基于Paillier加密的数据多副本持有性验证方案

云存储服务中,用户将数据存储在不可信的云储存服务器上,为检查云存储中服务提供商(CSP)是否按协议完整地存储了用户的所有数据副本,提出一种 支持对数据副本进行动态操作 的基于Paillier加密的数据多副本持有性验证方案, 即DMR-PDP方案。该方案为实现多副本检查,将文件块以文件副本形式存储在云服务器上,将各副本编号与文件连接后利用Paillier密码系统生成副本文件以防止CSP各服务器的合谋攻击。利用BLS签名实现对所有副本的批量验证。将文件标志和块位置信息添加到数据块标签中,以保证本方案的安全性,支持对文件的动态更新操作。安全性分析和仿真实验结果表明,该方案在安全性、通信和计算开销方面的性能优于其他文献提出的方案,极大地提高了文件存储和验证的效率,减少了计算开销。     

基于同态hash的数据多副本持有性证明方案

为检查云存储中服务提供商(CSP)是否按协议完整地存储了用户的所有数据副本,在分析并指出一个基于同态hash的数据持有性证明方案安全缺陷的基础上,对其进行了改进和扩展,提出了一个多副本持有性证明方案。为实现多副本检查,将各副本编号与文件连接后利用相同密钥加密以生成副本文件,既有效防止了CSP各服务器的合谋攻击,又简化了用户和文件的授权访问者的密钥管理;为提高检查效率,利用同态hash为数据块生成验证标签,实现了对所有副本的批量检查;为保证方案安全性,将文件标志和块位置信息添加到数据块标签中,有效防止了CSP进行替换和重放攻击。安全性证明和性能分析表明,该方案是正确和完备的,并具有计算、存储和通信负载低,以及支持公开验证等特点,从而为云存储中数据完整性检查提供了一种可行的方法。     

云存储中基于二进制向量索引的密文云数据排序查询方法

设计一种适用于公共云存储环境下的密文云数据排序查询方法,其核心思想是使用二进制向量索引,并且使用Hash函数计算向量元素为1的位置。这种方法使得建立索引向量非常方便,并且更易于建立查询向量以及进行后续数据更新操作。由用户对其文件集构建二进制向量索引,当用户要求访问包含某些关键词的文件时,首先根据查询关键词构建查询二进制向量,然后根据查询二进制向量与文件的索引二进制向量之间的内积判断该文件是否包含用户的查询关键词。根据内积计算结果可知哪些文件的相关性更强,并且内积计算效率高。实验表明,该方法的索引创建与查询效率都非常高。     

医疗大数据隐私保护多关键词范围搜索方案

随着医疗信息系统的急速发展,基于医疗云的信息系统将大量电子健康记录（EHRs）存储在医疗云系统中,利用医疗云强大的存储能力和计算能力对EHRs数据进行安全与统一的管理.尽管传统加密机制可以保证医疗数据在半诚实云服务器中的机密性,但对加密后的EHRs数据执行安全、快速、有效的范围搜索,仍是一个有待解决的关键问题.提出一种支持多关键词范围搜索的可搜索加密方案：利用向量积保持加密机制实现复杂查询结构的可搜索加密,可支持连接关键词查询、范围查询以及通配符的查询;通过随机化构建搜索索引和搜索陷门,实现搜索模式隐藏,达到搜索语句的隐私保护;采用矩阵哈达马积缩小所需密钥矩阵的维度.理论分析和实验结果表明：该方案在达到医疗数据隐私保证的同时,对用户的检索策略也进行了有效的隐私性保护,有效提高了检索效率,降低了创建索引及陷门所用时间,实现了多用户多文件下医疗数据的范围搜索能力.     

增量式多关键字可搜索加密算法

为满足加密文件的多关键字检索需求并解决云存储模式下文件频繁更新导致用户重构安全索引的问题,提出增量式多关键字可搜索加密算法。基于新型的多元素随机布隆过滤器,使用户提交的多个查询关键字被随机哈希并混合,在随机布隆过滤器中得到快速判定。该算法保障数据与查询机密性的同时,保护用户访问模式的隐私性,支持文件的独立更新,有效避免可搜索结构的整体重构,其效率与检索准确率与同类算法相比有较大提高。实验验证了该方案的实用性。     

