extends the functionality of oauth in Stirling PDF

2024-05-12 19:58:34 +02:00 · 2024-05-12 19:58:34 +02:00 · 811c19e00d
commit 811c19e00d
parent f2b7aeeb1c
49 changed files with 724 additions and 210 deletions
--- a/src/main/java/stirling/software/SPDF/config/security/CustomAuthenticationFailureHandler.java
+++ b/src/main/java/stirling/software/SPDF/config/security/CustomAuthenticationFailureHandler.java
@ -3,10 +3,12 @@ package stirling.software.SPDF.config.security;
 import java.io.IOException;
 import java.util.Optional;

-import org.springframework.beans.factory.annotation.Autowired;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 import org.springframework.security.authentication.BadCredentialsException;
 import org.springframework.security.authentication.LockedException;
 import org.springframework.security.core.AuthenticationException;
+import org.springframework.security.core.userdetails.UsernameNotFoundException;
 import org.springframework.security.web.authentication.SimpleUrlAuthenticationFailureHandler;
 import org.springframework.stereotype.Component;

@ -18,9 +20,12 @@ import stirling.software.SPDF.model.User;
@Component
 public class CustomAuthenticationFailureHandler extends SimpleUrlAuthenticationFailureHandler {

-    @Autowired private final LoginAttemptService loginAttemptService;
+    private LoginAttemptService loginAttemptService;

-    @Autowired private final UserService userService; // Inject the UserService
+    private UserService userService;
+
+    private static final Logger logger =
+            LoggerFactory.getLogger(CustomAuthenticationFailureHandler.class);

    public CustomAuthenticationFailureHandler(
            LoginAttemptService loginAttemptService, UserService userService) {
@ -34,22 +39,28 @@ public class CustomAuthenticationFailureHandler extends SimpleUrlAuthenticationF
            HttpServletResponse response,
            AuthenticationException exception)
            throws IOException, ServletException {
+
        String ip = request.getRemoteAddr();
        logger.error("Failed login attempt from IP: " + ip);

        String username = request.getParameter("username");
        if (!isDemoUser(username)) {
            if (loginAttemptService.loginAttemptCheck(username)) {
-                setDefaultFailureUrl("/login?error=locked");
-
+                response.sendRedirect("/login?error=locked");
+                return;
            } else {
                if (exception.getClass().isAssignableFrom(LockedException.class)) {
-                    setDefaultFailureUrl("/login?error=locked");
+                    response.sendRedirect("/login?error=locked");
+                    return;
+                } else if (exception instanceof UsernameNotFoundException) {
+                    response.sendRedirect("/login?error=oauth2AuthenticationError");
+                    return;
                }
            }
        }
        if (exception.getClass().isAssignableFrom(BadCredentialsException.class)) {
-            setDefaultFailureUrl("/login?error=badcredentials");
+            response.sendRedirect("/login?error=badcredentials");
+            return;
        }

        super.onAuthenticationFailure(request, response, exception);
--- a/src/main/java/stirling/software/SPDF/config/security/CustomAuthenticationSuccessHandler.java
+++ b/src/main/java/stirling/software/SPDF/config/security/CustomAuthenticationSuccessHandler.java
@ -2,7 +2,6 @@ package stirling.software.SPDF.config.security;

 import java.io.IOException;

-import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.security.core.Authentication;
 import org.springframework.security.web.authentication.SavedRequestAwareAuthenticationSuccessHandler;
 import org.springframework.security.web.savedrequest.SavedRequest;
@ -18,15 +17,10 @@ import stirling.software.SPDF.utils.RequestUriUtils;
 public class CustomAuthenticationSuccessHandler
        extends SavedRequestAwareAuthenticationSuccessHandler {

-    @Autowired private LoginAttemptService loginAttemptService;
-
    @Override
    public void onAuthenticationSuccess(
            HttpServletRequest request, HttpServletResponse response, Authentication authentication)
            throws ServletException, IOException {
-        String username = request.getParameter("username");
-        loginAttemptService.loginSucceeded(username);
-
        // Get the saved request
        HttpSession session = request.getSession(false);
        SavedRequest savedRequest =
--- a/src/main/java/stirling/software/SPDF/config/security/CustomLogoutSuccessHandler.java
+++ b/src/main/java/stirling/software/SPDF/config/security/CustomLogoutSuccessHandler.java
@ -2,10 +2,9 @@ package stirling.software.SPDF.config.security;

 import java.io.IOException;

-import org.springframework.context.annotation.Bean;
+import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.security.core.Authentication;
 import org.springframework.security.core.session.SessionRegistry;
-import org.springframework.security.core.session.SessionRegistryImpl;
 import org.springframework.security.web.authentication.logout.SimpleUrlLogoutSuccessHandler;

 import jakarta.servlet.ServletException;
@ -14,10 +13,8 @@ import jakarta.servlet.http.HttpServletResponse;
 import jakarta.servlet.http.HttpSession;

 public class CustomLogoutSuccessHandler extends SimpleUrlLogoutSuccessHandler {
-    @Bean
-    public SessionRegistry sessionRegistry() {
-        return new SessionRegistryImpl();
-    }
+
+    @Autowired SessionRegistry sessionRegistry;

