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Jakub Leško
Jakub Leško

Posted on • Updated on

Spring Security with JWT

#java #spring #security #jwt

Spring Security’s default behavior is easy to use for a standard web application. It uses cookie-based authentication and sessions. Also, it automatically handles CSRF tokens for you (to prevent man in the middle attacks). In most cases you just need to set authorization rights for specific routes, a method to retrieve the user from the database and that’s it.

On the other hand, you probably don’t need full session if you’re building just a REST API which will be consumed with external services or your SPA/mobile application. Here comes the JWT (JSON Web Token) – a small digitally signed token. All needed information can be stored in the token, so your server can be session-less.

JWT needs to be attached to every HTTP request so the server can authorize your users. There are some options on how to send the token. For example, as an URL parameter or in HTTP Authorization header using the Bearer schema:

Authorization: Bearer <token string>
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JSON Web Token contains three main parts:

  1. Header – typically includes the type of the token and hashing algorithm.
  2. Payload – typically includes data about a user and for whom is token issued.
  3. Signature – it’s used to verify if a message wasn’t changed along the way.

Example token

A JWT token from authorization header will probably look like this:

Bearer eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzUxMiJ9.eyJpc3MiOiJzZWN1cmUtYXBpIiwiYXVkIjoic2VjdXJlLWFwcCIsInN1YiI6InVzZXIiLCJleHAiOjE1NDgyNDI1ODksInJvbCI6WyJST0xFX1VTRVIiXX0.GzUPUWStRofrWI9Ctfv2h-XofGZwcOog9swtuqg1vSkA8kDWLcY3InVgmct7rq4ZU3lxI6CGupNgSazypHoFOA
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As you can see there are three parts separated with comma – header, claims, and signature. Header and payload are Base64 encoded JSON objects.

Header: 

{
  "typ": "JWT",
  "alg": "HS512"
}
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Claims/Payload: 

{
  "iss": "secure-api",
  "aud": "secure-app",
  "sub": "user",
  "exp": 1548242589,
  "rol": [
    "ROLE_USER"
  ]
}
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Example application

In the following example, we will create a simple API with 2 routes – one publicly available and one only for authorized users.

We will use page start.spring.io to create our application skeleton and select Security and Web dependencies. Rest of the options are up to your preferences.

Spring Initializr screenshot

JWT support for Java is provided by the library JJWT so we also need to add following dependencies to the pom.xml file:

<dependency>
    <groupId>io.jsonwebtoken</groupId>
    <artifactId>jjwt-api</artifactId>
    <version>0.10.5</version>
</dependency>
<dependency>
    <groupId>io.jsonwebtoken</groupId>
    <artifactId>jjwt-impl</artifactId>
    <version>0.10.5</version>
    <scope>runtime</scope>
</dependency>
<dependency>
    <groupId>io.jsonwebtoken</groupId>
    <artifactId>jjwt-jackson</artifactId>
    <version>0.10.5</version>
    <scope>runtime</scope>
</dependency>
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Controllers

Controllers in our example applications will be simple as much as possible. They will just return a message or HTTP 403 error code in case the user is not authorized.

@RestController
@RequestMapping("/api/public")
public class PublicController {

    @GetMapping
    public String getMessage() {
        return "Hello from public API controller";
    }
}
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@RestController
@RequestMapping("/api/private")
public class PrivateController {

    @GetMapping
    public String getMessage() {
        return "Hello from private API controller";
    }
}
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Filters

First, we will define some reusable constants and defaults for generation and validation of JWTs.

