For our new friends:

Logto is an Auth0 alternative designed for modern apps and SaaS products. It offers both Cloud and Open-source services to help you quickly launch your identity and management (IAM) system. Enjoy authentication, authorization, and multi-tenant management all in one.

We recommend starting with a free development tenant on Logto Cloud. This allows you to explore all the features easily.

In this article, we will go through the steps to quickly build the OAuth2 sign-in experience (user authentication) with Java Spring Boot and Logto.

Prerequisites

• A running Logto instance. Check out the introduction page to get started.
• Basic knowledge of Java Spring Boot.
• A usable OAuth2 account.

Create an application in Logto

Logto is based on OpenID Connect (OIDC) authentication and OAuth 2.0 authorization. It supports federated identity management across multiple applications, commonly called Single Sign-On (SSO).

To create your Traditional web application, simply follow these steps:

1. Open the Logto Console. In the "Get started" section, click the "View all" link to open the application frameworks list. Alternatively, you can navigate to Logto Console > Applications, and click the "Create application" button.
2. In the opening modal, click the "Traditional web" section or filter all the available "Traditional web" frameworks using the quick filter checkboxes on the left. Click the "Java Spring Boot" framework card to start creating your application.
3. Enter the application name, e.g., "Bookstore," and click "Create application".

🎉 Ta-da! You just created your first application in Logto. You'll see a congrats page which includes a detailed integration guide. Follow the guide to see what the experience will be in your application.

Integrate Java Spring Boot with Logto

tip:

• You may find the sample code for this guide in our spring-boot-sample github repository.
• No official SDK is required to integrate Logto with your Java Spring Boot application. We will use the Spring Security and Spring Security OAuth2 libraries to handle the OIDC authentication flow with Logto.

Configure your Java Spring Boot application

Adding dependencies

For gradle users, add the following dependencies to your build.gradle file:

build.gradle

dependencies {
  implementation 'org.springframework.boot:spring-boot-starter-thymeleaf'
	implementation 'org.springframework.boot:spring-boot-starter-web'
  implementation 'org.springframework.boot:spring-boot-starter-security'
	implementation 'org.springframework.boot:spring-boot-starter-oauth2-client'
}

For maven users, add the following dependencies to your pom.xml file:

pom.xml

<dependency>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-starter-thymeleaf</artifactId>
</dependency>
<dependency>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-starter-security</artifactId>
</dependency>
<dependency>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-starter-oauth2-client</artifactId>
</dependency>

OAuth2 Client Configuration

Register a new Java Spring Boot application in Logto Console and get the client credential and IdP configurations for your web application.

Add the following configuration to your application.properties file:

application.properties

spring.security.oauth2.client.registration.logto.client-name=logto
spring.security.oauth2.client.registration.logto.client-id={{YOUR_CLIENT_ID}}
spring.security.oauth2.client.registration.logto.client-secret={{YOUR_CLIENT_ID}}
spring.security.oauth2.client.registration.logto.redirect-uri={baseUrl}/login/oauth2/code/{registrationId}
spring.security.oauth2.client.registration.logto.authorization-grant-type=authorization_code
spring.security.oauth2.client.registration.logto.scope=openid,profile,offline_access
spring.security.oauth2.client.registration.logto.provider=logto

spring.security.oauth2.client.provider.logto.issuer-uri={{LOGTO_ENDPOINT}}/oidc
spring.security.oauth2.client.provider.logto.authorization-uri={{LOGTO_ENDPOINT}}/oidc/auth
spring.security.oauth2.client.provider.logto.jwk-set-uri={{LOGTO_ENDPOINT}}/oidc/jwks

Implementation

Before we dive into the details, here's a quick overview of the end-user experience. The sign-in process can be simplified as follows:

1. Your app invokes the sign-in method.
2. The user is redirected to the Logto sign-in page. For native apps, the system browser is opened.
3. The user signs in and is redirected back to your app (configured as the redirect URI).

Regarding redirect-based sign-in

1. This authentication process follows the OpenID Connect (OIDC) protocol, and Logto enforces strict security measures to protect user sign-in.
2. If you have multiple apps, you can use the same identity provider (Logto). Once the user signs in to one app, Logto will automatically complete the sign-in process when the user accesses another app.

To learn more about the rationale and benefits of redirect-based sign-in, see Logto sign-in experience explained.

---

In order to redirect users back to your application after they sign in, you need to set the redirect URI using the client.registration.logto.redirect-uri property in the previous step.

