Google Oauth recognizing G-Suite account - oauth-2.0

I am trying to add Google Sign In to my application. I want to limit who can sign in to a list of allowed companies (ie. a company that has a billing account with me). I intended to do this by limiting sign in to only G-Suite accounts. Is there any way to check if a user is trying to log in with a G-Suite account and is there any way to uniquely identify who owns the G-Suite (some kind of corporate identifier inside google)?

For G-Suite you can use the Hosted Domain (hd) parameter within OpenID Connect.
Be sure to heed the details as this only manipulates the UI and does not ensure the Authorization request. The APP must code the verification.

Related

How do I enable any domain to log into my Azure Active Directory app

My current application supports Microsoft and Google oAuth verification sign in. The idea is to give users the option of signing in with their personal accounts for ease of access. This is working fine with google, but AAD will only allow users with emails that end in the App ID URI domain to sign in
eg: App Id URI = someOrg.com/guid and their sign in = someUser#someOrg.com.
Attempting to sign in with a Microsoft account like an outlook or hotmail account redirects to a page saying
"We're unable to complete your request
Microsoft account is experiencing technical problems. Please try again later."
Is there a way to allow AAD to accept any Microsoft account in the login, or can it only accept users in a single domain?
Basics
Yes! Checkout https://aka.ms/aadv2. The v2 endpoint allows both personal Microsoft and Azure AD accounts to be signed in from a single app reg. You'll need to hit this special endpoint (can be done using the MSAL libraries) and setting your app audience in the Azure portal.
Details...
By default and using the following URLs (note the common piece):
https://login.microsoftonline.com/common/v2.0/authorize
https://login.microsoftonline.com/common/v2.0/token
If set to common, your app can sign in any domain and personal Microsoft accounts.
Other options
For the sake of covering everything, here's the other options:
common->organizations: Only allow Azure AD accounts
common->consumers: Only allow personal Microsoft accounts
common->[tenant_id]: Only allow accounts from the specified tenant
MSA as a guest
The edge case you may need to address is a personal Microsoft account added as a guest to an Azure AD tenant. When the user hits common, they'll be signed in as a personal Microsoft account; however, they may intend to sign into their domain. You can build around this by introducing a "enter your email" screen, then passing this as a hint to Microsoft via the common endpoint.

Google Directory user list from an app

I am creating an iOS app for internal use. We have a Google Domain. As part of the functionality of the app, I want to be able to search for all users in that domain. This can already be done in Gmail, the Apple Mail app, and others.
I found that you can use the Admin SDK for users.list to do exactly what I want to do. I created a Client ID for the iOS app and authorized my app to perform users.list.
However, now I get a permissions error for users who sign in with OAuth2:
I found that you can create a service account to make API requests on your behalf if you delegate it to have the authority. I'm not sure if this is what I want to do since this seems more like something for a secure server to do rather than an app. I'm also not sure how this integrates with a user (from our domain) who signs in with OAuth being able to list our users.
Is it possible to list/search the users in a Google domain purely through OAuth / frontend app?
Aside from caching your own list, I think there are two ways to give users the ability to list all users:
A. Undocumented call to this GAL API:
https://www.google.com/m8/feeds/gal/your-domain-goes-here/full?alt=json (source). You can test this in the Google OAuth Playground by selecting the scope for the Contacts V3 API or using the string https://www.google.com/m8/feeds/.
B. In the Admin console, create an "all users" group. Assign to a newly created Admin Role. Grant the admin role "read" in Privileges > Admin API Privileges > Users > Read (checked).

