Implementing One-Time Token Authentication with Spring Security

In today's digital landscape, providing secure and user-friendly authentication methods is crucial. One such method gaining popularity is One-Time Token (OTT) authentication, often implemented as "magic links" sent via email. Spring Security 6.4.0 provides robust built-in support for OTT authentication, including ready-to-use implementations. In this comprehensive guide, we'll explore how to implement secure OTT authentication using both built-in solutions and custom implementations.

Understanding One-Time Tokens vs. One-Time Passwords

Before diving into implementation, it's important to understand that One-Time Tokens (OTT) differ from One-Time Passwords (OTP). While OTP systems typically require initial setup and rely on external tools for password generation, OTT systems are simpler from a user perspective - they receive a unique token (usually via email) that they can use to authenticate.

Key differences include:

OTT doesn't require initial user setup
Tokens are generated and delivered by your application
Each token is typically valid for a single use and expires after a set time

Available Built-in Implementations

Spring Security provides two implementations of OneTimeTokenService:

InMemoryOneTimeTokenService:
- Stores tokens in memory
- Ideal for development and testing
- Not suitable for production or clustered environments
- Tokens are lost on application restart
JdbcOneTimeTokenService:
- Stores tokens in a database
- Suitable for production use
- Works in clustered environments
- Persistent storage with automatic cleanup

Using InMemoryOneTimeTokenService

Here's how to implement the simpler in-memory solution:

@Configuration
@EnableWebSecurity
public class SecurityConfig {
    @Bean
    public SecurityFilterChain filterChain(HttpSecurity http) throws Exception {
        http
            .authorizeHttpRequests(auth -> auth
                .requestMatchers("/login/**", "/ott/**").permitAll()
                .anyRequest().authenticated()
            )
            .formLogin(Customizer.withDefaults())
            .oneTimeTokenLogin(Customizer.withDefaults());  // Uses InMemoryOneTimeTokenService by default

        return http.build();
    }
}

Using JdbcOneTimeTokenService

For production environments, use the JDBC implementation:

@Configuration
@EnableWebSecurity
public class SecurityConfig {
    @Autowired
    JdbcTemplate jdbcTemplate;

    @Bean
    public OneTimeTokenService oneTimeTokenService() {
        return new JdbcOneTimeTokenService(jdbcTemplate);
    }

    @Bean
    public SecurityFilterChain filterChain(HttpSecurity http) throws Exception {
        http
            .authorizeHttpRequests(auth -> auth
                .requestMatchers("/login/**", "/ott/**").permitAll()
                .anyRequest().authenticated()
            )
            .formLogin(Customizer.withDefaults())
            .oneTimeTokenLogin(Customizer.withDefaults());

        return http.build();
    }
}

Required table structure for JdbcOneTimeTokenService:

CREATE TABLE one_time_tokens (
    token_value VARCHAR(255) PRIMARY KEY,
    username VARCHAR(255) NOT NULL,
    issued_at TIMESTAMP NOT NULL,
    expires_at TIMESTAMP NOT NULL,
    used BOOLEAN NOT NULL
);

Custom Implementation

For more control over the token generation and validation process, you can create a custom implementation:

1. Token Entity and Repository

@Entity
@Table(name = "one_time_tokens")
public class OneTimeToken {
    @Id
    @GeneratedValue
    private Long id;

    private String tokenValue;
    private String username;
    private LocalDateTime createdAt;
    private LocalDateTime expiresAt;
    private boolean used;

    // Getters and setters omitted for brevity
}

@Repository
public interface OneTimeTokenRepository extends JpaRepository<OneTimeToken, Long> {
    Optional<OneTimeToken> findByTokenValueAndUsedFalse(String tokenValue);
    void deleteByExpiresAtBefore(LocalDateTime dateTime);
}

2. Custom Token Service

@Service
@Transactional
public class PersistentOneTimeTokenService implements OneTimeTokenService {
    private static final int TOKEN_VALIDITY_MINUTES = 15;

    @Autowired
    private OneTimeTokenRepository tokenRepository;

    @Override
    public OneTimeToken generate(GenerateOneTimeTokenRequest request) {
        String tokenValue = UUID.randomUUID().toString();
        LocalDateTime now = LocalDateTime.now();

