The impression that I get though is that the PIN's are typically short (especially if we have to enter them every time it is to access the key). Now, how physic

The impression that I get though is that the PIN's are typically short (especially if we have to enter them every time it is to access the key). Now, how physically save are hardware keys that the actual private key can't be extracted from them? In contrast to an ATM or SIM we essentially rely on the device to enforce the "max number of attempts", not an external entity. Once the key is extracted brute forcing the PIN is not a problem, because it likely is going to be simple. Unless somehow the devices are going to enforce long PINs.