des.c

用ansi C编写的DES加密实现

#include <stdio.h>

static int ToHex( int x )
{
  if( x >= 0 && x <= 9 )
    return( x + '0' );
  else if( x >= 10 && x <= 15 )
    return( x + 'A' - 10 );
  else
    return( 0 );
}

static int ToBin( int c )
{
  if( c >= 'A' && c <= 'F' )
    return( c - 'A' + 10 );
  else if( c >= 'a' && c <= 'f' )
    return( c - 'a' + 10 );
  else if( c >= '0' && c <= '9' )
    return( c - '0' );
  else
    return( 0 );
}

static void Decrypt( char *Key, char *Data, int Size )
{
  int i, l;
  unsigned char c;

  l = strlen( Key );
  for( i = 0; i < Size; i ++ ){
    c = *Data;
    *Data = ( ( c << 5 ) + ( c >> 3 ) ) ^ Key[i % l];
    Data ++;
  }
}

static int pc1_tab[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
        };

static int pc2_tab[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
        };

static int mc_tab[16]=
        {
          1,1,2,2,2,2,2,2,1,2,2,2,2,2,2,1
        };

static int ip_tab[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,
	  59,51,43,35,27,19,11,3,
	  61,53,45,37,29,21,13,5,
	  63,55,47,39,31,23,15,7
        };

static int rip_tab[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
        };

static int e_tab[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
        };

static int p_tab[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
        };

static int s_tab[8][4][16]=
        {
	  {
            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,
          },
	  {
	    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,
          },
	  {
	    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,
          },
	  {
	    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,
          },
	  {
	    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,
          },
	  {
	    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,
          },
	  {
	    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,
	    6,11,13,8,1,4,10,7,9,5,0,15,14,2,3,12,
          },
	  {
	    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
          }
        };

static int ffk[32];
static int mw[64];
static int mkey[8][8];

static void mkey_tran( char *p )
{
  int i, j, k;

  for( i=0; i<16; i+=2 )
  {
    j = i >> 1;
    k = ToBin( p[i] );
    mkey[j][0] = ( k & 8 ) >> 3;
    mkey[j][1] = ( k & 4 ) >> 2;
    mkey[j][2] = ( k & 2 ) >> 1;
    mkey[j][3] = ( k & 1 ) >> 0;
    k = ToBin( p[i + 1] );
    mkey[j][4] = ( k & 8 ) >> 3;
    mkey[j][5] = ( k & 4 ) >> 2;
    mkey[j][6] = ( k & 2 ) >> 1;
    mkey[j][7] = ( k & 1 ) >> 0;
  }
}

static void data_tran( char *p )
{
  int i, j, k;

  for( i=0; i<16; i++ )
  {
    j = i << 2;
    k = ToBin( p[i] );
    mw[j] = ( k & 8 ) >> 3;
    mw[j + 1] = ( k & 4 ) >> 2;
    mw[j + 2] = ( k & 2 ) >> 1;
    mw[j + 3] = ( k & 1 ) >> 0;
  }
}

static void getk( ki, keyi )
int ki[16][48];
int keyi[64];
{
  int i,j,n,tem1,tem2,trav1[56];

  for( i=0; i<56; i++ )
    trav1[i]=keyi[pc1_tab[i]-1];
  for( i=0; i<16; i++ )
  {
    for( j=0; j<mc_tab[i]; j++ )
    {
      tem1=trav1[0];
      tem2=trav1[28];
      for( n=0; n<27; n++ )
      {
        trav1[n]=trav1[n+1];
        trav1[n+28]=trav1[n+28+1];
      }
      trav1[27]=tem1;
      trav1[55]=tem2;
    }
    for( n=0; n<48; n++ )
      ki[i][n]=trav1[pc2_tab[n]-1];
  }
  return;
}

static void des_f( fr, fk )
int fr[32];
int fk[48];
{
  int i, row, col, temp;
  int trav2[48],e0[32];

