Authenticating GWT-RPC calls with Google Identity Toolkit for Java - google-app-engine

I have a GWT-based app deployed on Google App Engine (Java). The app uses Google Account for authentication as described here: https://cloud.google.com/appengine/docs/java/users/ and uses GWT-RPC for communicating with the backend services. I use GAE's UserService to get the user object (and email ID) in my RemoteServiceServlet.
Now I want to replace Google Account with Google Identity Toolkit (GIT) so that I can offer more login options (Email, Google, Facebook etc.) to my users. I have created a small GAE-based sample application (non-GWT) using GIT and it works well. I used the GitKitClient library for Java to do the OAuth token authentication and get the user profile on the server.
But I'm wondering how GIT would work with GWT-RPC. Would the GAE UserService still work in my RemoteServiceServlet if I switch to GIT for login (instead of Google Account)? Or do I need to do the OAuth token authentication in my RemoteServiceServlet using the GitKitClient as I do in my non-GWT sample app?
I'm very new to GIT and OAuth and would appreciate any help on this matter.
Thanks.

GAE UserService does not recognize the Google Identity Toolkit token. You need to use the Google Identity Toolkit Java library to validate the Google Identity Toolkit token in your RemoteServiceServlet, in the same way as you already implemented in your sample GAE app.

Related

Methods of Authentication in Go for App Engine

I am building a reservation system in Google App Engine using Go. I need 2 forms of authentication in my program.
Public Form -- form built in Angular that is on our public website. I want my front-end to have some sort of credentials.json file to use when requesting the book and getOpenDates endpoints in my RESTful API running in Go on Google App Engine.
Private Companion App -- protected by username and password that the user supplies in my app built in Flutter. The app is requesting many endpoints in App Engine. I would like to use JWT to authenticate this portion, but I'm not 100% sure JWT is what I need.
I'm not sure if this tutorial on Identity Platform is what I want. I'm very new to App Engine and authentication in general, so I am a bit lost.
Please describe how I could implement these authentication methods in my RESTful API in Go running on Google's App Engine. I think I may be able to implement the username/password method using a tutorial like this but I'm very lost on the 1st form of authentication with just a credentials file as authentication. If I'm going in the complete wrong direction to accomplish what I want please tell me, but what I'm looking for is code or a tutorial describing how to authenticate using these 2 methods. Thanks for any help.
From what I understand, you want to have a golang backend API in App Engine that serves both your web frontend (1.) and your users app (2.).
I am going to suppose that any user with username/password can use both your frontends: the web app and the mobile app with these credentials.
The credentials.jsons are not designed to authenticate users of your services, but rather server to server communication.
With that in mind, I have found the guide Session based authentication in golang, that could help you to set up your backend to accept only authenticated requests over HTTPS. The web browser will automatically save the cookie, however you need to store the cookie in your mobile app.
For much more complicated scenarios for authenticating from different webpages, it is required to use OAuth2 as you can see in this thread. If you don't find any of your requirements listed in here it is probably overkill to use Auth0 nor OAuth2.

How to allow mobile apps to login with Facebook and Google to access web service on GAE?

