Authentication - create a new authentication method

This tutorial shows, how to add a new authentication method to CzechIdM. The authentication will be typically done by some external authority, such as OpenAM, OAuth, Facebook, Google etc.

Supported authentication methods are implemented in several Authenticators. So you need to create a new authenticator. After you install the authenticator, users will be allowed to authenticate to CzechIdM (using CzechIdM login page) by the new authentication method.

Something different holds for SSO. If you want the users to come to CzechIdM and be immediately logged in without the need to fill in any credentials (or be redirected to some other login page of e.g. Facebook), you need to implement a new IdmAuthenticationFilter (see SSO).

A combination of both situations is possible, e.g. the OpenAM module supports both SSO (if the user already has OpenAM token) and authentication against OpenAM through CzechIdM login page.

Step 1 - Choose the module

Your authenticator must belong to some backend module. You can create a new module, or choose an existing one. The authenticator will be called during authentication process only when the module is enabled.

If you decide to create a new module, please follow the tutorial.

Step 2 - Create the Authenticator class

Now you create a new Spring component, which implements the Authenticator interface. You should extend AbstractAuthenticator which has already some common methods implemented.

After you create the new class, you should:

  • Add the @Component annotation and specify a unique name for the component.
  • Add the annotation @Enabled and specify the module descriptor of the chosen module.
  • Implement the interface method getModule() by returning the module name.
  • Implement the interface method getName() by returning some name for your authenticator (this name will be seen in logs during the authentication process).
  • Implement the interface method getOrder(). First decide, whether your authenticator should be called before, or after the core authenticator (i.e. CzechIdM local authentication). If you want your authenticator to be called before, return something like DEFAULT_AUTHENTICATOR_ORDER - 10.
  • Implement the interface method getExceptedResult(). Depending on the type of your environment, you should decide whether the new authentication method must be successful always, or only for some users. For supported types see Authenticator's result type.

After this, your class would look similar to the following code (the example is taken from the OpenAM module):

package eu.bcvsolutions.idm.openam.authentication.impl;
 
// ... imports
 
@Component("openAMAuthenticator")
@Enabled(OpenAMModuleDescriptor.MODULE_ID)
@Description("OpenAM authenticator, which authenticates users against OpenAM.")
public class OpenAMAuthenticator extends AbstractAuthenticator implements Authenticator {
 
	private static final org.slf4j.Logger LOG = org.slf4j.LoggerFactory.getLogger(OpenAMAuthenticator.class);
 
	private static final String AUTHENTICATOR_NAME = "openam-authenticator";
 
	@Override
	public String getName() {
		return OpenAMAuthenticator.AUTHENTICATOR_NAME;
	}
 
	@Override
	public String getModule() {
		return EntityUtils.getModule(this.getClass());
	}
 
	@Override
	public int getOrder() {
		return DEFAULT_AUTHENTICATOR_ORDER - 10;
	}
 
	@Override
	public LoginDto authenticate(LoginDto loginDto) {
		// TODO add implementation
		return null;
	}
 
	@Override
	public AuthenticationResponseEnum getExceptedResult() {
		return AuthenticationResponseEnum.SUFFICIENT;
	}
}

Step 3 - Implement the authentication method

Now you must add the main thing - the implementation of the method public LoginDto authenticate(LoginDto loginDto).

The LoginDto input parameter contains username and password filled by the user. Note that the password is of the type GuardedString. When you want to get the real string value of the password, use the method asString(), but be sure you don't write this value anywhere in plaintext (particularly not in the log)!

If the credentials are not correct, the method authenticate should return NULL. If some other authentication error occurs (an error which should be logged), you should throw an exception.

If you successfully validate user name and password with your authentication method, you will need to find IdM identity and create JWT token, which will be used for following requests of the user. For getting the user by username, use the IdmIdentityService. For creating the JWT token and setting it into the output LoginDto, use the JwtAuthenticationService. Those services should be autowired by Spring.

The example implementation of autowiring the services and implementing the authenticate method follows. Note that it's recommended to implement your authentication method in a separate service (here OpenAMAuthenticationService) to keep the code clean and concise.

	private final IdmIdentityService identityService;
 
	private final JwtAuthenticationService jwtAuthenticationService;
 
	private final OpenAMAuthenticationService openAMAuthenticationService;
 
	@Autowired
	public OpenAMAuthenticator(IdmIdentityService identityService, 
			JwtAuthenticationService jwtAuthenticationService,
			OpenAMAuthenticationService openAMAuthenticationService) {
		super();
 
		Assert.notNull(identityService);
		Assert.notNull(jwtAuthenticationService);
		Assert.notNull(openAMAuthenticationService);
		//
		this.identityService = identityService;
		this.jwtAuthenticationService = jwtAuthenticationService;
		this.openAMAuthenticationService = openAMAuthenticationService;
	}
 
	// ... other implementation
 
	@Override
	public LoginDto authenticate(LoginDto loginDto) {
		String username = loginDto.getUsername();
		GuardedString password = loginDto.getPassword();
 
		if (username == null || password == null) {
			LOG.warn("Could not authenticate against OpenAM, username and password must be set");
			return null;
		}
 
