摘 要
信息技術的飛速發(fā)展，使人們的生活面貌發(fā)生了很大的變化，同時信息技術也促進了社會的發(fā)展。在計算機網絡深入普及的信息時代，信息本身就是時間，就是財富。如何保護信息的安全使之不被竊取及不至于被篡改或破壞，已成為當今普遍關注的重大問題。密碼是有效且可行的辦法。
本論文主要是介紹了文件加密以及一個小程序，從密鑰生成、DES加密原理、DES解密原理三方面闡述了DES算法的整個過程。并在此基礎上，在windows環(huán)境下，利用java實現(xiàn)DES加密與解密算法，以窗體界面方式完成一個本地的文件加解密演示器。
本論文共分為七部分。第一章從現(xiàn)代電子技術的發(fā)展揭示密碼學在科學領域中的重要性，從而說明選此課題作為畢業(yè)設計的原因。第二章講述了密碼學的基礎知識。第三章是本文的重點，以DES歷史回顧為起點，逐一揭示DES算法原理，并按密鑰生成、DES加密、DES解密的次序，利用java語言實現(xiàn)DES的加密與解密代碼的設計。第四章對窗體界面作簡要的介紹，說明本演示器的工作過程。第五章對DES存在的安全性進行分析及可行的解決方案。第六章對DES的工作模式進行簡要的介紹。第七章舉例對代碼進行測試，看是否符合標準的DES加密和解密。


關鍵詞：信息安全；密鑰；DES；加密；解密






















Abstract
The information technology rapid development, caused people’s life appearance to have the very big change, simultaneously the information technology also promoted society development. In the computer network thorough popularization information time, information itself is the time, is the wealth. How protects the information security to cause it not to be stole and as for not to tamper with or destruction, has become the major issue which now generally pays attention . The password is useful and effectible method.
This article mainly introduces the DES encryption and decipher algorithm java language realization, three aspects elaborated from key fresh、the encryption principle DES、the decryption principle DES algorithm entire has worked. And in this foundation, in windows environment, realizes the encryption and decryption algorithm using java, completes a local document by the window contact surface way to add the decipher demonstration.
The article divides into seven to blow. First chapter promulgates cryptology from the modern electronic technology development to be important in scientific domain, thus explained chooses this topic to take the graduation project originally. Second chapter narrated the cryptology elementary knowledge. Third chapter is this article key point, take narrates the DES history as the beginning, explain the DES algorithm principle, meanwhile how to make the encryption key、encrypts the DES、decrypts the DES as the line, realizes the DES encryption and decipher code using java language supposes discusses. Fourth chapter makes the simple introduction to the window contact surface, explain the working process of the decipher demonstration. Fifth chapter carries on the analysis to the DES existence security simultaneously to separate out the feasible solution. Sixth chapter carries on the brief introduction to the DES working pattern. Seventh chapter gives an example to carry on the test to the code, confirms whether conforms to the standard DES encryption and decryption.


KEYWORDS:Information security; key; DES; Encryption; Decipher




目錄
摘 要 I
Abstract II
第一章 引 言 1
1.1本課題的研究意義 2
1.2 攻擊 3
第二章 密碼學的基礎知識 5
2.1對稱密碼的模型 5
2.2密碼編碼學 6
2.3公鑰密碼學 6
2.4 Caesar密碼 7
2.5單表代換密碼 8
2.6 Playfair密碼 9
2.7 Hill密碼 10
2.8 多表代換密碼 11
2.9 一次一密 13
2.10 置換技術 14
2.11 轉輪機 15
2.12 隱寫術 16
第三章 數據加密標準DES 17
3.1簡化DES 17
3.1.1 S-DES的密鑰產生 17
3.1.2 S-DES加密 18
3.1.3 簡化DES的分析 19
3.2 DES 19
3.2.1 密鑰產生 22
3.2.2 DES解密 23
3.3 JAVA實現(xiàn)JCE中DES的加密和解密 23
3.3.1 JCE中DES加密 24
第四章 窗體界面 28
4.1界面視圖 28
4.2演示器工作工程 28
第五章 DES的安全性分析 29
5.1 DES的安全性 29
5.2 相關解決方案 29
第六章 DES工作模式 30
6.1電子密碼本模式ECB 30
6.2密碼分組鏈模式CBC 30
6.3 密碼反饋模式CFB 30
6.4 輸出反饋模式OFB 30
6.5 計數模式CTR 31
第七章 代碼測試 32
致 謝 33
參考文獻 34
附錄 35
附錄A：外文資料翻譯－原文部分 35
附錄B：外文資料翻譯－譯文部分 38
附錄C:程序代碼 40

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Campbell,K.,and Wiener,M.”Proof that DES is not a Group.” Proceedings,Crypto’92,1992;New York:Springer-Verlag.

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