Add tutotial doc

Author: duzumaki

docs/_images/application-register-device-code.png

@@ -9,4 +9,4 @@ Tutorials
    tutorial_03
    tutorial_04
    tutorial_05
-
+   tutorial_06

docs/_images/device-approve-deny.png

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+Device authorization grant flow
+====================================================
+
+Scenario
+--------
+In :doc:`Part 1 <tutorial_01>` you created your own :term:`Authorization Server` and it's running along just fine.
+You have devices that your users have, and those users need to authenticate the device against your
+:term:`Authorization Server` in order to make the required API calls.
+
+Device Authorization
+--------------------
+The OAuth 2.0 device authorization grant is designed for Internet
+connected devices that either lack a browser to perform a user-agent
+based authorization or are input-constrained to the extent that
+requiring the user to input text in order to authenticate during the
+authorization flow is impractical. It enables OAuth clients on such
+devices (like smart TVs, media consoles, digital picture frames, and
+printers) to obtain user authorization to access protected resources
+by using a user agent on a separate device.
+
+Point your browser to `http://127.0.0.1:8000/o/applications/register/` to create an application.
+
+Fill the form as shown in the screenshot below, and before saving, take note of the ``Client id``.
+Make sure the client type is set to "Public." There are cases where a confidential client makes sense,
+but generally, it is assumed the device is unable to safely store the client secret.
+
+.. image:: _images/application-register-device-code.png
+   :alt: Device Authorization application registration
+
+Ensure the setting ``OAUTH_DEVICE_VERIFICATION_URI`` is set to a URI you want to return in the
+`verification_uri` key in the response. This is what the device will display to the user.
+
+1: Navigate to the tests/app/idp directory:
+
+.. code-block:: sh
+
+    cd tests/app/idp
+
+To initiate device authorization, send this request:
+
+.. code-block:: sh
+
+    curl --location 'http://127.0.0.1:8000/o/device-authorization/' \
+        --header 'Content-Type: application/x-www-form-urlencoded' \
+        --data-urlencode 'client_id={your application\'s client id}'
+
+The OAuth2 provider will return the following response:
+
+.. code-block:: json
+
+    {
+        "verification_uri": "http://127.0.0.1:8000/o/device",
+        "expires_in": 1800,
+        "user_code": "A32RVADM",
+        "device_code": "G30j94v0kNfipD4KmGLTWeL4eZnKHm",
+        "interval": 5
+    }
+
+Go to `http://127.0.0.1:8000/o/device` in your browser.
+
+.. image:: _images/device-enter-code-displayed.png
+
+Enter the code, and it will redirect you to the device-confirm endpoint.
+
+Device-confirm endpoint
+-----------------------
+Device polling occurs concurrently while the user approves or denies the request.
+
+.. image:: _images/device-approve-deny.png
+
+Device polling
+--------------
+Note: You should already have the `/token` endpoint implemented in your authorization server before this.
+
+Send the following request (in the real world, the device makes this request):
+
+.. code-block:: sh
+
+    curl --location 'http://localhost:8000/o/token/' \
+        --header 'Content-Type: application/x-www-form-urlencoded' \
+        --data-urlencode 'device_code={the device code from the device-authorization response}' \
+        --data-urlencode 'client_id={your application\'s client id}' \
+        --data-urlencode 'grant_type=urn:ietf:params:oauth:grant-type:device_code'
+
+The response will be similar to this:
+
+.. code-block:: json
+
+    {
+        "access_token": "SkJMgyL432P04nHDPyB63DEAM0nVxk",
+        "expires_in": 36000,
+        "token_type": "Bearer",
+        "scope": "openid",
+        "refresh_token": "Go6VumurDfFAeCeKrpCKPDtElV77id"
+    }