root@rescue:~# cryptsetup luksFormat /dev/sda3
WARNING!
========
This will overwrite data on /dev/sda3 irrevocably.
Are you sure? (Type uppercase yes): YES
Enter passphrase:
Verify passphrase:
root@rescue:~# cryptsetup luksOpen /dev/sda3 sda3_crypt
Enter passphrase for /dev/sda3:
root@rescue:~# mkfs.ext4 /dev/mapper/sda3_crypt
mke2fs 1.42.12 (29-Aug-2014)
Creating filesystem with 9400745 4k blocks and 2351104 inodes
Filesystem UUID: 34378e71-7704-46f1-9a0a-c716967ad032
Superblock backups stored on blocks:
32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632, 2654208,
4096000, 7962624
Allocating group tables: done
Writing inode tables: done
Creating journal (32768 blocks): done
Writing superblocks and filesystem accounting information: done