How to use azure B2C with Essentials: Web Authenticator?

Phenek 116

Hello,
I am trying to consume B2C user flow authentification with Web Authenticator
(from essentials package Xamarin.forms or MAUI). Web-authenticator

I am unable to add correctly some parameters required for B2C
like 'client_id', 'scope', etc... inside the url, I got always 'bad url' message.

var url = new Uri("https://{tenant}.b2clogin.com/{tenant}.onmicrosoft.com/{policy}/oauth2/v2.0/authorize?client_id{ClientId}&response_type=code&scope={Scope}");  
var callbackUrl = new Uri("myapp://auth");  
var authResult = await WebAuthenticator.AuthenticateAsync(new WebAuthenticatorOptions  
   {  
      Url = url,  
      CallbackUrl = callbackUrl,  
      PrefersEphemeralWebBrowserSession = false,  
   });

Did someone achieved this kind of stuff?

JarvanZhang 23,936 Reputation points

2021-09-10T09:17:40.627+00:00

I am unable to add correctly some parameters required for B2C like 'client_id', 'scope', etc... inside the url, I got always 'bad url' message.

Hi, VicePhenek-7065. The parameters such as 'client_id' and 'scope' should be get in the Azure portal. For example, clicent_id is the application ID assigned to your app in the Azure portal.

For more details, please refer to this doc: https://learn.microsoft.com/en-us/azure/active-directory-b2c/authorization-code-flow#1-get-an-authorization-code
Phenek 116 Reputation points

2021-09-10T09:30:01.937+00:00
Yeah I know thx @JarvanZhang
But I was trying to use Web Authenticator and I don't know how to put parameters like 'client_id', 'scope', etc..

We need to add them in to http request like this

GET https://{tenant}.b2clogin.com/{tenant}.onmicrosoft.com/{policy}/oauth2/v2.0/authorize?client_id={ClientId}&response_type=code&scope={Scope}

But I think Web Authenticator if I do so will add at the end

?redirect_uri={callbackUrl}

But the ? character is wrong, tell me if I am wrong
JarvanZhang 23,936 Reputation points

2021-09-13T02:41:34.76+00:00

Sorry for my mistake. To put the parameter, try using '&' instead. You could search with the keyword as 'easy with Web Authenticator' to refer to the related documentation.
Rakesh Jagatap 6 Reputation points

2021-10-11T15:01:43.653+00:00

Hi, if the posted answer resolves your question, please mark it as the answer by clicking the check mark. Doing so helps others find answers to their questions.
Phenek 116 Reputation points

2021-10-11T15:33:51.897+00:00

It does not.
Phenek 116 Reputation points

2021-10-11T15:35:24.243+00:00

Xamarin.Authenticator id adding by it's self the parameter as with '?'
I can not change that, this this the default behavior.
JarvanZhang 23,936 Reputation points

2021-10-12T07:28:08.277+00:00

Hi, VicePhenek-7065. The request url could be customized, please check the code of the 'LoginService' in the doc. The code builds the url with required parameters. You could search with the keyword as 'easy with Web Authenticator' to refer to the related documentation.