Грамотное использование кучи

unsigned char **SubBytes(unsigned char **var)
{
  int l,r;
  unsigned char **res = new unsigned char *[N];
  for (int i = 0; i < N; i++)
    res[i] = new unsigned char [N];
  
  for(int i = 0; i < N; i++)
  {
    for(int j = 0; j < N; j++)
    {
      l = (var[i][j] >> 4) & 0xf;
      r = var[i][j] & 0xf;
      res[i][j] = sbox[l][r];
    }
  }
  return res;
}

void rijndael::In_fun(char *str, char *str2)
{
  int length = LengthFile(str); 
  int sh = 0; 
  
  unsigned char *buf = new unsigned char[GetRealLength(length)+N];
  
  unsigned char **state = new unsigned char *[N];
  for (int i = 0; i < N; i++)
    state[i] = new unsigned char [N];
  
  unsigned char **key = new unsigned char *[N];
  for (int i = 0; i < N; i++)
    key[i] = new unsigned char [N];
  
  for(int b = 0; b < LengthFile(str); b += N*N) 
  {
    state = Read_file(str,b);
    key = RSHash(str2);
    
    state = AddRoundKey(state,key);
  
    for(int i = 1; i <= 10; i++)
    {
      if(i!=10)
      {
    state = SubBytes(state);
    state = ShiftRows(state);
    state = MixColumns(state);
    key = KeySchedule(key,i-1);
    state = AddRoundKey(state,key);
      }
      else
      {
        state = SubBytes(state);
        state = ShiftRows(state);
        key = KeySchedule(key,i-1);
        state = AddRoundKey(state,key);
      }
    }
    
    for(int i = 0; i < N; i++)
    {
      for(int j = 0; j < N; j++)
      {
    buf[sh] = state[i][j];
    sh++;
      }
    }
  }
  
  int *pointer = (int*)(buf + GetRealLength(length)); 
  *pointer = length; 
  
  ofstream os("cipher.dat",ofstream::binary);
  os.write((char*)buf,GetRealLength(length)+N);
  os.close();
  
  for (int i = 0; i < N; i++)
  {
    delete[] state[i];
    delete[] key[i];
  }
    
  delete[] state;
  delete[] key;
  delete[] buf;
}