【正文】 apter 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. Fourth chapter makes the simple introduction to the window contact surface, explain the working process of the decipher demonstration and the DES working pattern. The fifth chapter explained that DES adds/the decipher algorithm system design mentality, as well as it realizes the method specifically. Keywords:Information security,Key,DES,Encryption,Decipher 長(zhǎng)沙學(xué)院畢業(yè)設(shè)計(jì) (論文 ) III 目 錄 摘 要 ............................................................................................................ I ABSTRACT ..................................................................................................II 第 1 章 緒論 ................................................................................................. 1 引言 .............................................................................................................................. 1 本課題的研究意義 ...................................................................................................... 3 攻擊 ............................................................................................................................. 4 第 2 章 密碼學(xué)的基礎(chǔ)知識(shí) ........................................................................... 6 對(duì)稱密碼的模型 .......................................................................................................... 6 密碼編碼學(xué) .................................................................................................................. 7 公鑰密碼學(xué) .................................................................................................................. 7 Caesar 密碼 ................................................................................................................. 9 單表代換密碼 ............................................................................................................ 10 Playfair 密碼 .............................................................................................................. 12 Hill 密碼 .................................................................................................................... 13 多表代換密碼 ........................................................................................................... 15 一次一密 ................................................................................................................... 17 置換技術(shù) ................................................................................................................. 18 轉(zhuǎn)輪機(jī) ..................................................................................................................... 19 隱寫術(shù) ..................................................................................................................... 20 MD5 ........................................................................................................................ 21 第 3 章 數(shù)據(jù)加密標(biāo)準(zhǔn) DES ........................................................................... 23 簡(jiǎn)化 DES .................................................................................................................... 23 SDES 的密鑰產(chǎn)生 ........................................................................................ 23 SDES 加密 .................................................................................................... 24 簡(jiǎn)化 DES 的分析 ........................................................................................... 24 DES ............................................................................................................................ 25 密鑰產(chǎn)生 ........................................................................................................ 27 DES 解密 ........................................................................................................ 28 第 4 章 DES 的安全性分析與工作模式 ........................................................ 29 DES 的安全性分析 ................................................................................................... 29 DES 的安全性 ............................................................................................... 29 相關(guān)解決方案 ............................................................................................... 30 DES 工作模式 ........................................................................................................... 30 長(zhǎng)沙學(xué)院畢業(yè)設(shè)計(jì) (論文 ) IV 電子密碼本模式 ECB.................................................................................... 30 密碼分組鏈模式 CBC ................................................................................... 31 密碼反饋模式 CFB ........................................................................................ 31 輸出反饋模式 OFB........................................................................................ 31 計(jì)數(shù)模式 CTR................................................................................................ 31 第 5 章 系統(tǒng)設(shè)計(jì)與實(shí)現(xiàn) .............................................................................. 33 DES 加 /解密算 法的系統(tǒng)設(shè)計(jì)思路 .......................................................................... 33 DES 加 /解密算法 .......................................................................................... 33 系統(tǒng)設(shè)計(jì)思路 ................................................................................................ 33 系統(tǒng)的加解密的實(shí)現(xiàn)及密文存儲(chǔ) ............................................................................ 33 系統(tǒng)的部分代碼 ........................................................................................................ 36 分析結(jié)果與小結(jié) ........................................................................................................ 39 分析結(jié)果 .............................................................