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iButton contact pad design

We need a contact pad that can work both as reader (1-wire master) and slave as a key. For this purpose we need a custom design contact pad. The main problem is that our design allows user to put key in wrong polarity. I believe that we can somehow find a shape that allows only one correct polarity for both modes.

Here is the 1-wire master mode
You still can switch key to the opposite side and lean it wrong side

Here is the 1-wire slave mode for key emulation
In this mode you have less chance of mistake but it still possible to switch polarity.

Original iButton contact pad have no chance to user mistake. I believe we can do the same contact pad design. Your suggestion is welcome.

What will happen if the polarity is switched? Will it notify or something?

Also, while I am not much familiar with 1wire tech specs, I think I heard of master keys that somewhat exists for a variety of intercoms. Will there be any of them predefined or I am obliged to scan the key first to use it to open things?

The design is ok by me (you could make a retractable part of a more convenient form but as I understood the absence of moving parts is one of the goals)