    @Override
    public void onLogoutSuccess(
@ -26,14 +23,9 @@ public class CustomLogoutSuccessHandler extends SimpleUrlLogoutSuccessHandler {
        HttpSession session = request.getSession(false);
        if (session != null) {
            String sessionId = session.getId();
-            sessionRegistry().removeSessionInformation(sessionId);
+            sessionRegistry.removeSessionInformation(sessionId);
        }

-        if (request.getParameter("oauth2AutoCreateDisabled") != null) {
-            response.sendRedirect(
-                    request.getContextPath() + "/login?error=oauth2AutoCreateDisabled");
-        } else {
-            response.sendRedirect(request.getContextPath() + "/login?logout=true");
-        }
+        response.sendRedirect(request.getContextPath() + "/login?logout=true");
    }
 }
--- a/src/main/java/stirling/software/SPDF/config/security/CustomUserDetailsService.java
+++ b/src/main/java/stirling/software/SPDF/config/security/CustomUserDetailsService.java
@ -22,7 +22,11 @@ public class CustomUserDetailsService implements UserDetailsService {

    @Autowired private UserRepository userRepository;

-    @Autowired private LoginAttemptService loginAttemptService;
+    private LoginAttemptService loginAttemptService;
+
+    CustomUserDetailsService(LoginAttemptService loginAttemptService) {
+        this.loginAttemptService = loginAttemptService;
+    }

    @Override
    public UserDetails loadUserByUsername(String username) throws UsernameNotFoundException {
@ -39,6 +43,10 @@ public class CustomUserDetailsService implements UserDetailsService {
                    "Your account has been locked due to too many failed login attempts.");
        }

+        if (user.getPassword() == null || user.getPassword().isEmpty()) {
+            throw new UsernameNotFoundException("Password must not be null");
+        }
+
        return new org.springframework.security.core.userdetails.User(
                user.getUsername(),
                user.getPassword(),
--- a/src/main/java/stirling/software/SPDF/config/security/InitialSecuritySetup.java
+++ b/src/main/java/stirling/software/SPDF/config/security/InitialSecuritySetup.java
@ -7,6 +7,8 @@ import java.nio.file.Paths;
 import java.util.List;
 import java.util.UUID;

+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.stereotype.Component;

@ -21,6 +23,8 @@ public class InitialSecuritySetup {

    @Autowired ApplicationProperties applicationProperties;

+    private static final Logger logger = LoggerFactory.getLogger(InitialSecuritySetup.class);
+
    @PostConstruct
    public void init() {
        if (!userService.hasUsers()) {
@ -29,6 +33,20 @@ public class InitialSecuritySetup {
                    applicationProperties.getSecurity().getInitialLogin().getUsername();
            String initialPassword =
                    applicationProperties.getSecurity().getInitialLogin().getPassword();
+            try {
+                // https://github.com/Stirling-Tools/Stirling-PDF/issues/976
+                userService.isUsernameValidWithReturn(initialUsername);
+            } catch (IllegalArgumentException e) {
+                Path pathToFile = Paths.get("configs/settings.yml");
+                try {
+                    if (Files.exists(pathToFile)) {
+                        Files.delete(pathToFile);
+                    }
+                } catch (IOException ex) {
+                    logger.info(ex.getMessage());
+                }
+                throw e;
+            }
            if (initialUsername != null && initialPassword != null) {
                userService.saveUser(initialUsername, initialPassword, Role.ADMIN.getRoleId());
            } else {
--- a/src/main/java/stirling/software/SPDF/config/security/LoginAttemptService.java
+++ b/src/main/java/stirling/software/SPDF/config/security/LoginAttemptService.java
@ -30,28 +30,31 @@ public class LoginAttemptService {
            new ConcurrentHashMap<>();

    public void loginSucceeded(String key) {
-        attemptsCache.remove(key);
+        attemptsCache.remove(key.toLowerCase());
    }

    public boolean loginAttemptCheck(String key) {
-        attemptsCache.compute(
-                key,
-                (k, attemptCounter) -> {
-                    if (attemptCounter == null
-                            || attemptCounter.shouldReset(ATTEMPT_INCREMENT_TIME)) {
-                        return new AttemptCounter();
-                    } else {
-                        attemptCounter.increment();
-                        return attemptCounter;
-                    }
-                });
-        return attemptsCache.get(key).getAttemptCount() >= MAX_ATTEMPTS;
+        return attemptsCache
+                        .compute(
+                                key.toLowerCase(),
+                                (k, attemptCounter) -> {
+                                    if (attemptCounter == null
+                                            || attemptCounter.shouldReset(ATTEMPT_INCREMENT_TIME)) {
+                                        return new AttemptCounter();
+                                    } else {
+                                        attemptCounter.increment();
+                                        return attemptCounter;
+                                    }
+                                })
+                        .getAttemptCount()
+                >= MAX_ATTEMPTS;
    }

    public boolean isBlocked(String key) {
-        AttemptCounter attemptCounter = attemptsCache.get(key);
+        AttemptCounter attemptCounter = attemptsCache.get(key.toLowerCase());
        if (attemptCounter != null) {
-            return attemptCounter.getAttemptCount() >= MAX_ATTEMPTS;
+            return attemptCounter.getAttemptCount() >= MAX_ATTEMPTS
+                    && !attemptCounter.shouldReset(ATTEMPT_INCREMENT_TIME);
        }
        return false;
    }
--- a/src/main/java/stirling/software/SPDF/config/security/SecurityConfiguration.java
+++ b/src/main/java/stirling/software/SPDF/config/security/SecurityConfiguration.java
@ -1,6 +1,5 @@
 package stirling.software.SPDF.config.security;

