Arch-Linux Fingerprint

Fingerprint Authentication Setup for Arch Linux

Complete guide for setting up fingerprint authentication on Arch Linux with SDDM and Hyprland.

Prerequisites

  • Arch Linux with SDDM display manager
  • Hyprland window manager
  • A working fingerprint reader

Installation

1. Install Required Package

sudo pacman -S fprintd

2. Enroll Your Fingerprint

# Enroll your fingerprint (follow the prompts - scan multiple times)
fprintd-enroll antonis

# Verify it works
fprintd-verify antonis

Replace antonis with your actual username.

Configuration

3. Configure PAM for System Authentication

Edit /etc/pam.d/system-auth:

sudo vim /etc/pam.d/system-auth

Add this line after the first pam_faillock.so preauth line:

auth       sufficient                  pam_fprintd.so

Your file should look like:

#%PAM-1.0
auth       required                    pam_faillock.so      preauth
auth       sufficient                  pam_fprintd.so
# Optionally use requisite above if you do not want to prompt for the password
# on locked accounts.
-auth      [success=2 default=ignore]  pam_systemd_home.so
auth       [success=1 default=bad]     pam_unix.so          try_first_pass nullok
auth       [default=die]               pam_faillock.so      authfail
auth       optional                    pam_permit.so
auth       required                    pam_env.so
auth       required                    pam_faillock.so      authsucc

4. Configure PAM for SDDM Login

Edit /etc/pam.d/sddm:

sudo vim /etc/pam.d/sddm

Use this configuration:

#%PAM-1.0
auth       sufficient   pam_fprintd.so max_tries=3
auth       required     pam_shells.so
auth       requisite    pam_nologin.so
auth       include      system-auth
-auth      optional     pam_gnome_keyring.so
-auth      optional     pam_kwallet5.so

account    include      system-login

password   include      system-login
-password  optional     pam_gnome_keyring.so use_authtok

session    optional     pam_keyinit.so force revoke
session    include      system-login
-session   optional     pam_gnome_keyring.so auto_start
-session   optional     pam_kwallet5.so auto_start

5. Configure PAM for Screen Lock (Hyprlock)

Create or edit /etc/pam.d/hyprlock:

sudo vim /etc/pam.d/hyprlock

Add:

#%PAM-1.0
auth       sufficient   pam_fprintd.so
auth       include      system-auth

Testing

Test Sudo

sudo echo "fingerprint test"

You should see a fingerprint prompt instead of password.

Test SDDM Login

  1. Log out or reboot
  2. At the SDDM login screen, select your username
  3. Press Enter (don’t type a password)
  4. Place your finger on the fingerprint reader
  5. You should be logged in

Test Screen Lock

Lock your screen (close laptop lid if configured), then unlock with your fingerprint.

Troubleshooting

Fingerprint Not Working

Check if the service is running:

systemctl status fprintd.service

Note: The service is socket-activated and starts on-demand, so it’s normal if it shows as inactive.

Check Enrolled Fingerprints

fprintd-list your-username

Re-enroll Fingerprint

fprintd-delete your-username
fprintd-enroll your-username

Check Logs

journalctl -u fprintd -f

Then try to authenticate in another terminal to see live logs.

Check kernel messages

dmesg | grep -i finger

Notes

  • SDDM Behavior: With most SDDM themes (including Chili), pressing Enter triggers fingerprint authentication. Password authentication at SDDM may not work when fingerprint is enabled due to PAM flow.
  • Sudo: Fingerprint works perfectly with sudo when configured in system-auth.
  • Security: Failed fingerprint attempts don’t trigger account lockout (faillock only applies to password attempts).
  • The sufficient keyword means: if fingerprint succeeds, authentication is complete; if it fails, it tries the next authentication method.

Optional: Customize SDDM Text

If using the Chili theme, you can customize the placeholder text:

sudo vim /usr/share/sddm/themes/chili/components/LoginForm.qml

Find line below and change:

placeholderText: "Fingerprint Authentication"

Save and restart SDDM:

sudo systemctl restart sddm

System Information

This guide was tested on:

  • OS: Arch Linux
  • Display Manager: SDDM with Chili theme
  • Window Manager: Hyprland
  • Screen Locker: Hyprlock