区块链性能的量化分析研究

区块链技术在很多领域有着广泛的应用前景，如何提高区块链性能是目前区块链应用面临的一个主要挑战。通过建立区块链性能的数学模型，研究区块大小、区块生成速率以及网络传输速度等因素与区块链性能和安全性之间的定量关系。通过量化分析可知，增加区块大小或区块生成速率可以等效地提升区块链性能和安全性，但是提升效果是边际递减的。而且增加区块大小或区块生成速率对区块链性能和安全性的提升作用受到网络传输速度的限制，区块大小和区块生成速率需要与网络传输速度相匹配，才能达到最佳的提升效果。该数学模型不仅可以为定制区块链系统提供理论支持，而且可以帮助人们理解区块链性能瓶颈，为进一步发展高效区块链技术的研究提供参考依据。     

评《区块链共识机制研究综述》

区块链是当前的研究热点,作为区块链核心技术之一的共识机制,更是受到研究人员和业界人士的广泛关注。《密码学报》2019年刊登的文章《区块链共识机制研究综述》较为深入、系统、全面地总结了现有的区块链共识机制。文章从系统模型、共识本质、激励模式和安全风险等多个角度,将共识机制分为经典分布式共识和区块链共识两大类,并对后者中的非授权共识又做了进一步细分和梳理。     

基于区块链的视频版权存储架构

区块链技术在数字版权管理领域不断拓宽. 区块链具备公开、透明的特性, 若将数字版权整体存储在区块链中, 版权隐私性难以保护, 同时由于区块大小的限制, 较大的版权文件难以存储. 文章提出一种基于深度学习的区块链视频版权管理架构, 该架构在保证视频版权能够在基本区块链存储的条件下, 采用OpenPose对人物类视频中人物姿势进行BODY_18的关键点输出, 对相关数字版权进行关键信息提取, 最终存储在区块链中, 既保证了信息的隐私性, 又保证了信息的高效存储.     

基于区块链的数据管理设计模式

区块链作为一种新兴的技术, 由于其去中心化, 透明性和不可篡改性而受到广泛关注. 对区块链的研究还处于早期阶段, 应用程序开发过程中仍然存在大量的数据管理问题, 如数据隐私、可伸缩性和延迟. 在本文中, 我们提出了区块链数据管理的设计模式, 即数据隐私保护模式, 哈希完整性模式, 状态通道模式, 帮助开发者易用区块链进行应用开发. 上述所有模式都在一个基于区块链的溯源系统——originChain中实现并验证, 并对其效果进行了讨论.     

区块链中Merkle树性能研究

区块链技术具有去中心化、安全可靠和不可篡改等特性,已经得到广大的重视.Merkle树是区块中核心组成部分,占据区块存储空间的96%以上,主要用来解决在区块链交易中的简化支付验证问题,因此选择合适的Merkle树结构会极大影响区块链系统性能.但是,目前缺乏公共的平台对不同区块链系统下的Merkle树性能进行分析和实验验证.本文提出了一整套相关性能评价与分析指标,从存储、验证和构建时间等方面,综合评价比特币、以太坊和超级账本三种主流区块链的Merkle树的性能.本文提出的指标及评价方法不仅为Merkle树的进一步研究提供了定量的数据支持,也为区块链从业者选择Merkle树结构提供了理论依据.     

基于Augur的交易者身份管理方案研究

随着物联网应用的快速发展,其安全问题也引起越来越多的关注.由于物联网设备众多,且信任机制缺失,物联网设备安全问题日益突出.区块链技术成为可能的解决途径.利用区块链技术的安全机制,物联网可以建立一套可信的加密系统,从而维护数据的安全.为探索如何利用区块链技术解决物联网设备安全问题,一个可行的解决方案是探索区块链应用的身份管理方案.本文通过对区块链应用Augur的身份管理技术进行研究,探索区块链应用的身份管理方案以及潜在风险,并针对Augur的身份管理方案潜在风险和设计缺陷攻击提出了一个基于信誉评估的安全解决方案.该方案选取了6个信誉指标和3种信誉计算方法,为交易者选择有效市场及其他Augur交易活动提供信誉依据.最后本文利用3个指标检验3种方法针对不同用户类型的评估准确度,为评估方法的选择提供了依据.     

