The MIFARE Classic story

The MIFARE Classic product from NXP Semiconductors has been much maligned over recent years and whilst some of the criticism is well justified by virtue of the inherent security problems, it is by no means the weakest card/RFID in use today. In this article we give a brief overview of the MIFARE Classic card, its use, design and security. We start by looking at the range of card and RFID products and placing the MIFARE Classic in its intended position. The process of risk assessment is then discussed as a means of choosing “appropriate” products and solutions. We then discuss the history of the MIFARE Classic, its design, security features and associated attacks. The long-lasting effects of the attacks and publicity are considered with respect to not only the MIFARE Classic, but for similar product risk reviews.     

典型三角网格细分算法

介绍7种典型的三角网格细分算法,对各种细分算法在连续性、具备优点及应用状况等几个方面进行比较和归类。为提高三角网格细分效果的可视化程度,将基于功能类机制的状态机模型作为软件运行模式,利用MFC和Open GL实现交互式显示控制,并在此基础上对最具典型意义的Loop算法进行原型实现,给出优化方法。     

经典信息检索模型的分类比较

信息检索的模型,主要是用于检索和排序的计算用户查询请求和信息的匹配程度的问题。目前已有的检索模型有布尔模型、向量模型、概率模型以及以上三个经典模型的变形模型。通过对经典模型进行分析比较,以便在设计具体的检索系统时,根据检索对象的特点,采取合适的检索模型,提高检索效率。     

Generating Classic Mosaics with Graph Cuts

Classic mosaic is an old and durable art form. Generating artificial classic mosaics from digital images is an interesting problem that has attracted attention in recent years. Previous approaches to mosaic generation are largely based on heuristics, and therefore it is harder to analyse, predict and improve their performance. In addition, previous methods have a number of disadvantages, such as requiring that the number of tiles in a mosaic is known a priori, or relying on extensive user interaction, or using heuristics for tile placement that lead to visible artefacts. We propose a classic mosaic generation algorithm that is based on a principled global optimization. Our approach is fully automatic. We design and optimize an objective function that incorporates the desired mosaic properties, such as tile alignment to significant image edges, prohibiting tile overlap, etc. Our optimization method is based on graph cuts, which proved to be a powerful optimization tool in graphics and computer vision. Experimental comparison to previous work demonstrate the advantages of our approach.     

Classic cryptanalysis using hidden Markov models

In this article, the authors present a detailed introduction to hidden Markov models (HMM). They then apply HMMs to the problem of solving simple substitution ciphers, and they empirically determine the accuracy as a function of the ciphertext length and the number of random restarts. Application to homophonic substitutions and other classic ciphers is briefly considered.     

论Word 2003经典教学案例

Word 2003是人们进行文字处理常用软件之一,是《大学计算机文化基础》课程的核心部分.其内容多而散,单独讲解,枯燥无味,无法吸引学生,无法激发学生学习热情,难以保证教学质量.笔者结合多年《大学计算机文化基础》教学经验,总结提出几个较为典型的教学案例,通过案例教学,激发学生对Word的学习兴趣,提高学生Word的学习能力及运用能力,提高教学质量.     

质疑某书AutoCAD精彩应用一例

图1是建筑上的井字梁造型,相信学过AutoCAD的朋友都能绘出来。不过,如何更简捷高效地完成呢?有一本介绍AtuoCAD精彩应用的书是这样做的:     

几种典型区块链共识机制的安全性分析

区块链技术源于比特币的出现,随着比特币和其他数字货币在金融市场的火爆,区块链技术得到了各界的广泛关注。共识机制是区块链技术的核心,区块链上的账本和数据都是共识机制的产物,一旦共识机制的安全性出现问题,区块链的可用性和信用度都将受到严重的打击。本文从共识机制的安全性出发,首先介绍区块链和共识机制的概念,然后对3种典型的区块链共识机制进行对比分析：通过逐一研究针对3种共识机制的攻击方法,对它们的一致性和敌手模型进行对比。最后,指出了目前区块链共识机制安全性分析上的局限性,并明确了未来研究共识机制安全性的方向。     

云计算环境下木马技术研究

该文探讨了木马技术的工作原理和工作方式,分析了经典木马的启动方式、连接方式、运行方式、传播方式、AAV方式等技术。然后进一步分析了木马技术在云计算环境下的最新发展趋势及新的特征。并通过实例来阐明木马犯罪的危害性和严重性。最后该文呼吁加大针对利用木马技术违法犯罪的打击和防范力度。     

还原经典理光GRD降至3699

作为充满神奇色彩的理光GR的数码版,理光GRD深得GR系列之精髓,有着优秀的成像质量与便携性能,深得各届专业摄影人士的追捧,成为诸多资深摄影师首选的单反备机.     

