You can enhance your files protection by enable server-side encryption.

Note: Encrypting files will increase their size by roughly 35%.


Here are the steps:

1) Click on add Apps button:



2) On left panel, click Not Enabled, look for Default Encryption Module and click Enable button:



3) Now, back to admin area, look for Server-Side Encryption link and select Enable:




4) Please read the warning note carefully, click Enable� encryption button if you are comfortable with it:



5) Logout your from your admin account and relogin again. Now back to Server-side encryption link, enter your recovery key password:



That's all.


For more details please refer to https://doc.owncloud.org/server/8.2/admin_manual/configuration_files/encryption_configuration.html