区块链技术与应用前瞻综述

区块链技术是一种去中心化、去信任化的分布式数据库技术方案。该数据库由参与系统的所有节点集体维护,具有去中心化、不可篡改、透明、安全等特性。区块链技术归功于比特币应用,它作为比特币的底层技术支持,是比特币系统的核心支撑。区块链技术 具有广阔的 发展前景,从关键技术、内容、原理、瓶颈、应用和前景几个方面进行介绍,对相关研究问题进行探讨。     

Industrial Blockchain: A state-of-the-art Survey

As an underlying and backbone technology of Bitcoin, Blockchain attracted extensive attention worldwide in recent years due to its unique characteristics of decentralization, openness, immutability, anonymity, etc., which enables it to build a trust basis through recording the point-to-point decentralized transactions in an immutable way via the attached timestamp, thereby improving system efficiency and reducing the cost without relying on the central agent. As it is considered to be a potentially revolutionary technology, Blockchain has been introduced into various industrial fields including finance, supply chain, manufacturing, healthcare, energy, and smart city. In this paper, we conduct a state-of-the-art survey of industrial Blockchain in terms of published articles between 2017 and 2020, and worldwide Blockchain movement including North America, Europe, and the Asia Pacific region so far. We conduct a statistic analysis of the collected articles in terms of three dimensions, which are year of publication, leading research institutes and researchers, and article classification to present a multi-dimensional trend or conclusion. Besides, we analyse articles that are cited over a certain number of times in detail to investigate the hot research directions. Finally, the challenges, opportunities, and future perspectives are discussed to summarize the main obstacles of industrial Blockchain and identify the open research questions in the near future.     

BlockU: Extended usage control in and for Blockchain

An electronic business transaction among untrusted bodies without consulting a mutually trusted party has remained widely accepted problem. Blockchain resolves this problem by introducing peer-to-peer network with a consensus algorithm and trusted ledger. Blockchain originally introduced for cryptocurrency that came with proof-of-work consensus algorithm. Due to some performance issues, scientists brought concept of permissioned Blockchain. Hyperledger Fabric is a permissioned Blockchain targeting business-oriented problems for industry. It is designed for efficient transaction execution over Blockchain with pluggable consensus model; however, there is limitation of rapid application development. Hyperledger introduced a new layer called Hyperledger Composer on top of the Fabric layer, which provides an abstract layer to model the business application readily and quickly. Composer provides a smart contract to extend the functionality and flexibility of Fabric layer and provides a way of communication with other systems to meet business requirements. Hyperledger Composer uses role-based access control (RBAC) model to secure access to its valuable assets. However, RBAC is not enough because many business deals require continuous assets monitoring. Our proposed model, BlockU, covers all possible access control models required by a business. BlockU can monitor assets continuously during transactions and updates attributes accordingly. Moreover, we incorporate hooks in Hyperledger Composer to implement extended permission model that provides extensive permission management capability on an asset. Subsequently, our proposed enhanced access control model is implemented with a minimal change to existing Composer code base and is backward compatible with the current security mechanism.     

基于区块链技术的P2P电能交易平台与配电网协同仿真

为了推动能源交易公平以及区块链技术在电力交易领域的应用,实现P2P电能交易平台与配电网高效配合,提出一种基于区块链技术的P2P电能交易平台与配电网的协同仿真框架.根据区块链去中心化、安全性强、可追溯的特点,提出分布式双边拍卖机制,结合智能合约,建立了能源交易模型并进行了仿真分析.最后,根据建立的协同仿真模型,通过两个场景下配电网参数的比较分析,得出了P2P电能交易机制对配电网影响的相关结论,为实现能源高效利用,电能交易安全稳定以及区块链技术在电能交易领域的落地推广提供了理论基础和技术支撑.     

