========================
Encryption Configuration
========================

The primary purpose of the ownCloud server-side encryption is to protect users' 
files on remote storage, such as Dropbox and Google Drive, and to do it easily 
and seamlessly from within ownCloud.

In ownCloud 9.0 the server-side encryption separates encryption of local and 
remote storage. This allows you to encrypt remote storage, such as Dropbox and 
Google, without having to also encrypt your home storage on your ownCloud 
server.

.. note:: Starting with ownCloud 9.0 we support Authenticated Encryption for all
   newly encrypted files. See https://hackerone.com/reports/108082 for more 
   technical information about the impact.
   
   For maximum security make sure to configure external storage with "Check for
   changes: Never". This will let ownCloud ignore new files not added via
   ownCloud, so a malicious external storage administrator could not add new
   files to the storage without your knowledge. Of course, this is not wise if
   your external storage is subject to legitimate external changes.

ownCloud server-side encryption encrypts files stored on the ownCloud server, 
and files on remote storage that is connected to your ownCloud server. 
Encryption and decryption are performed on the ownCloud server. All files sent 
to remote storage will be encrypted by the ownCloud server, and upon retrieval, 
decrypted before serving them to you and anyone you have shared them with.

.. note:: Encrypting files increases their size by roughly 35%, so you must 
   take this into account when you are provisioning storage and setting 
   storage quotas. User's quotas are based on the unencrypted file size, and 
   not the encrypted file size.

When files on external storage are encrypted in ownCloud, you cannot share them 
directly from the external storage services, but only through ownCloud sharing 
because the key to decrypt the data never leaves the ownCloud server.

ownCloud's server-side encryption generates a strong encryption key, which is 
unlocked by user's passwords. Your users don't need to track an extra 
password, but simply log in as they normally do. It encrypts only the contents 
of files, and not filenames and directory structures.

You should regularly backup all encryption keys to prevent permanent data loss. 
The encryption keys are stored in the following directories:

``data/<user>/files_encryption`` 
  Users' private keys and all other keys necessary to decrypt the users' files
``data/files_encryption``
  private keys and all other keys necessary to decrypt the files stored on a
  system wide external storage
  
When encryption is enabled, all files are encrypted and decrypted by the 
ownCloud application, and stored encrypted on your remote storage.
This protects your data on externally hosted storage. The ownCloud 
admin and the storage admin will see only encrypted files when browsing backend 
storage.  
  
.. warning:: Encryption keys are stored only on the ownCloud server, eliminating
   exposure of your data to third-party storage providers. The encryption app 
   does **not** protect your data if your ownCloud server is compromised, and it
   does not prevent ownCloud administrators from reading user's files. This 
   would require client-side encryption, which this app does not provide. If 
   your ownCloud server is not connected to any external storage services then 
   it is better to use other encryption tools, such as file-level or 
   whole-disk encryption. 
   
   Note also that SSL terminates at or before Apache on the ownCloud server,
   and all files will exist in an unencrypted state between the SSL connection
   termination and the ownCloud code that encrypts and decrypts files. This is
   also potentially exploitable by anyone with administrator access to your
   server. Read `How ownCloud uses encryption to protect your data
   <https://owncloud.org/blog/how-owncloud-uses-encryption-to-protect-your-
   data/>`_ for more information.
   
Before Enabling Encryption
--------------------------

Plan very carefully before enabling encryption because it is not reversible via 
the ownCloud Web interface. If you lose your encryption keys your files are not 
recoverable. Always have backups of your encryption keys stored in a safe 
location, and consider enabling all recovery options.

You have more options via the ``occ`` command (see :ref:`occ_encryption_label`)

.. _enable_encryption_label:

Enabling Encryption
-------------------

ownCloud encryption consists of two parts. The base encryption system is 
enabled and disabled on your Admin page. First you must enable this, and then 
select an encryption module to load. Currently the only available encryption 
module is the ownCloud Default Encryption Module.

First go to the **Server-side encryption** section of your Admin page and check 
**Enable server-side encryption**. You have one last chance to change your mind.

.. figure:: images/encryption3.png

After clicking the **Enable Encryption** button you see the message "No 
encryption module loaded, please load a encryption module in the app menu", so 
go to your Apps page to enable the ownCloud Default Encryption Module.

.. figure:: images/encryption1.png

Return to your Admin page to see the ownCloud Default Encryption 
Module added to the module selector, and automatically selected. Now you must 
log out and then log back in to initialize your encryption keys.

.. figure:: images/encryption14.png

When you log back in, there is a checkbox for enabling encryption on your home 
storage. This is checked by default. Un-check to avoid encrypting your home 
storage.

.. figure:: images/encryption15.png

Sharing Encrypted Files
-----------------------

After encryption is enabled your users must also log out and log back in to 
generate their personal encryption keys. They will see a yellow warning banner 
that says "Encryption App is enabled but your keys are not initialized, please 
log-out and log-in again." 

Share owners may need to re-share files after encryption is enabled; users 
trying to access the share will see a message advising them to ask the share 
owner to re-share the file with them. For individual shares, un-share and 
re-share the file. For group shares, share with any individuals who can't 
access 
the share. This updates the encryption, and then the share owner can remove the 
individual shares.

.. figure:: images/encryption9.png

Encrypting External Mountpoints
-------------------------------

You and your users can encrypt individual external mountpoints. You must have 
external storage enabled on your Admin page, and enabled for your users.

