Subversion Repositories Games.Chess Giants

// Chess Giants key generator

#include <stdio.h>

#include <string.h>

#include <ctype.h>

static unsigned long ComputeRegistrationCode (const char *email);

int main (int argc, char **argv)

{

   // program entrypoint

   if (argc != 2)

      return (1); // incorrect usage

   printf ("%ld", ComputeRegistrationCode (argv[1]));

   return (0); // return to OS

}

static unsigned long ComputeRegistrationCode (const char *email)

{

   // quick helper to see if the program is registered. It contains an address to potential crackers.

   // Notice: user's email address may be a wchar_t array, and thus may contain Unicode characters.

   // /!\ WARNING: THE CRACKER MESSAGE SHOULD NEVER CHANGE, AND NEITHER SHOULD THE ALGORITHM BELOW /!\

   static const char crackermsg[] = "Please, respect my work. DON'T PUBLISH if you crack my program. Thank you and happy cracking :)";

   unsigned long correct_activationcode;

   int byte_index;

   int length;

   // compute the maximal length of the string for which we need to checksum

   length = strlen (email);

   if (length > sizeof (crackermsg) - 1)

      length = sizeof (crackermsg) - 1; // bound it to the length of the cracker message

   // hash the supplied e-mail

   correct_activationcode = 5381; // start value

   for (byte_index = 0; byte_index < sizeof (crackermsg) - 1; byte_index++)

      correct_activationcode = ((correct_activationcode << 5) + correct_activationcode)

                                 + ((unsigned long) (length > 0 ? tolower (email[byte_index % length]) : 1) // prevent zero divide

                                    ^ (unsigned long) crackermsg[byte_index]); // hash = hash * 33 + (char(email) ^ char(crackermsg))

   correct_activationcode &= 0x7FFFFFFF; // make sure the results remain positive

   // return the correct code

   return (correct_activationcode);

}