DES加密解密算法的實現(xiàn)

1、裝訂線JIANGSU TEACHERS UNIVERSITY OF TECHNOLOGY 網(wǎng)絡安全課程設計報告 學 院： 計算機工程學院 專 業(yè)： 計算機科學與技術 班 級： 09計3W 學 號： 09141307 姓 名： 張 賽 指導老師： 古春生 一、DES算法的簡介DES算法的加密解密過程是一種采用傳統(tǒng)加密方法的區(qū)組密碼。它的算法是對稱的，既可用于加密又可用于解密。 DES算法的入口參數(shù)有三個：Key、Data、Mode。其中Key為8個字節(jié)共64位，是DES算法的工作密鑰；Data也為8個字節(jié)64位，是要被加密或被解密的數(shù)據(jù)；Mode為DES的工作方式，有兩種：加密或解密。 DES算

2、法是這樣工作的：如Mode為加密，則用Key 去把數(shù)據(jù)Data進行加密， 生成Data的密碼形式（64位）作為DES的輸出結果；如Mode為解密，則用Key去把密碼形式的數(shù)據(jù)Data解密，還原為Data的明碼形式（64位）作為DES的輸出結果。在通信網(wǎng)絡的兩端，雙方約定一致的Key，在通信的源點用Key對核心數(shù)據(jù)進行DES加密，然后以密碼形式在公共通信網(wǎng)（如電話網(wǎng)）中傳輸?shù)酵ㄐ啪W(wǎng)絡的終點，數(shù)據(jù)到達目的地后，用同樣的Key對密碼數(shù)據(jù)進行解密，便再現(xiàn)了明碼形式的核心數(shù)據(jù)。這樣，便保證了核心數(shù)據(jù)（如PIN、MAC等）在公共通信網(wǎng)中傳輸?shù)陌踩院涂煽啃浴?通過定期在通信網(wǎng)絡的源端和目的端同時改用新的K

3、ey，便能更進一步提高數(shù)據(jù)的保密性，這正是現(xiàn)在金融交易網(wǎng)絡的流行做法。二、DES算法的實現(xiàn)DES算法把64位的明文輸入塊變?yōu)?4位的密文輸出塊，它所使用的密鑰也是64位,其功能是把輸入的64位數(shù)據(jù)塊按位重新組合，并把輸出分為L0 、R0兩部分，每部分各長32位，其置換規(guī)則見下表： 58,50,12,34,26,18,10,2,60,52,44,36,28,20,12,4,62,54,46,38,30,22,14,6,64,56,48,40,32,24,16,8,57,49,41,33,25,17, 9,1,59,51,43,35,27,19,11,3,61,53,45,37,29,21,13,

4、5,63,55,47,39,31,23,15,7,即將輸入的第58位換到第一位，第50位換到第2位，依此類推，最后一位是原來的第7位。 L0、R0則是換位輸出后的兩部分，L0是輸出的左32位，R0 是右32位，例：設置換前的輸入值為D1D2D3D64，則經(jīng)過初始置換后的結果為：L0=D550D8；R0=D57D49.D7。經(jīng)過26次迭代運算后，得到L16、R16，將此作為輸入，進行逆置換，即得到密文輸出。逆置換正好是初始置的逆運算，例如，第1位經(jīng)過初始置換后，處于第40位，而通過逆置換，又將第40位換回到第1位，其逆置換規(guī)則如下表所示：40,8,48,16,56,24,64,32,39,7,4

5、7,15,55,23,63,31, 38,6,46,14,54,22,62,30,37,5,45,13,53,21,61,29, 36,4,44,12,52,20,60,28,35,3,43,11,51,19,59,27, 34,2,42,10,50,18,58 26,33,1,41, 9,49,17,57,25, 放大換位表 32, 1, 2, 3, 4, 5, 4, 5, 6, 7, 8, 9, 8, 9, 10,11, 12,13,12,13,14,15,16,17,16,17,18,19,20,21,20,21, 22,23,24,25,24,25,26,27,28,29,28,29,