This is in relation to my other question about the need to create a Facebook app.
I've been reading a lot about how to best approach login for mobile apps users (iOS and Android) that access my web service running on Google App Engine. I'm still not clear how to best do it as I would like to offer login with both Google and Facebook. The app and the web service does nothing with Facebook or Google other than I would like to piggyback on their login.
Having only login with Google for GAE is very easy and the same goes for using OpenIDConnect. Facebook unfortunately does not support this.
Reading an old question here on SO where someone wanted to do the same as I it looks like the app should do Facebook Login and then get a token that it passes to my backend which needs to be validated by contacting Facebook. Is this how to do it today?
I also found Google Identity Toolkit, which seem to be what I need. However, I do not have a website or just apps. I would need to have the apps do the Facebook login and somehow provide my web service with something so it can validate the login info.
Later on an app user should be able to log in using randomly Facebook, Google and my custom username/password. The app and the web service should know the user is logged in and authorize it to access the REST API.
How do I accomplish this? BTW, I'm using Go on GAE.
I would really appreciate if someone could explain if there are several options how to do this, pros and cons, and provide an overview of the best approach and what needs to be done.
Many thanks for any help with this!
UPDATE
OK, thanks a lot everyone for the help and pointers. I have successfully run the quickstart sample app for iOS for my GAE backend. Basically, created a Facebook app and permissions credentials on my web service on GAE so that the sample iOS app can log in.
A bit of a gap still before I have an authenticated user in the datastore and can authorize successive API calls.
Main open questions at this point:
how to get the gtoken in the iOS app after successful Facebook or Google login?
should I explicitly call an API on my web service to pass in the gtoken or is this somehow automatic with Gitkit API enabled?
Thanks for any help!
UPDATE
To answer #1 and #2 myself, there's a "successful sign-in url" that can be given in the app engine config so the app knows where to call with the gtoken. Then after that it's like explained in the answers.
Looks like you have an app and a backend on GAE.
If you are using google identity toolkit, it will allow you to signin with Facebook, Google, and email/password.
When user successfully signs in to your app using identity toolkit, your server should receive a gtoken. You have two options here:
Pass the gtoken to your app and save it there. When your app makes API calls to your backend, you app should attach the gtoken to every request. Your backend should verify the gtoken(https://developers.google.com/identity/toolkit/web/required-endpoints) for every API that needs authorization.
Verify the gtoken, generate a token that your backend can recognize/identify the user. Then pass the token to your app and everything else is the same as option 1.
If you do not want to use identity toolkit, you can implement facebook login on your app/backend and use facebook token to communicate between your app and backend.
Whatever your decision is, apps that use your API should pass you something that your backend can recognize/authorize the user.
The answer is about using Google Identity Toolkit (GIT). GIT itself is an identity provider, which would be integrated with your apps and backend. The flow works along these lines:
your app requests login via its GIT API
GIT will perform the federated login with Facebook or other 3rd party provider (transparent to your app) and returns a GIT token to the app (representing a unique user from your end-to-end system perspective, i.e. apps plus backend)
the app makes a request to the backend in which it passes the GIT token
the backend verifies the GIT token validity (using this go GIT client API, for example) and from it can extract the identity of the user and thus validate the request
You can find more detailed info about the backend token validation in the backent endpoint doc, look for these sections in particular:
Understanding the Identity Toolkit cookie/token
Getting information for users
Now the actual token validation on the backend may take a few seconds, so it might not be practical to do it for each and every REST request from the app. If so you'd need to somehow:
save the info that the user of that specific app instance is
authenticated in something like a "session" managed between your app and the backend
map a specific REST request received by the backend to a specific such authenticated "session"
But I'm not sure how exactly is this "session" functionality done in the apps+backend context, I didn't write any apps yet.

How to use OAuth2 / OpenID Connect with UserService?

I'm running several apps on Google App Engine. I am using the UserService for Authentication to be able to send emails on behalf of the user etc. and OAuth2 for API authorization.
I am now trying to publish the apps on the Google Apps Marketplace, but I received an email telling me it is required to use OAuth2 for authentication.
As I am just using the supported Google stack I assume there is a way to meet the requirements for publishing my apps on the Google Apps Marketplace but right now I'm stuck.
This is similar to another question. The challenge is that the User service is using still using OpenID. You'll need to use a Client library to authenticate the user.
Here are good samples in Python & Java.
Currently we use Openid 2.0 for user authentication and Oauth for authorization of other services. Openid 2.0 is deprecated and Google will not provide authentication using Open Id. For time line refer this link https://developers.google.com/+/api/auth-migration#timetable
So they are suggesting to use OpenidConnect for authentication of user. OpenIdConnect is a layer written over Oauth 2.0 for authentication of user.
For references visit http://openid.net/connect/ and https://developers.google.com/accounts/docs/OAuth2Login?hl=ja#appsetup

RestTemplate with basic authentication on Google App Engine

I have develop a Spring MVC Rest service on Google App Engine with Spring Security 3.1.
Since the service will be available only to my other apps, I have a basic authentication setup with predefined username and password.
Now, I have a client developed with RestTemplate. But I am not able to find a way to access my services securely with username and password, sent via RestTemplate.
I have gone through many articles, but most are using Apache HttpClient (not supported by google appengine).
SO, is there any alternatives to getting what i want on google appengine.
You can try the Basic Auth with URLFetch as this is supported by google, though you want to have the ssl enabled to for use Basic Auth.
You might want to see at this link, though not for appengine but should be good.
http://www.jpalace.org/docs/technotes/spring/rest-security.html

Google App Engine authentication with password

I am really fed up. All I see the Google App Engine tutorial was just making the example on how to authenticate without password. What if I want to authenticate directly from my gmail account, how can I do it???
User the google provided users service which can use your google account for auth.
https://developers.google.com/appengine/docs/python/gettingstarted/usingusers
Google App Engine provides several useful services based on Google infrastructure, accessible by applications using libraries included with the SDK. One such service is the Users service, which lets your application integrate with Google user accounts. With the Users service, your users can use the Google accounts they already have to sign in to your application.

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