大数加减法演示器

摘 要

随着计算机和通信技术的飞速发展，密码学已经渗透到了政治、经济、文化乃至个人隐私等领域，使用加密技术来保护信息的安全变得越来越重要。大数的运算作为密码的基础特别是在公钥密码中尤为重要。这篇的重点在于通过对大数的加减法运算学习来理解大数在计算机中的表示和存储，以及大数在计算机中的加减法运算的C程序实现，为以后的密码学研究打下基础。
分为两大部分,大数的基本知识部分和大数加减法的C语言实现部分。理论基础部分包括正文的第1章，第2章和第3章：第1章是C语言和MFC的简单介绍，第2章介绍大数运算的必要性以及密码的实现；第3章较详细地介绍大数在计算机中的表示及相关的思路。第4章介绍大数的预备知识和大数加减法的C语言实现。第5章介绍用C++做界面实现从窗口输入大数并进行加减法运算，以及附上测试时常见的错误及修改。最后在附录中附上常数列表、带参数的宏、和程序源代码。
这篇通过对大数加减法的运算掌握了大数在计算机中的表示大数与字符之间的转换。本对加密算法的运用以及在密码学中加密算法在日常生活中的运用范围及其运用方法提供了1些有用的参考。为密码的加密解密提供了计算基础。

关键词
密码学；大数；大数的表示；加法运算；减法运算。

Abstract

Along with the computer and the communication rapid development, the cryptology already seeped domain and so on politics, economy, culture and even individual privacy, the use encryption technology protects the  information the security to change more and more importantly, the big number operation took the password the foundation specially was especially is important in the male key password. This paper key point lies in through studies to the big number plus-minus method operation understands the big number in the computer expression and the memory. As well as the big number in the computer plus-minus method operation C procedure realization, will build the foundation for the later cryptology research. （转载自中国科教评价网http://www.nseac.com）
The paper divides into two major parts, Big number elementary knowledge part and large number plus-minus method C language realization part. Rationale part including main text first chapter, second chapter and third chapter: First chapter is the C language and the MFC simple introduction, second chapter of introduction large number operation necessity as well as password realization; Third chapter introduces the large number in detail in the computer expression and the correlation mentality. The fourth chapter introduction large number preparation knowledge and large number plus-minus method C language realization. The fifth chapter introduction makes the contact surface realization with C++ and carries on the plus-minus method operation from the window input large number, as well as when enclosed test common mistake and revision. Finally in appendix enclosed constant tabulation, belt parameter great, and procedure source code.
This paper through has grasped the big number to the big number plus-minus method operation in between the computer expression big number and the character transformation. The present paper the encryption algorithm has provided some useful references to the encryption algorithm utilization as well as in the cryptology in the daily life utilization scope and its using the method. Has provided the computation foundation for the password encryption decipher.

Key words
Cryptology ; Big number ; Big number expression ; Additive operation ; Subtraction operation.