What are these screw heads called? What tool is used?

No doubt but I wonder if theft was an issue?
It was to deter stealing this fuel door. The thief didn't have access to the inside end of the screw but owner probably has a key.
AMC Gremlin had a big fancy expensive fuel cap without any theft deterrent. I lost 1 off the 71 model and 1 off the 73 model. Dealer got about 14 dollars for it.

gremlin fuel cap.jpg