Designed this thinking about keys and keycards.
This system would use an obsidian pipe next to your door, you'll throw an item in there, it'll take the item and if its the correct one, drop it on a pressure pad inside and open the door, if not it goes on to your sorter/recycler. People will literally be GIVING you items as they try to figure out wtf your key is.
You could set it something obscure (Soulsand), expensive (Diamond Pickaxe), or obscure and expensive (Diamond Hoe) no one will want to guess what your key type is for fear of wasting stuff and giving it to you!
Do I get a cookie?