基于Shamir门限秘密分享的图像可视加密算法

采用Shamir门限秘密分享方案,提出一种带有认证功能的图像可视加密算法。该算法主要思想是,先将二值秘密图像分块得到数据,然后使用Shamir的门限秘密共享方案得到子秘密数据,同时用SM2签名算法对秘密图像进行签名,并将分享数据和签名信息嵌入载体图像。还原时需要指定张数的子秘密图像进行信息的提取、还原与认证。仿真实验结果表明,该秘密图像分享方案提高了秘密图像存储与传输的安全性。     

基于预测误差双重编码的大容量密文域可逆信息隐藏算法

针对目前密文域可逆信息隐藏算法嵌入容量较小的问题,提出了基于预测误差双重编码的大容量密文域可逆可分离信息隐藏算法。首先为了预留秘密信息的嵌入空间,图像拥有者利用基于预测误差的哈夫曼编码及扩展游程编码对图像进行预处理,然后加密图像;数据嵌入者在加密后的图像中嵌入秘密信息;接收者根据信息隐藏密钥可以准确无误地提取秘密信息,根据解密密钥可以无损恢复图像,两者无顺序要求。实验结果表明,预测误差双重编码的应用有效地提高了嵌入容量。     

一种保序加密域数据库认证水印算法

加密域水印技术适用于云环境下的隐私保护（加密）和数据安全认证（加水印）.通过结合保序加密、离散余弦变换、密码哈希和数字水印技术,提出了加密域数据库认证水印算法.首先对数据进行保序加密,以达到对敏感数据内容的隐私保护;对加密后的数据进行分组和离散余弦变换处理,然后将交流系数的哈希（Hashing）值作为认证信息嵌入到直流系数中来认证数据的完整性;可通过比对交流系数的哈希值和从直流系数中提取的水印信息,来判断加密数据是否受到篡改.水印嵌入设计很好地结合了保序加密的特性,使得对加密数据的水印嵌入不会影响到明文数据的正确恢复,利用密钥对加水印的加密数据库直接解密可得到原数据库.实验结果表明：所提出的算法不仅能够用于保护数据库中的内容隐私,而且能检测出不同程度的篡改和有效认证数据库数据的完整性.     

信息预处理的加密域大容量可逆图像信息隐藏

采用数独变换和Arnold变换对原始图像加密，完全保留了图像的冗余空间。嵌入过程中，利用DES加密算法对信息进行了压缩预处理，平均压缩了1.5倍；采用最高有效位算法将压缩后的信息嵌入载密图像。接收者采用异或运算提取出秘密信息，同时根据误差值完全恢复载体图像。实验表明，提出的方法不仅能够实现大容量信息可逆隐藏，而且还能完全重构载体图像，是一种可以广泛应用的加密域信息隐藏方法。     

基于图像秘密共享的密文域可逆信息隐藏算法

针对当前密文域可逆信息隐藏算法嵌入秘密信息后的携密密文图像的容错性与抗灾性不强,一旦遭受攻击或损坏就无法重构原始图像与提取秘密信息的问题,提出了一种基于图像秘密共享的密文域可逆信息隐藏算法,并分析了该算法在云环境下的应用场景。首先,将加密图像分割成大小相同的n份不同携密密文图像。然后,在分割的过程中将拉格朗日插值多项式中的随机量作为冗余信息,并建立秘密信息与多项式各项系数间的映射关系。最后,通过修改加密过程的内置参数,实现秘密信息的可逆嵌入。当收集k份携密密文图像时,可无损地恢复原始图像与提取秘密信息。实验结果表明,所提算法具有计算复杂度低、嵌入容量大和完全可逆等特点。在（3,4）门限方案中,所提算法的最大嵌入率可达4 bpp;在（4,4）门限方案中,其最大嵌入率可达6 bpp。所提算法充分发挥了秘密共享方案的容灾特性,在不降低秘密共享安全性的基础上,增强了携密密文图像的容错性与抗灾性,提高了算法的嵌入容量与云环境应用场景下的容灾能力,保证了载体图像与秘密信息的安全。     

同态公钥加密系统的图像可逆信息隐藏算法

同态加密技术在加密信息、对信息进行隐私保护的同时,还允许密文数据进行相应的算术运算(如云端可直接对同态加密后的企业经营数据进行统计分析),已成为云计算领域的一个研究热点.然而,由于云存在多种安全威胁,加密后信息的安全保护和完整性认证问题仍然突出.另外,信息在加密后丢失了很多特性,密文检索成为了云计算需要攻克的关键技术.为了实现对加密图像的有效管理及其安全保护,本文提出了一种基于同态加密系统的图像可逆信息隐藏算法.该算法首先在加密前根据密钥选择目标像素,并利用差分扩展DE(Difference Expansion)的方法将目标像素的各比特数据嵌入到其它像素中.然后,利用Paillier同态加密系统对图像进行加密得到密文图像.在加密域中,利用待嵌入信息组成伪像素,加密后替换目标像素,完成额外信息的嵌入.当拥有相应的密钥时,接收方可以分别在密文图像或明文图像中提取出已嵌入的信息.当图像解密后,通过提取出自嵌入目标像素的各比特数据来恢复原始图像.实验仿真结果表明,该算法能够在数据量保持不变的前提下完成同态加密域中额外信息的嵌入,信息嵌入快速高效,并可分别从加密域和明文域中提取出嵌入的信息.     