云存储中支持属性撤销的多关键词可搜索加密方案

云存储的便捷性和管理高效性使得越来越多的用户选择将数据存放在云端。为支持用户对云端加密数据进行检索,提出云存储中基于属性加密支持属性撤销的多关键词搜索方案。采用线性秘密共享矩阵来表示访问控制结构,实现密文细粒度访问控制,在属性撤销过程中不需要更新密钥,应对用户属性变更的情况,在此基础上构造基于多项式方程的搜索算法支持多关键词搜索,从而提高搜索精度。理论分析和实验结果表明,该方案具有陷门不可伪造性和关键词隐私性,能够保证用户数据的隐私和安全,相比CP-ABE方案,具有较高的存储性能和计算效率,功能性更强。     

云存储中一种动态模糊多关键字检索方案

随着云计算技术的迅速发展,云存储的数据安全和隐私保护问题受到了人们密切关注。为了保护用户的隐私数据,云端一般是以密文形式存储文件,给检索带来了不便。为了解决云环境中使用关键字查找密文文件的问题,有必要构建支持隐私保护的安全云存储系统。基于MRSE方案并引入了TF-IDF规则,给出了云环境下动态模糊多关键字排行搜索方案。并将第三方审计机制加入到系统当中,进行文件可持有性验证和密钥管理。     

支持多关键字分级的可搜索同态加密方案

为满足加密文件的多关键字检索需求并解决云存储下用户的隐私与数据安全的问题,提出改进的分级的多关键字可搜索加密方案。该方案保障数据与查询机密性的同时,利用向量空间模型构建可搜索索引,使用同态加密算法进行加解密,支持查询结果的分级检索,有效避免了服务器端返回相关度不大的文件。进一步的安全分析和性能评估表明,该方案在安全性上满足[CCA2]安全,降低了通信开销,也消除了不必要的流量开销。     

加密数据库快速关键词查询技术

为保证敏感信息的数据安全,用户通常会将其加密后存储到云端数据库,这为数据库管理及后续使用增加了难度。提出一种安全查询方案,在不暴露敏感信息的情况下可获得符合查询条件的结果集。使用伪随机函数和Bloom过滤器,对敏感信息的关键词集合进行预处理,在数据库中生成相应的索引数据结构,支持不固定数量的关键词查询与高效的数据更新。查询时,客户端计算出关键词相应的陷门并将其发送给服务器,服务器使用陷门执行查询,将多关键词计算出的陷门进行串接,可将多关键词查询问题转换成单关键词查询问题,并且不提高时间复杂度。此外,有效的陷门只能由拥有密钥的用户产生,陷门不会泄露任何敏感信息,故该方案不依赖完全可信的数据库服务提供商。与现有的采用特殊双层结构的加密方式相比,提高了查询效率,解决了加密数据库处理用户查询请求时的敏感信息泄露问题,且允许用户对敏感信息采用不同的加密方式,具有很强的兼容性。使用TPC-H的数据库测试方案和测试数据进行实验,实验结果证明了算法具有较高的执行效率。     

云计算环境中安全高效的关键词查找方案

针对云计算环境的特点,提出一个安全、高效的关键词查找方案（简称SEKS方案）。SEKS方案不仅能够在不泄露消息内容的情况下,让用户只需取回具有某些关键词的消息,并且能够让CSP参与到解密过程中,进一步减轻解密开销,从而更好地满足用户随时随地享受云计算服务的需求。     

Only connect: teaching, technology and telesis

Abstract This paper describes an approach to the design of interactive multimedia materials being developed in a European Community project. The developmental process is seen as a dialogue between technologists and teachers. This dialogue is often problematic because of the differences in training, experience and culture between them. Conditions needed for fruitful dialogue are described and the generic model for learning design used in the project is explained.     

European Community policy and the market

Abstract This paper starts with some reflections on the policy considerations and priorities which are shaping European Commission (EC) research programmes. Then it attempts to position the current projects which seek to capitalise on information and communications technologies for learning in relation to these priorities and the apparent realities of the marketplace. It concludes that while there are grounds to be optimistic about the contribution EC programmes can make to the efficiency and standard of education and training, they are still too technology driven.     

