【作者】 谢小琢；

【导师】 王尚平；

【作者基本信息】 西安理工大学 ， 计算机软件与理论， 2008， 硕士

【摘要】 近年来,基于互联网的考试系统应运而生。网络考试系统彻底改变传统的考试方式。传统的考试方式需要运用手工方式发放试题和提交试卷,手续繁琐、缓慢及效率低下。网络考试使得考试变得便利、高效,实现自动化的网络无纸化并且可以节省大量的人力物力。但是,在提供很多方便的同时,新的安全问题伴随而生。本文针对全国数模竞赛系统中试题集中发放、试卷集中收交及身份认证和答卷完整性等安全问题进行了分析,使用密码学理论和方法,提出了以PKI安全体系为基础、CA认证为核心的数学建模竞赛系统的解决方案,综合运用加密、数字签名、数字证书及时间戳技术实现试题及答卷在发放和收交过程中的保密性、完整性、不可否认性及试卷评阅中可能出现的作弊等安全问题,用加密技术解决试题集中下载中的拒绝服务问题,用时间戳技术解决试卷集中提交中的时效性问题。系统采用B/S模式进行信息发布和智能客户端下实现加密、签名和时间戳安全方案,并从用例模型分析、数据库设计和功能模块设计入手,对系统总体工作流程进行了描述。在理论研究和分析基础上,基于Windows Server 2003环境,建立了数学建摸竞赛认证机构,以CA为核心构建了基于PKI的时间戳服务框架模型。并在Visual Studio 2005和.Net Framwork 2.0环境下,编码实现了试题加解密、数字签名和提供时间戳服务的智能客户端程序。更多还原

【Abstract】 In recent years, Internet-based examination systems have come into being. Network Examination thoroughly changes the traditional way of examination. Traditional examination needs to give out examinenation papers and submit answer papers with manual mode, so it makes the procedure of examinenation cumbersome, slow and inefficient. Network examination makes examination become convenient, efficient, paperless with automation mode. It can save a lot of manpowers and material resources. However, it offers much convenience, at the same time ,many new problems about security come into being.In this thesis, aiming at the four problems of downloading the contest paper simultaneou -sly , submitting the answer papers simultaneously, validating the identity of players and validating the integrality of answer paper in the China mathematical contest in modeling ,a corresponding PKI-based security solution is put forward with the help of comprehensive application of data encryption, digital signature ,digital certificate and time-stamp technique to solve a series of security problems such as privacy, integrality, undeniability and cheat-preventing . At the same time , the problem of time efficiency in the process of downloading is solved with the help of encryption and the problem of the time efficiency in the process of submitting test paper is solved with the help of time-stamp. The system issues information in B/S and carries out paper encryption ,digital signature and time-stamp functions in smart client program. starting from the use case model analysis, database design and functionality modular design ,this thesis depicts the workflow of the overall system.On the basis of theory research and analysis, the author establishes CA of the China mathematical contest in modeling in Windows 2003 environment, and establishes the PKI-based framework of the time-stamp service in the core of CA. In Visual Studio 2005 and .Net Framwork 2.0 environment, the author develops a smart client program for contest test with paper encryption ,digital signature and time-stamp functions, which can be used to the China Mathematical Contest in Modeling .更多还原