数字影院中数字版权管理系统的研究与实现

分析了数字影院系统和数字版权管理(DRM)技术的特点,介绍了一套应用于数字影院的DRM系统。该系统采用多种内容安全保护机制,结合了加密技术、数字签名技术、版权描述语言、授权管理和分发技术等安全技术,可对用户进行授权和权限管理,保护了数字电影的机密性和完整性。     

一种新的DRM权限跟踪模型*

提出的基于身份的DRM权限跟踪模型,即授权用户可以在不同的设备上播放数字内容,提高了互操作性。内容服务器对数字内容部分加密,未加密部分嵌入数字水印。部分加密在保证安全的基础上,减小了计算复杂度。数字水印有双重功能：一是标志该内容受保护;二是颁发许可证依据,许可证服务器根据检测到的水印信息向用户颁发相应的许可证。数字水印是对用户使用权限的定义,数字水印的加载,实现了对数字内容整个生命周期的权限跟踪。分析表明该模型具有很好的安全性和有效性。     

一种基于虹膜特征的数字内容安全接入控制方法研究

提出了一种基于虹膜生物特征的数字内容安全接入控制方案.该方案结合了虹膜生物识别系统与数字签名等技术来提高接入控制的安全性.为了克服以往数字签名的缺点,采用了基于虹膜特征的PKI技术签名方法.系统中客户端将实时采集的虹膜代码传输到认证服务器进行处理,认证服务器能进行安全的用户身份决策,并能在硬件安全模块中进行签名.理论分析表明了提出的方案能有效增强数字内容接入控制的安全性,亦能克服一般PKI技术中密钥管理困难等问题.     

工作流环境下数字内容保护系统研究与实现

针对目前工作流系统中对敏感数字内容缺乏有力的安全保护的问题,研究并实现了一种在工作流环境下敏感数字内容流转安全保护系统。该系统基于数字版权管理系统(DRM)紧密结合工作流系统,通过使用并扩展工作流过程定义语言XPDL,使得数字版权管理系统能够充分利用工作流流程信息,解决了数字内容权限与工作流系统动态连接问题,从而实现了在不安全的网络环境下数字内容的安全分发与流转。     

描述用户行为的数字权限时序描述逻辑系统

数字权限管理技术（DRM）的核心是权限描述,而基于动作序列的权限描述模型主要是描述数字产品消费者（用户）允许产生的动作序列,通过动作序列分析,可跟踪权限的执行过程,方便地限制和预测用户在数字内容消费过程中的行为并审计其合理性。文章提出一种基于时序描述逻辑的逻辑推理系统,该系统不仅可以表达用户行为的静态特征,而且可以刻画用户行为之间的时序关系。     

基于Windows Media SDK的DRM系统开发

随着网络的发展，数字媒体文件的盗版问题的日益泛滥，Microsoft Windows Media9在编码过程中提供了对数字权限管理（DRM）的支持，可实现对数字媒体文件的加密保护。该文简要介绍了Microsoft的DRM技术原理及工作流程，叙述了如何采用DRM技术保护网站上的音频和视频资料。重点描述了如何基于Windows Media Rights Manager SDK创建认证服务器，提供认证许可的发放及身份的验证，如何基于Windows Media Encoder SDK创建一个数字权限管理（DRM）系统来生成密钥、打包、加密和发行数字媒体内容。     

一种可信计算支持的DRM系统及其安全协议研究

数字版权管理(Digital Rights Management,DRM)系统旨在端到端地保护数字内容的可控使用,然而客户端平台的安全隐患使得数字内容的合理使用受到威胁.在研究可信计算技术的基础上,提出可信计算技术与DRM系统相结合的可信DRM系统的一般结构,并重点阐述了可信计算技术在许可证分发和数字内容使用两个重点环节中的应用.进一步地,设计并提出一个可信DRM系统的身份认证及密钥协商协议,并给出其安全性分析.该协议实现许可证服务器对DRM客户端的身份认证及完整性验证,并产生共享密钥保护数字版权的发放.     

多媒体社交网络中的数字内容安全分发研究

多媒体社交网络(Multimedia Social Networks, MSN)的出现与快速发展,使用户间的信息交换与共享变得更 加便利,而随意分发受版权法律保护的数字内容的现象也愈演愈烈。这种开放式网络环境下的数字版权管理(Digital Rights Management, DRM)问题已成为目前的一个开放问题和重要挑战。针对社交网络用户节点间的数字内容共享 与传播行为,并基于支持可信验证代理方的远程证明,提出了多媒体社交网络环境下的数字内容分发体系框架及其安 全协议。与现有典型DRM方案的对比分析表明,新方案结合可信计算高安全性的用户终端平台,实现了安全增强、 可信、可控的数字版权保护机制,从而满足了用户终端平台的隐私保护需求。     

一个面向家庭网络的数字版权管理系统

随着消费电子产品的普及,家庭网络逐渐流行,但与此同时网络上数字内容的侵权问题也非常严重.提出了一种对家庭网络内数字内容进行版权保护的数字版权管理(DRM)系统.系统中,家庭网关设备负责管理家庭网络内的所有用户电子设备,并作为它们的代理与外部DRM服务器交互,以执行DRM功能.系统采用的组密钥技术可使得经过加密的数字内容只有合法用户设备才能解密并使用,而通过数字内容在用户设备之间的超级分发可实现家庭网络内的内容共享.     

