Where exactly Firebase custom authentication can be used and what are main uses? - firebase

Mainly token are used for authentication but firebase provides different
Sign-in providers like email and password, Facebook, Google, GitHub and Anonymous for authentication. Then what are this tokens used for?
Can anybody guide me to a use case where this custom tokens are useful?
Here's where I got to know about this Custom tokens:
https://www.youtube.com/watch?v=VuqEOjBMQWE&t=93s
https://firebase.google.com/docs/auth/admin/create-custom-tokens

Custom tokens are used when you want to use a Custom Auth System:
You can integrate Firebase Authentication with a custom authentication
system by modifying your authentication server to produce custom
signed tokens when a user successfully signs in. Your app receives
this token and uses it to authenticate with Firebase.
For example: Let's say you're developing an app that needs authentication, but you don't want to use the Auth Providers that Firebase supports (Google,Twitter,Facebook,etc). Let's say you want to use Instagram Auth.
Since Instagram Auth is not provided by Firebase you can't set your Realtime Database rules to auth!=null. You'll probably set it to public, which means that anyone can access your data and this is an obvious security risk(Your database is not safe at all).
So what you can do is create your custom auth system that allows a user to authenticate with Instagram and then give him a Custom Token. The user will then use this token when signing in to your Firebase App, and he will be recognized on Firebase Authentication. Which means that he can now access data that is protected by auth!=null. Your database no longer needs to be public.

Related

authentication with firebase authorization with custom service

I need to use the authentication service from firebase. but use my existing authorization service.
Can i use user token, sessions info from firebase.auth().onAuthStateChanged(function(user) {})
what is the best way/ways to manage these kind of use cases.
Should i also store my user details cookies, token etc?
You can implement a custom provider for Firebase Authentication. In this process:
You sign the user in to your service with their credentials as usual.
You then mint a token based on the user's profile.
The user then uses that token to sign in to Firebase.
The entire process is quite well documented on the links I included above.

Firebase Firestore integrate chat using existing backend for user data

I develop an iOS application and I'm using Node & Postgres for handling user data and authentication. I would like to add a chat feature to my app and I chose Firestore for this.
My question is how should I link the existing user data with a Firebase collection of users without re-implementing the authentication part from the ground up. Right now the authentication is based on JWTs with access and refresh tokens.
In order to link my existing users, I can add the userId already present in my database to the users collection that I will create in Firestore, but I need some kind of authentication to ensure security.
While the token for Firebase is also a JWT, it will probably have to be separate from your existing JWT, as it contains Firebase-specific information (such as the project ID), and they're signed with different keys.
After you authenticate the user with your own backend, mint a custom token for Firebase authentication with the information you want to use in Firebase/Firestore and security rules, pass that to the client, and sign them in to Firebase with it.

How to login to Firebase from an ERP system?

I would like to login to Firebase from an ERP system.
i.e. once logged into the ERP system, that login can be used to access a Firestore db.
The Firebase docs describe a common case: "Add an additional identifier on a user".
Is it possible to use this common case to login to Firebase from the ERP system?
Control Access with Custom Claims and Security Rules
User roles can be defined for the following common cases:
Add an additional identifier on a user. For example, a Firebase user could map to a different UID in another system.
If you want to use the users from an existing authentication system to authenticate against Firebase, you'll need to implement a custom authentication provider.
With such a provider, you:
Sign the user in with your existing system in a trusted environment (e.g. on a server).
You then use the user's credentials to mint a custom JWT token.
Send that token back the client, which then finally
Uses the custom token to sign in to Firebase.
At this point, the user is signed in to Firebase Authentication in the client, and their UID (and other properties from their token) are available in the Firestore security rules.

Firebase custom auth provider I don't control/have access to?

Is it possible to use a custom authentication provider which I don't have any control over?
I develop an app in addition to a teachable course. Teachable is a platform like shopify where you can create online courses.
I want to use it as an auth provider, so a user, that already has an account can login with his teachable account.
To my knowledge custom authentications with auth tokes work like this: I send a request to my server with the entered user credentials. From my server I use these credential to login to teachable, if that was successful my server gets a callback and I return a token to my client, so the login was successful.
However as far as I know teachable doesn't have an api option for me to login and get a callback if it was successful.
What can I do about this? Also are there any security issues I didn't realized?
Your understanding of the flow to add a custom provider to Firebase Authentication is correct. You need to be able get the authenticated token from the provider, and mint a Firebase custom token from it.
If the provider you're looking to add doesn't have an API, you won't be able to add it as a custom provider to Firebase though.
I don't immediately see another way to connect the provider without an API.

Using email/password authentication with basic Firebase app, would like to add username

I'm developing a basic messaging app with Firebase's built-in email/password authentication system. I'd like to add a key value "username" option to the resultant authData payload as a message author identifier that's not the user's email address.
I've read the official documentation front to back and from all accounts, the idea is to migrate over to a custom token authentication system if you're adding custom data to the authData, but i'd really like to keep the existing auth system as is, unless I can continue to use the same auth information already resident in Firebase but just with a new custom token auth login.
Thanks.
You cannot add custom attributes to the authData (or the auth variable in security rules) for the built-in email+password or OAuth providers. The common way around this limitation is as Jay commented to store the additional user data in your Firebase database under a /users/$uid node.
The only identity provider where you have control over the authData is when you use custom authentication.

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