Arch Linux

flatmoll

Member

Registered: 2024-12-01

Posts: 71

LighTuning fingerprint sensor with Plasma and fprintd

Greetings! I use Plasma 6 and my laptop fingerprint sensor is:

Bus 001 Device 002: ID 1c7a:0583 LighTuning Technology Inc. ETU905A88-E

The intended use is only after screen locking and sleep, not in terminal and not in display manager.
This device seem to fail for other people as well: https://linux-hardware.org/?id=usb:1c7a-0583

Steps to reproduce the problem:
1. Install fprintd with default library or with libfprint-tod-git.
2. Add fingerprint with Plasma Settings GUI, lock screen.
3. Observe "Failed to match fingerprint" message under password prompt (with slow motion camera ).
4. Find no enrolled fingerprints in both terminal and plasma GUI:

$ fprintd-list moll
found 1 devices
Device at /net/reactivated/Fprint/Device/0
Using device /net/reactivated/Fprint/Device/0
User moll has no fingers enrolled for Egis Technology (LighTuning) Match-on-Chip.

5. Enroll again but don't lock the screen, then find:

$ fprintd-list moll
found 1 devices
Device at /net/reactivated/Fprint/Device/0
Using device /net/reactivated/Fprint/Device/0
Fingerprints for user moll on Egis Technology (LighTuning) Match-on-Chip (press):
 - #0: right-index-finger
$ fprintd-verify
Using device /net/reactivated/Fprint/Device/0
Listing enrolled fingers:
 - #0: right-index-finger
Verify started!
Verifying: right-index-finger
Verify result: verify-no-match (done)
$ fprintd-verify    # it seems to delete the print after the first time
Using device /net/reactivated/Fprint/Device/0
ListEnrolledFingers failed: GDBus.Error:net.reactivated.Fprint.Error.NoEnrolledPrints: Failed to discover prints

Adding these lines to /etc/pam.d/kde and repeating steps 2-5 had no effect:

auth		sufficient  	pam_unix.so try_first_pass likeauth nullok
auth		sufficient  	pam_fprintd.so

Searching messages from journalctl -b, people suggest to "unclaim" the device in BIOS.
However, I don't have this setting (checked twice). The journal: https://0x0.st/8HOS.txt

Last edited by flatmoll (2025-01-20 17:09:25)

Nyctfall

Member

Registered: 2023-04-03

Posts: 82

Re: LighTuning fingerprint sensor with Plasma and fprintd

Seems like the libfprint X.Org upstream will probably be preoccupied with existential problems.
This could need manual patches/debugging with help from experienced people more familiar than me (I have no fingerprint reading hardware to test) with upstream and AUR firmware/drivers. Maybe this upstream issue, or Vendor ID "1c7a" Egistec might have some relevant info? Reverse engineering efforts seem to vary.

---

UNIX-Epic, UNIX-life!

fracorbas

Member

Registered: 2025-06-25

Posts: 1

Re: LighTuning fingerprint sensor with Plasma and fprintd

Hi,

I have the exact same issue, every time I try to use the fingerprint or even do

fprintd-verify

my registered fingerprints disapear.

I'm using Gnome and my laptop sensor is :

Bus 003 Device 002: ID 1c7a:05a1 LighTuning Technology Inc. ETU905A80-E

It seems my device is in the list you showed above, I just hope things has changed.

For me I added the fingerprints using the CLI with those commands :

fprintd-enroll -f right-index-finger
fprintd-enroll -f left-index-finger

they're well registered :

fprintd-list $USER
found 1 devices
Device at /net/reactivated/Fprint/Device/0
Using device /net/reactivated/Fprint/Device/0
Fingerprints for user fracorbas on Egis Technology (LighTuning) Match-on-Chip (press):
 - #0: right-index-finger
 - #1: left-index-finger

And the moment I try to use them with :

fprintd-verify

They dissapear. Same if I try to log with them or use the to authenticate in the terminal.

I also tried with the GUI, but the behavior stays the same.

Hope theres a solution.

Last edited by fracorbas (2025-06-25 21:30:50)