		String tokenId = openAMAuthenticationService.loginUserAndGetToken(username, password);
 
		if (tokenId == null) {
			LOG.info("User [{}] couldn't be authenticated against OpenAM.", username);
			return null;
		}
 
		LOG.info("Identity with username [{}] was authenticated by OpenAM and got token [{}]", username, tokenId);
 
		// ... other implementation
 
		IdmIdentityDto identity = identityService.getByUsername(username);
 
		if (identity == null) {
			throw new IdmAuthenticationException(MessageFormat.format(
					"Check identity can login: The identity [{0}] either doesn't exist or is deleted.", username));
		}
 
		return jwtAuthenticationService.createJwtAuthenticationAndAuthenticate(
				loginDto, identity, OpenAMModuleDescriptor.MODULE_ID);
	}

Step 4 - Implement the tests

You should implement unit tests that would cover your new authenticator. You should have tests for your service, which implements the authentication logic. For the authenticator tests, you can mock the outputs of the services and test only the logic contained in the authenticator.

Example:

package eu.bcvsolutions.idm.openam.authentication.impl;
 
// ... imports
 
public class OpenAMAuthenticatorTest extends AbstractUnitTest {
 
	@Mock
	private IdmIdentityService identityService;
 
	@Mock
	private JwtAuthenticationService jwtAuthenticationService;
 
	@Mock
	private OpenAMAuthenticationService openAMAuthenticationService;
 
	private OpenAMAuthenticator openAMAuthenticator;
 
	@Before
	public void init() {
		openAMAuthenticator = new OpenAMAuthenticator(identityService, jwtAuthenticationService,
				openAMAuthenticationService);
	}
 
	@Test
	public void testAuthenticateSuccess() {
 
		LoginDto loginDto = OpenAMTestUtil.createLoginDto();
		IdmIdentityDto idmIdentityDto = OpenAMTestUtil.createIdentityDto();
 
		when(openAMAuthenticationService.loginUserAndGetToken(loginDto.getUsername(), loginDto.getPassword())).thenReturn(TEST_TOKEN_ID);
 
		when(identityService.getByUsername(TEST_USERNAME)).thenReturn(idmIdentityDto);
 
		LoginDto responseLoginDto = new LoginDto(loginDto);
		responseLoginDto.setAuthenticationModule(OpenAMModuleDescriptor.MODULE_ID);
		when(jwtAuthenticationService.createJwtAuthenticationAndAuthenticate(eq(loginDto), eq(idmIdentityDto),
				eq(OpenAMModuleDescriptor.MODULE_ID))).thenReturn(responseLoginDto);
 
		LoginDto resultDto = openAMAuthenticator.authenticate(loginDto);
 
		verify(openAMAuthenticationService).loginUserAndGetToken(loginDto.getUsername(), loginDto.getPassword());
 
		verify(identityService).getByUsername(TEST_USERNAME);
 
		Assert.assertNotNull(resultDto);
		Assert.assertEquals(OpenAMModuleDescriptor.MODULE_ID, resultDto.getAuthenticationModule());
		Assert.assertEquals(TEST_USERNAME, resultDto.getUsername());
 
	}
 
	@Test
	public void testAuthenticateInvalidPassword() {
		LoginDto loginDto = OpenAMTestUtil.createLoginDto();
 
		when(openAMAuthenticationService.loginUserAndGetToken(loginDto.getUsername(), loginDto.getPassword())).thenReturn(null);
 
		LoginDto resultDto = openAMAuthenticator.authenticate(loginDto);
 
		verify(openAMAuthenticationService).loginUserAndGetToken(loginDto.getUsername(), loginDto.getPassword());
 
		Assert.assertNull(resultDto);
	}
 
	@Test
	public void testAuthenticateMissingIdentity() {
 
		LoginDto loginDto = OpenAMTestUtil.createLoginDto();
 
		when(openAMAuthenticationService.loginUserAndGetToken(loginDto.getUsername(), loginDto.getPassword())).thenReturn(TEST_TOKEN_ID);
 
		when(identityService.getByUsername(TEST_USERNAME)).thenReturn(null);
 
		Exception ex = null;
		try {
			openAMAuthenticator.authenticate(loginDto);
		} catch (IdmAuthenticationException e) {
			ex = e;
		}
		// Exception was returned because of non-existing identity
		Assert.assertNotNull(ex);
 
		verify(openAMAuthenticationService).loginUserAndGetToken(loginDto.getUsername(), loginDto.getPassword());
		verify(identityService).getByUsername(TEST_USERNAME);
 
	}
}

Step 5 - Build and install

Finally, build the module and install it to CzechIdM. Make sure your module is enabled in the Configuration.

Congratulations, your new authenticator is ready to use!

Step 1 - Choose the module

Your authentication filter must belong to some backend module. You can create a new module, or choose an existing one. The filter will be called during authentication process only when the module is enabled.

If you decide to create a new module, please follow the tutorial.

Step 2 - Create the IdmAuthenticationFilter class

Now you create a new Spring component, which implements the IdmAuthenticationFilter interface.

