Authenticate at Google Cloud Storage JSON API with Firebase ID token - firebase

I have a mobile app (Android/iOS) that uses the Firebase SDK for several Firebase services (including Authentication and Storage).
Now there's a subsystem within the app that can't directly access the Firebase SDK, but I need to upload files to Storage from this subsystem. HTTP(S) requests are possible, so I tried to use the Storage JSON API for uploading.
However, an OAuth 2.0 token is required for authorizing requests via the JSON API. Is there a simple way to receive such a token, when there's already a signed-in user in the Firebase SDK? It seems the only thing I get from the Firebase SDK is the "Firebase ID token" (JWT token), but I don't know how to convert it (or if this is even possible) to an accepted OAuth token for the JSON API.

I think you're trying to do the petition from the plugin itself and it might not have the permissions.
Did you pass it to sign In With Custom Token to the SDK when your users sing-in?
I read that after that, a Custom Token and credentials are attached to the user's profile.
Why don't you try to do the petition from the user's profile instead of doing it from the plugin?

Related

Firebase and Node,js: Sending emails from user's Gmail?

I am new to Firebase. I have linked Firebase to my React Native app, the Auth part is working and in the SCOPES array I am passing necessary scopes for sending emails https://www.googleapis.com/auth/gmail.send.
The Problem: On backend I am using Node.js and a Google Cloud project for sending emails, the way I wan this to work is that I will be sending a POST request to backend with the access token of user's account and then using that access token to send emails.
Is this something possible? I am basically using 2 different projects, one Firebase project for Authentication and giving Gmail permission and then another Google Cloud project for sending emails. I have whitelisted the Email sending project in Firebase Auth project.
Is this something possible? Is there any better way to achieve this?

Firebase Admin SDK - How to initialize with OAuth2 Refresh Token and communicate securely with web app?

I'm developing a web app (using Angular) which works with Firebase.
I installed the ngx-auth-firebaseui which is an easy to use library I used to perform user login. Since I need custom APIs I also developed an ExpressJs server that uses the Firebase Admin SDK.
I call ExpressJs APIs without any security for now (since I'm still in my local environment).
In order to use the Firebase Admin SDK, I followed the official docs, which say:
Once you have created a Firebase project, you can initialize the SDK with an authorization strategy that combines your service account file together with Google Application Default Credentials.
Firebase projects support Google service accounts, which you can use to call Firebase server APIs from your app server or trusted environment. If you're developing code locally or deploying your application on-premises, you can use credentials obtained via this service account to authorize server requests.
[...]
When authorizing via a service account, you have two choices for providing the credentials to your application. You can either set the GOOGLE_APPLICATION_CREDENTIALS environment variable, or you can explicitly pass the path to the service account key in code. The first option is more secure and is strongly recommended.
Locally I set the GOOGLE_APPLICATION_CREDENTIALS property and everything is okay. Does this also need to be set in the production environment or is there another method?
I would also like to use OAuth2 to secure communication between the web app and the server APIs, but I don't know how to integrate it within the authentication flow.
In addition, Firebase docs state:
The Admin SDKs also provide a credential which allows you to authenticate with a Google OAuth2 refresh token:
var refreshToken; // Get refresh token from OAuth2 flow
admin.initializeApp({
credential: admin.credential.refreshToken(refreshToken),
databaseURL: 'https://<DATABASE_NAME>.firebaseio.com'
});
but if I do this I receive the error:
.../node_modules/firebase-admin/lib/auth/credential.js:47
var tmp = from[key] || from[alt];
^
TypeError: Cannot read property 'clientId' of undefined
Question 1: Fireabase Admin SDK initialization -- How to handle locally vs. in production?
Answer: Using the Firebase Admin SDK requires initialization in the local development environment as well as the production server environment. In both environments, you may either set the GOOGLE_APPLICATION_CREDENTIALS environment variable, or you may explicitly pass the path to the service account key in code.
Question 2: How to use OAuth2 for secure communications between Wep App and Server APIs?
Answer: Verify Id Tokens
After a successful sign-in, send the user's ID token to your server using HTTPS. Then, on the server, verify the integrity and authenticity of the ID token and retrieve the uid from it. You can use the uid transmitted in this way to securely identify the currently signed-in user on your server.
Question 3: How to authenticate with a Google OAuth2 refresh token using the Firebase Admin SDK?
Answer from Manage User Sessions
Firebase Authentication sessions are long lived. Every time a user
signs in, the user credentials are sent to the Firebase Authentication
backend and exchanged for a Firebase ID token (a JWT) and refresh
token.
On the client (web app), the Firebase User has a refreshToken property to retrieve the current refresh token.
However, the standard approach to initialize the Admin SDK is to either set the GOOGLE_APPLICATION_CREDENTIALS environment variable or explicitly pass the path to the service account key in code.

How to authenticate a Firebase user to an IFTTT service?

