C + + Implement DES encryption algorithm instance parse _c language

The example described in this paper is a program code to implement DES encryption algorithm, in C + +, des encryption is a more commonly used encryption algorithm, and the application is very extensive. This CPP file can meet your DES encryption needs, the code is accompanied by a rich annotation, I believe that for everyone to understand the Des can play a great help.

The specific implementation code is as follows:

#include "memory.h" #include "stdio.h" enum {encrypt,decrypt};//encrypt: Encryption, decrypt: decrypting void Des_run (char Out[8],char in[
8],bool type=encrypt);
Set key void Des_setkey (const char key[8]); static void F_func (BOOL in[32],const bool ki[48])//f function static void S_func (BOOL out[32],const bool in[48]);//s box instead of/transformation STA
TIC void transform (bool *out, bool *in, const char *table, int len); static void Xor (BOOL *ina, const BOOL *INB, int len);/xor or static void Rotatel (bool *in, int len, int loop);/loop left//byte group conversion
The bitwise group is static void Bytetobit (bool *out,const char *in, int bits);
The bit groups are converted to byte group static void Bittobyte (char *out, const bool *in, int bits); Permutation IP Table const static char ip_table[64]={ 58,50,42,34,26,18,10,2,60,52,44,36,28,20,12,4,62,54,46,38,30,22,14,6,64,56,48,40,32,24,16,8,57,49,41,33,25,17,9,1,59,51,4
3,35,27,19,11,3,61,53,45,37,29,21,13,5,63,55,47,39,31,23,15,7}; Inverse permutation IP-1 table const static CHAR ipr_table[64]={ 40,8,48,16,56,24,64,32,39,7,47,15,55,23,63,31,38,6,46,14,54,22,62,30,37,5,45,13,53,21,61,29,36,4,44,12,52,20,60,28,35,3,43,11, 51,19,59,27,34,2,42,10,50,18,58,26,33,1,41,9,49,17,57,25}; E-bit Select table static const char e_table[48]={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-Transposition Table const static CHAR p_table[32]={
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-Select Table const static char pc1_table[56]={57,49,41,33,25,17,9,1, 58,50,42,34,26,18,10,2, 59,51,43,35,27,19,11,3,
60,52,44,36,63,55,47,39, 31,23,15,7,62,54,46,38, 30,22,14,6,61,53,45,37, 29,21,13,5,28,20,12,4};
   PC2-Select Table const static char pc2_table[48]={14,17,11,24,1,5,3,28, 15,6,21,10,23,19,12,4, 26,8,16,7,27,20,13,2,
41,52,31,37,47,55,30,40, 51,45,33,48,44,49,39,56, 34,53,46,42,50,36,29,32};
Left shift Table const static char loop_table[16]={1,1,2,2,2,2,2,2,1,2,2,2,2,2,2,1}; s Box const static char s_box[8][4][16]={//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, 3, 5, 0, 8, 2, 4, 9, 1, 7, 5, 3, 0,//s2 6, 15, 1, 8, 14, 6, 11, 3, 4, 9, 7, 2 3, 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 , 2, 8, 1, 3, 4, 2, one, 6, 7, 0, 5,, 9,//s3 10, 0, 9, 14, 6, 3, 15, 5, 1, 13, 12, 7, 1 1, 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 4, 7, 1, 0, 6, 9, 8, 7, 4, 3, 5, 2, 7, 13, 14, 3, 0, 6, 9, 10, 1, 2, 8, 5, 11,//S4 , 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, 4, 3, 0, 6, 1, 8, 9, 4, 5, one, 7, 2,//S5 2, 12, 4, 1, 7, 10, 11, 6, 8, 5, 3, 15, 13, 0, 1 4, 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, 2, 6, 0, 9, ten, 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, Ten, one, 1, 7, 6, 0, 8,//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,  9, 5, 0, 2, 3,//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
, 12, 9, 0, 3, 5, 6, 11}; static bool Subkey[16][48];//16 circle key void Des_run (char Out[8],char in[8], bool type) {static bool M[64],tmp[32],*li=&m[0], *ri=&m[32];
    Bytetobit (m,in,64);
    Transform (m,m,ip_table,64);
           if (Type==encrypt) {for (int i=0;i<16;i++) {memcpy (tmp,ri,32);
           F_func (Ri,subkey[i]);
           XOR (RI,LI,32);
       memcpy (li,tmp,32);
           }}else{for (int i=15;i>=0;i--) {memcpy (tmp,li,32);
           F_func (Li,subkey[i]);
           XOR (LI,RI,32);
       memcpy (ri,tmp,32);
    } transform (m,m,ipr_table,64);
Bittobyte (out,m,64);
    } void Des_setkey (const char key[8]) {static bool k[64], *kl=&k[0], *kr=&k[28];
    Bytetobit (k,key,64);
    Transform (k,k,pc1_table,56);
       for (int i=0;i<16;i++) {Rotatel (kl,28,loop_table[i]);
       Rotatel (Kr,28,loop_table[i]);
    Transform (subkey[i],k,pc2_table,48);
    } void F_func (bool in[32],const bool ki[48]) {static bool mr[48];
    Transform (mr,in,e_table,48);
    XOR (MR,KI,48);
    S_func (IN,MR);
Transform (in,in,p_table,32); } void S_fUNC (BOOL out[32],const bool in[48]) {for (char i=0,j,k;i<8;i++,in+=6,out+=4) {j= (in[0]<<1) +in[5];
       k= (in[1]<<3) + (IN[2]&LT;&LT;2) + (in[3]<<1) +in[4];
    Bytetobit (out,&s_box[i][j][k],4);
    } void Transform (bool *out,bool *in,const char *table,int len) {static bool tmp[256];
    for (int i=0;i<len;i++) tmp[i]=in[table[i]-1];
memcpy (Out,tmp,len); } void XOR (bool *ina,const bool *inb,int len) {for (int i=0;i<len;i++) ina[i]^=inb[i];} void Rotatel (BOOL *
    In,int Len,int loop) {static bool tmp[256];
    memcpy (Tmp,in,loop);
    memcpy (In,in+loop,len-loop);
memcpy (In+len-loop,tmp,loop); } void Bytetobit (bool *out,const char *in,int bits) {for (int i=0;i<bits;i++) out[i]= (in[i/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++) out[i/8]|=in[i]<< (i%8); } void Main () {char key[8]={' P ', 'R ', ' O ', ' g ', ' r ', ' A ', ' m '},str[8];
    Puts ("*****************des***********************");
    printf ("\ n");
    printf ("\ n");
    Puts ("Please input your words");
    Gets (str);
    printf ("\ n");
    Puts ("****************************************");
    Des_setkey (key);
    Des_run (Str,str,encrypt);
    Puts ("After encrypting:");
    Puts (str);
    printf ("\ n");
    Puts ("****************************************");
    Puts ("After decrypting:");
    Des_run (Str,str,decrypt);
    Puts (str);
    printf ("\ n");
    Puts ("****************************************");
printf ("\ n");

 }

Interested friends can test and run the example of this article, I believe that the C + + program can play a certain role in helping.