【作者】 洪锡联；

【导师】 黄九梅；

【作者基本信息】 北京化工大学 ， 计算机应用技术， 2008， 硕士

【摘要】 时钟同步问题是分布式操作系统中的一个经典问题,是分布式计算中的核心技术之一。随着计算机技术和网络通信技术的迅猛发展,异步网络环境中各节点的时钟同步问题变得越来越重要,同时,时钟同步问题也被赋予了新的内涵。时钟同步的安全性就是其一。客户端需要通过对服务器的认证来确认其是否可信,以避免有意或无意的恶意攻击。本论文主要分为三个部分:第一部分介绍了时钟同步的相关内容,包括物理时钟、逻辑时钟、世界协调时间和原子秒等概念。第二部分介绍了时钟同步系统的同步源、同步方法、同步模型,及其工作模式。接着对时间同步协议(Network Time Protocol)的工作原理、实现方式进行分析,同时在此基础上开发基于Java语言的时间同步客户端软件,并对客户端核心代码进行了分析。第三部分是对时间同步安全性进行讨论。除了介绍时间同步协议具有的抵抗机制、可能遭遇的恶意攻击及需要满足的假设条件,还对数字证书用于时间同步的可行性作出了分析。最后,对自动钥的特征及认证能力作了介绍。更多还原

【Abstract】 Time synchronization is not only a classical issue in the distributed operation system, but also one of the kernel techniques of the distributed applications. As the swift and violent development of computer and network communication technology, the clock synchronization between network nodes in an asynchronous environment becomes more and more important. Meanwhile, the new content and broad range are added in this research area of clock synchronization. Time synchronization security is the one. In order to avoiding evil or devil malicious attack,it is necessary for client to authenticate server proventic or not.This paper mainly consists of three parts: the first part introduces the related content of clock synchronization,including the concepts of physical clock, logical clock,universal time coordinated and atomic second.The second part introduces synchronization sources, synchronization method and synchronization model of time clock synchronization system, and its working mode. Then the working principle and implementation method of network time protocol is analyzed. At the same time,client software based on Java language is developed and its core code is analyzed.The third part is the discussion about clock synchronization security. Apart from introducing resistance mechanism, possible encountering malicious attack and presumed required limitation of network time protocol, the feasibility about digital certificate applied to time synchronization is analyzed. Lastly,the characteristic and authentication ability of autokey is mentioned.更多还原