Programming

void encrypt (unsigned long* entryvar)
{
   typedef struct{
      char one;
      char two;
      char three;
      char four;
   }comodin;

   comodin*   value;
   char       com;
   value=(comodin*)entryvar;
   
   com=value->one;
   value->one=value->four;
   value->four=com;
   com=value->two;
   value->two=value->three;
   value->three=com;
}

int main(void)
{
        unsigned long unenc=0xdeadbeef;
        unsigned long enc=0xdeadbeef;

        encrypt(&enc);
        printf("%x => %x\n", unenc, enc);

        encrypt(&enc);
        printf("%x => %x\n", unenc, enc);
}

deadbeef => efbeadde
deadbeef => deadbeef