Encryption settings can be configured in the mount options for an external
storage mount, see :ref:`external_storage_mount_options_label`
(:doc:`external_storage_configuration_gui`)

Enabling Users File Recovery Keys
----------------------------------

If you lose your ownCloud password, then you lose access to your encrypted 
files. If one of your users loses their ownCloud password their files are 
unrecoverable. You cannot reset their password in the normal way; you'll see a 
yellow banner warning "Please provide an admin recovery password, otherwise all 
user data will be lost".

To avoid all this, create a Recovery Key. Go to the Encryption section of your 
Admin page and set a recovery key password.

.. figure:: images/encryption10.png

Then your users have the option of enabling password recovery on their Personal 
pages. If they do not do this, then the Recovery Key won't work for them.

.. figure:: images/encryption7.png

For users who have enabled password recovery, give them a new password and 
recover access to their encrypted files by supplying the Recovery Key on the 
Users page.

.. figure:: images/encryption8.png

You may change your Recovery Key password.

.. figure:: images/encryption12.png

.. _occ_encryption_label:

occ Encryption Commands
-----------------------

If you have shell access you may use the ``occ`` command to perform encryption 
operations, and you have additional options such as decryption and creating a 
single master encryption key. See :ref:`encryption_label`  for detailed 
instructions on using ``occ``.

Get the current status of encryption and the loaded encryption module::

 occ encryption:status

This is equivalent to checking **Enable server-side encryption** on your Admin
page::

 occ encryption:enable
 
List the available encryption modules::

 occ encryption:list-modules

Select a different default Encryption module::

 occ encryption:set-default-module [Module ID]. 
 
The [module ID] is taken from the ``encryption:list-modules`` command.

Encrypt all data files for all users. For performance reasons, when you enable 
encryption on an ownCloud server only new and changed files are encrypted. This 
command gives you the option to encrypt all files. You must first put your 
ownCloud server into single-user mode to prevent any user activity until 
encryption is completed::

 occ encryption:encrypt-all

Decrypt all user data files, or optionally a single user::
 
 occ encryption:decrypt-all [username]

Move keys to a different folder, either locally or on a different server::

 occ encryption:change-key-storage-root
 
View current location of keys::

 occ encryption:show-key-storage-root
 
Create a new master key. Use this when you have a single-sign on 
infrastructure.  Use this only on fresh installations with no existing data, or 
on systems where encryption has not already been enabled. It is not possible to 
disable it::

 occ encryption:enable-master-key
 
Disabling Encryption
--------------------

You may disable encryption only with ``occ``. Make sure you have backups of all 
encryption keys, including users'. Put your ownCloud server into 
single-user mode, and then disable your encryption module with this command::

 occ maintenance:singleuser --on
 occ encryption:disable
 
Take it out of single-user mode when you are finished::

 occ maintenance:singleuser --off

Files Not Encrypted
-------------------

Only the data in the files in ``data/user/files`` are encrypted, and not the 
filenames or folder structures. These files are never encrypted:

- Existing files in the trash bin & Versions. Only new and changed files after 
  encryption is enabled are encrypted.
- Existing files in Versions
- Image thumbnails from the Gallery app
- Previews from the Files app
- The search index from the full text search app
- Third-party app data

There may be other files that are not encrypted; only files that are exposed to 
third-party storage providers are guaranteed to be encrypted.

LDAP and Other External User Back-ends
--------------------------------------

If you use an external user back-end, such as an LDAP or Samba server, and you 
change a user's password on the back-end, the user will be prompted to change 
their ownCloud login to match on their next ownCloud login. The user will need 
both their old and new passwords to do this. If you have enabled the Recovery 
Key then you can change a user's password in the ownCloud Users panel to match 
their back-end password, and then, of course, notify the user and give them 
their new password.

.. _upgrading_encryption_label:

Encryption migration to ownCloud 8.0
------------------------------------

When you upgrade from older versions of ownCloud to ownCloud 8.0, you must 
manually migrate
your encryption keys with the *occ* command after the upgrade is complete, like 
this
example for CentOS: *sudo -u apache php occ encryption:migrate-keys* You must 
run *occ* as
your HTTP user. See :doc:`../configuration_server/occ_command` to learn more 
about *occ*.

Encryption migration to ownCloud 8.1
------------------------------------

The encryption backend has changed in ownCloud 8.1 again, so you must take some 
additional steps to migrate encryption correctly. If you do not follow these 
steps you may not be able to access your files.

Before you start your upgrade, put your ownCloud server into 
``maintenance:singleuser`` mode (See :doc:`../maintenance/enable_maintenance`.) 
You must do this to prevent users and sync clients from accessing files before 
you have completed your encryption migration.

After your upgrade is complete, follow the steps in 
:ref:`enable_encryption_label` to 
enable the new encryption system. Then click the **Start Migration** button on 
your Admin page to migrate your encryption keys, or use the ``occ`` command. We 
strongly recommend using the ``occ`` command; the **Start Migration** button is 
for admins who do not have access to the console, for example installations on 
shared hosting. This example is for Debian/Ubuntu Linux::

 $ sudo -u www-data php occ encryption:migrate
 
This example is for Red Hat/CentOS/Fedora Linux::

 $ sudo -u apache php occ encryption:migrate
 
You must run ``occ`` as your HTTP user; see 
:doc:`../configuration_server/occ_command`.

When you are finished, take your ownCloud server out of 
``maintenance:singleuser`` mode.