-import java.io.IOException;
 import java.util.*;

 import org.springframework.beans.factory.annotation.Autowired;
@ -14,33 +13,30 @@ import org.springframework.security.config.annotation.method.configuration.Enabl
 import org.springframework.security.config.annotation.web.builders.HttpSecurity;
 import org.springframework.security.config.annotation.web.configuration.EnableWebSecurity;
 import org.springframework.security.config.http.SessionCreationPolicy;
-import org.springframework.security.core.Authentication;
 import org.springframework.security.core.GrantedAuthority;
 import org.springframework.security.core.authority.SimpleGrantedAuthority;
 import org.springframework.security.core.authority.mapping.GrantedAuthoritiesMapper;
 import org.springframework.security.core.session.SessionRegistry;
 import org.springframework.security.core.session.SessionRegistryImpl;
-import org.springframework.security.core.userdetails.UserDetailsService;
 import org.springframework.security.crypto.bcrypt.BCryptPasswordEncoder;
 import org.springframework.security.crypto.password.PasswordEncoder;
 import org.springframework.security.oauth2.client.registration.ClientRegistration;
 import org.springframework.security.oauth2.client.registration.ClientRegistrationRepository;
 import org.springframework.security.oauth2.client.registration.ClientRegistrations;
 import org.springframework.security.oauth2.client.registration.InMemoryClientRegistrationRepository;
-import org.springframework.security.oauth2.core.user.OAuth2User;
 import org.springframework.security.oauth2.core.user.OAuth2UserAuthority;
 import org.springframework.security.web.SecurityFilterChain;
-import org.springframework.security.web.authentication.AuthenticationSuccessHandler;
 import org.springframework.security.web.authentication.UsernamePasswordAuthenticationFilter;
 import org.springframework.security.web.authentication.rememberme.PersistentTokenRepository;
 import org.springframework.security.web.savedrequest.NullRequestCache;
 import org.springframework.security.web.util.matcher.AntPathRequestMatcher;

-import jakarta.servlet.ServletException;
-import jakarta.servlet.http.HttpServletRequest;
-import jakarta.servlet.http.HttpServletResponse;
-import jakarta.servlet.http.HttpSession;
+import stirling.software.SPDF.config.security.oauth2.CustomOAuth2AuthenticationFailureHandler;
+import stirling.software.SPDF.config.security.oauth2.CustomOAuth2AuthenticationSuccessHandler;
+import stirling.software.SPDF.config.security.oauth2.CustomOAuth2LogoutSuccessHandler;
+import stirling.software.SPDF.config.security.oauth2.CustomOAuth2UserService;
 import stirling.software.SPDF.model.ApplicationProperties;
+import stirling.software.SPDF.model.ApplicationProperties.Security.OAUTH2;
 import stirling.software.SPDF.model.User;
 import stirling.software.SPDF.repository.JPATokenRepositoryImpl;

@ -49,7 +45,7 @@ import stirling.software.SPDF.repository.JPATokenRepositoryImpl;
@EnableMethodSecurity
 public class SecurityConfiguration {

-    @Autowired private UserDetailsService userDetailsService;
+    @Autowired private CustomUserDetailsService userDetailsService;

    @Bean
    public PasswordEncoder passwordEncoder() {
@ -111,18 +107,7 @@ public class SecurityConfiguration {
                                                    new AntPathRequestMatcher("/logout"))
                                            .logoutSuccessHandler(new CustomLogoutSuccessHandler())
                                            .invalidateHttpSession(true) // Invalidate session
-                                            .deleteCookies("JSESSIONID", "remember-me")
-                                            .addLogoutHandler(
-                                                    (request, response, authentication) -> {
-                                                        HttpSession session =
-                                                                request.getSession(false);
-                                                        if (session != null) {
-                                                            String sessionId = session.getId();
-                                                            sessionRegistry()
-                                                                    .removeSessionInformation(
-                                                                            sessionId);
-                                                        }
-                                                    }))
+                                            .deleteCookies("JSESSIONID", "remember-me"))
                    .rememberMe(
                            rememberMeConfigurer ->
                                    rememberMeConfigurer // Use the configurator directly
@ -168,43 +153,33 @@ public class SecurityConfiguration {
            if (applicationProperties.getSecurity().getOAUTH2().getEnabled()) {