6、30,31,32, 1, 單純換位表 16,7,20,21,29,12,28,17, 1,15,23,26, 5,18,31,10, 2,8,24,14,32,27, 3, 9,19,13,30, 6,22,11, 4,25, 在f(Ri,Ki)算法描述圖中，S1,S2.S8為選擇函數(shù)，其功能是把6bit數(shù)據(jù)變?yōu)?bit數(shù)據(jù)。下面給出選擇函數(shù)Si(i=1,2.8)的功能表： 選擇函數(shù)Si 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,

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

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

9、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: 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

10、,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, 6,11,13,8,1,4,10,7,9,5,0,15,14,2,3,12, 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, 子密鑰Ki(48bit)的生成算法初始Key值為6

11、4位，但DES算法規(guī)定，其中第8、16、.64位是奇偶校驗位，不參與DES運算。故Key 實際可用位數(shù)便只有56位。即：經(jīng)過縮小選擇換位表1的變換后，Key 的位數(shù)由64 位變成了56位，此56位分為C0、D0兩部分，各28位，然后分別進行第1次循環(huán)左移，得到C1、D1，將C1（28位）、D1（28位）合并得到56位，再經(jīng)過縮小選擇換位2，從而便得到了密鑰K0（48位）。依此類推，便可得到K1、K2、.、K15，不過需要注意的是，16次循環(huán)左移對應的左移位數(shù)要依據(jù)下述規(guī)則進行： 循環(huán)左移位數(shù)1,1,2,2,2,2,2,2,1,2,2,2,2,2,2,1 以上介紹了DES算法的加密過程。 DES

12、算法的解密過程是一樣的，區(qū)別僅僅在于第一次迭代時用子密鑰K15，第二次K14、，最后一次用K0，算法本身并沒有任何變化。三、加密解密流程圖DES算法處理的數(shù)據(jù)對象是一組64比特的明文串。設該明文串為m=m1m2m64 (mi=0或1)。明文串經(jīng)過64比特的密鑰K來加密，最后生成長度為64比特的密文E。其加密算法和解密算法互逆，下面是加密算法過程流程圖：算法加密流程圖圖上可以看出加密的詳細算法，也可以逆過來，就是解密的算法流程圖四、 設計流程圖如下：五、 設計代碼：#include "memory.h"#include "stdio.h"enum 

13、; encrypt,decrypt;/ENCRYPT:加密，DECRYPT：解密void des_run(char out8,char in8,bool type=encrypt);/設置密鑰void des_setkey(const char key8);static void f_func(bool in32,const bool ki48);/f函數(shù)static void s_func(bool out32,const bool in48);/s盒代替/變換static void transform(bool *out, bool *in, const char *table, int

14、len);static void xor(bool *ina, const bool *inb, int len);/異或static void rotatel(bool *in, int len, int loop);/循環(huán)左移 /字節(jié)組轉換成位組static void bytetobit(bool *out,const char *in, int bits);/位組轉換成字節(jié)組static void bittobyte(char *out, const bool *in, int bits);/置換IP表conststatic char ip_table64=58,50,42,3

15、4,26,18,10,2,60,52,44,36,28,20,12,4,62,54,46,38,30,22,14,6,64,56,48,40,32,24,16,8,57,49,41,33,25,17,9,1,59,51,43,35,27,19,11,3,61,53,45,37,29,21,13,5,63,55,47,39,31,23,15,7;/逆置換IP-1表const static char ipr_table64=40,8,48,16,56,24,64,32,39,7,47,15,55,23,63,31,38,6,46,14,54,22,62,30,37,5,45,13,53,21,61

16、,29,36,4,44,12,52,20,60,28,35,3,43,11, 51,19,59,27,34,2,42,10,50,18,58,26,33,1,41,9,49,17,57,25;/E 位選擇表static const char e_table48=32,1, 2, 3, 4, 5,4, 5, 6, 7, 8, 9,8, 9, 10,11,12,13,12,13,14,15,16,17,16,17,18,19,20,21,20,21,22,23,24,25,24,25,26,27,28,29,28,29,30,31,32,1;/P換位表const static char

