Azure B2C

This post is going to cover enabling a social login for a site using Azure B2C for authentication. If you are new to this set of posts you can find the initial setup of the sample application in the  ASP.NET Core with Azure B2C Auth post. I would also recommend checking out the Azure B2C: Customize Layouts to learn how to change the provided UI to provide your users with a consistent look and feel that matches the rest of your application.

Social Login Provider Setup

Azure B2C supports most of the login provides you would expect such as Google, Facebook, Twitter, Microsoft, etc. as well as any provider that supports OpendID Connect. No matter which option you pick you will have to register/signup your application with the provider. Unfortunately, Azure B2C doesn’t provide links to the registration pages of the services it supports so it is up to you to find those yourself.

For this example, I’m going to be walking through the process using Google. You can get all the details of Google’s OpenID Connect offering in their docs. To get started we need to set up our application in the developer console. The link will take you to the dashboard where you will see a message about selecting or creating a new project. Click the Create link. In the next page enter the Project name and click Create.

After the creation process finishes click Credentials from the navigation menu on the left.

On the top of the screen select OAuth consent screen. On this page, you will need to at least enter an Application name and an Authorized domain of b2clogin.com (not shown in the screenshot, but still required) and click the Save button at the bottom of the page.

Next, select the Credentials tab and click the Create credentials button and select the OAuth client ID option.

On the next page, select Web application as the application type. Enter a Name. For the next two fields, you will need your tenant ID from Azure B2C. In the screenshot, you can see my where I did this with my tenant ID of testingorg3. Also, make sure and enter the URLs in all lower case, I had redirect issues using mixed casing. For Authorized JavaScript origins use the URL https://yourtenantid.b2clogin.com and for Authorized redirect URIs use https://yourtenantid.b2clogin.com/testingorg3.onmicrosoft.com/oauth2/authresp

After clicking create you will see a dialog with your client ID and client secret make note of these as they will be needed when we add the login provider in Azure B2C.

Azure B2C Changes

Now that we have the Google side setup head over to Azure and find your Azure B2C resource. Select Identity provides from the navigation menu and click the Add button.

Enter a Name, I’m just using the name of the provider. Then, click on Identity provider type which will trigger the Select social identity provider selection to show. Click Google and then click OK.

Next, click Setup this identity provider which will show a fly out where you will need to enter your Client ID and Client secret provided by Google. After entering your values click OK.

Next, click the Create button at the bottom of the Add identity provider screen. When this process is done we will have two identity providers for this B2C resource email and Google. Next, we need to enable our new Google provider for our sign up/sign in user flow. From the menu select User flows and then click the flow you have set up for Sign up and sign in.

Next, select Identity providers, this will show a list of providers available for the selected flow. Check any additional providers the flow should use, Google, in our case. Finally, click Save.

Try it out

With all the above change attempt a login with your application and you will see Google as a sign in option.

Wrapping Up

Hopefully the above will give you a jump start on adding support for social logins to your applications. Adding other providers will really close to what we did for Google from the Azure B2C prospective, of course the sign up process will vary by provider.

In the post ASP.NET Core with Azure B2C Auth we did a walkthrough of setting up the basics of Azure B2C and creating a new application that used our new B2C setup for auth. This post is going to be using that same setup to show how to replace the Microsoft provided pages for sign up/sign in with your own custom pages.

Custom Page Hosting

Our custom page needs to be hosted somewhere public with CORS enabled. If the test application was hosted somewhere public we could just us it, but since it is running on localhost that isn’t currently an option. We are going to use Azure Blob storage for hosting in this example.

Create A Storage Account

From the Azure Portal select Storage accounts.

Click the Add button.

Next, on the Create storage account page, I used a new resource group and tried storage accounts names until I found an unused one. For the rest of the fields, I took the defaults and then clicked Review + create.

On the review + create page it takes a few seconds for the account to be validated. After validation click the Create button.

After the storage deployment is complete click the Go to resource button.

Setup Blob storage

The above will land you on the Overview page for the new storage account. Select CORS from the menu.

Since this is just a test I’m allowing everything under the Blob service, for a real deploy I would recommend only allowing the values you expect requests from. After setting your values click the Save button.

Back on the storage menu on the right side of the screen select Blobs.

Click the + Container button to create a new blob storage container.

In the new container, page enter a name and select your public access level. I’m going with the most permissive access level, for a production system you will need to evaluate the appropriate access level for your use case. Click OK when done.

When done you will be returned to your list of containers. Click on the container that was just created to view the details.

Create a custom page

Now that we have our blob storage we need to create the HTML page that we want to to use instead of the default. The following is the code for the page I’m going to use. It is going to be super ugly as I’m not going to use any styling.

<!DOCTYPE html>
<html>
  <head>
    <title>Custom Page!</title>
  </head>
  <body>
    <h1>Custom Page!</h1>
    <div id="api"></div> 
  </body>
</html>

You can make this page look however you want, but it will always need the div with the ID of API as this is where Azure will inject the elements that actually handle the signup/sign in. Save your page.

Upload custom page to blob storage

Back in Azure click the Upload button and then select your file and click the Upload button.

