变异系数来度量区块链网络去中心化程度

区块链网络的最主要优点是去中心化,但大多数关于这个问题的研究缺乏量化,而且都没有针对区块链在实践中的去中心化程度进行度量.提出了一种基于统计学中变异系数来量化区块链网络去中心化程度的方法.利用变异系数,计算了出块数量和地址余额的数据离散程度,从而来量化区块链网络(以比特币和以太坊为例)的去中心化程度.计算结果表明,基于...     

A Blockchain-Based Architecture for Securing Industrial IoTs Data in Electric Smart Grid

There are numerous internet-connected devices attached to the industrial process through recent communication technologies, which enable machine-to-machine communication and the sharing of sensitive data through a new technology called the industrial internet of things (IIoTs). Most of the suggested security mechanisms are vulnerable to several cybersecurity threats due to their reliance on cloud-based services, external trusted authorities, and centralized architectures; they have high computation and communication costs, low performance, and are exposed to a single authority of failure and bottleneck. Blockchain technology (BC) is widely adopted in the industrial sector for its valuable features in terms of decentralization, security, and scalability. In our work, we propose a decentralized, scalable, lightweight, trusted and secure private network based on blockchain technology/smart contracts for the overhead circuit breaker of the electrical power grid of the Al-Kufa/Iraq power plant as an industrial application. The proposed scheme offers a double layer of data encryption, device authentication, scalability, high performance, low power consumption, and improves the industry’s operations; provides efficient access control to the sensitive data generated by circuit breaker sensors and helps reduce power wastage. We also address data aggregation operations, which are considered challenging in electric power smart grids. We utilize a multi-chain proof of rapid authentication (McPoRA) as a consensus mechanism, which helps to enhance the computational performance and effectively improve the latency. The advanced reduced instruction set computer (RISC) machines ARM Cortex-M33 microcontroller adopted in our work, is characterized by ultra-low power consumption and high performance, as well as efficiency in terms of real-time cryptographic algorithms such as the elliptic curve digital signature algorithm (ECDSA). This improves the computational execution, increases the implementation speed of the asymmetric cryptographic algorithm and provides data integrity and device authenticity at the perceptual layer. Our experimental results show that the proposed scheme achieves excellent performance, data security, real-time data processing, low power consumption (70.880 mW), and very low memory utilization (2.03% read-only memory (RAM) and 0.9% flash memory) and execution time (0.7424 s) for the cryptographic algorithm. This enables autonomous network reconfiguration on-demand and real-time data processing.     

Regional R&D Decentralization and Breakthrough Inventions: A Tale of Two Mechanisms

This study explores the relationship between regional R&D decentralization—i.e. the extent to which R&D activity is distributed among distinct firms collocated in the same geographic area and operating in the same technological domain—and the generation of breakthrough inventions. R&D decentralization might affect the chance of generating breakthrough inventions in two distinct ways. On the one hand, firms might just search in parallel along diverse technological paths, which augments the probability that at least some trajectories will lead to extremely valuable inventions. On the other hand, firms pursuing diverse paths might also exchange knowledge with each other, for instance through inventors' mobility, and such recombination possibly leads to a higher likelihood of producing breakthroughs. By assessing (a) the impact of R&D decentralization on the share of breakthrough inventions and (b) how this impact changes according to the rate of inventors' mobility in regions, this paper aims at understanding which mechanism, if any, actually operates.     

基于区块链和密码累加器的自我主权身份认证方案

针对现有基于区块链的身份认证方案中存在的认证流程复杂、需要多次区块链操作、链上数据不够精简、身份暴露后无法再次隐藏的问题,提出了一种基于区块链和密码累加器的自我主权认证方案。利用密码累加器成员验证高效性的特点,精简区块链数据存储,降低链上数据交互频率,提高系统性能和可扩展性;同时,提出了一种身份数据二次隐藏的方法,能够再次隐藏已披露的用户数据,进一步提高系统的安全性。经与现有身份认证方案进行对比分析和实验验证,表明该方案具有较低的存储、通信与计算成本和较高的可扩展性和安全性。     

区块链系统攻击与防御技术研究进展

区块链作为一种多技术融合的新兴服务架构,因其去中心化、不可篡改等特点,受到了学术界和工业界的广泛关注.然而,由于区块链技术架构的复杂性,针对区块链的攻击方式层出不穷,逐年增加的安全事件导致了巨大的经济损失,严重影响了区块链技术的发展与应用.从层级分类、攻击关联分析两个维度对区块链已有安全问题的系统架构、攻击原理、防御策...     

Survey of blockchain:principle,progress and application

Blockchain is a kind of distributed ledger technology that upgrades to a complete storage system by adding logic control functions such as intelligent contracts.With the changes of its classification,service mode and application requirements,the core technology forms of Blockchain show diversified development.In order to understand the Blockchain ecosystem thoroughly,a hierarchical technology architecture of Blockchain was proposed.Furthermore,each layer of blockchain was analyzed from the perspectives of basic principle,related technologies and research progress in-depth.Moreover,the technology selections and characteristics of typical Blockchain projects were summarized systematically.Finally,some application directions of blockchain frontiers,technology challenges and research prospects including Smart Cities and Industrial Internet were given.     

一种区块链的云计算电子取证模型

提出了一种区块链的云计算电子取证模型,设计基于Merkle Tree的证据保全及改进的共识算法,实现云计算环境下的去中心化电子取证,防止任何参与方,包括取证调查者、云服务提供商、用户等对取证信息的共谋篡改.实验结果表明,该模型能够有效地对电子证据信息进行保全和验证,保障取证数据的完整性和时效性.     

协同发展视角下的首都特大城市地区分圈层空间布局策略

由于诸多功能在北京中心城区过度聚集,北京“大城市病”问题凸现,2014年,中央提出疏解非首都核心功能,促进京津冀区域协同发展的国家战略,这为从更大尺度缓解首都人口资源环境矛盾提供了重要机遇.然而,京津冀城市间发展极差大,自然资源本底条件较差.在借鉴东京、纽约、伦敦的空间圈层布局经验基础上,梳理北京及区域的主要问题及已有城镇体系基础,立足区域协同发展的视角,打破行政边界,重点从30km、50km、150 km三个圈层提出首都特大城市地区的分圈层空间布局策略,并提出完善和创新配套体制机制支撑.     

基于区块链的微认证系统架构

针对现有微认证系统架构依靠中心化的管理模式,不能够保证微认证安全性的弊端,本研究利用了区块链的分布式结构,透明性与不可篡改性的特点,探讨了如何将区块链技术引入微认证系统的架构设计中.本文首先阐明了当前微认证系统中存在的弊端,介绍了区块链生态系统的基本概念;其次,设计并提出了基于区块链的微认证系统架构,以提供高效率且简单直观的微认证相关服务;最后,实现了解决方案的原型,验证了系统原型的性能表现,并进行了安全性探讨.实验结果表明,本文方法能很好地应用于微认证系统,以促进设计和实现基于区块链的微认证系统.