Note: You should not hardcode JWT signing key into your application code (we will ignore that for now in the example). You should use an environment variable or .properties file. Also, keys need to have an appropriate length. For example, HS512 algorithm needs a key with size at least 512 bytes.

public final class SecurityConstants {

    public static final String AUTH_LOGIN_URL = "/api/authenticate";

    // Signing key for HS512 algorithm
    // You can use the page http://www.allkeysgenerator.com/ to generate all kinds of keys
    public static final String JWT_SECRET = "n2r5u8x/A%D*G-KaPdSgVkYp3s6v9y$B&E(H+MbQeThWmZq4t7w!z%C*F-J@NcRf";

    // JWT token defaults
    public static final String TOKEN_HEADER = "Authorization";
    public static final String TOKEN_PREFIX = "Bearer ";
    public static final String TOKEN_TYPE = "JWT";
    public static final String TOKEN_ISSUER = "secure-api";
    public static final String TOKEN_AUDIENCE = "secure-app";

    private SecurityConstants() {
        throw new IllegalStateException("Cannot create instance of static util class");
    }
}
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The first filter will be used directly for user authentication. It’ll check for username and password parameters from URL and calls Spring’s authentication manager to verify them.

If username and password are correct, then the filter will create a JWT token and returns it in HTTP Authorization header.

public class JwtAuthenticationFilter extends UsernamePasswordAuthenticationFilter {

    private final AuthenticationManager authenticationManager;

    public JwtAuthenticationFilter(AuthenticationManager authenticationManager) {
        this.authenticationManager = authenticationManager;

        setFilterProcessesUrl(SecurityConstants.AUTH_LOGIN_URL);
    }

    @Override
    public Authentication attemptAuthentication(HttpServletRequest request, HttpServletResponse response) {
        var username = request.getParameter("username");
        var password = request.getParameter("password");
        var authenticationToken = new UsernamePasswordAuthenticationToken(username, password);

        return authenticationManager.authenticate(authenticationToken);
    }

    @Override
    protected void successfulAuthentication(HttpServletRequest request, HttpServletResponse response,
                                            FilterChain filterChain, Authentication authentication) {
        var user = ((User) authentication.getPrincipal());

        var roles = user.getAuthorities()
            .stream()
            .map(GrantedAuthority::getAuthority)
            .collect(Collectors.toList());

        var signingKey = SecurityConstants.JWT_SECRET.getBytes();

        var token = Jwts.builder()
            .signWith(Keys.hmacShaKeyFor(signingKey), SignatureAlgorithm.HS512)
            .setHeaderParam("typ", SecurityConstants.TOKEN_TYPE)
            .setIssuer(SecurityConstants.TOKEN_ISSUER)
            .setAudience(SecurityConstants.TOKEN_AUDIENCE)
            .setSubject(user.getUsername())
            .setExpiration(new Date(System.currentTimeMillis() + 864000000))
            .claim("rol", roles)
            .compact();

        response.addHeader(SecurityConstants.TOKEN_HEADER, SecurityConstants.TOKEN_PREFIX + token);
    }
}
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The second filter handles all HTTP requests and checks if there is an Authorization header with the correct token. For example, if the token is not expired or if the signature key is correct.

If the token is valid then the filter will add authentication data into Spring’s security context.

public class JwtAuthorizationFilter extends BasicAuthenticationFilter {

    private static final Logger log = LoggerFactory.getLogger(JwtAuthorizationFilter.class);

    public JwtAuthorizationFilter(AuthenticationManager authenticationManager) {
        super(authenticationManager);
    }

    @Override
    protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response,
                                    FilterChain filterChain) throws IOException, ServletException {
        var authentication = getAuthentication(request);
        if (authentication == null) {
            filterChain.doFilter(request, response);
            return;
        }

        SecurityContextHolder.getContext().setAuthentication(authentication);
        filterChain.doFilter(request, response);
    }

    private UsernamePasswordAuthenticationToken getAuthentication(HttpServletRequest request) {
        var token = request.getHeader(SecurityConstants.TOKEN_HEADER);
        if (StringUtils.isNotEmpty(token) && token.startsWith(SecurityConstants.TOKEN_PREFIX)) {
            try {
                var signingKey = SecurityConstants.JWT_SECRET.getBytes();

                var parsedToken = Jwts.parser()
                    .setSigningKey(signingKey)
                    .parseClaimsJws(token.replace("Bearer ", ""));

                var username = parsedToken
                    .getBody()
                    .getSubject();

                var authorities = ((List<?>) parsedToken.getBody()
                    .get("rol")).stream()
                    .map(authority -> new SimpleGrantedAuthority((String) authority))
                    .collect(Collectors.toList());

