Spring Security Authentication Provider

Spring Security provides a flexible and powerful authentication mechanism. An AuthenticationProvider is a core component that allows custom authentication logic. This tutorial will guide you through setting up a Spring Boot 3.2 application with Spring Security 6.1 and implementing a custom AuthenticationProvider.


  • JDK 17 or later
  • Maven or Gradle
  • IDE (IntelliJ IDEA, Eclipse, etc.)

Step 1: Set Up a Spring Boot Project

1.1 Create a New Spring Boot Project

Use Spring Initializr to create a new project with the following dependencies:

  • Spring Web
  • Spring Security
  • Thymeleaf (optional, for the frontend)

Download and unzip the project, then open it in your IDE.

1.2 Configure application.properties

Set up the application properties for your project. This file is located in the src/main/resources directory.

# src/main/resources/application.properties

# Server port

# Thymeleaf configuration (optional)

Step 2: Create a Custom Authentication Provider

2.1 Implement the CustomAuthenticationProvider

Create a class to implement the AuthenticationProvider interface.

package com.example.demo.security;

import org.springframework.security.authentication.AuthenticationProvider;
import org.springframework.security.authentication.BadCredentialsException;
import org.springframework.security.authentication.UsernamePasswordAuthenticationToken;
import org.springframework.security.core.Authentication;
import org.springframework.security.core.AuthenticationException;
import org.springframework.security.core.authority.SimpleGrantedAuthority;
import org.springframework.stereotype.Component;

import java.util.ArrayList;
import java.util.List;

public class CustomAuthenticationProvider implements AuthenticationProvider {

    public Authentication authenticate(Authentication authentication) throws AuthenticationException {
        String username = authentication.getName();
        String password = authentication.getCredentials().toString();

        if (authenticateUser(username, password)) {
            List<SimpleGrantedAuthority> authorities = new ArrayList<>();
            authorities.add(new SimpleGrantedAuthority("ROLE_USER"));

            return new UsernamePasswordAuthenticationToken(username, password, authorities);
        } else {
            throw new BadCredentialsException("Authentication failed");

    private boolean authenticateUser(String username, String password) {
        // Custom authentication logic (e.g., checking credentials against a database)
        return "user".equals(username) && "password".equals(password);

    public boolean supports(Class<?> authentication) {
        return authentication.equals(UsernamePasswordAuthenticationToken.class);


  • authenticate: Custom logic to authenticate the user.
  • authenticateUser: A helper method for the custom authentication logic.
  • supports: Checks if the AuthenticationProvider can handle the given authentication token.

Step 3: Configure Spring Security

3.1 Create a Security Configuration Class

Create a configuration class to set up Spring Security and register the custom AuthenticationProvider.

package com.example.demo.config;

import com.example.demo.security.CustomAuthenticationProvider;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.security.authentication.AuthenticationProvider;
import org.springframework.security.config.annotation.web.builders.HttpSecurity;
import org.springframework.security.core.userdetails.User;
import org.springframework.security.core.userdetails.UserDetails;
import org.springframework.security.core.userdetails.UserDetailsService;
import org.springframework.security.provisioning.InMemoryUserDetailsManager;
import org.springframework.security.web.SecurityFilterChain;
import org.springframework.beans.factory.annotation.Autowired;

public class SecurityConfig {

    private CustomAuthenticationProvider customAuthenticationProvider;

    public SecurityFilterChain securityFilterChain(HttpSecurity http) throws Exception {
            .authorizeHttpRequests(authorizeRequests ->
                    .requestMatchers("/login", "/resources/**").permitAll()
            .formLogin(formLogin ->
            .logout(logout ->

        return http.build();


  • SecurityFilterChain: Configures the security filter chain.
  • authorizeHttpRequests: Defines URL authorization.
  • formLogin: Configures form-based login.
  • logout: Configures logout functionality.
  • authenticationProvider: Registers the custom AuthenticationProvider.

Step 4: Create the Login and Home Pages

4.1 Create the Login Page

Create a login page using Thymeleaf. Create a file named login.html in the src/main/resources/templates directory.

<!DOCTYPE html>
<html xmlns:th="http://www.thymeleaf.org">
    <form th:action="@{/login}" method="post">
            <input type="text" name="username"/>
            <input type="password" name="password"/>
            <button type="submit">Login</button>
    <div th:if="${param.logout}">
        You have been logged out.
    <div th:if="${param.error}">
        Invalid username or password.

4.2 Create the Home Page

Create a home page that will be accessible only to authenticated users. Create a file named home.html in the src/main/resources/templates directory.

<!DOCTYPE html>
<html xmlns:th="http://www.thymeleaf.org">
    <h1>Welcome, <span th:text="${#httpServletRequest.remoteUser}">User</span>!</h1>
    <a th:href="@{/logout}">Logout</a>

Step 5: Create a Controller

5.1 Create the HomeController

Create a controller to handle requests to the login and home pages.

package com.example.demo.controller;

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

public class HomeController {

    public String login() {
        return "login";

    public String home() {
        return "home";


  • @Controller: Marks the class as a web controller.
  • @GetMapping("/login"): Maps GET requests for the login page.
  • @GetMapping("/"): Maps GET requests for the home page.

Step 6: Running and Testing the Application

6.1 Run the Application

Run the Spring Boot application using your IDE or the command line:

./mvnw spring-boot:run

6.2 Test the Login Functionality

  1. Open a web browser and navigate to http://localhost:8080.
  2. You will be redirected to the login page.
  3. Enter the username user and password password, and click the "Login" button.
    • You should be redirected to the home page and see a welcome message.
  4. Log out by clicking the "Logout" link.


In this tutorial, you have learned how to implement a custom AuthenticationProvider using Spring Security 6.1 in a Spring Boot 3.2 application. We covered:

  • Setting up a Spring Boot project with Spring Security.
  • Implementing a custom AuthenticationProvider for custom authentication logic.
  • Configuring Spring Security to use the custom AuthenticationProvider.
  • Creating login and home pages using Thymeleaf.
  • Creating a controller to handle requests.

By following these steps, you can effectively manage authentication in your Spring Boot applications using custom authentication logic with Spring Security.