What I need to know is whether or not someone that is already inside Hogwarts could create a Portkey to take them to a specific location in Hogwarts. So, let’s say they’re in the Potions classroom; they reach into their pocket, touch the Portkey, and it takes them to the Astronomy tower.
I’ve seen several questions here about Portkeys being made to travel into Hogwarts and out of Hogwarts, but none about Portkey travel inside Hogwarts. The aforementioned questions seemed to lead to the theory that only the headmaster could create a Portkey to travel to and from Hogwarts, though apparently nothing about Portkeys and Hogwarts is stated clearly in canon: only that Apparating to and from Hogwarts is impossible.
It seems to me that the magical barriers surrounding Hogwarts would only protect from travel into and out of the grounds, and that the use of Portkeys inside Hogwarts wouldn’t be detectable. I’ve also read that Portkeys have to be authorized by the Ministry, but fans seem uncertain as to whether or not the Ministry has anything set up to detect the use of unauthorized Portkeys, so I’m overlooking it at the moment; but, if any new info has come out about that, I’d appreciate a heads up.
(Edit): Some examples of other questions I’ve seen concerning Hogwarts and Portkeys on this site and others:
-This one (from Reddit) says more about my mention of the theory that the headmaster is an exception, as well as laying a bit of doubt on the idea that Barty Crouch Jr. was the sole reason the Triwizard Cup was a Portkey: https://www.reddit.com/r/AskScienceFiction/comments/3g2wqy/harry_potter_do_portkeys_work_at_hogwarts/