Configure redirect URIs

Switch to the application details page of Logto Console. Add a redirect URI http://localhost:3000/callback.

Just like signing in, users should be redirected to Logto for signing out of the shared session. Once finished, it would be great to redirect the user back to your website. For example, add http://localhost:3000/ as the post sign-out redirect URI section.

Then click "Save" to save the changes.

Implement the WebSecurityConfig

Create a new class WebSecurityConfig in your project

The WebSecurityConfig class will be used to configure the security settings for your application. It is the key class that will handle the authentication and authorization flow. Please check the Spring Security documentation for more details.

WebSecurityConfig.java

package com.example.securingweb;

import org.springframework.context.annotation.Configuration;
import org.springframework.security.config.annotation.web.configuration.EnableWebSecurity;

@Configuration
@EnableWebSecurity

public class WebSecurityConfig {
 // ...
}

Create a idTokenDecoderFactory bean

This is required because Logto uses ES384 as the default algorithm, we need to overwrite the default OidcIdTokenDecoderFactory to use the same algorithm.

WebSecurityConfig.java

import org.springframework.context.annotation.Bean;
import org.springframework.security.oauth2.client.oidc.authentication.OidcIdTokenDecoderFactory;
import org.springframework.security.oauth2.client.registration.ClientRegistration;
import org.springframework.security.oauth2.jose.jws.SignatureAlgorithm;
import org.springframework.security.oauth2.jwt.JwtDecoderFactory;

public class WebSecurityConfig {
  // ...

  @Bean
  public JwtDecoderFactory<ClientRegistration> idTokenDecoderFactory() {
    OidcIdTokenDecoderFactory idTokenDecoderFactory = new OidcIdTokenDecoderFactory();
    idTokenDecoderFactory.setJwsAlgorithmResolver(clientRegistration -> SignatureAlgorithm.ES384);
    return idTokenDecoderFactory;
  }
}

Create a LoginSuccessHandler class to handle the login success event

We will redirect the user to the /user page after a successful login.

CustomSuccessHandler.java

package com.example.securingweb;

import java.io.IOException;

import org.springframework.security.core.Authentication;
import org.springframework.security.web.authentication.AuthenticationSuccessHandler;

import jakarta.servlet.ServletException;
import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;

public class CustomSuccessHandler implements AuthenticationSuccessHandler {
  @Override
  public void onAuthenticationSuccess(HttpServletRequest request, HttpServletResponse response,
      Authentication authentication) throws IOException, ServletException {
    response.sendRedirect("/user");
  }
}

Create a LogoutSuccessHandler class to handle the logout success event

Clear the session and redirect the user to the home page.

CustomLogoutHandler.java

package com.example.securingweb;

import java.io.IOException;

import org.springframework.security.core.Authentication;
import org.springframework.security.web.authentication.logout.LogoutSuccessHandler;

import jakarta.servlet.ServletException;
import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;
import jakarta.servlet.http.HttpSession;

public class CustomLogoutHandler implements LogoutSuccessHandler {
  @Override
  public void onLogoutSuccess(HttpServletRequest request, HttpServletResponse response, Authentication authentication)
      throws IOException, ServletException {
    HttpSession session = request.getSession();

    if (session != null) {
      session.invalidate();
    }

    response.sendRedirect("/home");
  }
}

Update the WebSecurityConfig class with a securityFilterChain

securityFilterChain is a chain of filters that are responsible for processing the incoming requests and responses.

We will configure the securityFilterChain to allow access to the home page and require authentication for all other requests. Use the CustomSuccessHandler and CustomLogoutHandler to handle the login and logout events.

WebSecurityConfig.java

import org.springframework.context.annotation.Bean;
import org.springframework.security.config.annotation.web.builders.HttpSecurity;
import org.springframework.security.web.DefaultSecurityFilterChain;

public class WebSecurityConfig {
  // ...

