云计算环境下基于属性的撤销方案

针对云环境下密文策略属性基加密共享数据的访问权限撤销问题,提出了基于属性的撤销方案。方案中可信第三方从带有全局标识的用户属性集中查找满足密文访问结构的属性集,为该交集中的每个属性生成带有相同全局标识的密钥组件,通过组合密钥组件生成用户私钥。当发生撤销时,更新撤销用户属性的密钥组件并分发给拥有该属性的其他用户,同时生成对应的重加密密钥来对密文重加密。安全性分析和实验表明,本方案是选择明文攻击安全的,能有效实现属性的即时撤销,解决多授权结构密钥分发的同步问题。采用hash函数可使密文长度达到常数级,进一步减少资源开销,满足实际云环境中属性安全撤销的应用需求。     

一种支持属性撤销的外包属性加密方案

针对传统基于密文策略的属性加密方案在密钥生成、密文解密和属性撤销阶段计算开销大的问题,提出一种具有属性撤销功能的外包属性加密方案。在加密过程中使用线性秘密共享机制作为访问结构,将密钥生成和密文解密的部分计算外包,通过为每个用户的私钥设置版本号实现用户属性的撤销,同时证明方案在可重复的选择密文攻击下是安全的。实验结果表明,该方案的计算开销较低,并且能较好地实现密文策略的属性撤销功能。     

基于访问控制和中国剩余定理的数据库密钥管理方案的研究

针对密文数据库中数据项加密时会出现数据项密钥量大和安全需求高的问题,通过引入中国剩余定理来管理数据项密钥,提出了一种新的基于访问控制和中国剩余定理的密钥管理方案。当用户申请用户密钥时,密文数据库可以将用户u_i能够访问的大量数据项对应的密钥K_i"合成"用户密钥uki并保存;当用户ui提供用户密钥uk_i和密文查询请求CQR访问密文数据库时,系统会根据系统表和中国剩余定理将用户密钥uk_i再分解成数据项密钥K_i,用户就可以解密数据。该方案不仅实现了对用户访问权限的管理,还解决了大量数据项密钥带来的数据处理时间长、占用系统资源多等问题,提高了密文数据库中密钥管理的效率和安全性。论文最后实现了该密钥管理方案,并对比分析了该方案的安全性。     

隐藏访问结构的密文策略的属性基加密方案

在密文策略的属性基加密方案中,用户的私钥与属性集合关联,密文与访问策略关联,当且仅当用户私钥中所包含的属性满足嵌入在密文中的访问策略时,用户方能成功解密该密文。在现有方案的解密过程中,访问策略连同密文被发送给解密者,这意味着加密者的隐私被泄露。为解决该问题,提出了具有隐藏访问策略的密文策略属性基加密方案,以保护加密者的隐私;并基于DBDH假设,证明了该方案在标准模型中是选择明文安全的。     

基于安全三方计算的密文策略加密方案

针对现有密文策略属性加密方案存在用户密钥易泄露的问题,提出一种基于安全三方计算协议的密文策略方案。通过属性授权中心、云数据存储中心及用户之间进行安全三方计算构建无代理密钥发布协议,使用户端拥有生成完整密钥所必需的子密钥。安全分析表明,该方案能够有效消除单密钥生成中心及用户密钥在传输给用户过程中易泄露所带来的威胁,增强用户密钥的安全性。     

基于代理的即时属性撤销KP-ABE方案

属性撤销是属性基加密方案在实际应用中亟须解决的问题,已有支持间接撤销模式的可撤销属性基加密方案存在撤销延时或需要更新密钥及密文等问题。为此,提出一种间接模式下基于代理的支持属性即时撤销的密钥策略属性基加密方案,该方案不需要用户更新密钥及重加密密文,通过在解密过程中引入代理实现撤销管理,减轻了授权机构的工作量,其要求代理为半可信,不支持为撤销用户提供访问权限及解密密文。分析结果表明,该方案支持细粒度访问控制策略,并且可以实现系统属性的撤销、用户的撤销及用户的部分属性撤销。     

支持访问策略隐藏和密钥追踪的轻量级医疗数据共享方案

在传统的密文策略属性基加密(Ciphertext-Policy Attribute-Based,CP-ABE)方案中,访问策略是显式存在的,这可能会泄露数据所有者的隐私,在医疗场景中会给数据所有者带来潜在的安全隐患,因此支持访问策略隐藏的方案被陆续提出.但是多数方案在实现解密测试的过程中需要生成冗余密文或密钥组件,增加...     

