issue arranges IoT applications on the cloud-edge providers with various capabilities of atomic services though sufficient different QoS factors to support service level agreement (SLA) contracts. This paper presents a technical analysis on the cloud-edge service placement approaches in IoT systems. The key point of this technical analysis is to identify substantial studies in the service placement approaches which need additional consideration to progress more efficient and effective placement strategies in IoT environments. In addition, a side-by-side taxonomy is proposed to categorize the relevant studies on cloud-edge service placement approaches and algorithms. A statistical and technical analysis of reviewed existing approaches is provided, and evaluation factors and attributes are discussed. Finally, open issues and forthcoming challenges of service placement approaches are presented.     

基于属性密码体制的区块链安全技术研究进展

区块链是一种集合了分布式存储、点对点传输、共识机制、密码学算法和智能合约等关键技术的分布式账本,具有去中心化、不可篡改、透明化等特性.近年来区块链技术的安全性问题逐渐显露,阻碍了区块链应用的发展.本文介绍了区块链的基本概念与安全模型,分析了区块链的安全性问题;然后,基于属性密码体制,从访问控制、密钥管理、数据隐私保护这...     

无人机协作通信系统中基于区块链的频谱共享机制

为解决无人机与蜂窝网络在协作频谱共享中的激励与安全问题,提出了一种基于区块链的频谱共享机制。首先,为保证无人机在协作过程中的可靠性和真实性,采用基于信誉的赢家判决方法和维克里（Vickery）拍卖的付款规则,在保证无人机通信最小速率前提下提出最大化蜂窝网络传输容量的优化方案。其次,为避免集中机构带来隐私泄露等危险,提出基于区块链的拍卖框架,使用区块链存储并更新无人机的信誉值,并使用智能合约功能来验证和执行拍卖。最后,通过仿真验证区块链的防篡改性,表明所提机制具有激励兼容性并能提升蜂窝网络的传输容量,且与其他方案相比具有较低的协作中断百分比和较好的公平性。     

基于随机森林算法的模拟电路故障诊断

为提高模拟电路参变故障的诊断率,提出基于多特征向量提取和随机森林(RF)算法的模拟电路故障诊断新方法。采用时域和频域特征向量组合的多维特征向量以反映不同故障特征,经RF算法进行决策,并对决策树棵数及候选特征向量个数进行优化。故障诊断实验结果表明,所提方法能较好地实现容差模拟电路故障诊断,与支持向量机(SVM)方法相比,表现出更好的分类性能;与小波(包)特征提取方法相比,简化了多维数据特征提取步骤,易于实现在线故障诊断。     

A systematic literature review of blockchain cyber security

Since the publication of Satoshi Nakamoto's white paper on Bitcoin in 2008, blockchain has (slowly) become one of the most frequently discussed methods for securing data storage and transfer through decentralized, trustless, peer-to-peer systems. This research identifies peer-reviewed literature that seeks to utilize blockchain for cyber security purposes and presents a systematic analysis of the most frequently adopted blockchain security applications. Our findings show that the Internet of Things (IoT) lends itself well to novel blockchain applications, as do networks and machine visualization, public-key cryptography, web applications, certification schemes and the secure storage of Personally Identifiable Information (PII). This timely systematic review also sheds light on future directions of research, education and practices in the blockchain and cyber security space, such as security of blockchain in IoT, security of blockchain for AI data, and sidechain security.     

Integration of Internet of Things and blockchain technology in healthcare domain: A systematic literature review

Healthcare is a vitally important field in the industry and evolving day by day in the aspect of technology, services, computing, and management. Its potential significance can be increased by incorporating Internet of Things (IoT) technology to make it smart in the aspect of automating activities, which is then further reformed in the healthcare domain with the help of blockchain technology. Blockchain technology provides many features to IoT-based healthcare domain applications such as restructuring by securing traditional practices, data management, data sharing, patient remote monitoring, and drug analysis. In this study, a systematic literature review has been carried out in which a total of 52 studies were selected to conduct systematic literature review from databases PubMed, IEEE Access, and Scopus; the study includes IoT technology and blockchain integration in healthcare domain-related application areas. This study also includes taxonomy that mentions the aspects and areas in healthcare domain incorporating the traditional system with the integration of IoT and blockchain to provide transparency, security, privacy, and immutability. This study also includes the incorporation of related sensors, platforms of blockchain, the objective focus of selected studies, and future directions by incorporating IoT and blockchain in healthcare domain. This study will help researchers who want to work with IoT and blockchain technology integration in healthcare domain.     

A blockchain-based online language learning system

To check students’ daily language learning tasks and give students corresponding reasonable scores based on their daily behavior is hard for teachers. The existing online language learning systems are vulnerable and easy to be modified by teachers or system managers. Blockchain can provide immutable and trusted storage service and automatic calculation service. Therefore, a blockchain-based online language learning system is proposed in this paper to monitor students’ daily study and automatically evaluate their behavior so as to save teachers from tedious and complex homework verification workload and provide trusted and reliable evaluation on students’ behavior. This paper first introduces the current situation of language learning in universities and the related works on blockchain-based online language learning system. Then the system is detailed in its structure and smart contracts. At last, we implement this system and do the analysis and summary.

     

基于联盟链的运营商最佳缓存策略

基于区块链的边缘缓存技术可以实现更大范围的内容共享并提高缓存内容的使用效率。针对不同运营商各自建设边缘设备,缓存内容相互隔离,难以共享信息的问题,该文提出一种基于联盟链的边缘缓存系统框架并设计了内容共享和交易流程,实现了不同运营商之间的内容共享。此外,为了降低高维缓存节点的共识开销,设计了基于内容缓存的部分实用拜占庭容错(pPBFT)共识机制,仅选取缓存相关内容的联盟链节点作为验证智能合约的执行节点。最后,将运营商内容共享所带来的收益进行量化并构建为最大化收益的优化问题。通过所提出的内容缓存算法,得到了最优缓存决策的闭式表达式和与内容流行度相关的最优缓存策略。仿真结果表明,在该框架中所提出的共识机制和缓存策略能够有效增加运营商的缓存收益。     

Privacy preservation in permissionless blockchain: A survey

Permissionless blockchain, as a kind of distributed ledger, has gained considerable attention because of its openness, transparency, decentralization, and immutability. Currently, permissionless blockchain has shown a good application prospect in many fields, from the initial cryptocurrency to the Internet of Things (IoT) and Vehicular Ad-Hoc Networking (VANET), which is considered as the beginning of rewriting our digital infrastructure. However, blockchain confronts some privacy risks that hinder its practical applications. Though numerous surveys reviewed the privacy preservation in blockchain, they failed to reveal the latest advances, nor have they been able to conduct a unified standard comprehensive classification of the privacy protection of permissionless blockchain. Therefore, in this paper, we analyze the specific characteristics of permissionless blockchain, summarize the potential privacy threats, and investigate the unique privacy requirements of blockchain. Existing privacy preservation technologies are carefully surveyed and evaluated based on our proposed evaluation criteria. We finally figure out open research issues as well as future research directions from the perspective of privacy issues.