Right Auth with AngularJS, Django and external API service - python

I'm developing my first AngularJS application with Django as backend.
My overall architecture is composed of:
Public API json-rpc server (from which I must retrive data previous authentication process (the client send a user/password with a POST request, and then, the server response with a token string).
Django framework, I use this because I need to have some models and MySQL db for additional data; and because the Public API server doesn't support CORS (is a old version) and I've created an API Proxy with one view of Django.
Angular JS App that it served by Django.
Now, when the client first send user/password with AngularJS -> Django -> API server, the server respond with token, and henceforward the Client use token to make next requests.
My question is: What's the right approach to retain the token on the client (AngularJS) (or on Django if required) after the user did login??
Do you have any suggestion on my architecture?
Thanks in advance... and... sorry for my English :)

Depending from your needs you should think about storing the token in the session storage in the local storage or in a cookie(in this case the cookie is used as a storage mechanism and not as an authentication mechanism).

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Now, only authorized clients can access to the app and besides that, only authorized IP can connect.
But what if someone was listening in the middle of that connection ? He would see all the datas in clear.
Is there a way to encrypt those info, maybe with a password, and then decrypt it when it arrives ? (the client would have to update his app, but it's not a problem).
I was thinking maybe to create an "EncryptedResponse" instead of "Response" in my django app.
Thanks
If you don't have one already, purchase an SSL certificate and configure your site to load the API over HTTPS. That way the connection between the authorized client and your application would be encrypted which will prevent a man in the middle attack that you're describing.
If you're not going to load the API over HTTPS, then the authentication token, or API key, or whatever you're using to authenticate the client can also be intercepted.
However, if you're looking to stick to the encrypting the data route, I've found this guide that looks like it should help you be able do what you need to do:
http://gpiot.com/blog/encrypted-fields-pythondjango-keyczar/

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Samples are "3scale.net", offering free tier, other commercial solutions exist too.
Open source solution I am aware of is ApiAxle, which is much simpler, but still very useful.
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Using Authorization service
Another solution is to have some internal service evaluating set of client provided keys (providerid, appid, accesskey, ...) are authrized or not. For this purpose, you have to:
set up authorization service
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Sample code for 3scale is here: https://github.com/3scale/3scale_ws_api_for_python
Conclusions
Authentication proxy makes the application simple and not bothering about who is asking. This can be advantage until your application needs to know who is asking.
Authentication service requires changing your code.

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not detect that there are other servers in the backend (the URL should be the same host)
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The front-end server that you describe is essentially what is known as a reverse proxy.
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Nginx is a popular web server that works well as a reverse proxy.
Sounds like you want a single sign-on setup for a collection of service endpoints with a single entry point.
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Thank you.
In order to restrict your Endpoint to a specific application you can use OAuth2. This is because the OAuth2 flow does user authentication and in-turn the OAuth2 flow inherently authenticates the application requesting the OAuth2 access.
These two client samples detail how to enable authenticated calls on the client side. You have to register your apps in the Developer Console at http://cloud.google.com/console/ .
https://github.com/GoogleCloudPlatform/appengine-endpoints-helloendpoints-android (Starting after the Note in the readme)
https://github.com/GoogleCloudPlatform/appengine-endpoints-helloendpoints-ios/ (Step 8 in README)
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https://github.com/GoogleCloudPlatform/appengine-endpoints-helloendpoints-java-maven
Specifically, optional Step 2 in the README tells Cloud Endpoints to start looking for OAuth2 tokens in the request. If the Endpoints exposed method has a User parameter. It will populate it with a user instance only if an OAuth2 token was found, was generally valid, and the token was issued to a client ID defined in the API annotation on the service class.
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So, if you need only the WEB_CLIENT_ID to obtain the access_token and the renew_token, why you need the ANDROID_CLIENT_ID and IOS_CLIENT_ID? For security reasons.
The ANDROID_CLIENT_ID is linked to a RSA signature key through the SHA1 informed at backend setup. Thus your GAE app will grant (access_token, renew_token) only installed apps signed with the same key listed at your application console (and of course in your clientIds list)
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For server to server communication, traditional security advice would recommend some sort of IP range restriction at the web server level for the URLs in addition to whatever default security is in place. However, since you are making the call from a cloud provider to another cloud provider, your ability to permanently control the IP address of either the client and the server may diminished.
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Depending on what web framework you are using on the App Engine, there is probably already support for some or all of what I just mentioned. If you update this question with more specifics on your architecture or open a new question with more information, we could give you a more accurate recommendation.
SDC provides a secure tunnel from AppEngine to a private network elsewhere -- which could be your EC2 instance, if you run it there.

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