I'm trying to build an IFTTT service and connect it to my Firebase backend.
I need to authenticate user as indicated in the IFTTT docs:
https://platform.ifttt.com/docs/api_reference#service-authentication
IFTTT’s protocol supports OAuth2 authentication, including support for
refresh tokens if so desired.
Your service API should use access tokens for authentication and as a
source of identity. A single access token should correspond to a
single user account or resource owner on your service.
If refresh tokens are used, they must be non-expiring. If refresh
tokens are not used, access tokens must be non-expiring.
But I can only get short-lived access tokens from Firebase it seems. Where can I get or how can I generate such tokens from the Firebase auth SDK?
Update in response to #FrankvanPuffelen:
I'll create an IFTTT service running on a Node server (possibly simply Cloud Functions) that will use the Firebase RTDB to send formatted HTTP request back to IFTTT. IFTTT requires me to authorize user accounts. Their required UX is something like this:
If an IFTTT user tries to use my service on the IFTTT website,
an auth dialog for my service pops up.
The user logs in and confirms IFTTT's access to their data on my service.
Some OAuth 2.0 tokens are exchanged.
IFTTT servers will periodically send requests (authentified with those tokens) on behalf of the user to my server.
Part of the question is: Can I use the Firebase Auth API to get those tokens, etc. or do I need to create a new OAuth 2.0 "layer" with my own generated tokens for IFTTT?
PS: I'm very new to OAuth, so it's all a bit confusing to me, sorry if the question isn't very clear.
So IFTTT calls Cloud Functions, which then calls Realtime Database, and you want to authentication the IFTT user with Realtime Database. Is that correct? If so, you can either use an OAuth2 token or create a Firebase Authentication session cookie.
Use an OAuth2 token
I did this not too long ago for accessing the Realtime Database from Google Apps Script. The requirements are relatively simple (once you know them):
The OAuth2 tokens must be requested with the correct scopes: https://www.googleapis.com/auth/userinfo.email and https://www.googleapis.com/auth/firebase.database.
The OAuth2 access token must be present in the request to Realtime Database.
The authenticated user must be at least an editor on the Firebase project. Note that this is not a Firebase Authentication user, but a Google user account.
Also see:
How to integrate Firebase into Google Apps Script without using (deprecated) database secret
Use a Firebase Authentication session cookie
You can also use a Firebase Authentication session cookie, which can be longer-lived (up to 2 weeks) than a regular Firebase Authentication ID token (up to an hour). You'll want to set up a Cloud Function for creating the session cookie, call that from IFTTT, and then pass the session cookie with the IFTTT request and along to the Realtime Database.
For more on this, see:
the Firebase documentation on managing session cookies.
I'm posting my solution here, this is a rough draft of what I did at at the time.
I'm using this auth method: My API has users with non-expiring OAuth2 access tokens and have an Express server responding at a Firebase HTTPS Cloud Function endpoint. Currently, at the prototyping stage, it generates fake tokens from the UID that are successfully accepted by IFTTT.
It's a redirect-heavy authentification flow based on this old IFTTT api example: https://github.com/IFTTT/connect_with_ifttt_auth_sample
Here's the gist of it:
Tokens and Auth Codes are just randomized and encrypted UIDs for now.
/oauth/authorize redirects to my app.
The app asks the user if they want to authorize IFTTT
The app redirects to /oauth/authorize_user
/oauth/authorize_user generates a user-specific code and redirects the user to IFTTT with this code
IFTTT asks /oauth/token to exchange the code for a Bearer tokens.
IFTTT can now make requests on behalf of this user with this bearer token.
Sample code here: https://gist.github.com/nathanvogel/15ed311258b91d7ec3d25f44047780e2

Firebase get auth token through REST?

I'm trying to integrate Firebase into a Unity WebGL app, unlike iOS and Android there's no official Firebase plugin for it.
I'd like to try and use the Unity WWW class to make web requests to endpoints to do firebase authentication.
Is there an endpoint I can call passing the username and password to firebase that will return an auth token?
No, that would be a massive security hole for the end user who gives up their password to you. Users should only be typing passwords directly into the site that controls their account.
You should probably take a look into calling through to JavaScript to use the Firebase web SDKs.
WebGL: Interacting with browser scripting
Yes, Firebase Auth has a REST API that sends the email/password combo (as POST parameters) in an https call.
Firebase Auth REST API Sign in with email / password

Firebase CREDENTIAL for rest API

Firebase Rest API mentions that we can pass CREDENTIAL to provide access to authenticated nodes. However I was not able to find documentation on where I can find these credential or generate these credential. Custom tokens generated using NodeJS firebase-admin client also don't work.
https://firebase.google.com/docs/database/rest/save-data
https://docs-examples.firebaseio.com/rest/saving-data/auth-example.json?auth=CREDENTIAL
If you scrolled down a little on the same page, you would find the answer:
In the following example we send a POST request with an auth parameter, where CREDENTIAL is either our Firebase app secret or an authentication token...
Firebase secrets are legacy credentials you can find/create under Project settings - Service Accounts in the Console. Using one as the auth parameter gives the caller administrative access.
Or you can use a service account to generate admin level access tokens instead of relying on the legacy secrets. See here for the Java implementation.
Or if you have an authenticated user – for example you're implementing an API a client apps call via HTTP, passing along their current access token –, you can use that token directly to impersonate the user.
The custom authentication tokens serve a completely different purpose and are part of a different sign in flow. Therefore they do nothing via the REST API.

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