Authentication flow in Spring Boot - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to define a Spring Boot controller method that handles login requests.

Spring Boot

public ResponseEntity<String> login(@RequestBody LoginRequest [1]) {
    // method body
}

Drag options to blanks, or click blank then click option'

ArequestBody

BloginRequest

Cuser

Dcredentials

Attempts:

3 left

💡 Hint

Common Mistakes

Using generic names like 'user' or 'credentials' that are less clear.

Using names that conflict with Spring annotations.

The parameter name loginRequest clearly represents the login data object received in the request body.

2fill in blank

medium

Complete the code to inject the authentication manager bean into the service class.

Spring Boot

@Autowired
private [1] authenticationManager;

Drag options to blanks, or click blank then click option'

AAuthenticationService

BSecurityManager

CAuthManager

DAuthenticationManager

Attempts:

3 left

💡 Hint

Common Mistakes

Using custom or incorrect class names.

Confusing with service or manager classes not related to authentication.

The correct Spring Security interface to handle authentication is AuthenticationManager.

3fill in blank

hard

Fix the error in the code that authenticates a user with username and password.

Spring Boot

Authentication authentication = authenticationManager.authenticate(
    new UsernamePasswordAuthenticationToken([1], password)
);

Drag options to blanks, or click blank then click option'

Apassword

Bauthentication

Cusername

DuserDetails

Attempts:

3 left

💡 Hint

Common Mistakes

Swapping username and password parameters.

Passing the whole authentication object instead of username.

The first argument to UsernamePasswordAuthenticationToken must be the username, not the password.

4fill in blank

hard

Fill both blanks to create a JWT token after successful authentication.

Spring Boot

String token = jwtUtil.[1](authentication.getName(), [2]);

Drag options to blanks, or click blank then click option'

AgenerateToken

BvalidateToken

Cauthentication.getAuthorities()

Dauthentication.getCredentials()

Attempts:

3 left

💡 Hint

Common Mistakes

Using token validation method instead of generation.

Passing credentials instead of authorities.

Use generateToken to create the token and pass the username and authorities for claims.

5fill in blank

hard

Fill all three blanks to configure HTTP security to require authentication for all requests except login.

Spring Boot

http.csrf().disable()
    .authorizeHttpRequests()
    .requestMatchers("/login").[1]()
    .anyRequest().[2]()
    .and()
    .sessionManagement().sessionCreationPolicy([3]);

Drag options to blanks, or click blank then click option'

ApermitAll

Bauthenticated

CSessionCreationPolicy.STATELESS

DSessionCreationPolicy.ALWAYS

Attempts:

3 left

💡 Hint

Common Mistakes

Forgetting to disable CSRF for stateless APIs.

Using wrong session creation policy causing stateful sessions.

Not permitting access to login endpoint.

Allow all users to access /login without authentication, require authentication for other requests, and use stateless sessions for JWT.

Practice

1. What is the main purpose of the authentication flow in a Spring Boot application?

easy

A. To send emails to users after login

B. To style the user interface of the login page

C. To store user data in the database

D. To verify the identity of a user before granting access

Solution

1. Step 1: Understand authentication flow purpose

   Authentication flow is about checking who the user is before allowing access.

2. Step 2: Identify correct purpose in options

   Only To verify the identity of a user before granting access describes verifying user identity, which matches authentication.

3. Final Answer:

   To verify the identity of a user before granting access -> Option D

4. Quick Check:

   Authentication = Verify user identity [OK]

Hint: Authentication means checking who the user is [OK]

Common Mistakes:

• Confusing authentication with styling or data storage
• Thinking authentication sends emails
• Mixing authentication with authorization

2. Which of the following is the correct way to configure URL access rules in Spring Security?

easy

A. http.authorizeHttpRequests().requestMatchers("/admin/**").authenticated()

B. http.authorizeRequests().antMatchers("/private/**").denyAll()

C. http.authorizeRequests().anyRequest().allow()

D. http.authorizeRequests().requestMatchers("/public/**").permitAll()

Solution

1. Step 1: Identify correct method for URL rules in Spring Security

   Spring Security 6+ uses http.authorizeHttpRequests() with requestMatchers() for URL patterns.