                if (StringUtils.isNotEmpty(username)) {
                    return new UsernamePasswordAuthenticationToken(username, null, authorities);
                }
            } catch (ExpiredJwtException exception) {
                log.warn("Request to parse expired JWT : {} failed : {}", token, exception.getMessage());
            } catch (UnsupportedJwtException exception) {
                log.warn("Request to parse unsupported JWT : {} failed : {}", token, exception.getMessage());
            } catch (MalformedJwtException exception) {
                log.warn("Request to parse invalid JWT : {} failed : {}", token, exception.getMessage());
            } catch (SignatureException exception) {
                log.warn("Request to parse JWT with invalid signature : {} failed : {}", token, exception.getMessage());
            } catch (IllegalArgumentException exception) {
                log.warn("Request to parse empty or null JWT : {} failed : {}", token, exception.getMessage());
            }
        }

        return null;
    }
}
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Security configuration

The last part we need to configure is Spring Security itself. The configuration is simple, we need to set just a few details:

  • Password encoder – in our case bcrypt
  • CORS configuration
  • Authentication manager – in our case simple in-memory authentication but in real life, you’ll need something like UserDetailsService
  • Set which endpoints are secure and which are publicly available
  • Add our 2 filters into the security context
  • Disable session management – we don’t need sessions so this will prevent the creation of session cookies 
@EnableWebSecurity
@EnableGlobalMethodSecurity(securedEnabled = true)
public class SecurityConfiguration extends WebSecurityConfigurerAdapter {

    @Override
    protected void configure(HttpSecurity http) throws Exception {
        http.cors().and()
            .csrf().disable()
            .authorizeRequests()
            .antMatchers("/api/public").permitAll()
            .anyRequest().authenticated()
            .and()
            .addFilter(new JwtAuthenticationFilter(authenticationManager()))
            .addFilter(new JwtAuthorizationFilter(authenticationManager()))
            .sessionManagement()
            .sessionCreationPolicy(SessionCreationPolicy.STATELESS);
    }

    @Override
    public void configure(AuthenticationManagerBuilder auth) throws Exception {
        auth.inMemoryAuthentication()
            .withUser("user")
            .password(passwordEncoder().encode("password"))
            .authorities("ROLE_USER");
    }

    @Bean
    public PasswordEncoder passwordEncoder() {
        return new BCryptPasswordEncoder();
    }

    @Bean
    public CorsConfigurationSource corsConfigurationSource() {
        final UrlBasedCorsConfigurationSource source = new UrlBasedCorsConfigurationSource();
        source.registerCorsConfiguration("/**", new CorsConfiguration().applyPermitDefaultValues());

        return source;
    }
}
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Test

Request to public API 

GET http://localhost:8080/api/public
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HTTP/1.1 200 
X-Content-Type-Options: nosniff
X-XSS-Protection: 1; mode=block
Cache-Control: no-cache, no-store, max-age=0, must-revalidate
Pragma: no-cache
Expires: 0
X-Frame-Options: DENY
Content-Type: text/plain;charset=UTF-8
Content-Length: 32
Date: Sun, 13 Jan 2019 12:22:14 GMT

Hello from public API controller

Response code: 200; Time: 18ms; Content length: 32 bytes
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Authenticate user 

POST http://localhost:8080/api/authenticate?username=user&password=password
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HTTP/1.1 200 
Authorization: Bearer eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzUxMiJ9.eyJpc3MiOiJzZWN1cmUtYXBpIiwiYXVkIjoic2VjdXJlLWFwcCIsInN1YiI6InVzZXIiLCJleHAiOjE1NDgyNDYwNzUsInJvbCI6WyJST0xFX1VTRVIiXX0.yhskhWyi-PgIluYY21rL0saAG92TfTVVVgVT1afWd_NnmOMg__2kK5lcna3lXzYI4-0qi9uGpI6Ul33-b9KTnA
X-Content-Type-Options: nosniff
X-XSS-Protection: 1; mode=block
Cache-Control: no-cache, no-store, max-age=0, must-revalidate
Pragma: no-cache
Expires: 0
X-Frame-Options: DENY
Content-Length: 0
Date: Sun, 13 Jan 2019 12:21:15 GMT

