共查询到20条相似文献，搜索用时 562 毫秒
1.
指出了一种新的无证书部分盲签名机制存在公钥替换攻击,分析了形成攻击的原因,并且通过修改签名验证算法改进了该部分盲签名机制。分析表明,这一改进方案有效地防止了其存在的公钥替换攻击。 相似文献
2.
水银承诺方案是一般承诺方案的一种有趣变形.水银承诺方案中增加了soft解承诺阶段,soft解承诺阶段所公开的解承诺值不要求绑定性但是不能与真实的解承诺值冲突.讨论了多重非延展水银承诺方案.通常意义的非延展性是指敌手只允许存取一个承诺值,多重非延展性是指敌手可以存取任意数量的承诺值.已有结论说明多重非延展性是严格强于通常非延展性的安全性概念.采用多重非延展性的概念在于水银承诺方案本身固有的性质,给出多重非延展水银承诺方案的概念,以及基于多陷门水银承诺方案的一个具体构造. 相似文献
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范红 《中国科学院研究生院学报》2001,18(2):140-143
提出了一种新型的数字签名方案,在此签名方案中只需要很小的在线工作量,具有较短的公钥与私钥,需要交换的信息量较小.此方案是基于分解大整数问题的困难性. 相似文献
5.
基于环签名思想提出一个类似门限群签名的匿名签名方案,解决了门限群签名中管理员权限过大,而环签名又无法追踪签名人身份的问题。与已有的门限群签名方案相比,因保留了环签名的部分特征,新方案具有以下优点:(1)管理员的权限受到控制,必须和签名接收方合作才能共同追踪签名者的身份;(2)能方便更改门限值;(3)方便加入或注销群成员,系统参数只需少量改变。 相似文献
6.
给出公共参考串(CRS)模型下可否认零知识的一个正面结果:从Σ-协议到CRS模型下的可否认零知识的高效转化.由Pass在CRYPTO 2003中给出的下界可知,我们的编译器取得了最优的轮效率.此外,转化所增加的通信复杂度较小. 相似文献
7.
给出公共参考串(CRS)模型下可否认零知识的一个正面结果:从∑-协议到CRS模型下的可否认零知识的高效转化.由Pass在CRYPTO 2003中给出的下界可知,我们的编译器取得了最优的轮效率.此外,转化所增加的通信复杂度较小. 相似文献
8.
一个简单而安全的门限RSA签名方案 总被引：6，自引：0，他引：6
门限签名是普通数字签名的推广.门限签名的生成必须由多个成员合作才能完成,但验证只需要知道群体的公开密钥即可进行.基于有理数域上的插值公式,给出了一个需要庄家的门限RSA签名方案.该方案简单、安全,且部分签名的正确性是可以验证的. 相似文献
9.
利用PKI提出了一种新的公钥认证方案,该方案针对移动终端计算速度慢、存储量小的特点,本着尽量减少移动终端计算量、节省存储空间的原则,引入＂密钥短,安全性高＂的椭圆曲线密码体制进行加密和签名,并对加密和签名算法精心选择;采用归属方辅助证明的方法,使移动终端不传递和验证证书;移动终端和接入认证服务器之间以及各接入认证服务器间不需要预先存在安全关联;认证服务器间也不需要有相同的公钥参数,增强了系统的扩展性。 相似文献
10.
一个数字签名方案由两部分组成:签名算法和验证算法,使用签名算法进行签名,得到数字签名;通过验证算法判断其真实性。对基于RSA-TBOS密码体制的数字签名,讨论了它的优缺点和安全性。 相似文献
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A research group led by Prof. ZHAI Qiwei from the Institute for Nutritional Sciences under the CAS Shanghai Institutes for Biological Sciences has discovered that even relatively low doses of resveratrol-a chemical found in the skins of red grapes in red wine-can improve the sensitivity of mice to the hormone insulin according to a report in the October issue of Cell Metabolism.…… 《中国科学院院刊(英文版)》2008,22(1):14-15
Aresearch group led by Prof. ZHAI Qiwei from the Institute for Nutritional Sciences under the CAS Shanghai Institutes for Biological Sciences has discovered that even relatively low doses of resveratrol--a chemical found in the skins of red grapes and in red wine--can improve the sensitivity of mice to the hormone insulin, according to a report in the October,2007 issue of Cell Metabolism. As insulin resistance is often characterized as the most critical factor contributing to the development of Type 2 diabetes, the findings“provide a potential new therapeutic approach for preventing or treating” both conditions, the researchers said. 相似文献
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Marjorie Armstrong-Stassen Margaret Landstrom Ramona Lumpkin 《The Information Society》1998,14(2):153-164
This study examined how students who had no prior experience with videoconferencing would react to the use of videoconferencing as an instructional medium. Students enrolled in seven different courses completed a questionnaire at the beginning of the semester and again at the end of the semester. Students at the origination and remote sites did not differ in their reactions toward videoconferencing but there was a significant difference for gender. Women reacted less favorably to videoconferencing. Compared to the beginning of the semester, students reported significantly less positive attitudes toward taking a course through videoconferencing at the end of the semester. There were no significant differences in students' attitudes toward videoconferencing across courses at the beginning of the semester but there were significant differences across the courses at the end of the semester. The results suggest the need for better preparation for both students and instructors. 相似文献
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A joint study by Prof. ZHANG Zhibin from the CAS Institute of Zoology his co-workers from Norway US Swiss have indicated that historical outbreaks of migratory locusts in China were associated with cold spells suggesting that China's projected climate warming could decrease the pest's numbers. The study was published in Proceedings of the National Academy of Sciences on September .…… 《中国科学院院刊(英文版)》2008,22(1):6-7
Ajoint study by Prof. ZHANG Zhibin from the CAS Institute of Zoology and his co-workers from Norway, US and Swiss have indicated that historical outbreaks of migratory locusts in China were associated with cold spells, suggesting that China＇s projected climate warming could decrease the pest＇s numbers. The study was published in Proceedings of theNational Academy of Sciences on 17 September, 2007. 相似文献
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Caroline Haythornthwaite 《The Information Society》2001,17(3):211-226
