iCTF 2011. Challenge 29 ($800)

IsDebugProcess = 0;
 kernel32_base = 0;
 rdtsc_low = 0;
 rdtsc_high = 0;
 rdtsc_high2 = 0;
 kernel32_base = getKernel32Base();
 printf("Enter key: ");
 for ( i = 0; i < 0x30; ++i )
 {
   stdin = _iob_func();
   new_symb = fgetc(stdin);
   if ( (signed int)(unsigned __int8)new_symb < '0' || 
        (signed int)(unsigned __int8)new_symb > '9' )
   {
     if ( (signed int)(unsigned __int8)new_symb < 'a' || 
          (signed int)(unsigned __int8)new_symb > 'f' )
       break;
   }
   pass[i] = new_symb;
 }
 AntiDebugRdtsc(&rdtsc_high, &rdtsc_low);
 IsDebugProcess = (int (*)(void))GetIsDebugger(0xA36DC676u, 
                                               kernel32_base, 
                                               LoadLibraryW, 
                                               GetProcAddress);
 if ( i == 0x30 && IsDebugProcess() <= 0 )
 {
   v3 = 245 * (IsDebugProcess() + 3);
   i = (unsigned int)dword_40F000;
   AntiDebugRdtsc(&rdtsc_high2, &rdtsc_low);
   i += 32 * (rdtsc_high2 - rdtsc_high + 3);
   do
     result = i + 337;
   while ( i == 0xAF );
 }
 else
 {
   printf("Invalid key");
   result = -1;
 }

IsDebugProcess = 0; kernel32_base = 0; rdtsc_low = 0; rdtsc_high = 0; rdtsc_high2 = 0; kernel32_base = getKernel32Base(); printf("Enter key: "); for ( i = 0; i < 0x30; ++i ) { stdin = _iob_func(); new_symb = fgetc(stdin); if ( (signed int)(unsigned __int8)new_symb < '0' || (signed int)(unsigned __int8)new_symb > '9' ) { if ( (signed int)(unsigned __int8)new_symb < 'a' || (signed int)(unsigned __int8)new_symb > 'f' ) break; } pass[i] = new_symb; } AntiDebugRdtsc(&rdtsc_high, &rdtsc_low); IsDebugProcess = (int (*)(void))GetIsDebugger(0xA36DC676u, kernel32_base, LoadLibraryW, GetProcAddress); if ( i == 0x30 && IsDebugProcess() <= 0 ) { v3 = 245 * (IsDebugProcess() + 3); i = (unsigned int)dword_40F000; AntiDebugRdtsc(&rdtsc_high2, &rdtsc_low); i += 32 * (rdtsc_high2 - rdtsc_high + 3); do result = i + 337; while ( i == 0xAF ); } else { printf("Invalid key"); result = -1; }