How To Use Fingerprint Authentication Beyond Login in Ubuntu 18.04

In this article, we will explore how to extend the use of fingerprint authentication beyond just the login process in Ubuntu 18.04. We will discuss how to enable fingerprint authentication for terminal commands, Gnome actions, and the challenges faced when unlocking keyring items.

Enabling Fingerprint Login

Before we can use fingerprint authentication for other purposes, we need to ensure it’s enabled for login. To do this, navigate to Settings > Details > Users and enable fingerprint login. Follow the prompts to enroll your fingerprint(s).

Authenticating in the Terminal

To authenticate sudo commands in the terminal using your fingerprint, we need to modify the sudo PAM (Pluggable Authentication Modules) configuration file.

1. Open the terminal and type the following command:

   sudo nano /etc/pam.d/sudo

   This command opens the sudo PAM configuration file in the nano text editor with root privileges.
2. Add the following line at a suitable location in the file, such as after the @include common-auth line:

   auth sufficient pam_fprintd.so

   This line tells the PAM library that fingerprint authentication is a sufficient method for sudo commands.
3. Save the file by pressing Ctrl + O and then exit with Ctrl + X.

After these changes, you should be able to use your fingerprint to authenticate sudo commands in the terminal.

Authenticating in Gnome

To use fingerprint authentication for Gnome actions like installing applications, we need to modify the gdm-fingerprint PAM configuration file.

1. Open the terminal and type the following command:

   sudo nano /etc/pam.d/gdm-fingerprint

   This command opens the gdm-fingerprint PAM configuration file in the nano text editor with root privileges.
2. Add the following line at a suitable location in the file, such as after the auth required pam_fprintd.so line:

   auth sufficient pam_fprintd.so

   This line tells the PAM library that fingerprint authentication is a sufficient method for Gnome actions.
3. Save the file by pressing Ctrl + O and then exit with Ctrl + X.

After these changes, you should be able to use your fingerprint to authenticate Gnome actions.

Unlocking Keyring Items

Unfortunately, using fingerprint authentication to unlock keyring items is not currently supported in Ubuntu 18.04. This is due to the design of the keyring system, which requires a password to unlock the keyring and does not support other authentication methods.

Conclusion

After making the changes described in this article and rebooting your computer, you should be able to use fingerprint authentication for sudo commands and Gnome actions in Ubuntu 18.04. However, remember that the use of fingerprint authentication is a convenience and should not be relied upon as a sole security measure. Always have a strong password as a backup authentication method.

Please note that these steps are specific to Ubuntu 18.04 and the fprintd library. If you are using a different version of Ubuntu or a different fingerprint authentication library, the steps may vary. Always refer to the documentation for your specific version and library for the most accurate information.