It’s pretty cliché scene in movies and TV shows where someone needs to crack a code to a safe or a door, so they dust the keypad for fingerprints or use a thermal camera to see the heat signatures on the pad. While it doesn’t give the code outright, it reduces the domain of possible codes significant and, depending on the circumstances, can make it much easier (to the point of actually giving the code outright).
One solution to this is to replace the physical keypad with a touch-screen on which a number-pad is displayed, but the position of the numbers on the displayed pad are randomized instead of in standard phone/keyboard order. That way, each time you enter the code, you end up having to press on a different area of the screen and fingerprint/thermal attacks would be mitigated. Of course this would also have the side-effect of slightly increasing the time to enter the code and likely annoy the users, but it’s worth it for good security.
