#!/bin/bash

# Create a key file for LUKS and register it as contents of the initramfs image
function chrooted_job() {
	# Mount the rest of partitions by target /etc/fstab
	mount -a

	# Prepare the crypto tool in the install target
	echo "[Kaiten-Yaki] Installing cryptsetup-initramfs package."
	apt -qq install -y cryptsetup-initramfs

	# Prepare a new key file to embed in to the ramfs.
	# This new file contains a new key to open the LUKS volume. 
	# The new key is 4096byte length binary value. 
	# Because this key is sotred as "cleartext", in the target file sysmte,
	# only root is allowed to access this key file. 
	echo "[Kaiten-Yaki] Prepairing key file."
	mkdir /etc/luks
	dd if=/dev/urandom of=/etc/luks/boot_os.keyfile bs=4096 count=1 status=none
	chmod u=rx,go-rwx /etc/luks
	chmod u=r,go-rwx /etc/luks/boot_os.keyfile

	# Add the new key to the LUKS 2nd key slot. The passphrase is required to modify the LUKS keyslot.  
	echo "[Kaiten-Yaki] Adding a key to the key file."
	printf %s "${PASSPHRASE}" | cryptsetup luksAddKey --iter-time "${ITERTIME}" -d - "${DEV}${CRYPTPARTITION}" /etc/luks/boot_os.keyfile

	# Register the LUKS voluem to /etc/crypttab to tell "This volume is encrypted" 
	echo "[Kaiten-Yaki] Adding LUKS volume info to /etc/crypttab."
	echo "${CRYPTPARTNAME} UUID=$(blkid -s UUID -o value ${DEV}${CRYPTPARTITION}) /etc/luks/boot_os.keyfile luks,discard" >> /etc/crypttab

	# Add key file to the list of the intems in initramfs. 
	# See https://cryptsetup-team.pages.debian.net/cryptsetup/README.initramfs.html for detail
	echo "[Kaiten-Yaki] Directing to include keyfile into the initramfs"
	echo "KEYFILE_PATTERN=/etc/luks/*.keyfile" >> /etc/cryptsetup-initramfs/conf-hook
	echo "UMASK=0077" >> /etc/initramfs-tools/initramfs.conf

	# Finally, update the ramfs initial image with the key file. 
	echo "[Kaiten-Yaki] Upadting initramfs."
	update-initramfs -uk all

	# Leave chroot
}

# Execute job
chrooted_job