Thursday, March 12, 2015

dj-api-auth, a Django application providing AWS-alike API protection

Github: https://github.com/feifangit/dj-api-auth



dj-api-auth

dj-api-auth is a Django application, providing an AWS-alike API auth solution.

When I was seeking a simple solution rather than intricate OAuth, I was inspired by this article
Designing a Secure REST (Web) API without OAuth.
Thanks to the author and the comments.

Features

  1. API key, SEC key related forms
  2. Each API key can be associated with a set of API
  3. API can be associated with user, your legacy code with request.user underneath can work smoothly with dj-api-auth
  4. Add auth by simply put a decorator on your view.
  5. Discover API with auth enabled automatically, these auth-required APIs will display in assignable list when creating API keys
  6. A Django command to scan and update API information to database.

How it works

  1. Generate a pair of API key and SEC key, assign some APIs to it.

  2. Client put API key and current UNIX time as apikey and timestemp in requestURL

  3. Client also generate a signature by calculate a SHA256 value on the whole URL(without signature) by its known SEC key.

  4. Server side will verify
    • is timestamp from client in reasonable rift compare to server time.
    • is apikey from client exists
    • is the API client trying to access allowed for the apikey
    • compare the signature with the one calculated on server side by same algorithm

  5. if any verification failed, return 403 error with brief message


Add to your project

  1. Add djapiauth to INSTALLED_APPS in sttings.py
  2. There are two optional settings
  • API_AUTH_ALLOWED_TIME_RIFT
    • optional, set the allowed time rift between server time and the timestamp parameter in coming URL.
    • format : integer, unit: second
    • default : 300, (5 minutes)

  • API_AUTH_ADMIN_USER_FILTER
    • optional, when creating API keys, you can assign the API key to an user, this filter is used to filter the users showing in the API key creating form.
    • format: dictionary, the filter parameter will be passed to get_user_model().objects.filter(). e.g. {'name_startswith': 'admin'}
    • default: {}, means all users will show in the API key creating form.

Generate/Manage API and SEC key

If you have admin enabled for your project, you can find these features in admin site. Otherwise, you can import forms from djapiauth.forms or write your own form based on models in djapiauth.models

Add auth for views

  • For legacy views, we provide utility function url_with_auth in djapiauth.utility
# add auth for a browser-oriented view
url_with_auth(r'^hello/$', 'djapp.views.index'),
#...
  • For API views, simply add @api_auth for the view after from djapiauth.auth import api_auth
@api_auth
def api_whoami(request):
        return JsonResponse({"user": "feifan", "boss": "lidan zhou"})

Scan API

we have a Django command reloadentrypoints to help you to collect and save all auth-required APIs to database.

Error messages

  • parameter missing, any of apikey, timestamp or signature missing in URL
  • timestamp rift xxx, check your local time and server time. You can implement an API to return server time
  • entry point not allowed for the API key, check the assigned API for this API key in admin site or anywhere else you manage API keys
  • signature error, obviously, signature mismatch

DEMO

  • Source code under example/djapp folder.
  • Test code is under example/test/, we have python and javascript test code ready.

Server application provides 2 APIs

  • /hello/ : reused the code of index view, add an auth layer on it
  • /goodbye/ : a view you must access it by the signature stuff

DIY:

  • Start the djapp
  • there's already one pair of API+SEC keys: 483a570a, d7228d70cd7f456d9bfdc35ed8fee375
  • modify variable URL in test.py, or URL in test.js
  • Generate API key and SEC key from localhost:8000/admin/xxx, modify variable API_KEY and SEC_KEY in test.py or test.js
  • Run python test.py or node test.js
  • login admin site with admin user: admin/123, remove all APIs associated with 483a570a, try to run the test code again, you should see 403 errors __main__.APIException: (403, '{"error": "entry point not allowed for the API key"}')
  • modify the API key to an invalid one
  • modify the SEC key to an invalid one
  • modify your local time to one hour ago

Thanks

Thanks for the Javascript test code from Neil Chen (neil.chen.nj@gmail.com)

TODO

  • performance improvement for entry point matching in API permission check.



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