How secure is entering my beloved CD-Key into this page?

The Battlefield Key Hash Generator does not record any details regarding CD keys.

The converter is a simple client side JavaScript utility, this means the page is unable to transmit any inputted data to or from the page it it located on. This means the data inputted into the page is never passed to anywhere else.

What about the Key Hash - if I give someone that, they have my CD-Key, right?

Incorrect.
A Key hash is one way encryption, ie: you can not 'de-code' it to get a CD key.
Player Key Hashes are designed so admins can identify you on a server, be it to impose a ban, or to lift one.

If you have any further questions regarding the NZBattlefield.com Key Hash Generator, please contact the Administrator