Jeff I Jeff I - 20 days ago 6
Java Question

Custom Authentication Manager with Spring Security and Java Configuration

I am using Spring Security with SpringMVC to create a web application (I will refer to this as the WebApp for clarity) that speaks to an existing application (I will refer to this as BackendApp).

I want to delegate authentication responsibilities to the BackendApp (so that I don't need to synchronise the two applications).

To implement this, I would like the WebApp (running spring security) to communicate to the BackendApp via REST with the username and password provided by the user in a form and authenticate based on whether the BackendApp's response is 200 OK or 401 Unauthorised.

I understand I will need to write a custom Authentication Manager to do this however I am very new to spring and can't find any information on how to implement it.

I believe I will need to do something like this:

public class CustomAuthenticationManager implements AuthenticationManager{

@Override
public Authentication authenticate(Authentication authentication) throws AuthenticationException {

String username = authentication.getName();
String pw = authentication.getCredentials().toString();

// Code to make rest call here and check for OK or Unauthorised.
// What do I return?

}

}


Do I set authentication.setAuthenticated(true) if successful and false if otherwise and thats it?

Once this is written, how do I configure spring security to use this authentication manager using a java configuration file?

Thanks in advance for any assistance.

Answer

Take a look at my sample below. You have to return an UsernamePasswordAuthenticationToken. It contains the principal and the GrantedAuthorities. Hope I could help :)

public Authentication authenticate(Authentication authentication) throws AuthenticationException {
    String username = authentication.getPrincipal() + "";
    String password = authentication.getCredentials() + "";

    User user = userRepo.findOne(username);
    if (user == null) {
        throw new BadCredentialsException("1000");
    }
    if (user.isDisabled()) {
        throw new DisabledException("1001");
    }
    if (!encoder.matches(password, user.getPassword())) {
        throw new BadCredentialsException("1000");
    }
    List<Right> userRights = rightRepo.getUserRights(username);
    return new UsernamePasswordAuthenticationToken(username, password, userRights.stream().map(x -> new SimpleGrantedAuthority(x.getName())).collect(Collectors.toList()));
}

PS: userRepo and rightRepo are Spring-Data-JPA Repositories which access my custom User-DB

SpringSecurity JavaConfig:

@Configuration
@EnableWebMvcSecurity
public class MySecurityConfiguration extends WebSecurityConfigurerAdapter {

public MySecurityConfiguration() {
    super(false);
}

@Override
protected AuthenticationManager authenticationManager() throws Exception {
    return new ProviderManager(Arrays.asList((AuthenticationProvider) new AuthProvider()));
}

}