  @Bean
  public DefaultSecurityFilterChain securityFilterChain(HttpSecurity http) throws Exception {
    http
      .authorizeRequests(authorizeRequests ->
        authorizeRequests
          .antMatchers("/", "/home").permitAll() // Allow access to the home page
          .anyRequest().authenticated() // All other requests require authentication
      )
      .oauth2Login(oauth2Login ->
        oauth2Login
          .successHandler(new CustomSuccessHandler())
      )
      .logout(logout ->
        logout
          .logoutSuccessHandler(new CustomLogoutHandler())
      );
    return http.build();
  }
}

Create a home page

(You may skip this step if you already have a home page in your project)

HomeController.java

package com.example.securingweb;

import java.security.Principal;

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.GetMapping;

@Controller
public class HomeController {
  @GetMapping({ "/", "/home" })
  public String home(Principal principal) {
    return principal != null ? "redirect:/user" : "home";
  }
}

This controller will redirect the user to the user page if the user is authenticated, otherwise, it will show the home page. Add a sign-in link to the home page.

resources/templates/home.html

<body>
  <h1>Welcome!</h1>

  <p><a th:href="@{/oauth2/authorization/logto}">Login with Logto</a></p>
</body>

Create a user page

Create a new controller to handle the user page:

UserController.java

package com.example.securingweb;

import java.security.Principal;
import java.util.Map;

import org.springframework.security.oauth2.client.authentication.OAuth2AuthenticationToken;
import org.springframework.security.oauth2.core.user.OAuth2User;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;

@Controller
@RequestMapping("/user")
public class UserController {

  @GetMapping
  public String user(Model model, Principal principal) {
    if (principal instanceof OAuth2AuthenticationToken) {
      OAuth2AuthenticationToken token = (OAuth2AuthenticationToken) principal;
      OAuth2User oauth2User = token.getPrincipal();
      Map<String, Object> attributes = oauth2User.getAttributes();

      model.addAttribute("username", attributes.get("username"));
      model.addAttribute("email", attributes.get("email"));
      model.addAttribute("sub", attributes.get("sub"));
    }

    return "user";
  }
}

Once the user is authenticated, we will retrieve the OAuth2User data from the authenticated principal object. Please refer OAuth2AuthenticationToken and OAuth2User for more details.

Read the user data and pass it to the user.html template.

resources/templates/user.html

<body>
  <h1>User Details</h1>
  <div>
    <p>
    <div><strong>name:</strong> <span th:text="${username}"></span></div>
    <div><strong>email:</strong> <span th:text="${email}"></span></div>
    <div><strong>id:</strong> <span th:text="${sub}"></span></div>
    </p>
  </div>

  <form th:action="@{/logout}" method="post">
    <input type="submit" value="Logout" />
  </form>
</body>

Request additional claims

You may find some user information are missing in the returned object from principal (OAuth2AuthenticationToken). This is because OAuth 2.0 and OpenID Connect (OIDC) are designed to follow the principle of least privilege (PoLP), and Logto is built on top of these standards.

By default, limited claims are returned. If you need more information, you can request additional scopes to access more claims.

info:

A "claim" is an assertion made about a subject; a "scope" is a group of claims. In the current case, a claim is a piece of information about the user.

Here's a non-normative example the scope - claim relationship:

tip:

The "sub" claim means "subject", which is the unique identifier of the user (i.e. user ID).

Logto SDK will always request three scopes: openid, profile, and offline_access.

To retrieve additional user information, you can add extra scopes to the application.properties file. For example, to request the email, phone, and urn:logto:scope:organizations scope, add the following line to the application.properties file:

application.properties

  spring.security.oauth2.client.registration.logto.scope=openid,profile,offline_access,email,phone,urn:logto:scope:organizations

Then you can access the additional claims in the OAuth2User object.

Run and test the application

Run the application and navigate to http://localhost:8080.

• You will see the home page with a sign-in link.
• Click on the link to sign in with Logto.
• After successful authentication, you will be redirected to the user page with your user details.
• Click on the logout button to sign out. You will be redirected back to the home page.

Add OAuth2 connector

To enable quick sign-in and improve user conversion, connect with Java Spring Boot as an identity provider. The Logto social connector helps you establish this connection in minutes by allowing several parameter inputs.

To add a social connector, simply follow these steps:

1. Navigate to Console > Connectors > Social Connectors.
2. Click "Add social connector" and select "OAuth2".
3. Follow the README guide and complete required fields and customize settings.

nota:

If you are following the in-place Connector guide, you can skip the next section.

Set up Standard OAuth 2.0 app

Create your OAuth app

When you open this page, we believe you already know which social identity provider you want to connect to. The first thing to do is to confirm that the identity provider supports the OAuth protocol, which is a prerequisite for configuring a valid connector. Then, follow the identity provider's instructions to register and create the relevant app for OAuth authorization.