基于位平面循环异或的加密图像可逆信息隐藏

针对密文图像可逆信息隐藏中存在信息嵌入率不高的问题,提出一种基于图像位平面循环异或的可逆信息隐藏算法.将图像高位平面和其相邻的位平面依次循环异或构造新的图像,利用块重排列对新图像的位平面进行无损压缩以便腾出空间,对压缩后的图像进行加密之后在腾出的空间位置嵌入额外的秘密信息.接收方接收含有秘密信息的加密图像后,根据需求可以对图像进行可分离式的提取信息和无损恢复原始图像.实验结果表明,通过循环异或操作后的图像位平面更适合无损压缩,算法的嵌入容量得到显著提升.     

一种基于GF(23)的(K,N)有意义无扩张图像分存方案

传统有意义图像分存存在像素扩张,通常只对分存信息以较短的认证信息进行甄别,从而导致重构的秘密像素真实性无法准确鉴别。针对此问题,提出一种基于GF(2³)的(K,N)有意义无扩张图像分存方案。在该方案中,首先生成加密映射表并利用秘密像素的位置信息对秘密像素进行加密;然后将秘密像素的认证信息和加密像素在GF(2³)有限域下进行(K,N)分存,嵌入到掩体图像对应的像素中;最后将映射表的生成密钥进行(K,N)分存,计算每个子密钥的MD5值并公布到第3方公信方以防止掩体图像持有者作弊。实验结果表明,所提方案能准确地识别出秘密图像攻击区域,不存在任何像素扩张,掩体图像与秘密图像等大且嵌入分存信息的掩体图像具有较好的视觉质量。     

基于回归型支持向量机的医学图像可视可逆水印算法

随着医学影像技术的发展,医学图像成为医生诊断患者病情的主要依据,为了给患者提供更为准确的诊断和最佳的治疗方案,医学图像共享和专家远程诊断成为重要的诊疗手段。未被保护的医学图像在传输过程中易受到攻击或恶意篡改,为有效保护医学图像信息的完整性并限制未授权用户的使用,提出了一种基于回归型支持向量机的医学图像可视可逆水印算法。该算法首先将可视水印嵌入医学图像中;其次利用回归型支持向量机对水印图像的像素值进行预测,并计算出预测误差,利用纹理度等级自适应确定合适的亮度调节阈值,根据阈值生成一幅全局定位图,将全局定位图加入到原始图像中,以增强算法的鲁棒性;最后利用全局定位图和预测误差之间的相互关系生成一个可视可逆的水印,从而对医学图像进行加密保护。实验结果表明,所提可视可逆算法不仅可应用于传统医学图像,还首次应用于弥散加权图像,且该算法具有较好的鲁棒性和可逆性,能有效避免像素点溢出问题,实现可逆水印的正确提取,提取水印后的图像与原始图像没有任何差异。在水印信息未知的情况下,可视可逆水印去除困难,该特性可有效保护患者信息的完整性和医学图像的权威性。     

结合Kd-树和熵编码的密文图像可逆数据隐藏

目的 密文图像可逆数据隐藏技术既可以保证载体内容不被泄露,又可以传递秘密信息,在军事、医疗等方面发挥着重要的作用。然而,以往的大多数方法存在图像冗余未被充分利用、数据嵌入容量不足等问题。为解决这些问题,提出了一种结合Kd-树和熵编码的高容量密文图像可逆数据隐藏算法。方法 该方法在图像加密之前需要对图像应用中值边缘检测(median-edge detector,MED)算法计算预测误差,并把得到的预测误差绝对值图像划分为两个区域:S0区域和S1区域。根据Kd-树标签算法和熵编码生成辅助信息,在对图像使用加密密钥K_e加密之后嵌入辅助信息,生成加密图像;在秘密数据嵌入阶段,根据附加信息和数据隐藏密钥嵌入秘密数据,生成载密图像;在解密阶段可以根据附加信息、图像加密密钥和数据隐藏密钥提取秘密数据并无损恢复图像。结果 实验测试了BOWS-2(break our watermarking system 2nd)数据集,平均嵌入容量为3.910 bit/像素。与现有的几种方法进行比较,该算法可以获得更高的秘密数据嵌入容量。结论 该方法在图像加密前腾出空间,与相关算法相比,实现了更高的嵌入容量,并且可以实现原始图像的无损恢复。     

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.