Distributed key management for dynamic groups in MANETs

Most existing solutions to group security in Mobile Ad Hoc Networks (MANETs) rely on a multicast Core Based Tree (CBT) for key distribution. Such solutions, although suitable for systems with low mobility and static characteristics, are unsuitable for dynamic and sparse groups with changing neighborhoods. In this paper, we propose an entirely decentralized key generation mechanism, employing a central trusted entity only during initialization. Using our approach, keys can be established between group members with absolutely no prior communication. The solution relies on threshold cryptography and introduces a novel concept of Node-Group-Key (NGK) mapping. We have provided an extensive analytical model for the computations involved and communication costs and have also provided a lie detection mechanism. Simulation results show appreciable performance improvement and enhanced robustness.     

用视觉创造和谐——试析城市公共视觉传达设计

近年来,随着经济的快速发展和人们公共意识的不断增强,公共广告、公共标识的设计越来越受到广泛的关注。城市公共视觉传达设计研究对于当前的城市化建设、树立城市品牌具有很强的现实意义,它不仅需要我们在理论层面进行研究,更加应该重视它的实际运用。     

安迪·沃霍尔:消费社会的巫师

安迪·沃霍尔用机械复制的手法去表达他所要表达的内容,丝网作业法就是他要消除艺术家的个人手法的一种方法,"重复"和"挪用"被他用到了无以复加的地步。在消费社会高度发展的时代,安迪·沃霍尔用大众文化挑战了大众文化,但他的艺术成为了"批评性的艺术"。艺术进入大众文化,并不等于说它本身就是大众文化了,本文试图从安迪·沃霍尔的艺术入手来探讨艺术与消费社会的关系。     

城市公共空间中的危险性辨识

从城市公共空间的概念入手,对城市公共空间中的道路设置、铺装设置、公共设施以及植物配置方面存在的危险、有害因素进行分析、辨识;通过这个总结性研究有助于提出合理可行的设计方案,对有效地预防事故发生,减少财产损失和人员伤亡、伤害,降低事故发生率,具有很好的借鉴作用。     

SunOS下基于一次性口令和封装保护的网络安全设计与实现

多数网络守护神的实现很少考虑全球性访问的卷入问题,在某些情形下,这样的访问可允许灵敏信息的全球发布,如加密口令。在其它情形下,运行在网络任何地方的进程都会引起局部变化。针对可能出现的这些问题,在SumOS环境下,在防火墙上实施一次性口令认证以及封装保护措施,主些措施实现起来比较容易,而且可增强网络的安全性。     

一种稳健的公开数字图像水印技术

提出一种稳健的公开图像水印技术。随机选取若干象素点及其邻域,通过量化象素与邻域的均值之差来隐藏水印信息。实验表明,该方法简单、高效、安全性能好,且具有较好的不可感知性,对通常的图像处理及JPEG压缩等具有极好的稳健性。     

Cryptography Regulations for E-commerce and Digital Rights Management.

Strong encryption is an urgent need for e-commerce development, as it allows the privacy and secure transactions of the financial data. International regulations must allow the spreading of e-commerce and the associated encryption products, in order to establish a secure e-commerce environment that customers can trust and allowing an international deployment of e-commerce solutions without restrictions.     

A new approach to input device key design using fingerprints

A new approach to designing input device keys is proposed, and a TV remote controller is used as an example to demonstrate the new approach for studying the relationship between fingerprints and key geometry. One hundred subjects' fingerprints of thumbs and index fingers of both hands were collected, and a computer program was used for converting the fingerprint to a bitmap form. Subsequently, the data were analysed to provide some guidelines for determining the key size and key shape for the input device. Finally, the fingerprints were used to study the pattern of finger press and the justification for keycap curvature for finger placement. The results showed that the new approach can be useful in guiding designers of input device keys. A further benefit of this study is in providing a more systematic approach with considerable general potential for studying input device keys.     

Time-Constrained Keyframe Selection Technique

In accessing large collections of digitized videos, it is often difficult to find both the appropriate video file and the portion of the video that is of interest. This paper describes a novel technique for determining keyframes that are different from each other and provide a good representation of the whole video. We use keyframes to distinguish videos from each other, to summarize videos, and to provide access points into them. The technique can determine any number of keyframes by clustering the frames in a video and by selecting a representative frame from each cluster. Temporal constraints are used to filter out some clusters and to determine the representative frame for a cluster. Desirable visual features can be emphasized in the set of keyframes. An application for browsing a collection of videos makes use of the keyframes to support skimming and to provide visual summaries.     

Preferred VDT workstation settings, body posture and physical impairments

In a field study an adjustable VDT workstation was given to each of the 68 operators for one week. The preferred settings, the body postures and subjective evaluations were assessed during normal working activities of the operators. The preferred ranges disclose the following figures: keyboard height (home row above floor) 71-87 cm, screen height (centre above floor) 92-116 cm, viewing angles (eye to screen centre) + 2 to -26 degrees, visual distance (eye to screen) 61-93 cm. There was practically no correlation between preferred settings and anthropometric data of body length or eye levels above floor. The study of body postures revealed that the great majority of operators tend to lean backwards with trunk inclinations between 97 degrees and 121 degrees (95% confidence interval). Some of the preferred settings strongly differ from those recommended in many brochures and standards. The physical complaints in the neck-shoulder and back area are diminished with the preferred settings.