                http.oauth2Login(
-                        oauth2 ->
-                                oauth2.loginPage("/oauth2")
-                                        /*
-                                        This Custom handler is used to check if the OAUTH2 user trying to log in, already exists in the database.
-                                        If user exists, login proceeds as usual. If user does not exist, then it is autocreated but only if 'OAUTH2AutoCreateUser'
-                                        is set as true, else login fails with an error message advising the same.
-                                         */
-                                        .successHandler(
-                                                new AuthenticationSuccessHandler() {
-                                                    @Override
-                                                    public void onAuthenticationSuccess(
-                                                            HttpServletRequest request,
-                                                            HttpServletResponse response,
-                                                            Authentication authentication)
-                                                            throws ServletException, IOException {
-                                                        OAuth2User oauthUser =
-                                                                (OAuth2User)
-                                                                        authentication
-                                                                                .getPrincipal();
-                                                        if (userService.processOAuth2PostLogin(
-                                                                oauthUser.getAttribute("email"),
-                                                                applicationProperties
-                                                                        .getSecurity()
-                                                                        .getOAUTH2()
-                                                                        .getAutoCreateUser())) {
-                                                            response.sendRedirect("/");
-                                                        } else {
-                                                            response.sendRedirect(
-                                                                    "/logout?oauth2AutoCreateDisabled=true");
-                                                        }
-                                                    }
-                                                })
-                                        // Add existing Authorities from the database
-                                        .userInfoEndpoint(
-                                                userInfoEndpoint ->
-                                                        userInfoEndpoint.userAuthoritiesMapper(
-                                                                userAuthoritiesMapper())));
+                                oauth2 ->
+                                        oauth2.loginPage("/oauth2")
+                                                /*
+                                                This Custom handler is used to check if the OAUTH2 user trying to log in, already exists in the database.
+                                                If user exists, login proceeds as usual. If user does not exist, then it is autocreated but only if 'OAUTH2AutoCreateUser'
+                                                is set as true, else login fails with an error message advising the same.
+                                                 */
+                                                .successHandler(
+                                                        new CustomOAuth2AuthenticationSuccessHandler(
+                                                                applicationProperties, userService))
+                                                .failureHandler(
+                                                        new CustomOAuth2AuthenticationFailureHandler())
+                                                // Add existing Authorities from the database
+                                                .userInfoEndpoint(
+                                                        userInfoEndpoint ->
+                                                                userInfoEndpoint
+                                                                        .oidcUserService(
+                                                                                new CustomOAuth2UserService(
+                                                                                        applicationProperties))
+                                                                        .userAuthoritiesMapper(
+                                                                                userAuthoritiesMapper())))
+                        .userDetailsService(userDetailsService)
+                        .logout(
+                                logout ->
+                                        logout.logoutSuccessHandler(
+                                                new CustomOAuth2LogoutSuccessHandler(
+                                                        this.applicationProperties)));
            }
        } else {
            http.csrf(csrf -> csrf.disable())
@ -225,13 +200,13 @@ public class SecurityConfiguration {
    }

    private ClientRegistration oidcClientRegistration() {
-        return ClientRegistrations.fromOidcIssuerLocation(
-                        applicationProperties.getSecurity().getOAUTH2().getIssuer())
+        OAUTH2 oauth = applicationProperties.getSecurity().getOAUTH2();
+        return ClientRegistrations.fromIssuerLocation(oauth.getIssuer())
                .registrationId("oidc")
-                .clientId(applicationProperties.getSecurity().getOAUTH2().getClientId())
-                .clientSecret(applicationProperties.getSecurity().getOAUTH2().getClientSecret())
-                .scope("openid", "profile", "email")
-                .userNameAttributeName("email")
+                .clientId(oauth.getClientId())
+                .clientSecret(oauth.getClientSecret())
+                .scope(oauth.getScopes())
+                .userNameAttributeName(oauth.getUseAsUsername())
                .clientName("OIDC")
                .build();
    }
@ -256,9 +231,14 @@ public class SecurityConfiguration {

                        // Add Authorities from database for existing user, if user is present.
                        if (authority instanceof OAuth2UserAuthority oauth2Auth) {
+                            String useAsUsername =
+                                    applicationProperties
+                                            .getSecurity()
+                                            .getOAUTH2()
+                                            .getUseAsUsername();
                            Optional<User> userOpt =
                                    userService.findByUsernameIgnoreCase(
-                                            (String) oauth2Auth.getAttributes().get("email"));
+                                            (String) oauth2Auth.getAttributes().get(useAsUsername));
                            if (userOpt.isPresent()) {
                                User user = userOpt.get();
                                if (user != null) {
--- a/src/main/java/stirling/software/SPDF/config/security/UserService.java
+++ b/src/main/java/stirling/software/SPDF/config/security/UserService.java
@ -8,6 +8,8 @@ import java.util.UUID;
 import java.util.stream.Collectors;

 import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.context.MessageSource;
+import org.springframework.context.i18n.LocaleContextHolder;
 import org.springframework.security.authentication.UsernamePasswordAuthenticationToken;
 import org.springframework.security.core.Authentication;
 import org.springframework.security.core.GrantedAuthority;
@ -18,6 +20,7 @@ import org.springframework.security.crypto.password.PasswordEncoder;
 import org.springframework.stereotype.Service;

 import stirling.software.SPDF.controller.api.pipeline.UserServiceInterface;
+import stirling.software.SPDF.model.AuthenticationType;
 import stirling.software.SPDF.model.Authority;
 import stirling.software.SPDF.model.Role;
 import stirling.software.SPDF.model.User;
@ -33,19 +36,19 @@ public class UserService implements UserServiceInterface {

    @Autowired private PasswordEncoder passwordEncoder;