17、p_table32=16,7,20,21,29,12,28,17,1,15,23,26,5,18,31,10,2,8,24,14,32,27,3,9,19,13,30,6,22,11,4,25;/pc1選位表const static char pc1_table56=                           

18、0; 57,49,41,33,25,17,9,1,                             58,50,42,34,26,18,10,2,            &

19、#160;                59,51,43,35,27,19,11,3,                             60,52,4

20、4,36,63,55,47,39,                             31,23,15,7,62,54,46,38,              &#

21、160;              30,22,14,6,61,53,45,37,                             29,21,13,5,28,20,12,

22、4;/pc2選位表const static char pc2_table48=                                    14,17,11,24,1,5,3,28,     

23、0;                              15,6,21,10,23,19,12,4,                 

24、;                   26,8,16,7,27,20,13,2,                           &#

25、160;        41,52,31,37,47,55,30,40,                                    51,45,33,48,4

26、4,49,39,56,                                    34,53,46,42,50,36,29,32;/左移位數(shù)表const static char loop_table16=1,1,2,2,2,2,2,2,1

27、,2,2,2,2,2,2,1;/S盒const static char s_box8416=       /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,     

28、0; 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, 13

29、, 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     &#

30、160; 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,

31、 4, 15, 14, 3, 11, 5, 2, 12,       /s4       7, 13, 14, 3, 0, 6, 9, 10, 1, 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

32、, 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, 1

33、1, 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     &#

34、160; 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

35、, 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, 1

36、2, 3, 7, 14, 10, 15, 6, 8, 0, 5, 9, 2,       6, 11, 13, 8, 1, 4, 10, 7, 9, 5, 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

37、, 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;static bool subkey1648;/16圈子密鑰void des_run(char out8,char in8, bool type

38、)       static bool m64,tmp32,*li=&m0, *ri=&m32;       bytetobit(m,in,64);       transform(m,m,ip_table,64);       if(type=encrypt)       

39、;       for(int i=0;i<16;i+)                     memcpy(tmp,ri,32);                

40、0;    f_func(ri,subkeyi);                     xor(ri,li,32);                     memc

41、py(li,tmp,32);                     else              for(int i=15;i>=0;i-)          

42、60;          memcpy(tmp,li,32);                     f_func(li,subkeyi);              

43、       xor(li,ri,32);                     memcpy(ri,tmp,32);                   &

44、#160; transform(m,m,ipr_table,64);       bittobyte(out,m,64);void des_setkey(const char key8)       static bool k64, *kl=&k0, *kr=&k28;       bytetobit(k,key,64);       tra

45、nsform(k,k,pc1_table,56);       for(int i=0;i<16;i+)                     rotatel(kl,28,loop_tablei);            

46、  rotatel(kr,28,loop_tablei);              transform(subkeyi,k,pc2_table,48);       void f_func(bool in32,const bool ki48)       static bool mr48;    

47、   transform(mr,in,e_table,48);       xor(mr,ki,48);       s_func(in,mr);       transform(in,in,p_table,32);void s_func(bool out32,const bool in48)       for(char i=0,j,k

48、;i<8;i+,in+=6,out+=4)                     j=(in0<<1)+in5;              k=(in1<<3)+(in2<<2)+(in3<<1)+in4; 

49、60;            bytetobit(out,&s_boxijk,4);       void transform(bool *out,bool *in,const char *table,int len)       static bool tmp256;       for(int i

50、=0;i<len;i+)              tmpi=intablei-1;       memcpy(out,tmp,len);void xor(bool *ina,const bool *inb,int len)       for(int i=0;i<len;i+)     

51、;         inai=inbi;void rotatel(bool *in,int len,int loop)       static bool tmp256;       memcpy(tmp,in,loop);       memcpy(in,in+loop,len-loop);    

52、;   memcpy(in+len-loop,tmp,loop);void bytetobit(bool *out,const char *in,int bits)       for(int i=0;i<bits;i+)              outi=(ini/8>>(i%8) &1;void bittobyte(char *out,const bool *in,int bits)       memset(out,0,(bits+7)/8);       for(int i=0;i<bits;i+)