Here's my first crackme.

It is just 4kb in size and runs under win32.
It was written mostly in C.

You must make it say that it is Registered.
You cannot patch the exe.
There are two protections involved:
The first protection is a name/serial number passed as two arguments to the
program on the command line.
I will let you deduce the second protection from there.

No more clues.

Cronos.
