64位DES加密系统设与实现毕业论文.doc

64位DES加密系统设计与实现 摘　要 数据加密技术主要通过对网络中传输的信息进行数据加密来保障其安全性,是一种主动安全的防御策略。信息技术改变着人们的生活和工作方式，与此同时，信息安全也已成为世人关注的社会问题。密码技术是信息安全的关键技术,密码算法的快速实现日益重要,本文简要介绍了DES 算法的基本原理及具体实现过程,并分析了该算法的安全性,并着重对DES 算法的加密过程及优缺点进行了探讨。通过对分组密码DES 算法IP 变换、IP 逆变换、S- 盒换位表的分析, 找出了他们的换位规则, 根据这种规则提出了对DES 算法软件实现的改进方法。并结合C 编程环境,介绍了DES 加密程序实现的具体方法。 关键词 DES加密; C编程程序实现；算法 Abstract The encryption of the data safeguards its security mainly by encrypting the data transmitted by the netwoyrk.This active defensive device can voluntarily offer considerable safety protection for information with only a little cost . Information technology changes our life and work style. At the same time, Information security has become one of our important social problems. Cryptotechnique is the key technique of information security , a quick implementation of cryptographic algorithm has become more and more important.This paper introduces the basic elements of DES arithmetic and the realizing process of DES algorithm, analyze the security of DES arithmetic It focuses on the discussion of the encryption process and the pluses and minuses of DES algorithm.。Through the analysis of DES algorithm, IP commutation, IP- 1 commutation, S- box, find out their replacement rule and put forward the improvement methods of DES algorithm s software realization according to this kind of rule. The concrete method of programming to achieve DES encryption technique by C language were discussed. Key words DES encryption；C programming achievement of programme; 目次 一、引言------------------------------------- 二、DES加密算法----------------------------- （一）、DES加密算法的基本概念--------------- （二）、DES加密算法基本思想----------------- （三）、DES加密算法内在特性----------------- （四）、DES 加密算法的优点------------------- （五）、DES加密算法加密目的------------------ 三、DES加密算法流程分析--------------------- （一）、DES加密算法加密过程----------------- 子密钥的产生------------------------------------------------------- 换位操作————初始置换------------------------- 乘积变换 1、扩展置换--------------------------------------- 2、S-盒置换----------------------