Fingerprint

Hello !
I wanna make an application running in the background.
I wanna make possible :
the user to add différents fingerprints (for each finger)
and when the app detects (in the background) that a finger is placed on the captor; analyse it; and define exactly what finger it is.
I looked but I only see fingerprint for login etc…
How could I do that ?
Thanks so much and have a nice day !