Single sign-on flow using ASP.NET MVC + Active Directory

I'm looking into creating a single-sign-on portal built in ASP.NET MVC. This single sign on portal should give users the option to sign in with their individual account (which should be verified against AD) or their Facebook/Twitter account. What I'm still in the dark about is if the application/authentication flow I came up with is actually feasible. This is how it should work:
User logs into the SSOP with his AD account (using a custom form where he enters these credentials). The SSOP verifies these credentials against AD and logs the user into the SSOP accordingly. The SSOP then offers the user to start any of the applications he has access to (based on his group memberships in AD). These applications are built by various third parties and are not all .NET based. Clicking one of these applications in the SSOP should log the user into this application using the credentials authenticated against AD that were used to enter the SSOP. I currently do not know how this should be done, e.g. by using claims or some sort of auth token? Obviously the receiving application should support whatever option we choose, which means we're looking for a best practice of some sorts.
The social login part of the SSOP should work somewhere along the following lines: The user logs in using his social account. The first time he does, he also has to enter his AD account credentials so we can link his social account to a specific AD account. Every subsequent time the user logs in with his social account the SSOP should log in the linked AD user. That way the SSOP always uses a valid AD account to authenticate to the applications it offers the user. This also makes it easier to administrate the user base since these are all stored in AD. The social login links and any other SSOP specific data is stored in a custom data store (MS SQL db).
I've been looking into the ThinkTecture IdentityServer, but have yet to figure out how it can be used in this scenario or if this scenario is even feasible.
So, the question basically is: is this authentication flow even possible or remotely best practice? If so, where to begin? And if not, what is?

OAuth2 Merging Multiple Accounts from Twitter andother services

According to this question: Architecture for merging multiple accounts and registering a user account
Various answers have said that using email is a good way of establishing correspondence between different accounts and then doing automatic merging for multiple account sign in.
However, twitter is a major provider that does not provide email through their oauth API.
How can we reliably and automatically establish a correspondence between a twitter account and for example Google, Facebook, Github... etc accounts? So that we can auto-merge those accounts.
I'm writing a library to help in this, so it's not really useful to say do it manually, since I would like to provide options.
There is no secure-way to automatically do it, I implemented an application with local account/Twitter.Facebook/Google and I didn't have other choice.
I suggest you to allow your users to register with one method (local account, Twitter, Facebook, Google...) and create a page in "My account" that allow them to associate other accounts.
In Twitter a user can be identified by either a name or a key, you have no way to know them unless you explicitly ask them to the user.
Moreover now in Twitter 1.1 you have to redirect your user to Twitter to approve your application and then you get the OAuth token and security key. As you can see there must be an interaction with Twitter, at least if you need to perform some restricted queries on his behalf (e.g. create a Tweet).

What is the standard with oAuth for remembering users?

Me and my colleagues developing an application (both web application and mobile app(iPhone & android)), which includes a login process.
Currently, we have our own login mechanism (where users have signed for an account on our app, and have stored their info in our Database). We are looking into integrating oAuth and allowing users to login with Facebook, Twitter, LinkedIn and Google.
Now, when the users logs with any of those, as I understand the login process occurs outside our application and basically only get permission to access their resources.
My question is this: through oAuth, how do we remember users? i.e., users who login have read /write privileges and have preferences. How do we remember those when they don't actually sign up through our app.. Can we store their email address in our "Users" table??
What are the best practices in such a scenario?
Thanks for any info you can provide.
Having built authentication databases for a few different OAuth-enabled web sites, I can say that I've learned a few things that you should keep in mind.
You should have a table of users for your site that is completely independent of which OAuth provider they used for sign-up/sign-in. This enables your site users to combine multiple accounts together under their primary identity on your site. (For example, associate both Facebook and Twitter with you.)
When you let a user sign up, you should get an email address from them. Whether you ask Facebook for it, or if you have to ask directly. This enables you to "upgrade" users later from depending purely on third party OAuth to setting their own password on your site. (You simply send them a link to your password reset page in order to get them started creating their first password.)
You don't want to use email address as your primary key. I'm not sure if that's what you're actually describing or not, but you really want them to have a local user ID that you use for maintaining their session, etc. You then associate their Facebook ID or their Twitter ID with that local ID, and use the correspondence between such identifiers to match up which of your site's users to consider logged in.

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