SHA-3置换函数的差分转移概率分析

通过对SHA-3算法置换函数Keccak-f的分析,提出三维数组的循环移位方法。根据置换函数Keccak-f每一步变换的结构,构造出输出差分的布尔函数表达式。通过研究输出差的差分布尔函数表达式,证明了Keccak-f每一步变换的输入输出差分通过循环移位后,其差分转移概率不变。在此基础上,通过分析得出,当Keccak-f每一步变换的两个输入差分之间和对应输出差分之间均满足相同循环移位特性时,整个置换函数Keccak-f的输入输出差分在循环移位后,其差分转移概率不变。     

基于LUT的高速低硬件开销SHA-3算法设计

通过对SHA-3算法和查找表(Look-Up-Table,LUT)方法的研究,提出一种高速低硬件开销SHA-3算法设计方案。首先,该方案利用状态机实现SHA-3算法核心置换函数的轮运算,并结合LUT方法处理每轮运算的数据交换和数据存储;然后,采用硬件模块并行处理和存储单元共用的方式,提高SHA-3算法的速度、降低硬件开销。最后,在SMIC 65nm CMOS工艺下设计SHA-3算法,DC综合后电路面积为65 833μm~2,在1.2V电压下最高工作频率可达到150MHz,功耗为2.5mW。     

SHA-256输出序列的随机性研究

密码学中Hash函数能够用于数据完整性和消息认证以及数字签名,SHA-256是使用最广泛的一种Hash函数。针对SHA-256,用已有统计检测方法中的x2检验对其进行了随机性测试以及雪崩效应的测试,并对测试结果进行了分析讨论,指出了该算法中的一些不足之处,并验证了算法的有效性。     

基于局部碰撞算法的SHA-1改进算法设计与研究

SHA-1是一种哈希函数,它被广泛使用在电子商务这样的现代安全领域,特别是应用于数据加密通信、数字签名。很多的密码协议、标准中都包括了SHA-1算法,如著名的SSL、IPsec和PKCS。本文通过深入分析SHA-1算法及碰撞算法原理,找出SHA-1算法内部碰撞的原因,对算法中逻辑函数和压缩函数进行改进设计,得到基于局部碰撞算法的SHA-1改进算法。     

可重构计算平台上SHA系列函数的优化实现

针对当前哈希函数算法标准和应用需求不同的现状,以及同一系统对安全性可能有着不同的要求,采用可重构的设计思想,在对SHA-1、SHA-256、SHA-512三种哈希函数的不同特征进行深入分析的基础上,总结归纳出统一的处理模型。根据不同的要求,每一种SHA(SHA-1、SHA-256、SHA-512)系列哈希函数都可以单独灵活地执行。使用流水线,并在关键路径进行加法器的优化,提高了算法的吞吐率。并且使用效能比的概念,与M3服务器对比,可重构平台的效能比比通用服务器高很多。     

单向Hash函数SHA-1的统计分析与算法改进

对SHA-1算法的完备度、雪崩效应度、严格雪崩效应及抗碰撞性进行了逐拍统计分析。针对目前密码学界所揭示出的SHA-1设计缺陷,主要以增强SHA-1算法的非线性扩散特性及抗碰撞性为目标,对其进行改进。改进算法在混合函数中逆序使用改进后的扩展码字序列,并在算法首轮的混合函数中引入整数帐篷映射,加速了差分扩散,改变了原来固定的链接变量传递方式,修正了算法内部结构的设计缺陷。测试与分析结果表明,改进算法提高了非线性扩散程度,增强了算法的安全性。     

SHA-1差分路径搜索算法和连接策略研究

Hash函数SHA-1的攻击技术研究一直受到密码分析者的广泛关注,其中,差分路径构造是影响攻击复杂度大小的重要环节.提出了带比特条件的全轮差分路径构造方法,统一了第1轮差分路径构造和后3轮的差分路径构造.该方法既与原有第1轮路径构造相容,又能省去后3轮路径约简、消息约简等繁琐技术环节,具有良好的兼容性.此外,综合考虑状态差分、布尔函数差分与比特条件之间的制约关系,提出了带比特条件的前向扩展、后向扩展和中间连接这3个子算法,并提出3个指标——比特条件的更新次数、扩展结果的相容性和候选集合的正确率对中间连接的成功率进行评价,结合提前终止策略,提出了最优的中间连接算法.理论分析结果表明,该方法有助于提高SHA-1差分路径构造的成功率.最后,采用该算法进行路径搜索,可以得到正确的可用于碰撞搜索的差分路径.     

