# This outline of a CRUX installation for full-disk encryption is provided
# based on the experience of one user. There are many other possible ways
# to set up an encrypted disk. At every stage of the installation, you have a
# number of different options. It is easy to get overwhelmed by all the decisions
# involved.
# 
# Extra packages: lz4 if you choose this compression mode for the kernel,
# dracut and lvm2 to access the logical volumes when booting

parted -s -a optimal /dev/sda         \
       mklabel gpt                    \
       mkpart primary fat32 0% 500MiB \
       name 1 esp                     \
       set 1 esp on                   \
       mkpart primary 500MiB 4GiB     \
       name 2 swap                    \
       mkpart primary 4GiB 100%       \
       name 3 ENCRYPTED

mkfs.vfat /dev/sda1

cryptsetup -q -c aes-cbc-essiv:sha256 -d /dev/urandom create swap /dev/sda2
mkswap -f /dev/mapper/swap
swapon  /dev/mapper/swap

##### For AES Encryption
##### cryptsetup luksFormat --type luks2 -c aes-cbc-essiv:sha256 /dev/sda3

cryptsetup luksFormat --type luks2 -c serpent-xts-plain64 -s 512 /dev/sda3

##### The device node is now set up, but it needs a mapping to be usable as disk space
##### Replace 'ENCRYPTED' with whatever name you want
cryptsetup luksOpen /dev/sda3 ENCRYPTED
pvcreate /dev/mapper/ENCRYPTED

##### On the newly-mapped physical volume, create the desired logical volumes
vgcreate ENCRYPTED /dev/mapper/ENCRYPTED

lvcreate -L 30G ENCRYPTED -n root
lvcreate -L  4G ENCRYPTED -n var
lvcreate -L 50G ENCRYPTED -n usr
lvcreate -L  3G ENCRYPTED -n opt
lvcreate -l 100%FREE ENCRYPTED -n home

##### Format each logical volume with the desired filesystem
##### ("flash-friendly" FS works well with the encryption overhead, but btrfs or ext4 are also possible)
mkfs.f2fs /dev/mapper/ENCRYPTED-root
mkfs.f2fs /dev/mapper/ENCRYPTED-var
mkfs.f2fs /dev/mapper/ENCRYPTED-usr
mkfs.f2fs /dev/mapper/ENCRYPTED-opt
mkfs.f2fs /dev/mapper/ENCRYPTED-home

##### Mount the root FS where the CRUX installer expects it
mount /dev/mapper/ENCRYPTED-root  /mnt

##### Do the same for any partitions that will be written to during CRUX installation
mkdir /mnt/{var,usr,opt,home,boot}

mount /dev/mapper/ENCRYPTED-var   /mnt/var
mount /dev/mapper/ENCRYPTED-usr   /mnt/usr
mount /dev/mapper/ENCRYPTED-opt   /mnt/opt
mount /dev/mapper/ENCRYPTED-home  /mnt/home
mount /dev/sda1                   /mnt/boot

setup # --> Install these extra packages (cryptsetup lvm2 syslinux dracut lz4)

setup-chroot
passwd
localedef -i en_US -f UTF-8 en_US.UTF-8

cat <<EOF > /etc/fstab 

  /dev/mapper/ENCRYPTED-root  /      f2fs defaults 0 0
  #/dev/mapper/swap            swap   swap defaults 0 0
  /dev/sda1                   /boot  vfat defaults 0 0
  /dev/mapper/ENCRYPTED-var   /var   f2fs defaults 0 0
  /dev/mapper/ENCRYPTED-usr   /usr   f2fs defaults 0 0
  /dev/mapper/ENCRYPTED-opt   /opt   f2fs defaults 0 0
  /dev/mapper/ENCRYPTED-home  /home  f2fs defaults 0 0
EOF

##### Now write a custom initscript to create an encrypted swap partition with
##### randomized cipher on each boot
cat <<EOF > /etc/rc.d/swap
  #!/bin/sh

  PROG="/usr/sbin/cryptsetup"
  SWAP="swap"
  CIPH="aes-cbc-essiv:sha256"
  PART="/dev/sda2"

  case $1 in
  start)
    if [ -e /dev/mapper/swap ] ; then
      if swapon --show | grep -qs partition ; then
         exit 0
       else
        swapon /dev/mapper/${SWAP}
        exit 0
      fi
    else
      ${PROG} -q -c ${CIPH} -d /dev/urandom create ${SWAP} ${PART}
      mkswap -f /dev/mapper/${SWAP}
      swapon  /dev/mapper/${SWAP}
      exit 0
    fi
    ;;
  stop)
    swapoff -a
    sleep 1
    ${PROG} close /dev/mapper/${SWAP}
    ;;
  status)
    swapon --show
    ;;
  *)
    echo "usage: $0 [start|stop|status]"
    ;;
  esac
EOF

##### Make the above initscript executable, and add it to the SERVICES array
chmod +x /etc/rc.d/swap

vi /etc/rc.conf

  SERVICES=(swap lo net crond)

##### Continue configuring the network and building the kernel
vi /etc/rc.d/net

vi /etc/dracut.conf.d/modules.conf

  add_dracutmodules+=" crypt lvm "

cd /usr/src/linux-5.15.55
make menuconfig
make all && make modules_install

##### Install the kernel, syslinux bootloader, and initramfs
mkdir -p /boot/efi/BOOT
cp arch/x86/boot/bzImage /boot/efi/BOOT/vmlinuz-5.15.55
cp System.map /boot/efi/BOOT/System.map-5.15.55
cp .config /boot/efi/BOOT/config-5.15.55

dracut --kver 5.15.55 /boot/initramfs-5.15.55.img

cp /usr/share/syslinux/efi64/syslinux.efi /boot/efi/BOOT/bootx64.efi
cp /usr/share/syslinux/efi64/ldlinux.e64 /boot/efi/BOOT

vi /boot/efi/BOOT/syslinux.cfg

  PROMPT  1
  TIMEOUT 10
  DEFAULT CRUX

    LABEL  CRUX
    LINUX  vmlinuz-5.15.55
    APPEND root=/dev/mapper/ENCRYPTED-root rw rd.auto=1 
    INITRD initramfs-5.15.55.img

##### Reboot, and enjoy your new CRUX installation!