Backup/Restore, where are fingerprints stored?

General
#1

Maybe one of you guys know this.
No complaints here, just doing experiments.

XA2 4.3
I made a backup by dding mmcblk0p76 partition (as proposed by DrYak in the [xa2] Full-backup in terminal thread (click “see more comments” near the end)).

/dev/mmcblk0p76 contains / and /home if I got it correctly.
Then, I restored this on another XA2 freshly installed with 4.3.

Everything seems to be back (calendar, contacts, pictures, messages)
Except fingerprints, and I can’t record new ones. (“Error, your fingerprint could not be captured”).

So, I went to this question: Where are they stored, outside of / and /home ?
Optional side questions:
-are they uploaded somewhere on any cloud?
-could I convert them to images to see my digitalized fingerprints?

Cheers,

Fingerprint record lost randomly
'dd' backup fails
Finger print sensor stops working
#2

There is some variance between devices but basically fingerprint data storage / handling at least ought to be dictated by Android rules for biometric data - which is roughly: data acquired from biometric sensors is never available in raw/usable form. Access to sensors, data acquisition, processing, and matching is done in hardware backed trusted execution environment. When/if data is stored outside tee, it is encrypted in a way that makes it accessible only by tee sw on the device where it was originally recorded.

Data is signed with a device specific key and thus by design is not transferable from one device to another.

There probably is fingerprint data in the backup (under /var/lib/sailfish-fpd/) and - since it is invalid due to originating from another device - it is confusing some parts of the sw stack. You probably need to get rid of it. Something like:

  • systemctl stop systemctl stop sailfish-fpd
  • /usr/libexec/sailfish-fpd/fpslave --remove-all
  • /usr/libexec/sailfish-fpd/fpslave --flush-cache
  • systemctl stop systemctl start sailfish-fpd

No and no.

7 Likes
Android 13 and SailfishOS on Xperia 10 III
#3

Sounds like TCPA/Palladium made Fritz Chip/TPM Chip ?!

If so, then I suggest we all avoid it and go back to regular passwords! :slight_smile:

#4

Knowledge is magic!
Thanks a lot @spiiroin for your explanations, Works perfectly.
And for my fingers, I’m gonna get some ink :–)

@nero355, Hmmm… seriously?

EDIT:
Btw, fingerprint generated files seem to be located here:
/var/lib/sailfish-fpd/templates/

#5

At least read about it and draw your own conclusions! :wink: