One common method is to secure the hardware key with a PIN. The key will only do its work (e. g. sign things) if the correct PIN is entered. It will also destro

One common method is to secure the hardware key with a PIN. The key will only do its work (e. g. sign things) if the correct PIN is entered. It will also destroy the secrets it keeps (or even itself) after a given number of failed attempts. If this is not feasible for some reason, you need to change or revoke your secrets as soon as you know the key is stolen.