Token Authentication for RESTful API: should the t

Question

I'm building a RESTful API with Django and django-rest-framework.

As authentication mechanism we have chosen "Token Authentication" and I have already implemented it following Django-REST-Framework's documentation, the question is, should the application renew / change the Token periodically and if yes how? Should it be the mobile app that requires the token to be renewed or the web-app should do it autonomously?

What is the best practice?

Anybody here experienced with Django REST Framework and could suggest a technical solution?

(the last question has lower priority)

Answer 1

The author asked

the question is, should the application renew / change the Token periodically and if yes how? Should it be the mobile app that requires the token to be renewed or the web-app should do it autonomously?

But all of the answers are writing about how to automatically change the token.

I think change token periodically by token is meaningless. The rest framework create a token that has 40 characters, if the attacker tests 1000 token every second, it requires 16**40/1000/3600/24/365=4.6*10^7 years to get the token. You should not worried that the attacker will test your token one by one. Even you changed your token, the probability of guess you token is the same.

If you are worried that maybe the attackers can get you token, so you change it periodically, than after the attacker get the token, he can also change you token, than the real user is kicked out.

What you should really do is to prevent tha attacker from getting your user's token, use https.

By the way, I'm just saying change token by token is meaningless, change token by username and password is sometimes meanful. Maybe the token is used in some http environment (you should always avoid this kind of situation) or some third party (in this case, you should create different kind of token, use oauth2) and when the user is doing some dangerous thing like changing binding mailbox or delete account, you should make sure you will not use the origin token anymore because it may has been revealed by the attacker using sniffer or tcpdump tools.

Answer 2

Just thought I would add mine as this was helpful for me. I usually go with the JWT method but sometimes something like this is better. I updated the accepted answer for django 2.1 with proper imports..

authentication.py

from datetime import timedelta
from django.conf import settings
from django.core.exceptions import ObjectDoesNotExist
from django.utils import timezone
from rest_framework.authentication import TokenAuthentication
from rest_framework import exceptions

EXPIRE_HOURS = getattr(settings, 'REST_FRAMEWORK_TOKEN_EXPIRE_HOURS', 24)


class ExpiringTokenAuthentication(TokenAuthentication):
    def authenticate_credentials(self, key):
        try:
            token = self.get_model().objects.get(key=key)
        except ObjectDoesNotExist:
            raise exceptions.AuthenticationFailed('Invalid token')

        if not token.user.is_active:
            raise exceptions.AuthenticationFailed('User inactive or deleted')

        if token.created < timezone.now() - timedelta(hours=EXPIRE_HOURS):
            raise exceptions.AuthenticationFailed('Token has expired')

    return token.user, token

views.py

import datetime
from pytz import utc
from rest_framework import status
from rest_framework.response import Response
from rest_framework.authtoken.models import Token
from rest_framework.authtoken.views import ObtainAuthToken
from rest_framework.authtoken.serializers import AuthTokenSerializer


class ObtainExpiringAuthToken(ObtainAuthToken):
    def post(self, request, **kwargs):
        serializer = AuthTokenSerializer(data=request.data)

        if serializer.is_valid():
            token, created = Token.objects.get_or_create(user=serializer.validated_data['user'])
            if not created:
                # update the created time of the token to keep it valid
                token.created = datetime.datetime.utcnow().replace(tzinfo=utc)
                token.save()

            return Response({'token': token.key})
        return Response(serializer.errors, status=status.HTTP_400_BAD_REQUEST)

Answer 3

If you notice that a token is like a session cookie then you could stick to the default lifetime of session cookies in Django: https://docs.djangoproject.com/en/1.4/ref/settings/#session-cookie-age.

I don't know if Django Rest Framework handles that automatically but you can always write a short script which filters out the outdated ones and marks them as expired.

Answer 4

If someone is interested by that solution but wants to have a token that is valid for a certain time then gets replaced by a new token here's the complete solution (Django 1.6):

yourmodule/views.py:

import datetime
from django.utils.timezone import utc
from rest_framework.authtoken.views import ObtainAuthToken
from rest_framework.authtoken.models import Token
from django.http import HttpResponse
import json

class ObtainExpiringAuthToken(ObtainAuthToken):
    def post(self, request):
        serializer = self.serializer_class(data=request.DATA)
        if serializer.is_valid():
            token, created =  Token.objects.get_or_create(user=serializer.object['user'])

            utc_now = datetime.datetime.utcnow()    
            if not created and token.created < utc_now - datetime.timedelta(hours=24):
                token.delete()
                token = Token.objects.create(user=serializer.object['user'])
                token.created = datetime.datetime.utcnow()
                token.save()