一种自适应子融合集成多分类器方法

融合集成方法已经广泛应用在模式识别领域,然而一些基分类器实时性能稳定性较差,导致多分类器融合性能差,针对上述问题本文提出了一种新的基于多分类器的子融合集成分类器系统。该方法考虑在度量层融合层次之上通过对各类基多分类器进行动态选择,票数最多的类别作为融合系统中对特征向量识别的类别,构成一种新的自适应子融合集成分类器方法。实验表明,该方法比传统的分类器以及分类融合方法识别准确率明显更高,具有更好的鲁棒性。     

Avoiding semantic and temporal gaps in developing software intensive systems

Development of software intensive systems (systems) in practice involves a series of self-contained phases for the lifecycle of a system. Semantic and temporal gaps, which occur among phases and among developer disciplines within and across phases, hinder the ongoing development of a system because of the interdependencies among phases and among disciplines. Such gaps are magnified among systems that are developed at different times by different development teams, which may limit reuse of artifacts of systems development and interoperability among the systems. This article discusses such gaps and a systems development process for avoiding them.     

Designing economic np control charts: A programmed simulation approach

This paper presents control charts models and the necessary simulation software for the location of economic values of the control parameters. The simulation program is written in FORTRAN, requires only 10K of main storage, and can run on most mini and micro computers. Two models are presented - one describes the process when it is operating at full capacity and the other when the process is operating under capacity. The models allow the product quality to deteriorate to a further level before an existing out-of-control state is detected, and they can also be used in situations where no prior knowledge exists of the out-of-control causes and the resulting proportion defectives.     

The development of robot art

Going through a few examples of robot artists who are recognized worldwide, we try to analyze the deepest meaning of what is called “robot art” and the related art field definition. We also try to highlight its well-marked borders, such as kinetic sculptures, kinetic art, cyber art, and cyberpunk. A brief excursion into the importance of the context, the message, and its semiotics is also provided, case by case, together with a few hints on the history of this discipline in the light of an artistic perspective. Therefore, the aim of this article is to try to summarize the main characteristics that might classify robot art as a unique and innovative discipline, and to track down some of the principles by which a robotic artifact can or cannot be considered an art piece in terms of social, cultural, and strictly artistic interest. This work was presented in part at the 13th International Symposium on Artificial Life and Robotics, Oita, Japan, January 31–February 2, 2008     

Explanation and prediction: an architecture for default and abductive reasoning

Although there are many arguments that logic is an appropriate tool for artificial intelligence, there has been a perceived problem with the monotonicity of classical logic. This paper elaborates on the idea that reasoning should be viewed as theory formation where logic tells us the consequences of our assumptions. The two activities of predicting what is expected to be true and explaining observations are considered in a simple theory formation framework. Properties of each activity are discussed, along with a number of proposals as to what should be predicted or accepted as reasonable explanations. An architecture is proposed to combine explanation and prediction into one coherent framework. Algorithms used to implement the system as well as examples from a running implementation are given.     

Three Process Perspectives: Organizations, Teams, and People

This paper provides the author's personal views and perspectives on software process improvement. Starting with his first work on technology assessment in IBM over 20 years ago, Watts Humphrey describes the process improvement work he has been directly involved in. This includes the development of the early process assessment methods, the original design of the CMM, and the introduction of the Personal Software Process (PSP)^SM and Team Software Process (TSP){^SM}. In addition to describing the original motivation for this work, the author also reviews many of the problems he and his associates encountered and why they solved them the way they did. He also comments on the outstanding issues and likely directions for future work. Finally, this work has built on the experiences and contributions of many people. Mr. Humphrey only describes work that he was personally involved in and he names many of the key contributors. However, so many people have been involved in this work that a full list of the important participants would be impractical.     

基于复小波噪声方差显著修正的SAR图像去噪

提出了一种基于复小波域统计建模与噪声方差估计显著性修正相结合的合成孔径雷达(Synthetic Aperture Radar,SAR)图像斑点噪声滤波方法。该方法首先通过对数变换将乘性噪声模型转化为加性噪声模型,然后对变换后的图像进行双树复小波变换(Dualtree Complex Wavelet Transform,DCWT),并对复数小波系数的统计分布进行建模。在此先验分布的基础上,通过运用贝叶斯估计方法从含噪系数中恢复原始系数,达到滤除噪声的目的。实验结果表明该方法在去除噪声的同时保留了图像的细节信息,取得了很好的降噪效果。     

How do children do mathematics with LOGO?

Abstract  This paper considers some results of a study designed to investigate the kinds of mathematical activity undertaken by children (aged between 8 and 11) as they learned to program in LOGO. A model of learning modes is proposed, which attempts to describe the ways in which children used and acquired understanding of the programming/mathematical concepts involved. The remainder of the paper is concerned with discussing the validity and limitations of the model, and its implications for further research and curriculum development.