DES加密算法分析實驗報告

1、中北大學(xué)軟件學(xué)院信息安全技術(shù)實驗報告課程名稱：信息安全原理與實踐實驗名稱：DES加密算法指導(dǎo)教師：學(xué)生姓名：組 號：實驗日期：實驗地點：軟件學(xué)院實驗成績：27 / 28文檔可自由編輯打印一、實驗?zāi)康耐ㄟ^用DES算法對實際數(shù)據(jù)進行加密和解密來深刻了解DES的運行原理，進而加深對對稱加密算法的理解與認(rèn)識。二、實驗環(huán)境1) 合天網(wǎng)按實驗平臺2) 操作系統(tǒng)：運行Windows ，VS2010編譯環(huán)境。3) 驗證軟件：CAP(Cryptographic Analysis Program v4)軟件，該軟件位于桌面“cap4”文件夾內(nèi)。三、實驗內(nèi)容與實驗要求1) 使用cap實現(xiàn)DES算法的加解密2) 根據(jù)

2、對DES算法的介紹，自己創(chuàng)建明文信息，并選擇一個密鑰，編寫DES密碼算法的實現(xiàn)程序，實現(xiàn)加密和解密操作，并算結(jié)果將CAP4的運進行比較DES加解密算法的原理DES算法的加密流程圖及參數(shù)：DES的參數(shù)： 1.密鑰長度：56比特 2.輸入：64比特 3.輸出：64比特 4.運算輪數(shù)：16DES解密過程與加密過程完全相似，只不過將16次迭代的子密鑰順序倒過來，即 m = DES-1(c) = IP-1 T1T2.T15 T16 IP(c) 可以證明， DES-1 (DES (m) )=m使用cap實現(xiàn)DES算法的加解密 在“plaintext”框內(nèi)輸入需要加密的字符，本例輸入“beijing”，在C

3、iphers菜單中選擇“des”，出現(xiàn)des Cipher對話框，在密鑰框中輸入8位密鑰：“12345678”，點擊“Encipher”,如下圖： 可以在上圖看到加密成功，在“ciphertest”框出現(xiàn)二進制的密文。 加密操作完成。解密操作如下：將密文復(fù)制到Ciphertext中，選擇“Ciphers”菜單，選擇“DES”算法，輸入正確的數(shù)值產(chǎn)生密鑰，點擊“Decipher”進行解密，結(jié)果返回明文。嘗試不同的值，觀察返回的明文。四、實驗過程與分析加密解密時主要用到的五個函數(shù)進行分析：1）初始置換表，逆初始置換表，S-Box/初始置換表IPint IP_Table64 = 57,49,41,3

4、3,25,17,9,1, 59,51,43,35,27,19,11,3, 61,53,45,37,29,21,13,5, 63,55,47,39,31,23,15,7, 56,48,40,32,24,16,8,0, 58,50,42,34,26,18,10,2, 60,52,44,36,28,20,12,4, 62,54,46,38,30,22,14,6;/逆初始置換表IP-1 int IP_1_Table64 = 39,7,47,15,55,23,63,31, 38,6,46,14,54,22,62,30, 37,5,45,13,53,21,61,29, 36,4,44,12,52,20,6

5、0,28, 35,3,43,11,51,19,59,27, 34,2,42,10,50,18,58,26, 33,1,41,9,49,17,57,25, 32,0,40,8,48,16,56,24; /擴充置換表E int E_Table48 = 31, 0, 1, 2, 3, 4, 3,4, 5, 6, 7, 8,7,8, 9, 10,11,12,11,12,13,14,15,16,15,16,17,18,19,20,19,20,21,22,23,24,23,24,25,26,27,28,27,28,29,30,31, 0; /置換函數(shù)P int P_Table32 = 15,6,19,20

6、,28,11,27,16,0,14,22,25, 4,17,30, 9,1, 7,23,13,31,26, 2, 8,18,12,29,5,21,10, 3,24;/S盒int S8416 =/S1 14,4,13,1,2,15,11,8,3,10,6,12,5,9,0,7, 0,15,7,4,14,2,13,1,10,6,12,11,9,5,3,8, 4,1,14,8,13,6,2,11,15,12,9,7,3,10,5,0, 15,12,8,2,4,9,1,7,5,11,3,14,10,0,6,13, /S2 15,1,8,14,6,11,3,4,9,7,2,13,12,0,5,10, 3

7、,13,4,7,15,2,8,14,12,0,1,10,6,9,11,5, 0,14,7,11,10,4,13,1,5,8,12,6,9,3,2,15, 13,8,10,1,3,15,4,2,11,6,7,12,0,5,14,9, /S3 10,0,9,14,6,3,15,5,1,13,12,7,11,4,2,8, 13,7,0,9,3,4,6,10,2,8,5,14,12,11,15,1, 13,6,4,9,8,15,3,0,11,1,2,12,5,10,14,7, 1,10,13,0,6,9,8,7,4,15,14,3,11,5,2,12, /S4 7,13,14,3,0,6,9,10,1