基于密文策略属性加密的云存储访问控制方案

针对现有方案存在的访问策略公开、密文存储开销较大的问题,提出一种支持策略隐藏且固定长度密文的云存储访问控制方案,并在安全模型下证明方案可抵抗选择明文攻击。方案中用户私钥由多个授权机构共同生成,中央授权机构不参与生成任何主密钥与属性私钥;访问结构隐藏在密文之中,恶意用户无法通过访问结构获取敏感信息。此外,方案实现了固定密文长度,并且加密时的指数运算和解密时的双线性对运算次数均是固定值。最后,理论分析和实验结果表明该方案在密文长度和加解密时间上都明显优于对比方案。     

固定密文长度的可验证属性基外包解密方案

传统密钥策略属性基加解密方案存在密文长度随着属性增加而线性增加,在通信过程中消耗用户大量的通信带宽的缺点。提出了属性加密的改进方案,基于密钥策略属性加密,提出具有固定密文长度的可验证外包解密方案,在非单调访问结构实现密文长度固定,有效节省通信带宽,通过对外包密钥生成算法的改进,实现一次模指数运算,有效缩短外包密钥生成时间。通过运用哈希函数,实现外包解密的验证性,并对其安全性进行了证明。     

基于KP-ABE算法的云存储可验证安全删除方案

通过云存储将数据外包至远程服务器能够减轻本地负担,但由于云服务器不完全可信,当存储在云端的数据需要被删除时,缺乏有效的确定性删除机制可能导致隐私泄露等安全问题.为实现确定性删除,提出基于密钥策略属性加密算法(Key Policy Attribute-based Encryption,KP-ABE)的云存储可验证安全删除方案.该方案将外包数据与属性关联产生密文,以布尔电路构造访问结构生成私钥;通过撤销访问数据必需的属性使得被删除数据不可恢复,利用多分支路径树实现删除的可验证性.安全性分析证明了该方案在选择明文攻击下的安全性.进一步实验表明,该方案能够有效实现云数据细粒度访问控制和可验证删除,证实了其实用性.     

Call for Papers The 6^th International Conference on Grid and Cooperative Computing

Recent years have seen rapid advances in various grid-related technologies, middleware, and applications. The GCC conference has become one of the largest scientific events worldwide in grid and cooperative computing. The 6th international conference on grid and cooperative computing (GCC2007) Sponsored by China Computer Federation (CCF),Institute of Computing Technology, Chinese Academy of Sciences (ICT) and Xinjiang University ,and in Cooperation with IEEE Computer Soceity ,is to be held from August 16 to 18, 2007 in Urumchi, Xinjiang, China.     

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.     

法律信息库系统

本文分析了法律数据库的结构和特点，介绍了采用面向对象设计方法和超文本数据库技术开发和实现法律信息库系统将作为重要网络资源之一为不同用户进行法律咨询服务。     

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.     

International Journal of Automation and Computing Table of Contents

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Information for authors

正SCIENCE CHINA Information Sciences(Sci China Inf Sci),cosponsored by the Chinese Academy of Sciences and the National Natural Science Foundation of China,and published by Science China Press,is committed to publishing highquality,original results of both basic and applied research in all areas of information sciences,including computer science and technology;systems science,control science and engineering(published in Issues with odd numbers);information and communication engineering;electronic science and technology(published in Issues with even numbers).Sci China Inf Sci is published monthly in both print and electronic forms.It is indexed by Academic OneFile,Astrophysics Data System(ADS),CSA,Cabells,Current Contents/Engineering,Computing and Technology,DBLP,Digital Mathematics Registry,Earthquake Engineering Abstracts,Engineering Index,Engineered Materials Abstracts,Gale,Google,INSPEC,Journal Citation Reports/Science Edition,Mathematical Reviews,OCLC,ProQuest,SCOPUS,Science Citation Index Expanded,Summon by Serial Solutions,VINITI,Zentralblatt MATH.     

Erratum to: Fast global kernel fuzzy c-means clustering algorithm for consonant/vowel segmentation of speech signal

正Erratum to:J Zhejiang Univ-Sci C(ComputElectron)2014 15(7):551-563doi:10.1631/jzus.C1300320The original version of this article unfortunately contained mistakes.Algorithm 6 should be as follows:Algorithm 6 FGKFCM-F clustering Input:(1)X={x_1,x_2,…,x_N},,x_iR~d,i=1,2,…,N,the dataset;(2)C,1C≤N,the number of clusters;(3)ε0,the stopping criterion;     

Journal of Zhejiang University-SCIENCE C (Computers & Electronics) Total contents

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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.