luks encrypted file container

$ sudo apt-get install cryptsetup # or on redhat - yum install cryptsetup-luks
Reading package lists... Done
Building dependency tree
Reading state information... Done
cryptsetup is already the newest version (2:1.6.6-5ubuntu2).
0 upgraded, 0 newly installed, 0 to remove and 63 not upgraded.

$ truncate -s 100m myencryptedcontainer

$ cryptsetup -y -v luksFormat myencryptedcontainer

WARNING!
========
This will overwrite data on myencryptedcontainer irrevocably.

Are you sure? (Type uppercase yes): YES
Enter passphrase:
Verify passphrase:
Command successful.

$ sudo cryptsetup luksOpen ./myencryptedcontainer myencryptedfiles
Enter passphrase for ./myencryptedcontainer:

$ sudo mkfs.ext4 /dev/mapper/myencryptedfiles
mke2fs 1.43.1 (08-Jun-2016)
Creating filesystem with 100352 1k blocks and 25168 inodes
Filesystem UUID: 20e83401-5f8d-45d0-bfda-1d04599b6d92
Superblock backups stored on blocks:
  8193, 24577, 40961, 57345, 73729

Allocating group tables: done
Writing inode tables: done
Creating journal (4096 blocks): done
Writing superblocks and filesystem accounting information: done

$ mkdir myunencryptedsecrets

$ sudo mount /dev/mapper/myencryptedfiles /home/stephan/myunencryptedsecrets/

$ sudo chown -R stephan:stephan /home/stephan/myunencryptedsecrets/

$ echo "I'm some data" > /home/stephan/myunencryptedsecrets/somefile.txt

$ cat /home/stephan/myunencryptedsecrets/somefile.txt
I'm some data

$ sudo umount myunecryptedsecrets/

$ sudo cryptsetup luksClose myencryptedfiles