智能计算几种经典算法解析

随着计算机技术的飞速发展,智能计算方法的应用领域也越来越广泛。本文介绍了当前存在的一些智能计算方法,阐述了其工作原理和特点,同时对智能计算方法的发展进行了展望。     

Geogames: Designing Location-Based Games from Classic Board Games

The traditional image of interactive entertainment - games that reduce players' physical involvement to moving a joy stick - is obsolete. Games researchers and designers are already integrating complex movement into games. Location-based games involve body movements beyond figural space - that is, beyond the space of computer screens and small 3D objects. They focus on locomotion in vista space, typically a single room or sports field, or in environmental space, such as a neighborhood or city. Several location-based games have been designed for environmental space using localization technologies such as GPS. Some are adaptations of popular computer games, and others are rather straightforward chase games. A third type of game - what we call challenging location-based games - combines the intellectual and strategic appeal of classic board games with the real-time locomotion and physical involvement of location-based games. Furthermore, a straightforward approach to the spatial mapping of classic board games doesn't work. Instead, we developed the Geogames framework, which uses search techniques to identify a single temporal parameter for balancing sportive versus strategic elements     

智能计算几种经典算法解析

随着计算机技术的飞速发展,智能计算方法的应用领域也越来越广泛。本文介绍了当前存在的一些智能计算方法,阐述了其工作原理和特点,同时对智能计算方法的发展进行了展望。     

粗糙关系查询与经典关系查询的比较

在数据库查询过程中,经典关系数据库查询的是确定的、精确的信息,粗糙集理论在处理不确定性问题时,不需要提供问题所需处理的数据以外的先验信息,所以在处理不确定性信息的关系中应用很广。     

Classic group testing with cost for grouping and testing

We generalize the classical group testing problem to incorporate costs associated with pooling and inspection, both of which are significant factors in actual applications. We formulate the expected cost model as a nonlinear integer programming problem, prove several propositions and a theorem concerning when pooling is more efficient than individual testing, and determine the optimal group size such that the expected cost is minimized.     

中国古典家具设计的功利与伦理

中国古典家具设计在中国甚至世界的设计发展史上占有很高的地位,研究其设计思想对今天的设计能起到一种促进作用。而中国古典家具的功利与伦理这两端的设计精髓反映了不同的哲学内涵,对于指导今天的设计理论有着很好的启示。     

经典位置隐私保护算法分析与研究

在高速发展的信息时代,网络用户的隐私问题正受到普遍关注。而普试算法也正由于它能够为用户提供任何时间、任何地点、任何方式的方便服务使不同网络不同设备的人都得到满足而得到越来越多的应用。因此,我们在普适环境中,基于对位置隐私的分析,本文选取了包括Landmark Objects（LO）、False Dummies（FD）等在内的较为重要的不同位置隐私方法,并对其核心实现机制、特点以及优缺点等进行了分析。在此基础上,本文又对以上方法进行了比较并最终归纳总结了这些方法在面对多种形式攻击时的不足。     

Classic: A hierarchical clustering algorithm based on asymmetric similarities

The nearest neighbors relation (NNR) is defined in terms of a given asymmetric matrix of similarities of data items. This paper presents a new clustering algorithm, called CLASSIC, based on an iteratively defined nested sequence of NNRs. CLASSIC has been applied to various types of gestalt clustering problems. For CLASSIC applications in which asymmetric similarities are not available a priori, this paper also introduces a method for obtaining asymmetric similarities from Euclidean distances. This method has been used in the detection of gestalt clusters by CLASSIC.     

嵌入式系统及其开发领域典型特征分析

分析了嵌入式系统、嵌入式操作系统的典型特征 ,提出了嵌入式系统的典型开发模式 ,描述了典型的宿主机软件交叉开发集成环境、目标机可执行映像及两者之间的关系