Skein算法的流水线结构设计与实现

硬件实现的速度和性能是SHA-3算法甄选的重要指标。针对SHA-3末轮5个候选算法之一的Skein算法,结合其4轮迭代结构的关键路径较短而8轮迭代结构实现所用的选择器较少的优点,采用FPGA实现了一个两级流水线结构的Skein算法IP核。仿真验证结果表明,该算法在Xilinx Virtex-5上数据吞吐量达到6. 4Gbps,比之前的非流水线结构速度性能提高了82%以上,硬件资源利用率提高了2100,特别适用于Hash树计算。     

SHA-3轮函数中ρ、π及χ变换的逆变换

Keccak自2012年被宣布为新一代Hash函数标准SHA-3后受到密码学界的高度关注,成为当前Hash函数研究的热点。文中给出了SHA-3轮函数中ρ、π和χ三个变换的逆变换。ρ变换只在同一道内沿z轴正向循环移位,故依据其移位距离表沿z轴负方向移位同样距离即得到其逆变换ρ-1;π变换依赖于GF（5）上一个2阶变换矩阵,利用高斯消元法对此方阵求逆可得到其逆矩阵,也即得到了π变换的逆变换;χ变换是SHA-3轮函数中唯一的非线性变换,首先列出χ变换的真值表,然后通过真值表推导得出了其逆变换χ-1的布尔函数表达式。基于ρ^-1、π^-1和χ^-1,可利用中间相遇攻击的思想构造差分路径对SHA-3进行攻击,通过消息修改技术使差分路径以概率1通过χ-1,能够大大提高攻击成功的概率。     

BLAKE算法的硬件实现研究

随着对MD5和SHA1攻击方法的提出,美国国家标准技术研究所(NIST)组织启动了SHA-3的征集计划,目前已进入第3轮.BLAKE算法进入了最后一轮竞赛,文中首先综述了BLAKE算法从提交到目前为止在硬件评估方面的状况.在此基础上优化了BLAKE压缩函数在FPGA上实现的关键路径,并在FPGA平台上实现了BLAKE算法.和现有的BLAKE算法在FPGA上实现的吞吐率相比,文中实现结构的吞吐率又有提升.     

煤矿井下安全监控分站的设计及其仿真实现

为了设计一种具有低成本、低功耗、易操作、功能强且可靠性高的煤矿井下安全分站,针对煤矿安全生产实际,文章提出了采用MCS-51系列单片机为核心、具有CAN总线通信接口的煤矿井下安全监控分站的设计方案;首先给出煤矿井下安全监控分站的整体构架设计,然后着重阐述模拟量输入信号处理系统的设计过程,最后说明单片机最小系统及其键盘、显示、报警、通信等各个组成部分的设计;为验证设计方案的可行性与有效性,使用Proteus软件对设计内容进行仿真验证,设计的煤矿井下安全监控分站具有瓦斯、温度等模拟量参数超标报警功能和电机开停、风门开闭等开关量指示功能;仿真结果表明:设计的煤矿井下安全监控分站具有一定的实际应用价值.     

View-based model-driven architecture for enhancing maintainability of data access services

In modern service-oriented architectures, database access is done by a special type of services, the so-called data access services (DAS). Though, particularly in data-intensive applications, using and developing DAS are very common today, the link between the DAS and their implementation, e.g. a layer of data access objects (DAOs) encapsulating the database queries, still is not sufficiently elaborated, yet. As a result, as the number of DAS grows, finding the desired DAS for reuse and/or associated documentation can become an impossible task. In this paper we focus on bridging this gap between the DAS and their implementation by presenting a view-based, model-driven data access architecture (VMDA) managing models of the DAS, DAOs and database queries in a queryable manner. Our models support tailored views of different stakeholders and are scalable with all types of DAS implementations. In this paper we show that our view-based and model driven architecture approach can enhance software development productivity and maintainability by improving DAS documentation. Moreover, our VMDA opens a wide range of applications such as evaluating DAS usage for DAS performance optimization. Furthermore, we provide tool support and illustrate the applicability of our VMDA in a large-scale case study. Finally, we quantitatively prove that our approach performs with acceptable response times.     

