Thread: Bitwrap problems

Hello,

I'm writing a (very very bad) encryption program. I wanted to use bitwrap in my program, but for some reason, it's not working, and I can't quite see where.

Code:

// from encrypt.h
void encry(char* fileIN)
{
     fin.open(fileIN, ios::binary);
     if(!fin) cout << "fin.ERROR";
     
     fout.open("temp.cry", ios::binary);
     if(!fout) cout << "fout.ERROR";
     
     while(fin.get(a))
     {
          a = a ^ key[x++];
          if(strlen(key) == x) x = 0;
          
          bsl();
          
          fout << a;
     }
     
     fin.close();
     fout.close();
}

Code:

// bsl() - bitshift left. Code as follows.
void bsl()
{
     if(a > 127)
     {
          a = a << 1;
          a = a ^ 0x01;
     }
     
     if(a < 128)
     {
          a = a << 1;
          a = a & 0xFE;
     }
}





void bsr()
{
     if(((int)a % 2) == 0)
     {
          a = a >> 1;
          a = a & 0x7F;
     }
     
     if(((int)a % 2) == 1)
     {
          a = a >> 1;
          a = a ^ 0x80;
     }
}

Obviously, the decrypting function bitshifts right before XORing. If I try to encrypt / decrypt a simple text file containing ABCDE, I realise that only B and D get decrypted correctly. I'm guessing this means I've got something wrong with ODD-numbered ASCII characters... But I can't see what.

Thanks for your help.