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Deleted fingerprints not deleted


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I came across something odd with my Pro 1 (which is, by the way, an absolutely fantastic device).

I noticed what other users noticed as well: the fingerprint reader is not optimally placed, to put it mildly. After having sent some random messages to random people in my contact list, because I had accidentally unlocked the phone with my right thumb in my pocket, I decided to remove all fingerprints I recorded.

So at this point my list of fingerprints was empty. I decided to only add my right index finger. Strangely, next to that index finger, the device now also unlocks with my thumb, even though I had erased it. In addition: when the fingerprints list is empty, and I try to add my right thumb (again), it says: 'duplicate finger', even though the list is empty....!

So, it seems like somehow at least one fingerprint (my right thumb) was never really deleted.

Any idea whether this is a bug or a feature? Can someone confirm this behavior? I want to be able to unlock the device with a finger that is unlikely to unlock it accidentally....

Edited by Milly
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There are two places in the code that handle fingerprint data.  The vendor code is responsible for storing the actual fingerprint data corresponding to your finger and assigning it an identifier (ID).  This particular FP vendor stores its data under /persist which has caused other issues.  The vendor code tells the Android framework its list of ID values on request.  Android stores the ID values and some other bits of information in another place (under /data).

 

It is possible (I would say likely) that the issue is in the vendor code.  It probably isn't actually deleting your fingerprint data.  Unfortunately, I believe the vendor code is all binaries (no source code provided) even at the OEM level.  So this would be a difficult issue to investigate and even more difficult to fix without getting IdeaLTE (the phone OEM) and BetterLife (the FP vendor) involved.

 

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33 minutes ago, VaZso said:

Restart the phone - it works for me. 😀

Without joke - it forgets all of my fingerprints if I restart the phone.
I had only one time it remained set whe I have rebooted the phone several times to test something.

This is one of the "other issues" that I mentioned in my earlier post. The vendor data and framework data get out of sync under certain conditions, for example when you wipe data (aka. factory reset). This is a problem because the vendor data only seems able to hold 5 fingerprints and doesn't seem to ever delete its data.

 

So once you have registered 5 fingerprints total, any further fingerprints registered will not be saved in the vendor data until the vendor data in /persist is deleted (this is why it works until you reboot). Deleting the vendor data in /persist requires root access. Which means those using stock software are kind of screwed until the OEM fixes this.

 

 

Edited by tdm
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3 minutes ago, tdm said:

So once you have registered 5 fingerprints total, the only way to register more is to delete the vendor data in /persist. Which requires root access. Which means those using stock software are kind of screwed until the OEM fixes this.

I am using stock software without root access anyway so I don't know what really happen in my phone. :classic_wacko:

The only thing I know is I loose my stored fingerprints every time I restart my phone.
(It remained there only one time when I have checked the state of charging the phone while OS is not running, then set it up and checked again. I don't know why they remained set that time but every other restart caused my fingerprints to became unset, so I had to re-register everything.)

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Restarting does not solve it for me... Saved fingerprints are not forgotten. And when the list is empty after having deleted all prints, after restarting I still get the message 'duplicate fingerprint' if I want to add my right thumb. The data is still there.

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3 hours ago, Milly said:

Restarting does not solve it for me... Saved fingerprints are not forgotten. And when the list is empty after having deleted all prints, after restarting I still get the message 'duplicate fingerprint' if I want to add my right thumb. The data is still there.

These completely different behaviours are interesting anyway.

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6 hours ago, VaZso said:

These completely different behaviours are interesting anyway.

Yes, and it gets weirder. When I add all five fingers of my left hand (the maximum number of fingerprints the system allows), I can open the device with the first four of them, AND with the thumb of my right hand...! The fifth finger on my left hand, which I added succesfully, does not unlock my phone.

It appears as if my right thumb is now hardcoded into the system. I cannot delete it, I cannot overwrite it.

Edited by Milly
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23 hours ago, silversolver said:

Disable the fingerprint reader. Problem solved. 😛

My point of view as well, I'm afraid. 😉  I only have a "lockscreen" to keep from accidentally launching icons when pulling my phone from my pocket and it opens with just a swipe. I didn't keep a padlock on my old physical datebook with a lot of personal information.  Why do I need to lock my phone? (I know how people would answer that question-- but I really don't like being inconvenienced 😀).

Still, on principle, if there is a fingerprint reader on the phone, it should be made to work properly. 

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On 2/22/2020 at 3:50 PM, Hook said:

Still, on principle, if there is a fingerprint reader on the phone, it should be made to work properly. 

No disagreement there. I just think that's so sci-fi creepy. We are the borg.....welcome to the matrix....

Edited by silversolver
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