If you can't generate your key on **Ubuntu** (error message), you may add Yubico Team from PPA and install latest libpam-u2f and pamu2fcfg and try again.
Now you should be able to login into Linux without password, only with pressing your button on Solo and press enter.
Why **sufficient**? The difference between the keyword sufficient and required is, if you don't have your Solo available, you can also login, because the system falls back to password mode.
The login mechanism can be also used for additional features like:
Check out your folder **/etc/pam.d/** and do some experiments.
**But remember:** <br>
The login passwordless won't make your system more secure, but maybe more comfortable. If somebody have access to your Solo, this person will be also able to login into your system.
### Solo as second factor
To use Solo as second factor, for login into your Linux system, is nearly the same.
In case your Solo is not present, your password will be incrorrect. If Solo is plugged into your USB port, it will signal pressing the button and you will be able to login into Linux.
Why **required**? If you choose the option **sufficent** your Solo is optional. You could also login without second factor if your Solo is not connected.
**But remember:**<br>
If you loose your Solo you won't be able to login into your system.
# Using SoloKey to unlock a LUKS encrypted partition
[SoloKey Full Disk Encryption](https://github.com/saravanan30erd/solokey-full-disk-encryption), this project leverages SoloKey HMAC Challenge-Response mode for creating strong LUKS encrypted volume passphrases. You can encrypt the root OS partition and use Solo to unlock this encrypted partition in initramfs stage during boot process.