Securing a web service

[vbcode1980]

Hi,

I have a webservice on a database server that I use to query a database.
The data in this database is private information, and I want to prevent others from using this web service to access it.
I'm already using a special database user that only has limited access, but I don't think this is enough.
I want to make sure that no one else can access this web service.

How might I do this? (I can't hard code an IP address in it, because this might change)

I've read something about tokens and other complicated security mechanisms.
Is there an easy way to do this?

[Lightning]

You should use Usersname/password and/or certificates (and https ofcourse)