# Usbcrypt

Usbcrypt add support for encrypted system with luks encrypted keyfile on external drive 

### Prerequisities

[mkinitcpio](https://wiki.archlinux.org/index.php/Mkinitcpio#Installation)

### Installing

* On existing encrypt boot
* sdX0 : key partition
* sdY0 : luks drive

1. Create key on existing *small* partition
```shell
dd if=/dev/zero of=/dev/sdX0
cryptsetup luksFormat /dev/sdX0
cryptsetup open /dev/sdX0 key
dd if=/dev/random of=/dev/mapper/key
```

2. Add the key to LUKS
```shell
cryptsetup luksAddKey /dev/sdY0 /dev/mapper/key 
```

3. Install Usbcrypt
```shell
git clone https://github.com/sheychen290/usbcrypt.git
cd usbcrypt
cp install-usbcrypt /usr/lib/initcpio/install/usbcrypt
cp hooks-usbcrypt /usr/lib/initcpio/hooks/usbcrypt
```

4. Setup Usbcrypt
* /etc/mkinitcpio.conf : Change encrypt hook to usbcrypt
* mkinitcpio -P

5. Boot options
```shell
usbcryptdevice=UUID=XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX:key
```

6. Remove old passphrase
```shell
cryptsetup luksRemoveKey /dev/sdY0
```