Encrypt OS Disk

/etc/crypttab

linux UUID="18fbddd6-48a3-442e-9807-d02e30efc2bc" none luks

/etc/default/grub

GRUB_DEFAULT=0
GRUB_TIMEOUT_STYLE=hidden
GRUB_TIMEOUT=20
GRUB_DISTRIBUTOR=`lsb_release -i -s 2> /dev/null || echo Debian`
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"
GRUB_CMDLINE_LINUX=""
GRUB_ENABLE_CRYPTODISK=y
GRUB_PRELOAD_MODULES="luks cryptodisk lvm ext2"

/etc/initramfs-tools/conf.d/noresume.conf

RESUME=none