加密解密论文

目录

摘要...................................................................................................II Abstract................................................................................................ II 第一章概论.. (1)

1.1 课题背景 (1)

1.2 课题意义 (2)

第二章 DES算法设计简介及方案论述 (3)

2.1 设计简介 (3)

2.2 设计方案 (3)

2.2.1 DES的加密过程 (4)

2.2.1 DES的解密过程 (5)

第三章 DES算法详细设计 (6)

3.1 子密钥的产生 (6)

3.2 初始值换IP (7)

3.3 加密函数 (7)

3.4 逆初始值换1

IP (9)

第四章设计结果及分析 (10)

4.1 设计结果 (10)

4.2 设计结果分析 (12)

总结 (13)

致谢 (14)

参考文献 (15)

附录主要程序代码 (15)

摘要

DES（Data Encryption Standard）算法是美国国家标准局（NIST）于1977年公布由IBM公司研制的一种加密算法，并且批准它作为非机要部门使用的数据加密标准。自从公布以来，它一直超越国界，成为国际上商用保密通信和计算机通信的最常用的加密算法。DES也是曾被广泛使用的分组密码，遍及世界的政府，银行和标准化组织把DES 作为安全和论证通信的基础。DES算法公开是密码学史上里程碑式的事件。

DES算法是分组密钥，每次处理64位的明文数据，形成64位的密文。DES也是一个对称算法，加密解密使用相同的算法和密钥，密钥长度为56位，可以为任意的56位的数，且随时可更换。此次设计主要是对DES数据加密标准原理和流程的描述，D从初始变换、DES的迭代过程、密钥变换和逆置换等四个方面开始研究的，并且用Visual C ＋＋语言实现了它的模拟应用。

关键词：加密；解密；DES算法；Visual C＋＋

Abstract

DES (Data Encryption Standard) algorithm is that National institute of standards and technology (NIST) announced a kind of encryption algorithm developed by IBM in 1977,and approve for it as whether datum that confidential developments use encrypt standard. Since announcing, it has been surmounting the national boundaries all the time, and has been come the most frequently used of encryption algorithm in the communication of commercial secret and computer in the world .DES block ciphers that enjoys widespread use too, spread all over the government of the world, the bank and standardization tissue regarded DES as the foundation to prove safe and communication to organize. It is a milestone incident in the cryptography history that DES algorithm is disclosed.

The key that DES algorithm divides into groups, data are encrypted in 64-bit block each time, form the cipher texts of 64. DES is a symmetrical algorithm too. The same steps, with the same key, are used to reverse the encryption, the key length is 56-bit, and can be the numbers of 56 wanton, and can change at any time. This text is mainly description that encrypts the standard principle and process to the data of DES，and analyses the basic principle of DES encryption algorithm, separately from four parts etc to research that is initial permutation, the DES ‘s iteration course, key permutation and Inverse initial permu tation, and has realized its simulation application with Visual C＋＋language.

Keywords:Encrypt；Decrypt；DES algorithm；VC＋＋programming