Configure your connector

We ONLY support "Authorization Code" grant type for security consideration and it can perfectly fit Logto's scenario.

clientId and clientSecret can be found at your OAuth apps details page.

clientId: The client ID is a unique identifier that identifies the client application during registration with the authorization server. This ID is used by the authorization server to verify the identity of the client application and to associate any authorized access tokens with that specific client application.

clientSecret: The client secret is a confidential key that is issued to the client application by the authorization server during registration. The client application uses this secret key to authenticate itself with the authorization server when requesting access tokens. The client secret is considered confidential information and should be kept secure at all times.

tokenEndpointAuthMethod: The token endpoint authentication method is used by the client application to authenticate itself with the authorization server when requesting access tokens. To discover supported methods, consult the token_endpoint_auth_methods_supported field available at the OAuth 2.0 service provider’s OpenID Connect discovery endpoint, or refer to the relevant documentation provided by the OAuth 2.0 service provider.

clientSecretJwtSigningAlgorithm (Optional): Only required when tokenEndpointAuthMethod is client_secret_jwt. The client secret JWT signing algorithm is used by the client application to sign the JWT that is sent to the authorization server during the token request.

scope: The scope parameter is used to specify the set of resources and permissions that the client application is requesting access to. The scope parameter is typically defined as a space-separated list of values that represent specific permissions. For example, a scope value of "read write" might indicate that the client application is requesting read and write access to a user's data.

You are expected to find authorizationEndpoint, tokenEndpoint and userInfoEndpoint in social vendor's documentation.

authenticationEndpoint: This endpoint is used to initiate the authentication process. The authentication process typically involves the user logging in and granting authorization for the client application to access their resources.

tokenEndpoint: This endpoint is used by the client application to obtain an access token that can be used to access the requested resources. The client application typically sends a request to the token endpoint with a grant type and authorization code to receive an access token.

userInfoEndpoint: This endpoint is used by the client application to obtain additional information about the user, such as their fullname, email address or profile picture. The user info endpoint is typically accessed after the client application has obtained an access token from the token endpoint.

Logto also provide a profileMap field that users can customize the mapping from the social vendors' profiles which are usually not standard. The keys are Logto's standard user profile field names and corresponding values should be social profiles' field names. In current stage, Logto only concern 'id', 'name', 'avatar', 'email' and 'phone' from social profile, only 'id' is required and others are optional fields.

responseType and grantType can ONLY be FIXED values with authorization code grant type, so we make them optional and default values will be automatically filled.

For example, you can find Google user profile response and hence its profileMap should be like:

{
  "id": "sub",
  "avatar": "picture"
}

nota:

We provided an OPTIONAL customConfig key to put your customize parameters. Each social identity provider could have their own variant on OAuth standard protocol. If your desired social identity provider strictly stick to OAuth standard protocol, the you do not need to care about customConfig.

Config types

Name	Type	Required
authorizationEndpoint	string	true
userInfoEndpoint	string	true
clientId	string	true
clientSecret	string	true
tokenEndpointResponseType	enum	false
responseType	string	false
grantType	string	false
tokenEndpoint	string	false
scope	string	false
customConfig	Record<string, string>	false
profileMap	ProfileMap	false

ProfileMap fields	Type	Required	Default value
id	string	false	id
name	string	false	name
avatar	string	false	avatar
email	string	false	email
phone	string	false	phone

Save your configuration

Double check you have filled out necessary values in the Logto connector configuration area. Click "Save and Done" (or "Save changes") and the OAuth2 connector should be available now.

Enable OAuth2 connector in Sign-in Experience

Once you create a social connector successfully, you can enable it as a "Continue with OAuth2" button in Sign-in Experience.

1. Navigate to Console > Sign-in experience > Sign-up and sign-in.
2. (Optional) Choose "Not applicable" for sign-up identifier if you need social login only.
3. Add configured OAuth2 connector to the "Social sign-in" section.

Testing and Validation

Return to your Java Spring Boot app. You should now be able to sign in with OAuth2. Enjoy!

Further readings

End-user flows: Logto provides a out-of-the-box authentication flows including MFA and enterprise SSO, along with powerful APIs for flexible implementation of account settings, security verification, and multi-tenant experience.

Authorization: Authorization defines the actions a user can do or resources they can access after being authenticated. Explore how to protect your API for native and single-page applications and implement Role-based Access Control (RBAC).

Organizations: Particularly effective in multi-tenant SaaS and B2B apps, the organization feature enable tenant creation, member management, organization-level RBAC, and just-in-time-provisioning.

Customer IAM series Our serial blog posts about Customer (or Consumer) Identity and Access Management, from 101 to advanced topics and beyond.