Friday, September 27, 2013

Using Ubuntu and have a Fingerprint Reader on your laptop? Make it work!


This PPA contains packages that add a comprehensive fingerprint-based authentication functionality to Ubuntu, including a seamless integration into GNOME 2.x, Unity and GNOME 3.x. At this time of writing it supports releases of Ubuntu are 12.04, 12.10, 13.04. Please note that since version 12.10 these packages are present in the standard repositories (still, this PPA supports a wider range of fingerprint readers).

Step 1
You should be running Ubuntu 12.04, 12.10, 13.04 or any derivative thereof, and you need to have a supported fingerprint reader. To find out your reader's ID, run the lsusb command and look into the sixth column of the output. Supported devices are:
          045e:00bb    08ff:1683    08ff:2580    08ff:268d
     045e:00bc    08ff:1684    08ff:2660    08ff:268e
     045e:00bd    08ff:1685    08ff:2680    08ff:268f
     045e:00ca    08ff:1686    08ff:2681    08ff:2691
     0483:2015    08ff:1687    08ff:2682    08ff:2810
     0483:2016    08ff:1688    08ff:2683    08ff:5501
     05ba:0007    08ff:1689    08ff:2684    08ff:5731
     05ba:0008    08ff:168a    08ff:2685    138a:0001
     05ba:000a    08ff:168b    08ff:2686    138a:0005
     061a:0110    08ff:168c    08ff:2687    138a:0008
     08ff:1600    08ff:168d    08ff:2688    147e:1000
     08ff:1660    08ff:168e    08ff:2689    147e:2016
     08ff:1680    08ff:168f    08ff:268a    147e:2020
     08ff:1681    08ff:2500    08ff:268b    147e:3001
     08ff:1682    08ff:2550    08ff:268c    1c7a:0603

Step 2
If you have a supported device add this PPA to your sources:
      sudo add-apt-repository ppa:fingerprint/fprint
   sudo apt-get update
   sudo apt-get upgrade

Step 3
Install the software:
     sudo apt-get install libfprint0 fprint-demo libpam-fprintd gksu-polkit

Step 4
Launch “fprint project demo” from your Unity/GNOME applications menu and check that you can enroll and verify your fingerprints and that your reader is indeed supported.  This does NOT save your fingerprints. This just test to make sure it is working.

Step 5
Run fprintd-enroll in terminal to save your fingerprints.

If you have experimented with fingerprint authentication before and have changed your /etc/pam.d/common-auth, you may be presented with a screen asking whether you want to override those changes. Select Yes. Under very special circumstances, you may get an error saying
    pam-auth-update: Local modifications to /etc/pam.d/common-*, not updating.
  pam-auth-update: Run pam-auth-update --force to override.
In this case, run sudo pam-auth-update --force, exactly as suggested, and enable the fprintd profile manually. Leave the standard system profiles (Unix, Keyring and ConsoleKit) enabled as well.

Known issues

1. No fingerprint and password at the same time
At the moment, you cannot type in your password right away when you are asked for fingerprint. You need to make the fingerprint authentication fail first (swipe wrong finger or let it time out) before you are asked for password. This is a limitation of PAM because its modules mustn't be threaded and hence cannot support multiple means of authentication at the same time.
2. Missing support in gksu. When you run Synaptic or a similar graphical application that requires unlimited, full root privileges, the standard authentication window doesn't get displayed. Yet the fingerprint reader is ready, and a swipe will authenticate the user. The informative window not appearing is a major bug in GNOME's gksu, which will never be fixed because of its inner limitations. Instead, a replacement called gksu-polkit is being developed (its latest version is in this PPA). With this package installed, you can then adjust your menu items to call gksu-polkit instead of gksu. Go to System > Preferences > Main Menu, select the item you want to modify, click Properties and in the Command field change "gksu [options...] command" to "gksu-polkit /full/path/to/command" (note that you need to drop all the options to gksu, if any, and full path to command is required).

Note on keyrings and passwordless logins

If you log in with your fingerprint, the default keyring manager will not have access to your password or any other secret data to decrypt your enciphered content with. The same applies to encrypted partitions and their automatic unlocking with libpam-mount or eCryptFS. Please note that it is not possible to unlock the keyring unless you have typed in your password (there's nothing to unlock it with, and having a key stored somewhere on disk is a very naïve and insecure solution). There are basically 2 possible solutions to the keyring issue:
1. Keep logging in with your password as before (you will need to make the fingerprint authentication fail first by scanning a wrong finger) and then use fingerprint only for sudo and locked screens. This way you will have your standard password available in your session, and keyring and encrypted partitions will work as before.
2. Remove the password from your default keyring. This way the passwords in it will be stored unencrypted, but this may be perfectly acceptable for you if you store only insensitive data in it (such as passwords to Wi-Fi networks). If you decide to take this route, here is a short how-to: Go to Applications > Accessories > Passwords and Encryption Keys, card Passwords, right click on Passwords: login, Change Password and set it to empty string.

Creative Commons License
Using Ubuntu and have a Fingerprint Reader on your laptop? Make it work! by Randy Rowland is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.