A pragmatic multi-method investigation of discrepant technological events: Coping,attributions, and ‘accidental’ learning

Discrepant technological events or situations that entail a problem, a misunderstanding or a difficulty with the Information Technology (IT) being employed, are common in the workplace, and can lead to frustration and avoidance behaviors. Little is known, however, about how individuals cope with these events. This paper examines these events by using a multi-method pragmatic approach informed by coping theory. The results of two studies – a critical incident study and an experiment – serve to build and test, respectively, a theoretical model that posits that individuals use a variety of strategies when dealing with these events: they experience negative emotions, make external attributions, and adopt engagement coping strategies directed at solving the event, eventually switching to a disengagement coping strategy when they feel they have no control over the situation. Furthermore, users’ efforts may result in ‘accidental’ learning as they try to overcome the discrepant IT events through engagement coping. The paper ends with a discussion of the results in light of existing literature, future opportunities for research, and implications for practice.     

The Distributed Time-Triggered Simulation Scheme: Core Principles and Supporting Execution Engine

Distributed real-time simulation is a young technology field but its practice is under increasing demands. In recent years the author and his collaborators have been establishing a new approach called the distributed time-triggered simulation (DTS) scheme which is conceptually simple and easy to use but widely applicable. The concept was initiated in the course of developing a new-generation object-oriented real-time programming scheme called the time-triggered message-triggered object (TMO) programming scheme. Some fundamental issues inherent in distributed real-time simulation that were learned during recent experimental studies are discussed along with some approaches for resolving the issues. An execution engine developed to support both the TMOs engaged in control computation and the TMOs engaged in DTS is also discussed along with its possible extensions that will enable significantly larger-scale DTSs.     

Software-Konfigurationsmanagement in großen Softwareprojekten

Zusammenfassung Mit zunehmender Größe der Softwaresysteme verschärfen sich die für die Software-Herstellung typischen Probleme: Beherrschen großer Objektmengen, Erhalten der Systemkonsistenz, Kontrolle der ständigen Änderungseinflüsse und Gewährleisten einer langen Lebensdauer. Die Disziplin Konfigurationsmanagement bildet den methodischen Ansatz, diese Probleme besser zu beherrschen. Software-Konfigurationsmanagement faßt die Herstellung von Softwaresystemen als eine Abfolge von kontrollierten Änderungen an gesicherten Zwischen- und Endergebnissen auf. Dargestellt werden die Objekte und Funktionen des Software-Konfigurationsmanagements sowie die hierfür in großen Software-Projekten benötigten Methoden, Instanzen und Hilfsmittel.     

Information for Authors

正http://www.zju.edu.cn/jzus http://www.springerlink.com Aim The Journals of Zhejiang University-SCIENCE(A/B/C)are edited by the international board of distinguished Chinese and foreign scientists,and are aimed to present the latest developments and achievements in scientific research in China and     

Editorial:Brain-machine interface(BMI) and cyborg intelligence

正Brain-machine interfaces(BMIs)aim at building a direct communication pathway between the brain and an external device,and represent an area of research where significant progress has been made during the past decade.Based on BMIs,mind information can be read out by neural signals to control     

Information for Authors

正http://www.zju.edu.cn/jzus http://www.springerlink.com Aim The Journals of Zhejiang University-SCIENCE(A/B/C)are edited by the international board of distinguished Chinese and foreign scientists,and are aimed to present the latest developments and achievements in scientific research in China and overseas to the world’s scientific circles,especially to stimulate     

SCIENCE CHINA Information Sciences SUBJECT INDEX TO VOLUME 57(2014)

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Information for Authors

正http://www.zju.edu.cn/jzus http://www.springerlink.com Aim The Journals of Zhejiang University-SCIENCE(A/B/C)are edited by the international board of distinguished Chinese and foreign scientists,and are aimed to present the latest developments and achievements in scientific research in China and overseas to the world’s scientific circles,especially to stimulate