A computer-mediated group is a complex entity whose members exchange many types of information via multiple means of communication in pursuit of goals specific to their environment. Over time, they coordinate technical features of media with locally enacted use to achieve a viable working arrangement. To explore this complex interaction, a case study is presented of the social networks of interactions and media use among members of a class of computer-supported distance learners. Results show how group structures associated with project teams dominated who communicated with whom, about what, and via which media over the term, and how media came to occupy their own communication niches: Webboard for diffuse class-wide communication; Internet Relay Chat more to named others but still for general communication across the class; and e-mail primarily for intrateam communication. Face-to-face interaction, occurring only during a short on-campus session, appears to have had a catalytic effect on social and emotional exchanges. Results suggest the need to structure exchanges to balance class-wide sharing of ideas with subgroup interactions that facilitate project completion, and to provide media that support these two modes of interaction. 相似文献
15.
Active biological molecules functional structures can be fabricated into a bio-mimetic system by using molecular assembly method. Such materials can be used for the drug delivery disease diagnosis therapy new nanodevice construction.…… 《中国科学院院刊(英文版)》2008,22(1):22-22
Active biological molecules and functional structures can be fabricated into a bio-mimetic system by using molecular assembly method. Such materials can be used for the drug delivery, disease diagnosis and therapy, and new nanodevice construction. 相似文献
16.
《中国科学院院刊(英文版)》2008,22(1):2-3
CAS should stick to the principle of rendering service to, and giving impetus for, the development of China＇s science enterprise by making S＆T innovations, said CAS President LU Yongxiang. The CAS president made the remarks in a recent talk to communicate the gist of the winter session of the Party＇s Leading-member Group at CAS, which was held from 7 to 11 January in Beijing. 相似文献
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《中国科学院院刊(英文版)》2008,22(1)
With great care, Dr. ZHOU Zhonghe takes out a package wrapped by cotton tissue from a drawer and says: "This is the gem of our collections: the fossil of a bird that lived 125 million years ago!" Then, pointing at a tiny mound, he explains: "Look, this is the claw and that is the head. It was in the egg shell and ready to hatch ... The species fell into a family of waterside inhabitants." 相似文献
18.
Electronic data interchange (EDI) provides means for interorganizational communication, creates network externalities, requires an advanced information technology (IT) infrastructure, and relies on standards. In the diffusion of such innovations, institutional involvement is imperative. Such institutions contain governmental agencies, national and global standardization organizations, local government, and nonprofit private organizations like industry associations. The last type of organizations we call intermediating institutions. They intermediate or coordinate ("inscribe") the activities of a group of would-be adopters. Unfortunately, little is known of how these organizations shape the EDI diffusion trajectory. In this article we examine one specific type of intermediating organizations?industry associations?and how they advanced the EDI diffusion process in the grocery sectors of Hong Kong, Denmark and Finland. We identify six institutional measures, placed into a matrix formed by the mode of involvement (influence vs. regulation) and the type of diffusion force (supply push vs. demand pull), that can be mobilized to further the EDI diffusion. Industry associations were found to be active users of all these measures to varying degrees. Their role was critical especially in knowledge building, knowledge deployment, and standard setting. Furthermore, institutional involvement varied due to policy and cultural contingencies and power dependencies. 相似文献
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Leah A. Lievrouw 《The Information Society》2000,16(2):155-159
This essay focuses on universal service and the Internet as means to support social and political participation. The emphasis on access to telecommunications systems in conventional approaches to universal service is contrasted with access to content. A model of the information environment is described that accounts for the roles of content and conduit, both of which are necessary conditions to achieve true access. A method is outlined for employing information indicators to observe or measure the information environment. 相似文献
20.
Puay Tang 《The Information Society》1998,14(1):19-31
The increasing prospects of digital piracy has prompted the perceived need by electronic publishers to adopt technical systems of protection, and governments to reform their copyright laws. This article is a preliminary study of the management of intellectual property by electronic publishers, defined as those involved in the production of online databases, and CD-ROMs. It focuses on three main issues: (1) how electronic publishers view the increasing threat of piracy; (2) the methods of protection employed to protect intellectual property in digital format; and (3) the importance of technological protection of intellectual property in electronic publications. The analysis is based on a sample of 23 UK electronic publishers. The interviews revealed an interesting assortment of protection methods and did not show that technological protection was a preferred way. Instead, the means of protection, in addition to copyright law, comprised niche markets, pricing, trust, bad publicity, and nontechnical and technical means. 相似文献