After you create the new class, you should:

  • Add the @Component annotation and specify a unique name for the component.
  • Add the annotation @Enabled and specify the module descriptor of the chosen module.
  • Add the annotation @Order. First decide, if your filter should be called before, or after the core JwtIdmAuthenticationFilter (i.e. CzechIdM local authentication). If the filter should do only SSO and shouldn't authorize every request, its order should be a positive number.

After this, your class would look similar to the following code (the example is taken from the OpenAM module):

package eu.bcvsolutions.idm.openam.authentication.filter;
 
// ... imports
 
@Order(10)
@Component("openAMIdmAuthenticationFilter")
@Enabled(OpenAMModuleDescriptor.MODULE_ID)
public class OpenAMIdmAuthenticationFilter implements IdmAuthenticationFilter {
 
	private static final Logger LOG = LoggerFactory.getLogger(OpenAMIdmAuthenticationFilter.class);
 
	@Override
	public boolean authorize(String token, HttpServletRequest req, HttpServletResponse res) {
		// TODO add implementation
		return false;
	}
}

Step 4 - Specify headers and implement the authentication method

The filter will be called only when the HTTP request contains specified headers. You must know which header contains tokens for your authentication method and return its name in the overriden method getAuthorizationHeaderName(). For example, BasicIdmAuthenticationFilter uses the header "Basic" to hold user name and login in Base64. In the example, the token is in request cookies, so we specify the header name "Cookie".

You can also override the method getAuthorizationHeaderPrefix() to specify the prefix of the header value.

Now you must add the main thing - the implementation of the method public boolean authorize(String token, HttpServletRequest req, HttpServletResponse res).

The input variable token is the value (without prefix), which was contained in the specified header. Note that for cookies, the value is concatenated from all request cookies, so you should rather use the whole HttpServletRequest to obtain the cookie you are interested in.

If the authentication is not successful, the method authorize should return false. Don't throw any exception even if any other authentication error occurs, because it would break the authentication filter chain completely.

If you successfully validate the user with your authentication method, you will need to find IdM identity and create JWT token, which will be used for following requests of the user. For getting the user, obtain their username from the external authority, and use the IdmIdentityService. Then create LoginDto with this user name. For creating the JWT token and setting it into the output LoginDto, use the JwtAuthenticationService. Those services should be autowired by Spring.

The example implementation of autowiring the services and implementing the interface methods follows. Note that it's recommended to implement your authentication method in a separate service (here OpenAMTokenValidationService) to keep the code clean and concise.

	@Autowired
	private OpenAMTokenValidationService openAMTokenValidationService;
 
	@Autowired
	private IdmIdentityService identityService;
 
	@Autowired
	private JwtAuthenticationService jwtAuthenticationService;
 
	@Override
	public boolean authorize(String token, HttpServletRequest req, HttpServletResponse res) {
		try {
			String tokenId = openAMTokenValidationService.retrieveTokenId(req);
 
			if (tokenId == null) {
				LOG.debug("No cookie for OpenAM");
				return false;
			}
 
			String userName = openAMTokenValidationService.retrieveUserNameForToken(tokenId, true);
 
			if (userName == null) {
				// Remove invalid cookie so next requests won't need to try validation again
				openAMTokenValidationService.removeTokenFromHeaders(res);
 
				LOG.info("TokenId for OpenAM is no longer valid, removing invalid token from headers. User must authenticate first.");
				return false;
			}
 
			LOG.info("TokenId for OpenAM is valid for user [{}].", userName);
 
			IdmIdentityDto identity = identityService.getByUsername(userName);
 
			if (identity == null) {			
				throw new IdmAuthenticationException(MessageFormat.format(
						"Check identity can login: The identity "
						+ "[{0}] either doesn't exist or is deleted.",
						userName));
			}
 
			LoginDto loginDto = createLoginDto(userName);
 
			LoginDto fullLoginDto = jwtAuthenticationService.createJwtAuthenticationAndAuthenticate(loginDto,
					identity, OpenAMModuleDescriptor.MODULE_ID);
 
			return fullLoginDto != null;
 
		} catch (IdmAuthenticationException e) {
			LOG.warn("Authentication exception raised during OpenAM authentication: [{}].", e.getMessage());
		} catch (Exception e) {
			LOG.error("Exception was raised during OpenAM authentication: [{}].", e.getMessage(), e);
		}
 
		return false;
	}
 
	private LoginDto createLoginDto(String userName) {
		LoginDto ldto = new LoginDto();
		ldto.setUsername(userName);
		return ldto;
	}
 
	@Override
	public String getAuthorizationHeaderName() {
		return "Cookie";
	}
 
	@Override
	public String getAuthorizationHeaderPrefix() {
		return "";
	}

Step 4 - Implement the tests

You should implement unit tests that would cover your new filter. You should have tests for your service, which implements the authentication logic. For the filter tests, you can mock the outputs of the services and test only the logic contained in the filter.

Step 5 - Build and install

Finally, build the module and install it to CzechIdM. Make sure your module is enabled in the Configuration.