Important

This has been tested on 2016 ThinkPad X270.
Made for the ID 138a:0097 Validity Sensors, Inc. scanner.

Demo

Demo

https://www.youtube.com/watch?v=oYyE5cBVhgk

Successful read:

Failed read (and successful in the end):

Setup on Arch

Firstly, check if you have the right fingerprint sensor by running lsusb:

~ lsusb
Bus 001 Device 007: ID 138a:0097 Validity Sensors, Inc.

(It might work with a different scanner, you can try it.)

Install python-validity:

yay -S python-validity

Note

You might need to install libfprint-vfs009x-git in addition if it doesn't work alone, I am not sure yet

Scan your finger:

fprintd-enroll

Verify it with:

fprintd-verify

Unlocking after suspend

Normally, the reader stops working after suspending your laptop, so here is a fix:

Create a service file:

sudo nano /etc/systemd/system/restart_fprintd_after_sleep.service

Paste this code into the file:

[Unit]
Description=Restart services to fix fingerprint integration
After=suspend.target hibernate.target hybrid-sleep.target suspend-then-hibernate.target

[Service]
Type=oneshot
ExecStart=systemctl restart open-fprintd.service python3-validity.service

[Install]
WantedBy=suspend.target hibernate.target hybrid-sleep.target suspend-then-hibernate.target

And activate it:

sudo systemctl enable --now restart_fprintd_after_sleep.service

PAM:

Now, to activate the reader after running sudo, add this on top of /etc/pam.d/system-auth:

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

You can enable fingerprint login in swaylock, by adding the same code into /etc/pam.d/swaylock.
Or on your login screen (ly, etc.) (/etc/pam.d/system-login), SDDM (/etc/pam.d/sddm), ...

Troubleshooting

You can look at this "issue", it should help you. Thanks bc09880! :)

Here is the most important part:

1. Clear the Fingerprint Database

The first thing I tried was deleting all registered fingerprints, as this is a common step for resolving issues with corrupted records. This is necessary after successfully enabling the python3-validity service:

fprintd-delete $USER

Expected result: Fingerprints deleted on DBus driver

2. Verify that No Fingerprints Were Registered

After clearing the database, I checked that no fingerprints remained registered by running:

fprintd-verify

Expected result: No fingers enrolled for this device.

3. Try Registering the Fingerprints Again

After clearing the database and confirming it was empty, I resumed the fingerprint registration process. I first registered the left index finger (which worked without issues), then I tried registering the right index finger.

Register Left Index Finger:

fprintd-enroll -f left-index-finger

Expected result: enroll-completed (successful registration)

Register Right Index Finger (after clearing the database):

fprintd-enroll -f right-index-finger

Expected result: enroll-completed (successful registration after clearing the database)

Lessons Learned

What DIDN'T Work:

* **Simply running `fprintd-enroll`** did not resolve the issue. The fingerprint registration wouldn’t complete, and the error kept occurring.

* Trying to register **right-index-finger** multiple times without clearing the database.

* Using the incorrect command `sudo fprintd-delete right-index-finger` (instead of clearing the entire database with `$USER`).

* Restarting the services alone without clearing the database.

What DID Work:

* **Completely clearing** the database with `fprintd-delete $USER`.

* **Starting fresh** with all records deleted.

* First registering the finger that worked (left index), and then the problematic one (right index).

Troubleshooting 2

^{From python-validity}

List devices failed

If fprintd-enroll returns with

list_devices failed:

or

GDBus.Error:net.reactivated.Fprint.error.NoSuchDevice

you can check the logs of the python3-validity daemon using

sudo systemctl status python3-validity

If it's not running, you can enable and/or start it by substituting status with enable or start.

Errors on startup

If systemctl status python3-validity complains about errors on startup, you may need to factory-reset the fingerprint chip. Do that like so:

sudo systemctl stop python3-validity
sudo validity-sensors-firmware
sudo python3 /usr/share/python-validity/playground/factory-reset.py
sudo systemctl start python3-validity
fprintd-enroll

At some of the above points you may get a Device busy error, depending on how systemctl plays along. Kill offending processes if necessary, or re-run systemctl stop python3-validity, in case it has automatically been restarted.