+    @Autowired private MessageSource messageSource;
+
    // Handle OAUTH2 login and user auto creation.
    public boolean processOAuth2PostLogin(String username, boolean autoCreateUser) {
+        if (!isUsernameValidWithReturn(username).equals(username)) {
+            return false;
+        }
        Optional<User> existUser = userRepository.findByUsernameIgnoreCase(username);
        if (existUser.isPresent()) {
            return true;
        }
        if (autoCreateUser) {
-            User user = new User();
-            user.setUsername(username);
-            user.setEnabled(true);
-            user.setFirstLogin(false);
-            user.addAuthority(new Authority(Role.USER.getRoleId(), user));
-            userRepository.save(user);
+            saveUser(username, AuthenticationType.OAUTH2);
            return true;
        }
        return false;
@ -128,30 +131,46 @@ public class UserService implements UserServiceInterface {
        return userOpt.isPresent() && userOpt.get().getApiKey().equals(apiKey);
    }

-    public void saveUser(String username, String password) {
+    public void saveUser(String username, AuthenticationType authenticationType)
+            throws IllegalArgumentException {
        User user = new User();
-        user.setUsername(username);
-        user.setPassword(passwordEncoder.encode(password));
+        user.setUsername(isUsernameValidWithReturn(username));
        user.setEnabled(true);
+        user.setFirstLogin(false);
+        user.addAuthority(new Authority(Role.USER.getRoleId(), user));
+        user.setAuthenticationType(authenticationType);
        userRepository.save(user);
    }

-    public void saveUser(String username, String password, String role, boolean firstLogin) {
+    public void saveUser(String username, String password) throws IllegalArgumentException {
        User user = new User();
-        user.setUsername(username);
+        user.setUsername(isUsernameValidWithReturn(username));
+        user.setPassword(passwordEncoder.encode(password));
+        user.setEnabled(true);
+        user.setAuthenticationType(AuthenticationType.WEB);
+        userRepository.save(user);
+    }
+
+    public void saveUser(String username, String password, String role, boolean firstLogin)
+            throws IllegalArgumentException {
+        User user = new User();
+        user.setUsername(isUsernameValidWithReturn(username));
        user.setPassword(passwordEncoder.encode(password));
        user.addAuthority(new Authority(role, user));
        user.setEnabled(true);
+        user.setAuthenticationType(AuthenticationType.WEB);
        user.setFirstLogin(firstLogin);
        userRepository.save(user);
    }

-    public void saveUser(String username, String password, String role) {
+    public void saveUser(String username, String password, String role)
+            throws IllegalArgumentException {
        User user = new User();
-        user.setUsername(username);
+        user.setUsername(isUsernameValidWithReturn(username));
        user.setPassword(passwordEncoder.encode(password));
        user.addAuthority(new Authority(role, user));
        user.setEnabled(true);
+        user.setAuthenticationType(AuthenticationType.WEB);
        user.setFirstLogin(false);
        userRepository.save(user);
    }
@ -209,8 +228,8 @@ public class UserService implements UserServiceInterface {
        return authorityRepository.findByUserId(user.getId());
    }

-    public void changeUsername(User user, String newUsername) {
-        user.setUsername(newUsername);
+    public void changeUsername(User user, String newUsername) throws IllegalArgumentException {
+        user.setUsername(isUsernameValidWithReturn(newUsername));
        userRepository.save(user);
    }

@ -235,6 +254,40 @@ public class UserService implements UserServiceInterface {
    }

