thanks everyone for answers but it did not work so well.

I tried this for few weeks:
lock the trunk with the master-key (big key)
and then open the door with the vallet key (small key).

the vallet can open only the door, not the trunk and not the glove-compartment. once I open the door, I push the button to pop the trunk and voila-the trunk is open.

so how can I secure the trunk so that only a person with the master key can open the trunk?

Is there a hidden lock of the trunk somewhere?

thanks