区块链：元宇宙的核心基础设施

当前,元宇宙产业热度极高,或将形成庞大的信息消费生态,成为数字经济的重要组成部分,然而业界对于元宇宙概念的定义多为叙事性描述,缺乏体系化研究和工程化应用。元宇宙产业发展的基础是厘清其本质和内涵,明确元宇宙的基础设施和技术体系,以对元宇宙产业的工程应用提供实际帮助。通过分析元宇宙的背景和产业情况,研究元宇宙内涵和外延,提出区块链是元宇宙的核心基础设施,可从技术平台、应用场景、协作机制等方面对元宇宙提供关键支持。元宇宙的技术参考模型包括元网络、元系统、元服务、元应用、元空间等5层,而区块链的关键技术组件覆盖了元宇宙技术参考模型的核心部分,密码学和分布式身份认证体系可支撑元宇宙的组织、身份、资产、活动等4个关键要素以建立元宇宙的身份价值网络,金融资产协议、加密货币体系和数字资产凭证也将辅助构建元宇宙经济金融体系。同时,对基于区块链的元宇宙概念和术语体系、技术体系的集成方法、分布式商业应用场景等未来发展方向进行展望。     

基于CP-ABE和区块链的数据安全共享方法

数据共享是打破大数据时代“数据孤岛”困境的有力途径，而如何保证数据安全共享是当前面临的主要问题.为此，本文基于区块链技术和密文—策略基于属性的加密（Ciphertext-Policy Attribute-Based Encryption，CP-ABE）提出DOB框架，使用智能合约和序列化方法将CP-ABE的系统公钥、用户属性、密文和用户密钥等存储在链数据库中，同时设置数据库的访问权限和注册认证数据集，实现数据的细粒度共享.实验结果表明：相比于Jemel等人提出的Timely CPABE with Blockchain方案，DOB框架能进一步提高数据共享的安全性.     

Secure decentralized peer-to-peer training of deep neural networks based on distributed ledger technology

The accuracy and performance of deep neural network models become important issues as the applications of deep learning increase. For example, the navigation system of autonomous self-driving vehicles requires very accurate deep learning models. If a self-driving car fails to detect a pedestrian in bad weather, the result can be devastating. If we can increase the model accuracy by increasing the training data, the probability of avoiding such scenarios increases significantly. However, the problem of privacy for consumers and lack of enthusiasm for sharing their personal data, e.g., the recordings of their self-driving car, is an obstacle for using this valuable data. In Blockchain technology, many entities which cannot trust each other in normal conditions can join together to achieve a mutual goal. In this paper, a secure decentralized peer-to-peer framework for training the deep neural network models based on the distributed ledger technology in Blockchain ecosystem is proposed. The proposed framework anonymizes the identity of data providers and therefore can be used as an incentive for consumers to share their private data for training deep learning models. The proposed framework uses the Stellar Blockchain infrastructure for secure decentralized training of the deep models. A deep learning coin is proposed for Blockchain compensation.

     

一种基于分组的区块链共识算法

区块链作为一门新技术,因为其去中心化、不可篡改等性质而被广泛研究。但由于公有链共识算法存在效率低、浪费资源等缺陷,研究者们转向对节点规模较小的联盟链的研究。目前联盟链使用的共识算法为传统的分布式共识算法,受制于节点的规模。当节点数目上升时,系统中的通信量也会上升。提出一种分组的共识算法,第一阶段通过盲签名投票选取胜利节点,第二阶段使用PBFT算法进行主节点的选取,有效缓解单纯使用PBFT算法带来的节点数目增多通信量过大的问题。最后使用该共识算法提出一种物联网系统的架构。     

一种基于区块链的安全云存储方案设计

云存储方式是将数据上传到云服务器中,以此来减轻本地存储的负担。然而,把数据存储到不受信任的第三方云服务器上,可能导致一些数据安全隐患的出现,其中最典型的是数据的完整性问题和隐私问题。针对数据完整性问题和隐私问题,提出一种基于区块链的云存储方案。该方案利用区块链的梅克尔树属性、匿名性、不可篡改等特点构建安全云存储系统,有效地解决了数据完整性问题和隐私保护问题。     

The landscape of Blockchain research: impacts and opportunities

Blockchain technology has emerged as an important research domain in recent years. It not only supports the secure and efficient storage and processing of information but may also transform the business principles and processes embedded in traditional centralized organizations and societies. This editorial first provides a framework that identifies the emerging areas of blockchain research. The key characteristics of this framework in Blockchain 1.0, 2.0, and 3.0 are defined and introduced. The impacts and opportunities associated with blockchain research are identified and discussed. At last, the six articles in this special issue are characterized using the proposed research framework of blockchain research.

