共查询到20条相似文献，搜索用时 312 毫秒
1.
随着电子邮件的应用越来越广泛,其安全问题也越来越突出。PGP是用于加密电子邮件的一种软件,它采用多种算法把对称加密和非时称加密的优点高效地结合起来,具有安全性好,操作方便等优点。文章主要介绍了电子邮件存在的安全问题及PGP的主要功能,分析了PGP的核心算法及其安全性,描述了PGP加密、解密电子邮件的原理。最后以实例说明了PGP在电子邮件中的具体应用。 相似文献
2.
电子邮件系统PGP分析和网络安全策略 总被引：1，自引：0，他引：1
在比较详细地分析一个能够提供保密、鉴别、数字签名和压缩的电子邮件系统PGP的基础上 ,对常用的加密方法的代价和性能进行比较 ;由此提出在进行网络安全策略设计时 ,要综合、合理地运用各种加密算法。 相似文献
3.
本文简要地介绍计算机簿件加密的必要性及PC机上簿件加密的一般方法。在此基础上着重讨论了几种磁盘文件的簿加密方法,它们作为一般用户文件和数据信息的加密方法,具有一定的应用价值。 相似文献
4.
戎成 《海南师范学院学报》2007,20(1):38-41
无线局域网（WLAN）是当前高校校园网建设的一个重要方向,但是由于无线局域网通过电磁波传输数据,先天具有广播的特性,容易被窃听、截获和篡改,安全性保障不足.虚拟专用网（VPN）是在公共网络信道上采用隧道技术建立起专用加密信道,若将VPN与WLAN相结合,在开放式广播网络中建立专用加密信道,则将大大加强校园WLAN的安全性. 相似文献
5.
陈志阳 《中国职业技术教育》2003,(9):59-59
对一个工程人员来说AutoCAD使用非常重要,主要表现在不仅要会用,速度也要快。那如何提高速度呢?这里列举几种方法,希望对一些初学朋友能有所帮助。 一、发掘简写优势,开启加密文件 大家都知道LJNE命令在COMMAND输入时可简化为L,为何会如此呢?因为在AutoCAD中有一个加密文件ACAD.PGP中定义了 相似文献
6.
对正项式几何规划问题（PGP）提出一近线性化方法,这类优化问题能广泛应用于工程设计非线性系统的鲁棒稳定性分析等实际问题中。使用指数变换及利用分段线性化技术转变每个指数项为一些带绝对值项的和,再将绝对值项线性化,最终将原问题转化为一个线性规划问题。数值实验表明,本文的方法是可行的,能近似地求其问题（PGP）的全局最优解。 相似文献
7.
将PGP(Pretty Good Privacy)的工作原理引入一种加密强度和规模均可伸缩的安全文件系统,可满足不同层次用户的要求;支持多种认证方式,能有效地和PKI协调工作,可以很好地集成在电子商务和电子政务平台上。使用核心态数据加解密的方式,处理性能更高,用户操作数据时间延迟性小;由于系统和操作系统实现了无缝连接,用户操作透明度高。 相似文献
8.
李守国 《濮阳职业技术学院学报》1994,(3)
伴随着科技的迅速发展,软件的开发,越来越多的硬件系统和软件系统走向市场。倘若你使用的微机配有较大的内存容量,且系统还能够扩展,那么你就可以建立一个或多个虚拟磁盘,然后使用它。设置虚拟磁盘,可以达到提高系统运行速度之目的。如果你所使用的系统中含有字库,并且在正常使用该系统时,字库被装在硬盘上,那么为了减少磨损硬盘有必要设置虚拟磁盘。这是因为,无论是编辑或排版文字时,都要频繁地读取硬盘中的字库方能工作,致使系统运行速度减慢,且对硬盘有较大的磨损。设置虚拟磁盘,应根据DOS系统版本、微机的内存和所要运行的系统而决定,但内存容量必须大于运行系统所占的空间,否则系统不能运行。以用虚拟磁盘运行WPS为例,具体实现步骤如下: 相似文献
9.
对现有的基于磁盘的数据备份恢复方法进行分析,提出在SAN环境下,一种实现基于虚拟磁盘服务(VDS,Virtual DiskService)和卷影复制服务(vSS,Volume Shadow Copy Service)的数据备份和恢复方法,考虑备份策略,减小备份窗口,保证安全性,满足低成本快速数据备份的需求. 相似文献
10.
单联杰 《中小学信息技术教育》2010,(2):90-92
在计算机教室中存储学生的资料一般有四种方式：本地磁盘存储、本地磁盘配合文件夹加密存储、在线WEB存储、建立服务器“网络盘”存储。这四种方式在多名学生共用同一计算机的条件下都存在一些问题。 相似文献
11.
吴泽勋 《闽西职业技术学院学报》2005,7(4):114-116
廉价的虚拟主机是个人或中小型企业用户构建网络服务器的常用方式,文件的上传和下载是网络中常用到的功能。分别以是否有上传组件和存放在服务器硬盘还是存放在数据库中完整地讨论了虚拟主机下完成文件的上传和下载功能。 相似文献
12.
Redundant array of inexpensive disk (RAID)10 is known as the most reliable disk array architecture to tolerate up to half of total disk failures, but failure of two disks in the same mirror set still results in data loss. In this paper, we propose a new disk array architecture, mirroring and parity protected RAID (MP-RAID), which combines both mirroring and parity techniques to further improve reliability of disk arrays. The main idea behind MP-RAID is to protect the data by both mirroring and parity techniques: keep two copies of data in the same mirror set and update the parity block in the log disk within the same parity groups. Reliability analysis shows that the reliability of MP-RAID, in terms of mean time to data loss (MTTDL), is much better than RAID10 and RAID5. 相似文献
13.