8、,2,8,5,11,12,4,15, 13,8,11,5,6,15,0,3,4,7,2,12,1,10,14,9, 10,6,9,0,12,11,7,13,15,1,3,14,5,2,8,4, 3,15,0,6,10,1,13,8,9,4,5,11,12,7,2,14, /S5 2,12,4,1,7,10,11,6,8,5,3,15,13,0,14,9, 14,11,2,12,4,7,13,1,5,0,15,10,3,9,8,6, 4,2,1,11,10,13,7,8,15,9,12,5,6,3,0,14, 11,8,12,7,1,14,2,13,6,15,0,9,10,4,5,3, /S6

9、12,1,10,15,9,2,6,8,0,13,3,4,14,7,5,11, 10,15,4,2,7,12,9,5,6,1,13,14,0,11,3,8, 9,14,15,5,2,8,12,3,7,0,4,10,1,13,11,6, 4,3,2,12,9,5,15,10,11,14,1,7,6,0,8,13, /S7 4,11,2,14,15,0,8,13,3,12,9,7,5,10,6,1, 13,0,11,7,4,9,1,10,14,3,5,12,2,15,8,6, 1,4,11,13,12,3,7,14,10,15,6,8,0,5,9,2, 6,11,13,8,1,4,10,7,9,5,

10、0,15,14,2,3,12, /S8 13,2,8,4,6,15,11,1,10,9,3,14,5,0,12,7, 1,15,13,8,10,3,7,4,12,5,6,11,0,14,9,2, 7,11,4,1,9,12,14,2,0,6,10,13,15,3,5,8, 2,1,14,7,4,10,8,13,15,12,9,0,3,5,6,11;/置換選擇1int PC_156 = 56,48,40,32,24,16,8, 0,57,49,41,33,25,17, 9,1,58,50,42,34,26, 18,10,2,59,51,43,35, 62,54,46,38,30,22,14, 6

11、,61,53,45,37,29,21, 13,5,60,52,44,36,28, 20,12,4,27,19,11,3;/置換選擇2int PC_248 = 13,16,10,23,0,4,2,27, 14,5,20,9,22,18,11,3, 25,7,15,6,26,19,12,1, 40,51,30,36,46,54,29,39, 50,44,32,46,43,48,38,55, 33,52,45,41,49,35,28,31; /對左移次數(shù)的規(guī)定 intMOVE_TIMES16=1,1,2,2,2,2,2,2,1,2,2,2,2,2,2,1; 2）移位操作函數(shù)/字節(jié)轉(zhuǎn)換成二進制int

12、ByteToBit(ElemType ch, ElemType bit8) int cnt; for(cnt = 0;cnt cnt)&1; return 0; /二進制轉(zhuǎn)換成字節(jié)int BitToByte(ElemType bit8,ElemType *ch) int cnt; for(cnt = 0;cnt 8; cnt+) *ch |= *(bit + cnt)cnt; return 0;/將長度為8的字符串轉(zhuǎn)為二進制位串int Char8ToBit64(ElemType ch8,ElemType bit64) int cnt; for(cnt = 0; cnt 8; cnt+) Byt

13、eToBit(*(ch+cnt),bit+(cnt3); return 0;/將二進制位串轉(zhuǎn)為長度為8的字符串int Bit64ToChar8(ElemType bit64,ElemType ch8) int cnt; memset(ch,0,8); for(cnt = 0; cnt 8; cnt+) BitToByte(bit+(cnt3),ch+cnt); return 0;3）密鑰相關(guān)的函數(shù)/生成子密鑰int DES_MakeSubKeys(ElemType key64,ElemType subKeys1648) ElemType temp56; int cnt; DES_PC1_Tra

14、nsform(key,temp); /PC1置換 for(cnt = 0; cnt 16; cnt+) /16輪跌代，產(chǎn)生16個子密鑰 DES_ROL(temp,MOVE_TIMEScnt);/循環(huán)左移 DES_PC2_Transform(temp,subKeyscnt);/PC2置換，產(chǎn)生子密鑰 return 0;/密鑰置換1int DES_PC1_Transform(ElemType key64, ElemType tempbts56) int cnt; for(cnt = 0; cnt 56; cnt+) tempbtscnt = keyPC_1cnt; return 0;/密鑰置換2i

15、nt DES_PC2_Transform(ElemType key56, ElemType tempbts48) int cnt; for(cnt = 0; cnt 48; cnt+) tempbtscnt = keyPC_2cnt; return 0;/循環(huán)左移int DES_ROL(ElemType data56, int time) ElemType temp56; /保存將要循環(huán)移動到右邊的位 memcpy(temp,data,time); memcpy(temp+time,data+28,time); /前28位移動 memcpy(data,data+time,28-time); m

16、emcpy(data+28-time,temp,time); /后28位移動 memcpy(data+28,data+28+time,28-time); memcpy(data+56-time,temp+time,time); return 0;4）IP置換相關(guān)函數(shù)/IP置換int DES_IP_Transform(ElemType data64) int cnt; ElemType temp64; for(cnt = 0; cnt 64; cnt+) tempcnt = dataIP_Tablecnt; memcpy(data,temp,64); return 0;/IP逆置換int DES

