Authored by: bluffer on Monday, February 13 2006 @ 06:56 PM CET

some one over at irc was asking for explanation in simple terms
and i ended up creating a simple c keygenme to this crackme

all this crackme does is

takes each and every charecter of your username adds 0x0a to each of them and adds them all and multiplies it with 0x7a69 and prints it out as decimal :)

sounds complicated ? lets check with calc.exe
choose username as 1234
1 = 0x31 = 49 decimal
2= 0x32
3 = 0x33
4 = 0x33
so it does
(((0x31+0x0a) + (0x32+0x0a) +(0x33+0x0a) +0x34+0x0a)) * 0x7a69 )
==(0x3b+ 0x3c + 0x3d + 0x3e ) * 0x7a69
==(0xf2 * 0x7a69)
==0x73B742
it will print this as decimal
=7583554
thats the serial for username 1234
ok here is a simple keygen i wrote for this

#include <stdio.h>
char name[200];
int namelen,serial,i;
int main()
{
printf("keygen to tdc1\nenter your name :\t");
scanf("%[a-zA-Z0-9]%n",&name,&namelen);
if(namelen < 4 || namelen > 8)
        {
        printf("your name should be between 4 and 8 charecters\n");
        }
else
        {
                for(i=0; i<namelen ; i++)
                {
                serial = ((serial + name[i])+ 10);
                }
                serial = serial*0x7a69;
                printf("your serial is %d\n",serial);
        }
}

ok thats all for now regards