研究Linux系统中多路径磁盘过滤驱动程序的设计和实现。驱动程序将物理磁盘的多路径封装为一个虚拟没备。虚拟设备的I／O请求转发到磁盘设备上执行,由路径选择算法将主机的负载均衡地分配到各路径上。当路径发生故障时由驱动程序将失败的I／O请求切换到其它路径,屏蔽了路径故障。驱动程序利用多路径改善了主机的I／O性能,提高了系统的可用性。 相似文献
14.
胡鸣 《上海大学学报(英文版)》2005,9(5):411-414
1IntroductionIn the past ,for disk-scheduling problems , peopleused disk-scheduling algorithms[1]based on disk armposition. Disk rotation was ignored and only the mov-ing distance of disk heads into was takeninto account .Thus ,the problemof seekti me was turnedinto one ofseek distance and further to absolute sumof the differ-ence between cylinders .Suppose that the head beginsat cylinderC0and the schedule order isC1,C2,…,Cn.The total number of cylinders the heads traversehas the following … 相似文献
15.
随着信息技术的发展,人们之间的信息交流变得越来越频繁,移动存储设备由于具有容量大、易携带等优点,应用十分广泛。为了提高移动存储设备的安全性,设计并实现了基于虚拟盘的国密安全移动存储设备,通过在物理盘驱动程序和文件系统之间嵌入一个虚拟驱动程序,将移动存储设备中的镜像文件虚拟为一个安全分区;在移动存储设备上开辟一个隐藏区,安全区配置信息都保存在隐藏区内,并使用SM4国密算法保证数据安全性;采用多线程技术,利用CPU性能提升安全分区内文件的加解密速度。 相似文献
16.
利用密度泛函理论方法(B3LYP、B3PW91、B3P86),使用6-31G**和6-311G**基组计算了13个取代氯化苯化合物的键离解能。结果表明,使用的计算方法和基组对计算C-Cl键离解能影响很大,且B3P86/6-311G**方法是计算含C-Cl键的取代氯苯化合物键离解能的最可信的方法。进一步讨论了取代基效应对取代氯苯化合物C-Cl键离解能的影响,结果表明取代基效应对取代氯苯化合物C-Cl键离解能的影响非常小。 相似文献
17.
Oskar Casquero Ramón Ovelar Jesús Romo Manuel Benito Mikel Alberdi 《Interactive Learning Environments》2016,24(1):49-67
The main objective of this paper is to analyse the effect of the affordances of a virtual learning environment and a personal learning environment (PLE) in the configuration of the students' personal networks in a higher education context. The results are discussed in light of the adaptation of the students to the learning network made up by two undergraduate, inter-university and online courses. Besides, we also examine the influence of this effect in the learning process. The findings reflect the effectiveness of a PLE for facilitating student participation and for assisting students in the creation of larger and more balanced personal networks with richer social capital. However, the findings do not provide evidences about a difference in the learning performance between the two environments. From a methodological point of view, this paper serves as an illustration of the analysis of personal networks on digital data collected from technology-enhanced learning environments. 相似文献
18.
何承 《深圳信息职业技术学院学报》2006,4(3):20-24
该文通过对硬盘保护卡的特性及其主要保护模式的分析,提出了基于保护卡的通用性规划和专用性规划两种机房系统规划模式,并对两种模式进行了比较和分析。 相似文献
19.
As a new promising paradigm, cloud computing can make good use of economics of scale and elastically deliver almost any IT
related services on demand. Nevertheless, one of the key problems remaining in cloud computing is related to virtual machine
images, which require a great amount of space/time to reposit/provision, especially with diverse requests from thousands of
users simultaneously. In this paper, by using the splitting and eliminating redundant data techniques, a space and time efficient
approach for virtual machines is proposed. The experiments demonstrate that, compared with existing solutions, our approach
can conserve more disk space and speed up the provisioning of virtual machines. 相似文献
20.
Virtual and Physical Experimentation in Inquiry-Based Science Labs: Attitudes, Performance and Access 总被引：2，自引：2，他引：0
This study investigated the learning dimensions that occur in physical and virtual inquiry-based lab investigations, in first-year
secondary chemistry classes. This study took place over a 2 year period and utilized an experimental crossover design which
consisted of two separate trials of laboratory investigation. Assessment data and attitudinal data were gathered and analyzed
to measure the instructional value of physical and virtual lab experiences in terms of student performance and attitudes.
Test statistics were conducted for differences of means for assessment data. Student attitudes towards virtual experiences
in comparison to physical lab experiences were measured using a newly created Virtual and Physical Experimentation Questionnaire
(VPEQ). VPEQ was specifically developed for this study, and included new scales of Usefulness of Lab, and Equipment Usability
which measured attitudinal dimensions in virtual and physical lab experiences. A factor analysis was conducted for questionnaire
data, and reliability of the scales and internal consistency of items within scales were calculated. The new scales were statistically
valid and reliable. The instructional value of physical and virtual lab experiences was comparable in terms of student performance.
Students showed preference towards the virtual medium in their lab experiences. Students showed positive attitudes towards
physical and virtual experiences, and demonstrated a preference towards inquiry-based experiences, physical or virtual. Students
found virtual experiences to have higher equipment usability as well as a higher degree of open-endedness. In regards to student
access to inquiry-based lab experiences, virtual and online alternatives were viewed favorably by students. 相似文献