text: #include "DES.h"
  
  
  void IP(bool M[64]){
      int 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
      };
      bool new_M[64];
      for(int i=0; i<64; i++){
          new_M[i] = M[IP[i]-1];
      }
      for(int i=0; i<64; i++){
          M[i] = new_M[i];
      }
  }
  
  
  void Inverse_IP(bool M[64]){
      int inverseIP[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
      };
      bool new_M[64];
      for(int i=0; i<64; i++){
          new_M[i] = M[inverseIP[i]-1];
      }
      for(int i=0; i<64; i++){
          M[i] = new_M[i];
      }
  }
  
  
  void F(const bool R1[32], const bool K[48], bool result[32]){
      bool E[48], B[48], C[32];
      int m, n, num;
      int pre[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
      };
      int SBox[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
              }
      };
      int PBox[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
      };
      for(int i=0; i<48; i++){
          E[i]=R1[pre[i]-1];
          // XOR
          if(E[i]==K[i]){
              B[i] = 0;
          }else{
              B[i] = 1;
          }
      }
      for(int i=0; i<8; i++){
          m = B[6*i+1]*8 + B[6*i+2]*4 + B[6*i+3]*2 + B[6*i+4];
          n = B[6*i]*2 + B[6*i+5];
          num = SBox[i][n][m];
          for(int j=0; j<4; j++){
              if(num>=pow(2,3-j)){
                  num = num - (int)pow(2,3-j);
                  C[4*i+j] = 1;
              }else{
                  C[4*i+j] = 0;
              }
          }
          for(int l=0; l<32; l++){
              result[l] = C[PBox[l]-1];
          }
      }
  }
  
  
  void En_DES(const bool M[64],bool K[64],char final[16]){
      int i, loop, num;
      bool L1[32],R1[32];
      bool L2[32],R2[32];
      bool Key[16][48];
      bool result[32];
      bool finalB[64];
      bool M2[64];
      for(i=0; i<64; i++) M2[i]=M[i];
      IP(M2);	//IP
      for(i=0; i<32; i++){
          L1[i] = M2[i];
          R1[i] = M2[i+32];
      }
      CreateKeyOfLoop(K, Key);	// Generate key
      for(loop=0; loop<16; loop++){	// 16 loops
          for(i=0; i<32; i++) L2[i] = R1[i];
          F(R1, Key[loop], result);
          for(i=0; i<32; i++){
              if(result[i]==L1[i]) R2[i]=0;
              else R2[i] = 1;
          }
          for(i=0; i<32; i++){
              L1[i] = L2[i];
              R1[i] = R2[i];
          }
      }
      for(i=0; i<32; i++){
          finalB[i] = R2[i];		// L<=>R
          finalB[i+32] = L2[i];
      }
      Inverse_IP(finalB);
      for(i=0; i<16; i++){
          num = finalB[4*i]*8 + finalB[4*i+1]*4 + finalB[4*i+2]*2 + finalB[4*i+3];
          if(num>=0&&num<=9) final[i] = to_ascii('0'+num);
          else final[i] = to_ascii('A' + num - 10);
      }
  }
  
  
  void De_DES(const bool M[64], bool K[64], char final[16]){
      int i, loop, num;
      bool L1[32], R1[32];
      bool L2[32], R2[32];
      bool Key[16][48];
      bool result[32];    // F
      bool finalB[64];
      bool M2[64];
      for (i=0; i<64; i++) M2[i] = M[i];
      IP(M2);	//IP
      for(i=0; i<32; i++){
          L1[i] = M2[i];
          R1[i] = M2[i+32];
      }
      CreateKeyOfLoop(K, Key);
      for(loop=0; loop<16; loop++){	// 16 loops
          for(i=0; i<32; i++) L2[i] = R1[i];
          F(R1, Key[15-loop], result);
          for(i=0; i<32; i++){
              if(result[i]==L1[i]) R2[i] = 0;
              else R2[i] = 1;
          }
          for(i=0; i<32; i++){
              L1[i] = L2[i];
              R1[i] = R2[i];
          }
      }
      for(i=0; i<32; i++){
          finalB[i] = R2[i];
          finalB[i+32] = L2[i];
      }
      Inverse_IP(finalB);
      for(i=0; i<16; i++){
          num = finalB[4*i]*8 + finalB[4*i+1]*4 + finalB[4*i+2]*2 + finalB[4*i+3];
          if(num>=0 && num<=9) final[i] = to_ascii('0' + num);
          else final[i] = to_ascii('A' + num - 10);
      }
  }
  
  
  void CreateKeyOfLoop(const bool K[64], bool Key[16][48]){
      int C0[28], D0[28];
      int C1[28], D1[28];
      int temp[56];
      int a[2],b[2];
      int i, loop;
      int LS[16] = {1, 1, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 1};
      int 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
      };
      int 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
      };
      for(i=0; i<28; i++){
          C0[i] = K[PC_1[i]-1];
          D0[i] = K[PC_1[i+28]-1];
      }
      for(loop=0; loop<16; loop++){
          for(i=0; i<LS[loop]; i++){
              a[i] = C0[i];
              b[i] = D0[i];
          }
          for(i=0; i<28-LS[loop]; i++){
              C1[i] = C0[i+LS[loop]];
              D1[i] = D0[i+LS[loop]];
          }
          for(i=28-LS[loop]; i<28; i++){
              C1[i] = a[i+LS[loop]-28];
              D1[i] = b[i+LS[loop]-28];
          }
          for(i=0; i<28; i++){
              temp[i] = C1[i];
              temp[i+28] = D1[i];
          }
          for(i=0; i<28; i++){
              C0[i] = C1[i];
              D0[i] = D1[i];
          }
          for(i=0; i<48; i++){
              Key[loop][i] = temp[PC_2[i]-1];
          }
      }
  }
  