# ownCloud 8.2 Server Administration Manual

# External Storage Authentication mechanisms

ownCloud storage backends accept one or more authentication schemes such as passwords, OAuth, or token-based, to name a few examples. Each authentication scheme may be implemented by multiple authentication mechanisms. Different mechanisms require different configuration parameters, depending on their behaviour.

## Special Mechanisms

The None authentication mechanism requires no configuration parameters, and is used when a backend requires no authentication.

The Built-in authentication mechanism itself requires no configuration parameters, but is used as a placeholder for legacy storages that have not been migrated to the new system and do not take advantage of generic authentication mechanisms. The authentication parameters are provided directly by the backend.

## Password-based Mechanisms

The Username and password mechanism requires a manually-defined username and password. These get passed directly to the backend.

The Session credentials mechanism uses the ownCloud login credentials of the user to connect to the storage. These are not stored anywhere on the server, but rather in the user session, giving increased security. The drawback is that sharing is disabled when this mechanism is in use, as ownCloud has no access to the storage credentials and so other users cannot use it.

## Public-key Mechanisms

Currently only the RSA mechanism is implemented, where a public/private keypair is generated by ownCloud and the public half shown in the GUI. The keys are generated in the SSH format, and are currently 1024 bits in length. Keys can be regenerated with a button in the GUI.

## OAuth

OAuth 1.0 and OAuth 2.0 are both implemented, but currently limited to the Dropbox and Google Drive backends respectively. These mechanisms require additional configuration at the service provider, where an app ID and app secret are provided and then entered into ownCloud. Then ownCloud can perform an authentication request, establishing the storage connection.