# Prepare YubiKey

Download or mount [yubikey-full-disk-encryption](https://github.com/agherzan/yubikey-full-disk-encryption) and install it
in your Arch Linux Live environment. This is needed because we will format the 4th partition with YubiKey.

## Installation
Open the *yubikey-full-disk-encryption* folder and run `make`.

```
cd yubikey-full-disk-encryption
make install
```


## Prepare 2nd slot
Now it's time to prepare the second slot of our YubiKey for the challenge response authentication. Touch will be also enabled.

```
ykpersonalize -v -2 -ochal-resp -ochal-hmac -ohmac-lt64 -ochal-btn-trig -oserial-api-visible
```

## Configure ykfde
Open `/etc/ykfde.conf` and set `YKFDE_CHALLENGE_SLOT=2` because we want to use the second slot. 
Set `YKFDE_CHALLENGE_PASSWORD_NEEDED=1` so it asks for the password (2FA). Leave other settings as is, it will be changed
later.

> Please compare it carefully with the latest version you have downloaded. 

```ini
# Configuration for yubikey-full-disk-encryption. ("") means an empty value.

### *REQUIRED* ###

# Set to non-empty value to use 'Automatic mode with stored challenge (1FA)'.
#YKFDE_CHALLENGE=""

# Use 'Manual mode with secret challenge (2FA)'.
YKFDE_CHALLENGE_PASSWORD_NEEDED="1"

# Choose YubiKey slot configured for 'HMAC-SHA1 Challenge-Response' mode. Possible values are "1" or "2".
YKFDE_CHALLENGE_SLOT="2"

### OPTIONAL ###

# Set partition UUID. Leave empty to use 'cryptdevice' kernel parameter.
#YKFDE_DISK_UUID=""

# Set LUKS encrypted volume name. Leave empty to use 'cryptdevice' kernel parameter.
#YKFDE_LUKS_NAME=""

# If left empty this will be set as "/dev/disk/by-uuid/$YKFDE_DISK_UUID" -- device to unlock with 'cryptsetup luksOpen'.
#YKFDE_LUKS_DEV=""

# Optional flags passed to 'cryptsetup luksOpen'. Example: "--allow-discards" for TRIM support. Leave empty to use cryptdevice kernel parameter.
#YKFDE_LUKS_OPTIONS=""

# Number of times to assemble passphrase and run 'cryptsetup luksOpen'. Defaults to "5".
#YKFDE_CRYPTSETUP_TRIALS="5"

# Number of seconds to wait for inserting YubiKey, "-1" means 'unlimited'. Defaults to "30".
#YKFDE_CHALLENGE_YUBIKEY_INSERT_TIMEOUT="30"

# Number of seconds passed to 'sleep' after succesful decryption. Defaults to empty, meaning NO sleep.
#YKFDE_SLEEP_AFTER_SUCCESSFUL_CRYPTSETUP=""

# Enable verbose output. It will print all secrets to terminal. Use only for debugging.
#DBG="1"
```

## Encrypt 4th partition
Next step is to format the 4th partition. You can modify the arguments if you know what you are doing. 

> Ensure that you use the 4th partition, replace `[device 4th partition]` with the 4th partition of your device e.g. `nvme0n1p4`

```
ykfde-format --cipher aes-xts-plain64 --key-size 512 --hash sha256 --iter-time 5000 --type luks2 /dev/[device 4th partition]
ykfde-open -d /dev/[device 4th partition] -n cryptlvm
```

Display the crypt volume with `ls -la /dev/mapper/`. Next step is to prepare the logical volumes.