After upload, you will be returned to the list of items in your current container. Click the item you just created. In the details copy the URL as we are going to need it to give B2C the location of our custom page.

B2C use custom page

In your portal head back to your Azure AD B2C page and select User flows.

Select the flow you want to use the custom page for. In our case, we are going to be using the flow for Sign up and sign in.

In the Customize section select Page layouts.

In the bottom of the page select Yes for  Use custom page content and past the link to your blob from above into the Custome page URI field and click Save.

Try it out

With all of the above setup you can now go back to the application using B2C and hit your sign in link and you will see your custom page. Here is what the one in the sample looks like.

Obviously, this example is really ugly and isn’t something you would do to your users, but it gives you the basic idea of how to use a custom page.

Wrapping Up

Hopefully the above will help you get started with customizing you B2C related pages to give your users a more consistent look and feel. The above only uploaded an HTML page to blob storage, but you could also upload a CSS file or any other assets you need. Also, don’t forget if your site is publicly accessible the assets can be stored with the rest of your application in that is appropriate, just remember to configure CORS to allow requests from Azure.

If you want more information on this topic check out the official docs from Microsoft on the subject.

I ran into a previous co-work a while back and they were talking about using Azure’s B2C for authentication on their apps. It sounded like a good solution. This blog post is going to cover getting the Azure B2C setup and will cover creating a sample application that will use B2C for authorization.

Create Azure Active Directory B2C

This all assumes you already have an Azure account. If you don’t you can sign up for a free trial (not an affiliate link). After you are signed up head to the Azure Portal.

Note: you can skip this section if you want to use the default Active Directory that is on your Azure account.

In the upper left click the Create a resource link.

In the search box look for Azure Active Directory B2C.

After selecting Azure Active Directory B2C more information will load to the right in a new panel. Click the Create button to continue.

Next, select if you want to create a new B2C tenant or use an existing one. I don’t have an existing one so the following flow will be for creating a new tenant.

On the next panel, you will need to enter an organization name and initial domain name. After entering valid values click the create button.

Switch Active Directory

Now that the new directory has been created we need to switch to the new directory in the Azure Portal. In the left panel click Azure Active Directory.

Click the Switch directory link.

A new panel will show on the right side of the screen with a list of directories you have available. Select the one you created in the steps above or an existing one you would like to use.

Using the search box in the top middle of the portal find Azure AD B2C.

Sample Application

Before moving forward on the Azure side we are going to create our sample client application. This little detour will make it easier for me to point out what values in Azure need to go where in the application configuration.

To create a new web application already set up to use Azure B2C use the following .NET CLI command from a command prompt. There is also a Visual Studio template if you prefer that route.

dotnet new webapp --auth IndividualB2C

In the resulting application, your appsettings.json will have the following section for AzureAdB2C.

"AzureAdB2C": {
  "Instance": "https://login.microsoftonline.com/tfp/",
  "ClientId": "11111111-1111-1111-11111111111111111",
  "CallbackPath": "/signin-oidc",
  "Domain": "qualified.domain.name",
  "SignUpSignInPolicyId": "",
  "ResetPasswordPolicyId": "",
  "EditProfilePolicyId": ""
}

Azure AD B2C Setup

Back to the Azure portal and the Azure AD B2C service page. In the Overview page, the first thing we need to make note of and use to set some configuration values in our application for is the Domain name.

In your appsettings.json file use this value for your Domain value.

"Domain": "TestingOrg3.onmicrosoft.com"

The subdomain is also used to build the Instance like the following.

"Instance": "https://TestingOrg3.b2clogin.com/tfp/"

On the panel that loads hit the Add button. On the new Application panel, we need to give the application a Name, select the type of clients which is Web App / Web API in our case. Next, is the Reply URL which with default setup is your base url/sigin-oidc. I messed this value up in the beginning and got some really strange errors. Finally hit the Create button.

After the creation process is complete copy the value in the Application ID field and use it as ClientId in your appsettings.json file.

Back in Azure select the User flows (policies) option.

At the top of the panel that loads click the New user flow button. The next panel shows a selection of flows that can be added. The application we are making will use both the Sign up and sign in flow and the Password rest flow. I’m only going to walk through the first one, but the second one is very smiliar. Click on the Sign up and sign in like.

In the creation process you will need to set a Name for the flow and select the Identity providers that are valid for the flow. You also have the choice of fields to collect with this flow and which ones should be returned with the claim. After those options are set click the Create button.

The Name form this screen will need to be entered in your appsettings.json file for the SignUpSignInPolicyId value. Here is what I ended up with in my settings file with the Sign Up and Reset Password policies.

"SignUpSignInPolicyId": "B2C_1_SignInOut",
"ResetPasswordPolicyId": "B2C_1_PasswordReset"

Run the sample

At this point, you can run your sample application and click the Sign in link and you will see a page similar to the following which is coming from Azure B2C.

There are ways to customize the pages users will see under the associated flow in Azure.

Wrapping Up

I hit quite a few issues getting Azure B2C setup. I hope this post will help you all bypass some of the issues I hit.