Can I use browser authentication to make RESTful calls to GAE? - google-app-engine

We're writing a Desktop application that relies on Google Appengine to authenticate the user and retrieve and store data associated to it.
The way we'd like to authenticate the user is that on launching the application the browser is launched at the login url for our application. Then the user logins there, and then the application makes restful calls without any OAUTH object, but re-using the browser session. I'm questioned that this won't work, since we cannot so transparently use the browser session. Is that correct?
Any alternatives beside authenticating from within the app using the ClientLoginApi?
I'm aware of:
How do you access an authenticated Google App Engine service from a (non-web) python client?

The only way to do this is if you can capture the authentication cookie used by the browser, and send it yourself. Obviously, there's no browser- or platform- independent way to do this.
A better option would be to use OAuth, with OAuth for installed apps to obtain the original token.

Related

What is the best approach for using OpenID Connect in a mobile app to authenticate the user to a backend?

I'm working on a product with two apps: one a single-page web app, and the other a native mobile app. Both make use of the same backend API. Currently the user authenticates using username/password credentials to establish a session cookie. I'm planning on adding support for authentication using OpenID Connect.
For the web app, I'm looking at following the advice for "JavaScript Applications with a Backend" in "OAuth 2.0 for Browser-Based Apps". In that scenario, the authorization code gets sent to the backend, which obtains the ID token and begins a cookie-based session.
I'm trying to work out how this would work on Mobile. The "go to" implementation of OAuth/OIDC on mobile appears to be AppAuth. From what I can see, AppAuth uses a different approach where you end up doing the auth code exchange on the device to get the ID token.
Should I have the mobile app send the ID token on to the backend to prove the user identity (and then begin the session)? Is there any best practice around doing this? Presumably at least the backend would need to validate the JWT and verify the signature?
Alternatively, can AppAuth be used to do a similar flow as done on the web app as mentioned above?
The mobile case does indeed work differently, and is defined in RFC8252, which defines the AppAuth pattern. Both the web and mobile cases have this in common:
Open a system browser at the Authorization Server URL with a Code Flow request URL
Cookies are not used in mobile views, and mobile apps can store tokens securely, unlike browser based apps. The mobile app will send access tokens to APIs, and also make token refresh requests when needed.
Out of interest there are easy to run versions of each in my online code samples, if you want something to compare against. Both flows are tricky to implement though.

appengine access via oauth2 python script (replacing ClientLogin)

I have an App Engine project which:
uses google.appengine.api.get_current_user() to handle users (and login:required)
has a URL to collect some data (which requires login)
has Google users but on a custom domain
I used to have a script to pull the data using the old https://www.google.com/accounts/ClientLogin interface, but now that interface is deprecated, I'm trying to work out what I need to do to get OAuth2 working to access my App Engine URL with a user value set.
I have worked my way through OAuth2 for devices to get myself an access key for my script (i.e. I can run it, authenticate in a web browser, then poll for the access key), as described in OAuth2 For Devices.
But I'm not sure:
what scope I should be using to request the access_token compatible with get_current_user(),
how to pass this in my request to App Engine so that it can create the the user header, and
whether I need to modify my app to use this access_token, eg adding callbacks etc
With regards to the last point, user was set by google's front end infrastructure so I’m hoping that that same infrastructure can somehow convert my OAuth access_token into a login name without me needing to update my app to do the callback part, because it should all be in appengine's infrastructure right and user is set before the request comes to my app.

