The three basic rules for password security are:
- Never write your password down. Someone might find your note.
- Never use the same password for different services. Otherwise you give the operators of one service access to the other.
- Change your password when it gets compromised.
Fingerprints violate all of these rules. You leave them (write them down) whenever and touch a smooth surface. You only have ten fingers, so you’ll end up reusing your credentials for different services. Got a front door with a fingerprint lock and a passport? Congratulations, you just handed the keys to your home to every country, including your own, you visit. Good luck, changing them!