     

公开选举代表投票的DAG共识机制

区块链作为一种创新型的分布式账本技术, 以其去中心化、可追溯、防篡改等特性, 在未来许多行业中具有广泛的应用前景. 但现有单链式结构的区块链存在并发低、高延迟等问题. 一种基于有向无环图(directed acyclic graph, DAG)结构的新型账本技术的出现有望突破传统区块链的性能瓶颈, 但目前基于DAG型区块链系统的共识机制并不成熟. 本文针对典型DAG型区块链系统Nano网络的ORV共识机制存在的安全性问题进行改进, 提出了一种基于代表选举模型的公开选举代表投票共识机制, 即OERV (open election representative voting). 使主要代表节点的权益得到了分散, 增强了去中心化程度, 提高了网络安全性. 实验结果表明, OERV算法性能高效, 能够在不牺牲系统效率的同时增强系统的稳定性和安全性, 对于推动DAG型区块链共识机制的研究有着重要的现实意义.     

A review study on blockchain-based IoT security and forensics

The term Internet of Things (IoT) represents all communicating countless heterogeneous devices to share data and resources via the internet. The speedy advance of IoT devices proposes limitless benefits, but it also brings new challenges regarding security and forensics. Likewise, IoT devices can generate a massive amount of data that desires integrity and security during its handling and processing in an efficient way. IoT devices and data can be vulnerable to various types of cyber-crimes at each IoT layer. For combating these cyber-crimes in IoT infrastructure, IoT forensic term has shown up. The IoT forensic is the process of performing digital forensic investigation in the IoT environment in a forensically sound and timely fashion manner. Sundry challenges face the IoT forensics that requires urgent solutions and mitigation methods; digital evidence needs to be collected, preserved, analyzed, processed, and reported in a trusted manner to be acceptable for presenting in the court of law. Preserving the evidence unchanged or tampered with is the most critical challenge in digital forensics. Authentication is another challenge facing digital forensics; who is allowed to deal with the evidence? One of the most recent solutions for supporting IoT forensics is the use of Blockchain. Using Blockchain in digital forensics guarantees data integrity, immutability, scalability, and security. Therefore, this paper presents a comprehensive review of IoT security and forensics with the integration with Blockchain technology. It begins by providing an inclusive discussion of IoT security, as well as the need for IoT forensics, and the concepts of Blockchain. Then, a review of Blockchain-based IoT security and forensics issues is presented. Finally, a discussion of open research directions is provided.

     

Contract law 2.0: ‘Smart’ contracts as the beginning of the end of classic contract law

The paper analyzes legal issues associated with the application of existing contract law provisions to so-called Smart contracts, defined in the paper as ‘agreements existing in the form of software code implemented on the Blockchain platform, which ensures the autonomy and self-executive nature of Smart contract terms based on a predetermined set of factors’. The paper consists of several sections. In the second section, the paper outlines the peculiarities of Blockchain technology, as currently implemented in Bitcoin cryptocurrency, which forms the core of Smart contracts. In the third section, the main characteristic features of Smart contracts are described. Finally, the paper outlines key tensions between classic contract law and Smart contracts. The concluding section sets the core question for analysis of the perspectives of implementation of this technology by governments: ‘How to align the powers of the government with Blockchain if there is no central authority but only distributed technologies’. The author suggests two solutions, neither of which is optimal: (1) providing the state authorities with the status of a Superuser with extra powers; and (2) relying on traditional remedies and enforcement practices, by pursuing specific individuals – parties to a Smart contract – in offline mode.     

区块链技术在水利行业应用场景的分析

作为新一代信息技术,区块链技术的应用潜力受到政府和企业的高度重视。区块链主要包括 P2P 分布式网络和传播、非对称加密、共识机制和智能合约等技术,具有去中心化、公开透明、难以篡改、可追溯和安全可靠等特点,有望解决数据共享、证照管理、档案管理、水利监督、取用水监管、水质监测和水权交易等水利业务的痛点,加快智慧水利发展,为实现水治理体系和能力现代化提供强力支撑和驱动,具有广泛的应用前景。