    public boolean isUsernameValid(String username) {
-        return username.matches("[a-zA-Z0-9]+");
+        // Checks whether the simple username is formatted correctly
+        boolean isValidSimpleUsername =
+                username.matches("^[a-zA-Z0-9][a-zA-Z0-9@._+-]*[a-zA-Z0-9]$");
+        // Checks whether the email address is formatted correctly
+        boolean isValidEmail =
+                username.matches(
+                        "^(?=.{1,64}@)[A-Za-z0-9]+(\\.[A-Za-z0-9_+.-]+)*@[^-][A-Za-z0-9-]+(\\.[A-Za-z0-9-]+)*(\\.[A-Za-z]{2,})$");
+        return isValidSimpleUsername || isValidEmail;
+    }
+
+    public String isUsernameValidWithReturn(String username) throws IllegalArgumentException {
+        if (!isUsernameValid(username)) {
+            String message =
+                    messageSource.getMessage(
+                            "invalidUsernameMessage", null, LocaleContextHolder.getLocale());
+            throw new IllegalArgumentException(message);
+        }
+        return username;
+    }
+
+    public boolean hasPassword(String username) {
+        Optional<User> user = userRepository.findByUsernameIgnoreCase(username);
+        if (user.isPresent() && user.get().hasPassword()) {
+            return true;
+        }
+        return false;
+    }
+
+    public boolean isAuthenticationTypeByUsername(
+            String username, AuthenticationType authenticationType) {
+        Optional<User> user = userRepository.findByUsernameIgnoreCase(username);
+        if (user.isPresent() && user.get().getAuthenticationType() != null) {
+            return user.get().getAuthenticationType().equalsIgnoreCase(authenticationType.name());
+        }
+        return false;
    }
 }
--- a/src/main/java/stirling/software/SPDF/config/security/oauth2/CustomOAuth2AuthenticationFailureHandler.java
+++ b/src/main/java/stirling/software/SPDF/config/security/oauth2/CustomOAuth2AuthenticationFailureHandler.java
@ -0,0 +1,40 @@
+package stirling.software.SPDF.config.security.oauth2;
+
+import java.io.IOException;
+
+import org.springframework.security.authentication.LockedException;
+import org.springframework.security.core.AuthenticationException;
+import org.springframework.security.core.userdetails.UsernameNotFoundException;
+import org.springframework.security.oauth2.core.OAuth2AuthenticationException;
+import org.springframework.security.oauth2.core.OAuth2Error;
+import org.springframework.security.web.authentication.SimpleUrlAuthenticationFailureHandler;
+import org.springframework.stereotype.Component;
+
+import jakarta.servlet.ServletException;
+import jakarta.servlet.http.HttpServletRequest;
+import jakarta.servlet.http.HttpServletResponse;
+
+@Component
+public class CustomOAuth2AuthenticationFailureHandler
+        extends SimpleUrlAuthenticationFailureHandler {
+
+    @Override
+    public void onAuthenticationFailure(
+            HttpServletRequest request,
+            HttpServletResponse response,
+            AuthenticationException exception)
+            throws IOException, ServletException {
+        if (exception instanceof OAuth2AuthenticationException) {
+            OAuth2Error error = ((OAuth2AuthenticationException) exception).getError();
+            getRedirectStrategy()
+                    .sendRedirect(request, response, "/login?error=oAuth::" + error.getErrorCode());
+        } else if (exception instanceof LockedException) {
+            getRedirectStrategy().sendRedirect(request, response, "/login?error=locked");
+        } else if (exception instanceof UsernameNotFoundException) {
+            getRedirectStrategy()
+                    .sendRedirect(request, response, "/login?error=oauth2AuthenticationError");
+        } else {
+            super.onAuthenticationFailure(request, response, exception);
+        }
+    }
+}
--- a/src/main/java/stirling/software/SPDF/config/security/oauth2/CustomOAuth2AuthenticationSuccessHandler.java
+++ b/src/main/java/stirling/software/SPDF/config/security/oauth2/CustomOAuth2AuthenticationSuccessHandler.java
@ -0,0 +1,74 @@
+package stirling.software.SPDF.config.security.oauth2;
+
+import java.io.IOException;
+
+import org.springframework.security.core.Authentication;
+import org.springframework.security.oauth2.core.user.OAuth2User;
+import org.springframework.security.web.authentication.SavedRequestAwareAuthenticationSuccessHandler;
+import org.springframework.security.web.savedrequest.SavedRequest;
+import org.springframework.stereotype.Component;
+
+import jakarta.servlet.ServletException;
+import jakarta.servlet.http.HttpServletRequest;
+import jakarta.servlet.http.HttpServletResponse;
+import jakarta.servlet.http.HttpSession;
+import stirling.software.SPDF.config.security.UserService;
+import stirling.software.SPDF.model.ApplicationProperties;
+import stirling.software.SPDF.model.ApplicationProperties.Security.OAUTH2;
+import stirling.software.SPDF.model.AuthenticationType;
+import stirling.software.SPDF.utils.RequestUriUtils;
+
+@Component
+public class CustomOAuth2AuthenticationSuccessHandler
+        extends SavedRequestAwareAuthenticationSuccessHandler {
+
+    ApplicationProperties applicationProperties;
+    UserService userService;
+
+    public CustomOAuth2AuthenticationSuccessHandler(
+            ApplicationProperties applicationProperties, UserService userService) {
+        this.applicationProperties = applicationProperties;
+        this.userService = userService;
+    }
+
+    @Override
+    public void onAuthenticationSuccess(
+            HttpServletRequest request, HttpServletResponse response, Authentication authentication)
+            throws ServletException, IOException {
+
+        OAuth2User oauthUser = (OAuth2User) authentication.getPrincipal();
+
+        // Get the saved request
+        HttpSession session = request.getSession(false);
+        SavedRequest savedRequest =
+                session != null
+                        ? (SavedRequest) session.getAttribute("SPRING_SECURITY_SAVED_REQUEST")
+                        : null;
+        if (savedRequest != null
+                && !RequestUriUtils.isStaticResource(savedRequest.getRedirectUrl())) {
+            // Redirect to the original destination
+            super.onAuthenticationSuccess(request, response, authentication);
+        } else {
+            OAUTH2 oAuth = applicationProperties.getSecurity().getOAUTH2();
+            String username = oauthUser.getAttribute(oAuth.getUseAsUsername());
+            if (userService.usernameExistsIgnoreCase(username)
+                    && userService.hasPassword(username)
+                    && !userService.isAuthenticationTypeByUsername(
+                            username, AuthenticationType.OAUTH2)
+                    && oAuth.getAutoCreateUser()) {
+                response.sendRedirect(
+                        request.getContextPath() + "/logout?oauth2AuthenticationError=true");
+                return;
+            } else {
+                try {
+                    userService.processOAuth2PostLogin(username, oAuth.getAutoCreateUser());
+                    response.sendRedirect("/");
+                    return;
+                } catch (IllegalArgumentException e) {
+                    response.sendRedirect("/logout?invalidUsername=true");
+                    return;
+                }
+            }
+        }
+    }
+}
--- a/src/main/java/stirling/software/SPDF/config/security/oauth2/CustomOAuth2LogoutSuccessHandler.java
+++ b/src/main/java/stirling/software/SPDF/config/security/oauth2/CustomOAuth2LogoutSuccessHandler.java
@ -0,0 +1,87 @@
+package stirling.software.SPDF.config.security.oauth2;
+
+import java.io.IOException;
+
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.security.core.Authentication;
+import org.springframework.security.core.session.SessionRegistry;
+import org.springframework.security.core.userdetails.UserDetails;
+import org.springframework.security.oauth2.core.user.OAuth2User;
+import org.springframework.security.web.authentication.logout.SimpleUrlLogoutSuccessHandler;
+import org.springframework.stereotype.Component;
+
+import jakarta.servlet.ServletException;
+import jakarta.servlet.http.HttpServletRequest;
+import jakarta.servlet.http.HttpServletResponse;
+import jakarta.servlet.http.HttpSession;
+import stirling.software.SPDF.model.ApplicationProperties;
+import stirling.software.SPDF.model.ApplicationProperties.Security.OAUTH2;
+
+@Component
+public class CustomOAuth2LogoutSuccessHandler extends SimpleUrlLogoutSuccessHandler {