Securing RESTful API in Google App Engine

I'm trying to figure out how to implement the following authentication flow:
The user accesses a web application (most likely to be written using Ruby on Rails) and authenticates (e.g., username/password).
The client consumes data via AJAX provided by a RESTful API built on Google App Engine (Python, webapp2).
Requirements:
Only users authenticated in the web application (Rails) should be able to access the API hosted on App Engine.
Users can have different roles in the web application (Rails), and the API (App Engine) needs to know what roles are associated to the given user to restrict access to certain data.
The client should be able to call the API (App Engine) directly via AJAX, without routing all requests through the web application (Rails).
I'm looking for suggestions on how to implement such workflow. Should I use OAuth (or OAuth2) for accessing the API? Should the OAuth provider live on App Engine and the web application (Rails) ask the API for a token on behalf of the user? If so, what is the best way to allow only the web application (Rails) to request OAuth tokens? Or should I consider a completely different strategy?
Any suggestions are greatly appreciated. I'm also looking for suggestions of libraries to implement OAuth in the context above.
I suggest you use caution if you are considering implementing an API built on the Google App Engine using OAuth for your security layer. I am currently involved in a project that is struggling to solve exactly this problem. The OAuth layer over the GAE is still new and considered by Google to be "experimental". Google's documentation is minimal at this point. What there is begins here. I wish you the best if you try to proceed, and I will do my best to offer help if you do.
My solution to this same problem was to write my own three-way authentication (like OAuth):
After the user is authenticated on the RoR server, it responds with a temporary token. This token is stored on the RoR server, is good for 60 seconds, and contains the user's roles.
The browser sends this token (using AJAX) to the webapp2 server. It's like logging in on that server using just the token.
The webapp2 server forwards the token on to the RoR server to make sure it is valid.
The RoR server makes sure the token hasn't expired and immediately deletes the token to prevent duplicate requests. If the token is valid, the RoR server responds with the user's roles.
If the response from the RoR server is good, the webapp2 server responds to the browser's AJAX call (in step 2) with a cookie indicating that this user is now logged in. The session should contain the user's roles.
Subsequent requests to the webapp2 server will include the cookie so that server can respond according to the user's roles.

Authenticate to Google AppEngine application which use federated login from Windows Client Application

I'm plan on deploy a Java application to Google AppEngine and use federated login (still experimental according to Google). The application is pretty simple Java EE application which expose RESTful interface for simple CRUD operations.
I then want to be able to authenticate to this application using Windows Client Application written in C#.
I think the application should be able to open a window with a browser in ti which will present the login page of my web application and after successful authentication I should be able to get the login token or a cookie to use in the rest of my HTTP requests.
Is it possible to do such thing using federated login? I've found a post explain how to do it using google proprietary login.
Thank you,
Ido.
I've manage to make this work much easier then I thought it would be.
When I send HTTP request to my web service I get 302 Found response with response header name Location which point to the login page.
I use WebBrowser control, register to it Navigated even and navigate to the URL in the Location header.
When the Navigated even fire I use the code from this answer to get the cookies container.
I check each cookie until I find one with the name ACSID and store it.
For every web request to my service I add cookie name ACSID with the value saved at step 4.
This is not the most secure way of doing this. I will add check for the domain of the cookie but this looks good.

GoogleApp Engine authentication using Google ID from Blackberry

I am developing an app to be hosted on Google App Engine. Users will be able to use their Google IDs to login to the app. The app also has a client counterpart in the form of a Blackberry Application.
My question is - is there a suggested way for my app to collect the user's Google credentials so that I can authenticate it against Google using OpenID semantics? In Android, for example, I can use the Accounts API so that I don't need to explicitly ask the user to enter credentials. What's the way to do this in Blackberry?
I see 2 ways, neither of which is ideal:
Write my own form in my native Blackberry app where the user enters Google ID and password, which I then use to obtain the authenticator token and perform the rest of the authentication behind the scenes. But the point is - it is inappropriate to ask a user to trust my app with their Google credentials.
Use standard Google Open ID Authentication mechanism - which opens up the web browser and displays Google's Open ID login page. Although this is a one-time thing (after which I can save the authentication token so that future requests to GAE do not require any prompting for credentials), the user experience is still disruptive since it involves opening the browser in addition to my native BB app.
So, what's the suggested way forward?
Using the browser to authenticate is pretty much the only standard way to do this. A number of Android apps do this for OAuth or OpenID endpoints too. Depending on how the Blackberry's protocol handlers work, you should be able to set a continue URL that results in your app being called back by the browser when authentication completes.

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