Unlocking a computer programatically is hard and should be so. Locking on the other hand isn't. Perhaps you could lock upon fail to NFC authenticate every x sec

Unlocking a computer programatically is hard and should be so. Locking on the other hand isn't. Perhaps you could lock upon fail to NFC authenticate every x seconds. That only answers part of the question, since the attacker would still have x seconds to snoop around every time he logged in, but would be such a nuisance that he probably would give up.