+
+    @Autowired SessionRegistry sessionRegistry;
+
+    private ApplicationProperties applicationProperties;
+
+    public CustomOAuth2LogoutSuccessHandler(ApplicationProperties applicationProperties) {
+        this.applicationProperties = applicationProperties;
+    }
+
+    @Override
+    public void onLogoutSuccess(
+            HttpServletRequest request, HttpServletResponse response, Authentication authentication)
+            throws IOException, ServletException {
+
+        boolean isOAuthUser = true;
+        String param = "logout=true";
+        if (authentication == null) {
+            response.sendRedirect("/");
+            return;
+        }
+        Object pri = authentication.getPrincipal();
+        if (pri instanceof UserDetails) {
+            UserDetails userDetails = (UserDetails) pri;
+            isOAuthUser = userDetails.getPassword() == null;
+        } else if (pri instanceof OAuth2User) {
+            isOAuthUser = true;
+        }
+
+        OAUTH2 oauth = applicationProperties.getSecurity().getOAUTH2();
+        String provider = oauth.getProvider() != null && isOAuthUser ? oauth.getProvider() : "";
+
+        if (request.getParameter("oauth2AuthenticationError") != null) {
+            param = "error=oauth2AuthenticationError";
+        } else if (request.getParameter("invalidUsername") != null) {
+            param = "error=invalidUsername";
+        }
+        HttpSession session = request.getSession(false);
+        if (session != null) {
+            String sessionId = session.getId();
+            sessionRegistry.removeSessionInformation(sessionId);
+        }
+
+        switch (provider) {
+            case "keycloak":
+                String logoutUrl =
+                        oauth.getIssuer()
+                                + "/protocol/openid-connect/logout"
+                                + "?client_id="
+                                + oauth.getClientId()
+                                + "&post_logout_redirect_uri="
+                                + response.encodeRedirectURL(
+                                        "http://" + request.getHeader("host") + "/login?" + param);
+                response.sendRedirect(logoutUrl);
+                break;
+            case "google":
+            default:
+                if (request.getParameter("oauth2AutoCreateDisabled") != null) {
+                    response.sendRedirect(
+                            request.getContextPath() + "/login?error=oauth2AutoCreateDisabled");
+                } else {
+                    response.sendRedirect(request.getContextPath() + "/login?logout=true");
+                }
+                break;
+        }
+    }
+}
--- a/src/main/java/stirling/software/SPDF/config/security/oauth2/CustomOAuth2UserService.java
+++ b/src/main/java/stirling/software/SPDF/config/security/oauth2/CustomOAuth2UserService.java
@ -0,0 +1,52 @@
+package stirling.software.SPDF.config.security.oauth2;
+
+import java.util.HashMap;
+import java.util.Map;
+
+import org.springframework.security.oauth2.client.oidc.userinfo.OidcUserRequest;
+import org.springframework.security.oauth2.client.oidc.userinfo.OidcUserService;
+import org.springframework.security.oauth2.client.userinfo.OAuth2UserService;
+import org.springframework.security.oauth2.core.OAuth2AuthenticationException;
+import org.springframework.security.oauth2.core.OAuth2Error;
+import org.springframework.security.oauth2.core.oidc.user.DefaultOidcUser;
+import org.springframework.security.oauth2.core.oidc.user.OidcUser;
+
+import stirling.software.SPDF.model.ApplicationProperties;
+
+public class CustomOAuth2UserService implements OAuth2UserService<OidcUserRequest, OidcUser> {
+
+    private final OidcUserService delegate = new OidcUserService();
+
+    private ApplicationProperties applicationProperties;
+
+    public CustomOAuth2UserService(ApplicationProperties applicationProperties) {
+        this.applicationProperties = applicationProperties;
+    }
+
+    @Override
+    public OidcUser loadUser(OidcUserRequest userRequest) throws OAuth2AuthenticationException {
+        String usernameAttribute =
+                applicationProperties.getSecurity().getOAUTH2().getUseAsUsername();
+        try {
+
+            OidcUser user = delegate.loadUser(userRequest);
+            Map<String, Object> attributes = new HashMap<>(user.getAttributes());
+
+            // Ensure the preferred username attribute is present
+            if (!attributes.containsKey(usernameAttribute)) {
+                attributes.put(usernameAttribute, attributes.getOrDefault("email", ""));
+                usernameAttribute = "email";
+            }
+
+            // Return a new OidcUser with adjusted attributes
+            return new DefaultOidcUser(
+                    user.getAuthorities(),
+                    userRequest.getIdToken(),
+                    user.getUserInfo(),
+                    usernameAttribute);
+        } catch (java.lang.IllegalArgumentException e) {
+            throw new OAuth2AuthenticationException(
+                    new OAuth2Error(e.getMessage()), e.getMessage(), e);
+        }
+    }
+}
--- a/src/main/java/stirling/software/SPDF/config/security/oauth2/CustomOAuthUserService.java
+++ b/src/main/java/stirling/software/SPDF/config/security/oauth2/CustomOAuthUserService.java
@ -0,0 +1,57 @@
+package stirling.software.SPDF.config.security.oauth2;
+
+import java.util.HashMap;
+import java.util.Map;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.security.oauth2.client.oidc.userinfo.OidcUserRequest;
+import org.springframework.security.oauth2.client.oidc.userinfo.OidcUserService;
+import org.springframework.security.oauth2.client.userinfo.OAuth2UserService;
+import org.springframework.security.oauth2.core.OAuth2AuthenticationException;
+import org.springframework.security.oauth2.core.OAuth2Error;
+import org.springframework.security.oauth2.core.oidc.user.DefaultOidcUser;
+import org.springframework.security.oauth2.core.oidc.user.OidcUser;
+
+import stirling.software.SPDF.model.ApplicationProperties;
+
+public class CustomOAuthUserService implements OAuth2UserService<OidcUserRequest, OidcUser> {
+
+    private static final Logger logger = LoggerFactory.getLogger(CustomOAuthUserService.class);
+
+    private final OidcUserService delegate = new OidcUserService();
+
+    private ApplicationProperties applicationProperties;
+
+    public CustomOAuthUserService(ApplicationProperties applicationProperties) {
+        this.applicationProperties = applicationProperties;
+    }
+
+    @Override
+    public OidcUser loadUser(OidcUserRequest userRequest) throws OAuth2AuthenticationException {
+        String usernameAttribute =
+                applicationProperties.getSecurity().getOAUTH2().getUseAsUsername();
+        try {
+
+            OidcUser user = delegate.loadUser(userRequest);
+            Map<String, Object> attributes = new HashMap<>(user.getAttributes());
+
+            // Ensure the preferred username attribute is present
+            if (!attributes.containsKey(usernameAttribute)) {
+                attributes.put(usernameAttribute, attributes.getOrDefault("email", ""));
+                usernameAttribute = "email";
+                logger.info("Adjusted username attribute to use email");
+            }
+
+            // Return a new OidcUser with adjusted attributes
+            return new DefaultOidcUser(
+                    user.getAuthorities(),
+                    userRequest.getIdToken(),
+                    user.getUserInfo(),
+                    usernameAttribute);
+        } catch (java.lang.IllegalArgumentException e) {
+            throw new OAuth2AuthenticationException(
+                    new OAuth2Error(e.getMessage()), e.getMessage(), e);
+        }
+    }
+}
--- a/src/main/java/stirling/software/SPDF/controller/api/UserController.java
+++ b/src/main/java/stirling/software/SPDF/controller/api/UserController.java
@ -47,8 +47,11 @@ public class UserController {
            model.addAttribute("error", "Username already exists");
            return "register";
        }
-
-        userService.saveUser(requestModel.getUsername(), requestModel.getPassword());
+        try {
+            userService.saveUser(requestModel.getUsername(), requestModel.getPassword());
+        } catch (IllegalArgumentException e) {
+            return "redirect:/login?messageType=invalidUsername";
+        }
        return "redirect:/login?registered=true";
    }

