[Gambas-user] Security, how to check if a library is genuine?

[bb]

I am working on a non-intrusive authorisation method to see if a user
is allowed to run an application. In order to do so they must belong to
a specific hardcoded group.
It is (currently) implemented as a library. So the actual library
"could" be replaced by a user with another library that just returns
true.

So, does anyone have a good idea how the application could check
whether "authlib" is the genuine library?

tia
bruce