            #return Response({'token': token.key})
            response_data = {'token': token.key}
            return HttpResponse(json.dumps(response_data), content_type="application/json")

        return HttpResponse(serializer.errors, status=status.HTTP_400_BAD_REQUEST)

obtain_expiring_auth_token = ObtainExpiringAuthToken.as_view()

yourmodule/urls.py:

from django.conf.urls import patterns, include, url
from weights import views

urlpatterns = patterns('',
    url(r'^token/', 'yourmodule.views.obtain_expiring_auth_token')
)

your project urls.py (in the urlpatterns array):

url(r'^', include('yourmodule.urls')),

yourmodule/authentication.py:

import datetime
from django.utils.timezone import utc
from rest_framework.authentication import TokenAuthentication
from rest_framework import exceptions

class ExpiringTokenAuthentication(TokenAuthentication):
    def authenticate_credentials(self, key):

        try:
            token = self.model.objects.get(key=key)
        except self.model.DoesNotExist:
            raise exceptions.AuthenticationFailed('Invalid token')

        if not token.user.is_active:
            raise exceptions.AuthenticationFailed('User inactive or deleted')

        utc_now = datetime.datetime.utcnow()

        if token.created < utc_now - datetime.timedelta(hours=24):
            raise exceptions.AuthenticationFailed('Token has expired')

        return (token.user, token)

In your REST_FRAMEWORK settings add ExpiringTokenAuthentication as an Authentification class instead of TokenAuthentication:

REST_FRAMEWORK = {

    'DEFAULT_AUTHENTICATION_CLASSES': (
        'rest_framework.authentication.SessionAuthentication',
        #'rest_framework.authentication.TokenAuthentication',
        'yourmodule.authentication.ExpiringTokenAuthentication',
    ),
}

Answer 5

It is good practice to have mobile clients periodically renew their authentication token. This of course is up to the server to enforce.

The default TokenAuthentication class does not support this, however you can extend it to achieve this functionality.

For example:

from rest_framework.authentication import TokenAuthentication, get_authorization_header
from rest_framework.exceptions import AuthenticationFailed

class ExpiringTokenAuthentication(TokenAuthentication):
    def authenticate_credentials(self, key):
        try:
            token = self.model.objects.get(key=key)
        except self.model.DoesNotExist:
            raise exceptions.AuthenticationFailed('Invalid token')

        if not token.user.is_active:
            raise exceptions.AuthenticationFailed('User inactive or deleted')

        # This is required for the time comparison
        utc_now = datetime.utcnow()
        utc_now = utc_now.replace(tzinfo=pytz.utc)

        if token.created < utc_now - timedelta(hours=24):
            raise exceptions.AuthenticationFailed('Token has expired')

        return token.user, token

It is also required to override the default rest framework login view, so that the token is refreshed whenever a login is done:

class ObtainExpiringAuthToken(ObtainAuthToken):
    def post(self, request):
        serializer = self.serializer_class(data=request.data)
        if serializer.is_valid():
            token, created =  Token.objects.get_or_create(user=serializer.validated_data['user'])

            if not created:
                # update the created time of the token to keep it valid
                token.created = datetime.datetime.utcnow()
                token.save()

            return Response({'token': token.key})
        return Response(serializer.errors, status=status.HTTP_400_BAD_REQUEST)

obtain_expiring_auth_token = ObtainExpiringAuthToken.as_view()

And don't forget to modify the urls:

urlpatterns += patterns(
    '',
    url(r'^users/login/?$', '<path_to_file>.obtain_expiring_auth_token'),
)

Answer 6

I've tried @odedfos answer but I had misleading error. Here is the same answer, fixed and with proper imports.

views.py

from django.utils import timezone
from rest_framework import status
from rest_framework.response import Response
from rest_framework.authtoken.models import Token
from rest_framework.authtoken.views import ObtainAuthToken

class ObtainExpiringAuthToken(ObtainAuthToken):
    def post(self, request):
        serializer = self.serializer_class(data=request.DATA)
        if serializer.is_valid():
            token, created =  Token.objects.get_or_create(user=serializer.object['user'])

            if not created:
                # update the created time of the token to keep it valid
                token.created = datetime.datetime.utcnow().replace(tzinfo=utc)
                token.save()

            return Response({'token': token.key})
        return Response(serializer.errors, status=status.HTTP_400_BAD_REQUEST)

authentication.py

from datetime import timedelta
from django.conf import settings
from django.utils import timezone
from rest_framework.authentication import TokenAuthentication
from rest_framework import exceptions

EXPIRE_HOURS = getattr(settings, 'REST_FRAMEWORK_TOKEN_EXPIRE_HOURS', 24)

class ExpiringTokenAuthentication(TokenAuthentication):
    def authenticate_credentials(self, key):
        try:
            token = self.model.objects.get(key=key)
        except self.model.DoesNotExist:
            raise exceptions.AuthenticationFailed('Invalid token')

        if not token.user.is_active:
            raise exceptions.AuthenticationFailed('User inactive or deleted')

        if token.created < timezone.now() - timedelta(hours=EXPIRE_HOURS):
            raise exceptions.AuthenticationFailed('Token has expired')

        return (token.user, token)