        OneTimeToken token = new OneTimeToken();
        token.setTokenValue(tokenValue);
        token.setUsername(request.getUsername());
        token.setCreatedAt(now);
        token.setExpiresAt(now.plusMinutes(TOKEN_VALIDITY_MINUTES));
        token.setUsed(false);

        return return new DefaultOneTimeToken(token.getTokenValue(),token.getUsername(), Instant.now());
    }

    @Override
    public Authentication consume(ConsumeOneTimeTokenRequest request) {
        OneTimeToken token = tokenRepository.findByTokenValueAndUsedFalse(request.getTokenValue())
            .orElseThrow(() -> new BadCredentialsException("Invalid or expired token"));

        if (token.getExpiresAt().isBefore(LocalDateTime.now())) {
            throw new BadCredentialsException("Token has expired");
        }

        token.setUsed(true);
        tokenRepository.save(token);

        UserDetails userDetails = loadUserByUsername(token.getUsername());
        return new UsernamePasswordAuthenticationToken(
            userDetails, null, userDetails.getAuthorities());
    }
}

Implementing Token Delivery

Spring Security doesn't handle token delivery, so you'll need to implement it:

@Component
public class EmailMagicLinkHandler implements OneTimeTokenGenerationSuccessHandler {
    @Autowired
    private JavaMailSender mailSender;

    private final OneTimeTokenGenerationSuccessHandler redirectHandler = 
        new RedirectOneTimeTokenGenerationSuccessHandler("/ott/check-email");

    @Override
    public void handle(HttpServletRequest request, HttpServletResponse response, 
                      OneTimeToken token) throws IOException, ServletException {
        String magicLink = UriComponentsBuilder.fromHttpUrl(UrlUtils.buildFullRequestUrl(request))
            .replacePath(request.getContextPath())
            .replaceQuery(null)
            .fragment(null)
            .path("/login/ott")
            .queryParam("token", token.getTokenValue())
            .toUriString();

        SimpleMailMessage message = new SimpleMailMessage();
        message.setTo(getUserEmail(token.getUsername()));
        message.setSubject("Your Sign-in Link");
        message.setText("Click here to sign in: " + magicLink);

        mailSender.send(message);
        redirectHandler.handle(request, response, token);
    }
}

Customizing URLs and Pages

Spring Security provides several customization options:

@Configuration
@EnableWebSecurity
public class SecurityConfig {
    @Bean
    public SecurityFilterChain filterChain(HttpSecurity http) throws Exception {
        http
            .formLogin(Customizer.withDefaults())
            .oneTimeTokenLogin(ott -> ott
                .generateTokenUrl("/custom/generate-token")  // Custom token generation URL
                .submitPageUrl("/custom/submit-token")       // Custom token submission page
                .showDefaultSubmitPage(false)               // Disable default submit page
            );

        return http.build();
    }
}

Production Considerations

When deploying OTT authentication in production:

Choose the Right Implementation
- Use JdbcOneTimeTokenService or custom implementation for production
- InMemoryOneTimeTokenService should only be used for development/testing
Configure Email Delivery

   spring.mail.host=smtp.your-provider.com
   spring.mail.port=587
   spring.mail.username=your-username
   spring.mail.password=your-password
   spring.mail.properties.mail.smtp.auth=true
   spring.mail.properties.mail.smtp.starttls.enable=true

Security Best Practices
- Set appropriate token expiration times (15 minutes recommended)
- Implement rate limiting for token generation
- Use HTTPS for all endpoints
- Monitor failed authentication attempts
- Ensure tokens are single-use and invalidated immediately after use
- Implement automatic cleanup of expired tokens
- Use secure random token generation to prevent guessing

How It Works

User requests a token by submitting their email address
System generates a secure token and sends a magic link via email
User clicks the link and is redirected to the token submission page
System validates the token and authenticates the user if valid

Conclusion

Spring Security's OTT support provides a robust foundation for implementing secure, user-friendly authentication. Whether you choose the built-in implementations or create a custom solution, you can offer your users a passwordless login option while maintaining high security standards.

When implementing OTT authentication, remember to:

Choose the appropriate implementation for your environment
Implement secure token delivery
Configure proper token expiration
Follow security best practices
Create user-friendly error handling and redirects
Implement proper email templating for a professional look

By following this guide, you can implement a secure and user-friendly OTT authentication system that meets your application's needs while leveraging Spring Security's robust security features.

Reference: https://docs.spring.io/spring-security/reference/servlet/authentication/onetimetoken.html

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