<Response body is empty>

Response code: 200; Time: 167ms; Content length: 0 bytes
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Request to private API with token 

GET http://localhost:8080/api/private
Authorization: Bearer eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzUxMiJ9.eyJpc3MiOiJzZWN1cmUtYXBpIiwiYXVkIjoic2VjdXJlLWFwcCIsInN1YiI6InVzZXIiLCJleHAiOjE1NDgyNDI1ODksInJvbCI6WyJST0xFX1VTRVIiXX0.GzUPUWStRofrWI9Ctfv2h-XofGZwcOog9swtuqg1vSkA8kDWLcY3InVgmct7rq4ZU3lxI6CGupNgSazypHoFOA
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HTTP/1.1 200 
X-Content-Type-Options: nosniff
X-XSS-Protection: 1; mode=block
Cache-Control: no-cache, no-store, max-age=0, must-revalidate
Pragma: no-cache
Expires: 0
X-Frame-Options: DENY
Content-Type: text/plain;charset=UTF-8
Content-Length: 33
Date: Sun, 13 Jan 2019 12:22:48 GMT

Hello from private API controller

Response code: 200; Time: 12ms; Content length: 33 bytes
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Request to private API without token

You’ll get HTTP 403 message when you call secured endpoint without a valid JWT.

GET http://localhost:8080/api/private
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HTTP/1.1 403 
X-Content-Type-Options: nosniff
X-XSS-Protection: 1; mode=block
Cache-Control: no-cache, no-store, max-age=0, must-revalidate
Pragma: no-cache
Expires: 0
X-Frame-Options: DENY
Content-Type: application/json;charset=UTF-8
Transfer-Encoding: chunked
Date: Sun, 13 Jan 2019 12:27:25 GMT

{
  "timestamp": "2019-01-13T12:27:25.020+0000",
  "status": 403,
  "error": "Forbidden",
  "message": "Access Denied",
  "path": "/api/private"
}

Response code: 403; Time: 28ms; Content length: 125 bytes
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Conclusion

The goal of this article is not to show the one correct way how to use JWTs in Spring Security. It’s an example of how you can do it in your real-life application. Also, I did not want to go too deep into the topic so few things like token refreshing, invalidation, etc. are missing but I’ll cover these topics probably in the future.

tl;dr You can find the full source code of this example API in my GitHub repository.

Top comments (44)

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petros0 profile image
Petros Stergioulas • • Edited

Great Article! Good job!

A quick question: Why here are you checking the header and not the authentication object?

I mean, you already checked the header in getAuthentication()

        var authentication = getAuthentication(request);
        var header = request.getHeader(SecurityConstants.TOKEN_HEADER);

        if (StringUtils.isEmpty(header) || !header.startsWith(SecurityConstants.TOKEN_PREFIX)) {
            filterChain.doFilter(request, response);
            return;
        }
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Like this, should also work, or not? :D

        var authentication = getAuthentication(request);

        if (authentication == null) {
            filterChain.doFilter(request, response);
            return;
        }
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Again, great article!

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kubadlo profile image
Jakub Leško •

Well, you're right. My bad 😀
I'll update the code. Thanks for your attention 🙂

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devc0n profile image
Ricardo Jobse • • Edited

For starters, great introduction to JWT security! But i was looking around to see if i could authenticate users with a database instead of the in memory database that is used by default. Do you happen to have an example for this?

EDIT:
Few minutes after i asked the question i stumbled upon the answer...

for those interested i changed this:

auth.inMemoryAuthentication()
        .withUser("user")
        .password(passwordEncoder().encode("password"))
        .authorities("ROLE_USER");

to this

auth.userDetailsService(customUserDetailsService)
        .passwordEncoder(passwordEncoder());

password encoder is just a constructor for a BcryptEncoder, and the userdetail service provides a method to load by username from the repository, and get authorities.

