edwardbetts / yubikey-luks

Two factor authentication for harddisk encryption

Yubikey for LUKS

This package is inspired and based on https://github.com/tfheen/ykfde.

This enables you to use the yubikey as 2FA for LUKS. The Password you enter is used as challenge for the yubikey

The keyscript allows to boot the machine with either the password and the Yubikey or with a normal password from any key slot.

initialize Yubikey

Initialize the Yubikey for challenge response in slot 2

ykpersonalize -2 -ochal-resp -ochal-hmac -ohmac-lt64 -oserial-api-visible

install package

Build the package:

make builddeb

Install the package:

dpkg -i DEBUILD/yubikey-luks_0.?-1_all.deb

Assign a Yubikey to an LUKS slot

You can now assign the Yubikey to a slot using the tool

yubikey-luks-enroll

Technically this is done by writing the response to your password (1st factor knowlege) created by the Yubikey (2nd factor possession) to a key slot.

Admitted - If the attacker was able to phish this response which looks like this: bd438575f4e8df965c80363f8aa6fe1debbe9ea9 it can be used as normal password.

Changing the welcome text

If you want to change the welcome text a.k.a. the passphrase prompt you can edit the file /etc/ykluks.cfg.

After changing this file, you need to run

update-initramfs -u

so that the changes get transferred to the initramfs.

Manage several Yubikeys and Machines

It is possible to manage several Yubikeys and machines. You need to use privacyIDEA to manage the Yubikeys and the privacyIDEA admin client to push the Yubikey responses to the LUKS slots.

See https://github.com/privacyidea/privacyideaadm and https://github.com/privacyidea/privacyidea