des.c

用c语言实现的des算法

//#include <des.h>
#define uint unsigned int
#define uchar unsigned char

//初始换位表
uchar Ip[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};
                
//最后换位表
uchar Ipr[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}; 
                 
//密钥的压缩型换位表1
uchar Pc_1[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};
                  
//密钥的压缩型换位表2
uchar Pc_2[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};
                 
//扩展型换位表
uchar Ex[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};
                
//换位表P
uchar Px[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};
   
//各层移位次数
uchar ShTb[16] = {1,1,2,2,2,2,2,2,
                  1,2,2,2,2,2,2,1};
                  
                  
//S盒代替表
uchar Sbox[32][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}};


unsigned char g_ucPreKey[8]; // = {0x68,0xc1,0x23,0x97,0xae,0x94,0x1c,0x1c}; //密钥
uchar Key[16][8]; //存放子密钥
uchar ShRf[8] = {0x80,0x40,0x20,0x10,0x08,0x04,0x02,0x01};


struct para
{
   uchar *input;
   uchar *ip;
   uchar row;
   uchar col;
   uchar *buf;
};

      


//=============================================================
// 换位，input：输入，ip：换位表，len：换位表长度，buf：输出
//=============================================================
void Exchange(uchar *input,uchar *ip,uchar row,uchar col,uchar *buf)
{
   uchar i,j,k,row1,col1,tmp;
   for(i=0; i<row; i++)
      buf[i] = 0;
   k=0;
   for(j=0; j<row; j++)
   {
      for(i=0; i<col; i++)
      {
         tmp = ip[k] - 1;
         row1 = tmp/8; 
         col1 = tmp%8; 
         if(ShRf[col1] & input[row1])
         {
            buf[j] |= ShRf[i]; 
         }
         k++;
      }
   }
}


void Exchange1(struct para pm)
{
   uchar i,j,k,row1,col1,tmp;
   for(i=0; i<pm.row; i++)
      pm.buf[i] = 0;
   k=0;
   for(j=0; j<pm.row; j++)
   {
      for(i=0; i<pm.col; i++)
      {
         tmp = pm.ip[k] - 1;
         row1 = tmp/8; 
         col1 = tmp%8; 
         if(ShRf[col1] & pm.input[row1])
         {
            pm.buf[j] |= ShRf[i]; 
         }
         k++;
      }
   }
}



//================================================================
// 56位数的前28位和后28位各循环左移一位
// 输入：input，56位数；输出：input，移位后的56位数
//================================================================
void Shift(uchar input[7])
{
   char i;
   uchar tmp=0;
   if(input[0] & 0x80)
      tmp = 0x01;
   input[0] <<= 1;
   for(i=1; i<7; i++)
   {
      if(input[i] & 0x80)
         input[i-1] |= 0x01;
      input[i] <<= 1;      
   }
   if(input[3] & 0x10)
      input[6] |= 0x01;
   if(tmp)
      input[3] |= 0x10;
   else
      input[3] &= 0xef;
}


//======================================================================
// 产生16个子密钥，输入：PreKey，密钥；输出：Key，16个子密钥
//======================================================================
void GenerateKey(uchar Keyseed[8])
{
   uchar output[7],i,j;
   struct para pm;
   pm.input = Keyseed;
   pm.ip = Pc_1;
   pm.row = 7;
   pm.col = 8;
   pm.buf = output;
   Exchange1(pm); //压缩型换位
   for(i=0; i<16; i++)
   {
      for(j=0; j<ShTb[i]; j++)
         Shift(output);
      pm.input = output;
      pm.ip = Pc_2;
      pm.row = 8;
      pm.col = 6;
      pm.buf = Key[i];
      Exchange1(pm); //压缩型换位
   }
}





//异或
void Xor(uchar in1[],uchar in2[],uchar len)
{
   uchar i;
   for(i=0; i<len; i++)
      in1[i] ^= in2[i];
}




//==================================================================
// 计算f(r,k),rx：输入，key：密钥，output：输出
//==================================================================
void FunRK(uchar rx[4],uchar *key,uchar output[4])
{
   uchar rx1[8],i,j,row,col,ch,tmp,out[4];
   for(i=0; i<4; i++)
      out[i] = 0;

   //Exch_E(rx,rx1);
   for(i=0; i<4; i++)
   {
      j = (i+3)%4;
      row = i*2;
      rx1[row] = rx[i]>>1;
      if(rx[j] & 0x01)
         rx1[row] |= 0x80;
      rx1[row+1] = rx[i]<<3;
      if(rx[(j+2)%4] & 0x80)
         rx1[row+1] |= 0x04;
   }
   Xor(rx1,key,8);
   for(i=0; i<8; i++)
   {
      row = 0;
      col = 0;
      if(rx1[i] & 0x04)
         row |= 0x01;
      if(rx1[i] & 0x80)
         row |= 0x02;
      col = (rx1[i]&0x78)>>3;
      ch = Sbox[i*4+row][col];
      if(!(i%2)) 
         ch <<= 4;
      out[i/2] |= ch;
   }
   //Exchange(out,Px,4,8,output);
   for(i=0; i<4; i++)
      output[i] = 0;
   ch=0;
   for(j=0; j<4; j++)
   {
      for(i=0; i<8; i++)
      {
         tmp = Px[ch] - 1;
         row = tmp/8; 
         col = tmp%8; 
         if((0x80>>col) & out[row])
         {
            output[j] |= (0x80>>i); 
         }
         ch++;
      }
   }
}



//====================================================================
// 加密，输入：input，64位明文；输出：input，64位密文
//====================================================================
void Des(uchar input[8])
{
   uchar output[8],rxtmp[4],i,j;
   uchar rx[4],lx[4];
   
   Exchange(input,Ip,8,8,output);
   
   for(i=0; i<4; i++)
   {
      lx[i] = output[i];
      rx[i] = output[4+i];
   }
   
   for(i=0; i<16; i++)
   {
      FunRK(rx,Key[i],rxtmp);
      Xor(rxtmp,lx,4);
      for(j=0; j<4; j++)
      {
         lx[j] = rx[j];
         rx[j] = rxtmp[j];
      }
   }
   for(i=0; i<4; i++)
   {
      output[4+i] = lx[i];
      output[i] = rx[i];
   }
   Exchange(output,Ipr,8,8,input);
}


//==================================================================
// 解密，输入：input，64位密文；输出：input，64位明文
//==================================================================
void Desr(uchar input[8])
{
   uchar output[8],lx[4],rx[4],rxtmp[4],i,j;
   Exchange(input,Ip,8,8,output);
   for(i=0; i<4; i++)
   {
      rx[i] = output[i];
      lx[i] = output[4+i];
   }
   for(i=0; i<16; i++)
   {
      FunRK(lx,Key[15-i],rxtmp);
      Xor(rxtmp,rx,4);
      for(j=0; j<4; j++)
      {
         rx[j] = lx[j];
         lx[j] = rxtmp[j];
      }
   }
   for(i=0; i<4; i++)
   {
      output[4+i] = rx[i];
      output[i] = lx[i];
   }
   Exchange(output,Ipr,8,8,input);
}