Securized TAGs needed

Hi all,
I am working for the French police on a project that will allow the policeman to do an inventory of all the key devices that are in a police car before the police car goes in operations.
I had the idea to mark via RFID tags all these key devices (fire extinguisher, flashlight, ...) that stay in the car.
This police car may be a "hidden" police car.

So the tags need to be securized so that only the allowed RFID readers can activate the tag.
I don't want a bad guy to pass by all the cars and trucks in a given street with a RFID reader, by activating the RFID reading of a RFID reader, discover that there are RFIDs tags in a car (even if the returned data are crypted) and hence know that the "normal looking car" is in fact a police car (or truck).

This same kind of tags can be used for very expensive assets (haute couture clothes, computers, ...).

Any info or advises are more than welcomed.
We have a real opportunity if such tags exist.

If anything remains unclear please contact me.
Philippe PIEMONT