Use google credentials to login into UWP C# app

user_5499386 0
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I'm trying to make a login for a UWP app that I'm developing for a client that has a @<theircompay>.com email that uses G Suite. It doesn't have to access any user data, they just want it as an authentication so that only people that have a company email can access the app.

It would be great if they could login from within the app without having to use a web browser, and even better if it could remember them so they wouldn't have to login every single time.

I've been looking at OAuth 2.0 and several other solutions google has but can't really understand which one to use and much less how.

I looked into this answer but it doesn't seem like a good idea to ship your certificate file with your app.

So basically if this can be done, what (if any) certificates or credentials do I need to get from Google, and how would I handle them and the login through my C# code?

Edit

The app is 100% client side, no server backend

uwp google-api c#
3 Answers

Answer from Roamsz is great but didnt work for me because I found some conflicts or at least with the latest build 17134 as target, it doesn't work. Here are the problem, in his Github sample, he is using returnurl as urn:ietf:wg:oauth:2.0:oob . this is the type of url, you can't use with web application type when you create new "Create OAuth client ID" in the google or firebase console. you must use "Ios" as shown below. because web application requires http or https urls as return url.

from google doc

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According to his sample he is using Client secret to obtain access token, this is not possible if you create Ios as type. because Android and Ios arent using client secret. It is perfectly described over here

client_secret The client secret obtained from the API Console. This value is not needed for clients registered as Android, iOS, or Chrome applications.

So you must use type as Ios, No Client Secret needed and return url is urn:ietf:wg:oauth:2.0:oob or urn:ietf:wg:oauth:2.0:oob:auto difference is that auto closes browser and returns back to the app. other one, code needs to be copied manually. I prefer to use urn:ietf:wg:oauth:2.0:oob:auto

Regarding code: please follow his github code. Just remove the Client Secret from the Access Token Request.

EDIT: it looks like I was right that even offical sample is not working after UWP version 15063, somebody created an issue on their github

https://github.com/Microsoft/Windows-universal-samples/issues/642

user_4924820

I'm using pretty straightforward code with Google.Apis.Oauth2.v2 Nuget package. Note, that I'm using v.1.25.0.859 of that package. I tried to update to the lastest version (1.37.0.1404), but this surprisingly doesn't work with UWP. At the same time v. 1.25.0.859 works just fine.

So, unless there's a better option, I would recommend to use a bit old, but working version of Nuget package.

This is my code:

            credential = await GoogleWebAuthorizationBroker.AuthorizeAsync(
                new Uri("ms-appx:///Assets/User/Auth/google_client_secrets.json"),
                new[] { "profile", "email" },
                "me",
                CancellationToken.None);

            await GoogleWebAuthorizationBroker.ReauthorizeAsync(credential, CancellationToken.None);

Then you can retrieve access token from: credential.Token.AccessToken.

user_8177670
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