摘 要
隨著計算機和通訊技術的飛速發展，密碼學已經滲透到了政治、經濟、文化乃至個人隱私等領域，使用加密技術來保護資訊的安全變得越來越重要。大數的運算作為密碼的基礎特別是在公鑰密碼中尤為重要。這篇論文的重點在於通過對大數的加減法運算學習來理解大數在計算機中的表示和儲存，以及大數在計算機中的加減法運算的C程式實現，為以後的密碼學研究打下基礎。
論文分為兩大部分,大數的基本知識部分和大數加減法的C語言實現部分。理論基礎部分包括正文的第1章，第2章和第3章：第1章是C語言和MFC的簡單介紹，第2章介紹大數運算的.必要性以及密碼的實現；第3章較詳細地介紹大數在計算機中的表示及相關的思路。第4章介紹大數的預備知識和大數加減法的C語言實現。第5章介紹用C++做介面實現從視窗輸入大數並進行加減法運算，以及附上測試時常見的錯誤及修改。最後在附錄中附上常數列表、帶引數的巨集、和程式原始碼。
這篇論文通過對大數加減法的運算掌握了大數在計算機中的表示大數與字元之間的轉換。本論文對加密演算法的運用以及在密碼學中加密演算法在日常生活中的運用範圍及其運用方法提供了1些有用的參考。為密碼的加密解密提供了計算基礎。
關鍵詞
密碼學；大數；大數的表示；加法運算；減法運算。
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.
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.