How to encrypts rootfs partition:Banana Pi cryptroot auto boot on Ubuntu 16.04

please reference below link:

Banana-pi encrypted sata disk bootstrap

BananaPi-M1-Plus, Linux, busybox

This script I had written for creating image which may be burnt into SD-card of Banana Pi M1+ slot. This script uses loop device for imitating a block device. It creates zero file and then formats it on two partitions. First partition is for the bootloader (U-Boot) and second partition’s for rootfs. The script encrypts rootfs partition with cryptsetup and also creates initramfs, which decrypts rootfs partition at boot time.

Banana Pi cryptroot auto boot on Ubuntu 16.04