Android Question System Key Signing

What do you mean by system key, do you mean something like an NFC Tag?

If so then yes it's definitely possible as I've done it for one of my clients a couple of years ago, here is the NFC Tag tutorial from Erel.

https://www.b4x.com/android/forum/threads/nfc-reading-and-writing.64451/#content

This is only for NFC Tags and nothing else.

Shutting down the device is another matter, locking the app until the correct details are detected is aa simpl enough task to do though.

Signing with the System key makes the app seen as system and so it can directly shut down the device. This is something I seriously need to do. As far as I can find out, even a kiosk app that is device owner can do this.

Oh that...

Take a look at this kiosk code from erel.

https://www.b4x.com/android/forum/threads/device-owner-tasklock-kiosk-apps-2017.81765/

Thanks Peter, the kiosk is already all set up. I need it to be able to shutdown the tablet withoyr user interaction.

I guess it is not possible unless the Device is rooted.