17、_IP_1_Transform(ElemType data64) int cnt; ElemType temp64; for(cnt = 0; cnt 64; cnt+) tempcnt = dataIP_1_Tablecnt; memcpy(data,temp,64); return 0;/擴展置換int DES_E_Transform(ElemType data48) int cnt; ElemType temp48; for(cnt = 0; cnt 48; cnt+) tempcnt = dataE_Tablecnt; memcpy(data,temp,48); return 0;/P

18、置換int DES_P_Transform(ElemType data32) int cnt; ElemType temp32; for(cnt = 0; cnt 32; cnt+) tempcnt = dataP_Tablecnt; memcpy(data,temp,32); return 0;/異或int DES_XOR(ElemType R48, ElemType L48 ,int count) int cnt; for(cnt = 0; cnt count; cnt+) Rcnt = Lcnt; return 0;/S盒置換int DES_SBOX(ElemType data48) i

19、nt cnt; int line,row,output; int cur1,cur2; for(cnt = 0; cnt 8; cnt+) cur1 = cnt*6; cur2 = cnt2; /計算在S盒中的行與列 line = (datacur11) + datacur1+5; row = (datacur1+13) + (datacur1+22) + (datacur1+33; datacur2+1 = (output&0X04)2; datacur2+2 = (output&0X02)1; datacur2+3 = output&0x01; return 0;/交換int DES_S

20、left32, ElemType right32) ElemType temp32; memcpy(temp,left,32); memcpy(left,right,32); memcpy(right,temp,32); return 0; 5）加解密函數(shù)/加密單個分組int DES_EncryptBlock(ElemType plainBlock8, ElemType subKeys1648, ElemType cipherBlock8) ElemType plainBits64; ElemType copyRight48; int cnt; Char8ToBit64(plainBlock,

21、plainBits); /初始置換（IP置換） DES_IP_Transform(plainBits); /16輪迭代 for(cnt = 0; cnt = 0; cnt-) memcpy(copyRight,cipherBits+32,32); /將右半部分進行擴展置換，從32位擴展到48位 DES_E_Transform(copyRight); /將右半部分與子密鑰進行異或操作 DES_XOR(copyRight,subKeyscnt,48); /異或結(jié)果進入S盒，輸出32位結(jié)果 DES_SBOX(copyRight); /P置換 DES_P_Transform(copyRight); /

22、將明文左半部分與右半部分進行異或 DES_XOR(cipherBits,copyRight,32); if(cnt != 0) /最終完成左右部的交換 DES_S); /加密文件 此函數(shù)是合天提供例子，不是DES算法關(guān)鍵函數(shù)，可修改。生成的文本文件，需要二進制工具打開與CAP對照intDES_Encrypt(char*plainFile,char*keyStr,char*cipherFile)FILE*plain,*cipher; intcount; ElemTypeplainBlock8,cipherBlock8,keyBlock8; ElemTypebKey64;ElemTypesubKe

23、ys1648;if(plain=fopen(plainFile,rb)=NULL) returnPLAIN_; if(cipher=fopen(cipherFile,wb)=NULL) returnCIPHER_; /設(shè)置密鑰 memcpy(keyBlock,keyStr,8); /將密鑰轉(zhuǎn)換為二進制流 Char8ToBit64(keyBlock,bKey); /生成子密鑰 DES_MakeSubKeys(bKey,subKeys); while(!feof(plain) /每次讀8個字節(jié)，并返回成功讀取的字節(jié)數(shù) if(count=fread(plainBlock,sizeof(char),8

24、,plain)=8) DES_EncryptBlock(plainBlock,subKeys,cipherBlock); fwrite(cipherBlock,sizeof(char),8,cipher); if(count) /填充 memset(plainBlock+count,0,7-count); /最后一個字符保存包括最后一個字符在內(nèi)的所填充的字符數(shù)量 plainBlock7=8-count; DES_EncryptBlock(plainBlock,subKeys,cipherBlock); fwrite(cipherBlock,sizeof(char),8,cipher); fcl

25、ose(plain); fclose(cipher); returnOK; /解密文件此函數(shù)是合天提供例子，不是算法關(guān)鍵函數(shù)，可修改 intDES_Decrypt(char*cipherFile,char*keyStr,char*plainFile) FILE*plain,*cipher; intcount,times=0; long; ElemTypeplainBlock8,cipherBlock8,keyBlock8; ElemTypebKey64; ElemTypesubKeys1648; if(cipher=fopen(cipherFile,rb)=NULL) returnCIPHER_; if(plain=fopen(plainFile,wb)=NULL) returnPLAIN_; /設(shè)置密鑰 memcpy(keyBlock,keyStr,8); /將密鑰轉(zhuǎn)換為二進制流 Char8ToBit64(keyBlock,bKey); /生成子密鑰 DES_MakeSubKeys(bKey,subKeys);