  for( i=0; i<48; i++ )
  {
    trav2[i]=fr[e_tab[i]-1];
    trav2[i]=trav2[i]^fk[i];
  }
  for( i=0; i<8; i++ )
  {
    row=trav2[i*6]*2+trav2[i*6+5];
    col=trav2[i*6+1]*8+trav2[i*6+2]*4+trav2[i*6+3]*2+trav2[i*6+4];
    temp=s_tab[i][row][col];
    e0[i*4]=temp/8;
    e0[i*4+1]=(temp%8)/4;
    e0[i*4+2]=(temp%4)/2;
    e0[i*4+3]=temp%2;
  }
  for( i=0; i<32; i++ )
    ffk[i]=e0[p_tab[i]-1];
}

void DESEncrypt( char *Key, char *InData, char *OutData )
{
  int i,j;
  int trav[64], l0[32], l[64], r0[32];
  static int k[16][48];
  static flag=1;
  if ( flag ) {
      
      mkey_tran(Key);
      getk(k,mkey);
      flag=0;
  }
  data_tran(InData);
  for( i=0; i<64; i++ )
    trav[i]=mw[ip_tab[i]-1];
       
  for( i=0; i<32; i++ )
  {
    l0[i]=trav[i];
    r0[i]=trav[i+32];
  }

  for( i=0; i<16; i++ )
  {
    des_f(r0,k[i]);
    for( j=0; j<32; j++ )
    {
      l[j]=r0[j];
      l[j+32]=l0[j]^ffk[j];
    }
    for( j=0; j<32; j++ )
    {
      l0[j]=l[j];
      r0[j]=l[j+32];
    }
  }
  for( i=0; i<32; i++ )
  {
    l[i]=r0[i];
    l[i+32]=l0[i];
  }
  for( i=0; i<64; i++ )
    trav[i]=l[rip_tab[i]-1];

  for( i=0; i<16; i++ )
  {
    j = i << 2;
    OutData[i] = ToHex( ( trav[j] << 3 ) + ( trav[j + 1] << 2 )
        + ( trav[j + 2] << 1 ) + ( trav[j + 3] << 0 ) );
  }
}

void DESDecrypt( char *Key, char *InData, char *OutData )
{
  int i,j;
  int trav[64], l0[32], l[64], r0[32];
  int k[16][48];
 
  mkey_tran(Key);
  data_tran(InData);

  getk(k,mkey);
  for( i=0; i<64; i++ )
    trav[i]=mw[ip_tab[i]-1];
       
  for( i=0; i<32; i++ )
  {
    r0[i]=trav[i];
    l0[i]=trav[i+32];
  }

  for( i=15; i>=0; i-- )
  {
    des_f(l0,k[i]);
    for( j=0; j<32; j++ )
    {
      l[j]=l0[j];
      l[j+32]=r0[j]^ffk[j];
    }
    for( j=0; j<32; j++ )
    {
      r0[j]=l[j];
      l0[j]=l[j+32];
    }
  }
  for( i=0; i<32; i++ )
  {
    l[i]=l0[i];
    l[i+32]=r0[i];
  }
  for( i=0; i<64; i++ )
    trav[i]=l[rip_tab[i]-1];

  for( i=0; i<16; i++ )
  {
    j = i << 2;
    OutData[i] = ToHex( ( trav[j] << 3 ) + ( trav[j + 1] << 2 )
        + ( trav[j + 2] << 1 ) + ( trav[j + 3] << 0 ) );
  }
}
int main()
{
     char *source="117704";
     char  test[7];
     char *Key="1234567890123456";  //设置主密钥
     char outdata1[40];
     char outdata2[40];
     long  ret=0,i,j;
     memset(outdata1,0x00,sizeof(outdata1));
     memset(outdata2,0x00,sizeof(outdata2));
     DESEncrypt(Key,source,outdata1);
     printf("source string=[%s]\n",source);
     for(ret=0;ret<1000000;ret++) {
        sprintf(test,"7ld",ret);
        DESEncrypt(Key,test,outdata2); //加密
        if(strcmp(outdata1,outdata2)==0)
           printf("succeed[%s]\n",test);
     }
     printf("sec string =[%s]\n",outdata1);
     
     DESDecrypt(Key,outdata1,outdata2);  //解密
     printf("source string=[%s]\n",outdata2);
     return 0;
}