基于智能卡的数字电影版权管理系统

提出了基于智能卡的数字电影版权管理方案。该方案将密钥数据存储于智能卡中并且解密运算全在卡内完成,与通用的软件方案相比提高了系统的安全性,用户认证时使用的是卡内信息而非用户信息或设备信息,不仅保护了用户隐私,还实现了权力转移的功能。开发了基于智能卡的数字电影DRM系统,实现了数字电影加密分发、授权和权利转移等系统功能,满足了数字电影版权保护的安全需求。     

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。     

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.     

Editorial: Special issue on recent advances in hybrid control theory and applications

正The demands of a rapidly advancing technology for faster and more accurate controllers have always had a strong influence on the progress of automatic control theory.In recent years control problems have been arising with increasing frequency in widely different areas,which cannot be addressed using conventional control techniques.The principal reason for this is the fact that a highly competitive economy is forcing systems to operate in regimes where     

Information for Authors

正Aim The Journals of Zhejiang University-SCIENCE(A/B/C)areedited by the international board of distinguished Chinese andforeign scientists,and are aimed to present the latest devel-opments and achievements in scientific research in China andoverseas to the world’s scientific circles,especially to stimulateand promote academic exchange between Chinese and for-eign scientists everywhere.     

Enhancing a leaf radiative transfer model to estimate concentrations and in vivo specific absorption coefficients of total carotenoids and chlorophylls a and b from single-needle reflectance and transmittance

The relative concentrations of different pigments within a leaf have significant physiological and spectral consequences. Photosynthesis, light use efficiency, mass and energy exchange, and stress response are dependent on relationships among an ensemble of pigments. This ensemble also determines the visible characteristics of a leaf, which can be measured remotely and used to quantify leaf biochemistry and structure. But current remote sensing approaches are limited in their ability to resolve individual pigments. This paper focuses on the incorporation of three pigments—chlorophyll a, chlorophyll b, and total carotenoids—into the LIBERTY leaf radiative transfer model to better understand relationships between leaf biochemical, biophysical, and spectral properties.Pinus ponderosa and Pinus jeffreyi needles were collected from three sites in the California Sierra Nevada. Hemispheric single-leaf visible reflectance and transmittance and concentrations of chlorophylls a and b and total carotenoids of fresh needles were measured. These data were input to the enhanced LIBERTY model to estimate optical and biochemical properties of pine needles. The enhanced model successfully estimated reflectance (RMSE = 0.0255, BIAS = 0.00477, RMS%E = 16.7%), had variable success estimating transmittance (RMSE = 0.0442, BIAS = 0.0294, RMS%E = 181%), and generated very good estimates of carotenoid concentrations (RMSE = 2.48 µg/cm², BIAS = 0.143 µg/cm², RMS%E = 20.4%), good estimates of chlorophyll a concentrations (RMSE = 10.7 µg/cm², BIAS = − 0.992 µg/cm², RMS%E = 21.1%), and fair estimates of chlorophyll b concentrations (RMSE = 7.49 µg/cm², BIAS = − 2.12 µg/cm², RMS%E = 43.7%). Overall root mean squared errors of reflectance, transmittance, and pigment concentration estimates were lower for the three-pigment model than for the single-pigment model. The algorithm to estimate three in vivo specific absorption coefficients is robust, although estimated values are distorted by inconsistencies in model biophysics. The capacity to invert the model from single-leaf reflectance and transmittance was added to the model so it could be coupled with vegetation canopy models to estimate canopy biochemistry from remotely sensed data.     

Mr. Twinn’s bombes

This article discusses the history and design of the special versions of the bombe key-finding machines used by Britain’s Government Code & Cypher School (GC&CS) during World War II to attack the Enigma traffic of the Abwehr (the German military intelligence service). These special bombes were based on the design of their more numerous counterparts used against the traffic of the German armed services, but differed from them in important ways that highlight the adaptability of the British bombe design, and the power and flexibility of the diagonal board. Also discussed are the changes in the Abwehr indicating system that drove the development of these machines, the ingenious ways in which they were used, and some related developments involving the bombes used by the U.S. Navy’s cryptanalytic unit (OP-20-G).