LuCiFeR's First C++ Crackme - Keygen

/**
    Logic for keygen ripped off from assembly
    http://crackmes.de/users/lucifer/first_c_crackme/
**/
#ifdef _MSC_VER
    #define _CRT_SECURE_NO_WARNINGS
#endif

#include <stdio.h>
#include <conio.h>
#include <string.h>
#include <stdlib.h>

void main()
{
    char test[20];
    int res;

    printf("Enter Username: ");
    scanf("%s", test);

    int len = strlen(test);

    __asm
    {
            pushad;                 //save contents of registry - so that we don't screw the flow
            sub esp, 50;                //for our dirty work
            mov edx, len;
            imul edx, edx, 0x875CD;
            mov eax, 0x51EB851F;
            mul edx;
            mov eax, edx;
            shr eax, 5;
            imul eax, eax, -0x370;
            mov edx, 0;
            push edx;
            push eax;
            fild QWORD PTR SS : [ESP];
            lea esp, DWORD PTR SS : [ESP + 0x8];
            fstp QWORD PTR SS : [ESP + 0x8];
            mov eax, [ESP + 8];
            mov res, eax;               //save the result required
            add esp, 50;                //adjust stack
            popad;                  //reload saved registry entries
    }

    printf("%i-x019871", res);
    _getch();
    return;
}