Secure Java Spring Boot apps using Azure Active Directory B2C

This article demonstrates a Java Spring Boot web app that signs in users on your Azure Active Directory B2C tenant using the Azure AD B2C Spring Boot Starter client library for Java. It uses the OpenID Connect protocol.

The following diagram shows the topology of the app:

The client app uses the Azure AD B2C Spring Boot Starter client library for Java to sign in a user and obtain an ID token from Azure AD B2C. The ID token proves that the user is authenticated with Azure AD B2C and enables the user to access protected routes.

Prerequisites

• JDK version 15. This sample was developed on a system with Java 15, but it might be compatible with other versions.
• Maven 3
• Java Extension Pack for Visual Studio Code is recommended for running this sample in Visual Studio Code.
• An Azure AD B2C tenant. For more information, see Tutorial: Create an Azure Active Directory B2C tenant
• Visual Studio Code
• Azure Tools for Visual Studio Code

Recommendations

• Some familiarity with the Spring Framework.
• Some familiarity with Linux/OSX terminal.
• jwt.ms for inspecting your tokens.
• Fiddler for monitoring your network activity and troubleshooting.
• Follow the Microsoft Entra ID Blog to stay up-to-date with the latest developments.

Set up the sample

The following sections show you how to set up the sample application.

Clone or download the sample repository

To clone the sample, open a Bash window and use the following command:

git clone https://github.com/Azure-Samples/ms-identity-msal-java-samples.git
cd 4-spring-web-app/1-Authentication/sign-in-b2c

Alternatively, navigate to the ms-identity-msal-java-samples repository, then download it as a .zip file and extract it to your hard drive.

This sample comes with a preregistered application for demo purposes. If you'd like to use your own Azure AD B2C tenant and application, register and configure the application in the Azure portal. For more information, see the Register the app section. Otherwise, continue with the steps in the Run the sample section.

Choose the Azure AD B2C tenant where you want to create your applications

To choose your tenant, use the following steps:

1. Sign in to the Azure portal.

2. If your account is present in more than one Azure AD B2C tenant, select your profile in the corner of the Azure portal, and then select Switch directory to change your session to the desired Azure AD B2C tenant.

Create user flows and custom policies

To create common user flows like sign-up, sign-in, profile edit, and password reset, see Tutorial: Create user flows in Azure Active Directory B2C.

You should consider creating custom policies in Azure Active Directory B2C as well. However, this task is beyond the scope of this tutorial. For more information, see Azure AD B2C custom policy overview.

Add external identity providers

See Tutorial: Add identity providers to your applications in Azure Active Directory B2C.

Register the app (java-spring-webapp-auth-b2c)

To register the app, use the following steps:

1. Navigate to the Azure portal and select Azure AD B2C.

2. Select App Registrations on the navigation pane, then select New registration.

3. In the Register an application page that appears, enter the following application registration information:

   • In the Name section, enter a meaningful application name for display to users of the app - for example, java-spring-webapp-auth-b2c.
   • Under Supported account types, select Accounts in any identity provider or organizational directory (for authenticating users with user flows).
   • In the Redirect URI (optional) section, select Web in the combo-box and enter the following redirect URI: http://localhost:8080/login/oauth2/code/.

4. Select Register to create the application.

5. On the app's registration page, find and copy the Application (client) ID value to use later. You use this value in your app's configuration file or files.

6. Select Save to save your changes.

7. On the app's registration page, select the Certificates & secrets pane on the navigation pane to open the page to generate secrets and upload certificates.

8. In the Client secrets section, select New client secret.

9. Type a description - for example, app secret.

10. Select one of the available durations as per your security concerns - for example, In 2 years.

11. Select Add. The generated value is displayed.

12. Copy and save the generated value for use in later steps. You need this value for your code's configuration files. This value isn't displayed again, and you can't retrieve it by any other means. So, be sure to save it from the Azure portal before you navigate to any other screen or pane.

Configure the app (java-spring-webapp-auth-b2c) to use your app registration

Use the following steps to configure the app:

1. Open the project in your IDE.

2. Open the src/main/resources/application.yml file.

3. Find the client-id property and replace the existing value with the application ID or clientId of the java-spring-webapp-auth-b2c application from the Azure portal.

4. Find the client-secret property and replace the existing value with the value you saved during the creation of the java-spring-webapp-auth-b2c application from the Azure portal.

5. Find the base-uri property and replace the two instances of the value fabrikamb2c with the name of the Azure AD B2C tenant in which you created the java-spring-webapp-auth-b2c application in the Azure portal.

6. Find the sign-up-or-sign-in property and replace it with the name of the sign-up/sign-in user-flow policy you created in the Azure AD B2C tenant in which you created the java-spring-webapp-auth-b2c application in the Azure portal.

7. Find the profile-edit property and replace it with the name of the password reset user-flow policy you created in the Azure AD B2C tenant in which you created the java-spring-webapp-auth-b2c application in the Azure portal.

8. Find the password-reset property and replace it with the name of the edit profile user-flow policy you created in the Azure AD B2C tenant in which you created the java-spring-webapp-auth-b2c application in the Azure portal.

9. Open the src/main/resources/templates/navbar.html file.

10. Find the references to the b2c_1_susi and b2c_1_edit_profile flows and replace them with your sign-up-sign-in and profile-edit user-flows.