2. Step 2: Check which option uses correct syntax and meaning

   http.authorizeHttpRequests().requestMatchers("/admin/**").authenticated() uses authorizeHttpRequests() and requestMatchers() with authenticated(), which is correct.

3. Final Answer:

   http.authorizeHttpRequests().requestMatchers("/admin/**").authenticated() -> Option A

4. Quick Check:

   Use authorizeHttpRequests() + requestMatchers() [OK]

Hint: Use authorizeHttpRequests() with requestMatchers() in Spring Security 6+ [OK]

Common Mistakes:

• Using deprecated authorizeRequests() in new Spring versions
• Using denyAll() incorrectly for access control
• Using anyRequest().allow() which is invalid

3. Given this Spring Security configuration snippet, what happens when a user accesses /dashboard without logging in?

http
  .authorizeHttpRequests(auth -> auth
    .requestMatchers("/public/**").permitAll()
    .anyRequest().authenticated()
  )
  .formLogin();

medium

A. The user can access /dashboard without login

B. The user is redirected to the login page

C. The user gets a 403 Forbidden error

D. The user sees a blank page

Solution

1. Step 1: Analyze URL access rules

   /public/** URLs are open, but any other request requires authentication.

2. Step 2: Check behavior for unauthenticated access to /dashboard

   Since /dashboard is not under /public, it requires login. formLogin() triggers redirect to login page.

3. Final Answer:

   The user is redirected to the login page -> Option B

4. Quick Check:

   Unauthenticated access redirects to login [OK]

Hint: AnyRequest().authenticated() means login required [OK]

Common Mistakes:

• Thinking permitAll() applies to all URLs
• Expecting 403 error instead of redirect
• Assuming access without login

4. Identify the error in this Spring Security configuration snippet:

http
  .authorizeHttpRequests(auth -> auth
    .requestMatchers("/admin/**").permitAll()
    .anyRequest().authenticated()
  )
  .formLogin();

medium

A. formLogin() is missing a login page URL

B. anyRequest().authenticated() should come before requestMatchers()

C. permitAll() on /admin/** allows unrestricted access to admin pages

D. requestMatchers() should be replaced with antMatchers()

Solution

1. Step 1: Review access rules for /admin/**

   permitAll() means anyone can access /admin/** without login, which is usually a security risk.

2. Step 2: Check order and methods

   Order is correct; anyRequest().authenticated() applies after permitAll(). formLogin() without URL uses default login page, which is valid.

3. Final Answer:

   permitAll() on /admin/** allows unrestricted access to admin pages -> Option C

4. Quick Check:

   permitAll() means open access [OK]

Hint: permitAll() means no login needed, risky on admin URLs [OK]

Common Mistakes:

• Thinking order of matchers is wrong here
• Assuming formLogin() needs explicit URL
• Confusing requestMatchers() with antMatchers()

5. You want to create a custom authentication flow that checks a user's email and password against a database and then grants access. Which Spring Boot component should you implement to handle this logic?

hard

A. UserDetailsService to load user data and PasswordEncoder to check password

B. AuthenticationEntryPoint to redirect users after login

C. CorsConfiguration to allow cross-origin requests

D. HttpFirewall to block unauthorized IP addresses

Solution

1. Step 1: Identify component for loading user info

   UserDetailsService is designed to load user details like email and password from a database.

2. Step 2: Identify component for password checking

   PasswordEncoder is used to verify the password matches the stored hash securely.

3. Step 3: Confirm other options are unrelated

   AuthenticationEntryPoint handles unauthorized access, not authentication logic. CorsConfiguration and HttpFirewall serve different purposes.

4. Final Answer:

   UserDetailsService to load user data and PasswordEncoder to check password -> Option A

5. Quick Check:

   Custom auth uses UserDetailsService + PasswordEncoder [OK]

Hint: UserDetailsService loads users; PasswordEncoder checks passwords [OK]

Common Mistakes:

• Confusing AuthenticationEntryPoint with authentication logic
• Using CorsConfiguration for authentication
• Thinking HttpFirewall handles login checks