Re: Fingerprints, versus an effective "hash" code of the print created on-board
If someone has the hash of your fingerprint, they can use it to compare to another fingerprint by using that same hashing algorithm. That's like someone having your unsalted encrypted password, it isn't plaintext but it is not a good thing if you want to keep whatever it protects secure. A password, at least you can change that. Your fingerprint, not so much.
This why Apple makes a big deal out of the fact your fingerprint hash data never leaves the Secure Element on an iPhone (if you backup and restore it, you need to re-enroll your fingerprints because that data isn't part of the backup)