Run the sample

az login

az upgrade

az extension add --name containerapp --upgrade

az extension add --name containerapp --upgrade --allow-preview true

az provider register --namespace Microsoft.App
az provider register --namespace Microsoft.OperationalInsights

export RESOURCE_GROUP="ms-identity-containerapps"
export LOCATION="canadacentral"
export ENVIRONMENT="env-ms-identity-containerapps"
export API_NAME="ms-identity-api"
export JAR_FILE_PATH_AND_NAME="./target/ms-identity-spring-boot-webapp-0.0.1-SNAPSHOT.jar"

az group create  \
    --name $RESOURCE_GROUP \
    --location $LOCATION \

az containerapp env create \
    --name $ENVIRONMENT \
    --resource-group $RESOURCE_GROUP \
    --location $LOCATION

az containerapp env show \
    --name $ENVIRONMENT \
    --resource-group $RESOURCE_GROUP \
    --query properties.defaultDomain

az containerapp up \
    --name $API_NAME \
    --resource-group $RESOURCE_GROUP \
    --location $LOCATION \
    --environment $ENVIRONMENT \
    --artifact <JAR_FILE_PATH_AND_NAME> \
    --ingress external \
    --target-port 8080 \
    --query properties.configuration.ingress.fqdn

Explore the sample

Use the following steps to explore the sample:

1. Notice the signed-in or signed-out status displayed at the center of the screen.
2. Select the context-sensitive button in the corner. This button reads Sign In when you first run the app. Alternatively, select the link to token details. Because this page is protected and requires authentication, you're automatically redirected to the sign-in page.
3. On the next page, follow the instructions and sign in with an account of your chosen identity provider. You can also choose to sign up or sign in to a local account on the B2C tenant using an email address.
4. Upon successful completion of the sign-in flow, you should be redirected to the home page - which shows the sign in status - or the token details page, depending on which button triggered your sign-in flow.
5. Notice that the context-sensitive button now says Sign out and displays your username.
6. If you're on the home page, select ID Token Details to see some of the ID token's decoded claims.
7. Edit your profile. Select edit profile to change details like your display name, place of residence, and profession.
8. Use the button in the corner to sign out. The status page reflects the new state.

About the code

This sample demonstrates how to use Azure AD B2C Spring Boot Starter client library for Java to sign in users into your Azure AD B2C tenant. The sample also makes use of the Spring Oauth2 Client and Spring Web boot starters. The sample uses claims from the ID token obtained from Azure AD B2C to display the details of the signed-in user.

Contents

The following table shows the contents of the sample project folder:

ID token claims

To extract token details, the app makes use of Spring Security's AuthenticationPrincipal and OidcUser object in a request mapping, as shown in the following example, as shown in the following example. See the Sample Controller for the full details of how this app makes use of ID token claims.

import org.springframework.security.oauth2.core.oidc.user.OidcUser;
import org.springframework.security.core.annotation.AuthenticationPrincipal;
//...
@GetMapping(path = "/some_path")
public String tokenDetails(@AuthenticationPrincipal OidcUser principal) {
    Map<String, Object> claims = principal.getIdToken().getClaims();
}

Sign-in and sign-out links

For sign-in, the app makes a request to the Azure AD B2C sign-in endpoint automatically configured by Azure AD B2C Spring Boot Starter client library for Java, as shown in the following example:

<a class="btn btn-success" href="/oauth2/authorization/{your-sign-up-sign-in-user-flow}">Sign In</a>

For sign-out, the app makes a POST request to the logout endpoint, as shown in the following example:

<form action="#" th:action="@{/logout}" method="post">
  <input class="btn btn-warning" type="submit" value="Sign Out" />
</form>

Authentication-dependent UI elements

The app has some simple logic in the UI template pages for determining content to display based on whether the user is authenticated, as shown in the following example using Spring Security Thymeleaf tags:

<div sec:authorize="isAuthenticated()">
  this content only shows to authenticated users
</div>
<div sec:authorize="isAnonymous()">
  this content only shows to not-authenticated users
</div>

Protect routes with WebSecurityConfigurerAdapter

By default, the app protects the ID Token Details page so that only signed-in users can access it. The app configures these routes from the app.protect.authenticated property from the application.yml file. To configure your app's specific requirements, you can extend WebSecurityConfigurerAdapter in one of your classes. For an example, see this app's SecurityConfig class, shown in the following code:

@EnableWebSecurity
public class SecurityConfig extends WebSecurityConfigurerAdapter {

    @Value("${app.protect.authenticated}")
    private String[] protectedRoutes;

    private final AADB2COidcLoginConfigurer configurer;

    public SecurityConfig(AADB2COidcLoginConfigurer configurer) {
        this.configurer = configurer;
    }

    @Override
    protected void configure(HttpSecurity http) throws Exception {
        // @formatter:off
        http.authorizeRequests()
            .antMatchers(protectedRoutes).authenticated()     // limit these pages to authenticated users (default: /token_details)
            .antMatchers("/**").permitAll()                  // allow all other routes.
            .and()
            .apply(configurer)
            ;
        // @formatter:off
    }
}

More information

• Microsoft identity platform (Microsoft Entra ID for developers)
• Overview of Microsoft Authentication Library (MSAL)
• Quickstart: Register an application with the Microsoft identity platform
• Quickstart: Configure a client application to access web APIs
• Understanding Microsoft Entra ID application consent experiences
• Understand user and admin consent
• Application and service principal objects in Microsoft Entra ID
• National Clouds
• MSAL code samples
• Microsoft Entra ID Spring Boot Starter client library for Java
• Azure Active Directory B2C Spring Boot Starter client library for Java
• Microsoft Authentication Library for Java (MSAL4J)
• MSAL4J Wiki
• ID tokens
• Access tokens in the Microsoft identity platform

For more information about how OAuth 2.0 protocols work in this scenario and other scenarios, see Authentication Scenarios for Microsoft Entra ID.