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fmukendi profile image
fmukendi •

Hi . Could you please explain where you got the JWT Token From?
When doing the operation below

GET http://localhost:8080/api/private
Authorization: Bearer eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzUxMiJ9.eyJpc3MiOiJzZWN1cmUtYXBpIiwiYXVkIjoic2VjdXJlLWFwcCIsInN1YiI6InVzZXIiLCJleHAiOjE1NDgyNDI1ODksInJvbCI6WyJST0xFX1VTRVIiXX0.GzUPUWStRofrWI9Ctfv2h-XofGZwcOog9swtuqg1vSkA8kDWLcY3InVgmct7rq4ZU3lxI6CGupNgSazypHoFOA
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kubadlo profile image
Jakub Leško •

Hi. You can find JWT in HTTP header Authorization in response from /api/authenticate.

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morensya93 profile image
Faisal Morensya •

But from your post it says <Response body is empty>

This response body should be the token right?

Thread Thread
 
kubadlo profile image
Jakub Leško •

Yes, response body is empty since JWT is sent via HTTP header.
I'll update that code snipped since it's bit confusing.

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jakemccabenc profile image
JakeMcCabeNC •

This is a great explanation! I have been trying to get this to work for weeks and now I get it!

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kubadlo profile image
Jakub Leško •

Thank you! I'm writing another article about token refreshing so stay tuned :)

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kzmfullstack4 profile image
Saeid Kazemi •

But i'm curious to know how to use UserDetails ?here ?

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kivimango profile image
Kivimango •

Hello ! Im waiting for your article about implementing token refreshing.Any plans to do in the future ?

Thread Thread
 
kubadlo profile image
Jakub Leško • • Edited

Hello Kivimango. I'm sorry that it takes so long but I have too much work to do so the article is still a draft. But I promise I'll try to complete the article asap.

I already started with code updates in a separate branch, so you can check the progress there

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jakemccabenc profile image
JakeMcCabeNC •

Awesome! Another thing that I have been trying to understand is how to extend what you have to a user repository.

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rafasmxp profile image
rafuru •

I have like 3 weeks looking for a clear explanation of the basic jwt integration with spring security..

Great Job!

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nottanho profile image
Tân Hồ •

Thank for the tutorial. But I don't really agree with your coding style, should be more careful thought. Like the code below, the authentication object should not get from the first place.

    @Override
    protected void doFilterInternal(...) throws ... 
    {
        var authentication = getAuthentication(request);
        var header = request.getHeader(SecurityConstants.TOKEN_HEADER);
        if (StringUtils.isEmpty(header)...
           return...
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mikewakawski profile image
mikewakawski •

Thank you for the tutorial. I was wondering how can i implement the @PreAuthorize annotation and the whole roles thing in my spring security(I've looked into other tutorials but it didn't help). Thank you for your time.

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nicoforlano profile image
nicoforlano •

Hey! Great article, helped me a lot!

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chriswjarvis profile image
Christopher Jarvis • • Edited

Hey just wanted to let you know this was sooooo helpful! Thank you for your time and talent at teaching!

If anyone else is struggling with the seemingly high complexity of the spring security framework, I have a few things to add that I've learned in my struggles:

  1. The reason there is so much is to simplify building enterprise-scale roles-based authentication/authorization logic.
  2. It aims to be an almost out of the box solution for a server rendered mvc style web app If you are just trying to secure the backend for your relatively simple SPA style web app then the framework certainly seems like overkill, but articles like this make it easy to find what you need!
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chriswjarvis profile image
Christopher Jarvis •

also if it helps anyone:

if you want to put the username/id whatever you are storing as the subject in jwt onto the request (so that your secured endpoints know which user is accessing):

in AuthorizationFilter#doFilterInternal(): request.setAttribute("username", authentication.getPrincipal());

in ur controllers: public @RequestBody ReturnType yourMethod(@RequestAttribute("username") String username) { ... }

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bvsantos profile image
bvsantos •

Hello! First of all really nice guide!
I tried to implement it, i did exactly as you did but i keep getting this error starting on the method authenticationManager.authenticate(authenticationToken) in class JwtAuthenticationFilter:

java.lang.NoSuchMethodError: 'boolean org.springframework.security.crypto.password.PasswordEncoder.upgradeEncoding(java.lang.String)

What could it be?

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