@ -92,7 +95,11 @@ public class UserController {
        }

        if (newUsername != null && newUsername.length() > 0) {
-            userService.changeUsername(user, newUsername);
+            try {
+                userService.changeUsername(user, newUsername);
+            } catch (IllegalArgumentException e) {
+                return new RedirectView("/account?messageType=invalidUsername");
+            }
        }

        // Logout using Spring's utility
--- a/src/main/java/stirling/software/SPDF/controller/web/AccountWebController.java
+++ b/src/main/java/stirling/software/SPDF/controller/web/AccountWebController.java
@ -109,8 +109,9 @@ public class AccountWebController {
                OAuth2User userDetails = (OAuth2User) principal;

                // Retrieve username and other attributes
-                username = userDetails.getAttribute("email");
-
+                username =
+                        userDetails.getAttribute(
+                                applicationProperties.getSecurity().getOAUTH2().getUseAsUsername());
                // Add oAuth2 Login attributes to the model
                model.addAttribute("oAuth2Login", true);
            }
--- a/src/main/java/stirling/software/SPDF/model/ApplicationProperties.java
+++ b/src/main/java/stirling/software/SPDF/model/ApplicationProperties.java
@ -1,6 +1,10 @@
 package stirling.software.SPDF.model;

+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collection;
 import java.util.List;
+import java.util.stream.Collectors;

 import org.springframework.boot.context.properties.ConfigurationProperties;
 import org.springframework.context.annotation.Configuration;
@ -221,6 +225,10 @@ public class ApplicationProperties {
            private String clientId;
            private String clientSecret;
            private boolean autoCreateUser;
+            private String useAsUsername;
+            private String provider;
+
+            private Collection<String> scopes = new ArrayList<String>();

            public boolean getEnabled() {
                return enabled;
@ -262,6 +270,37 @@ public class ApplicationProperties {
                this.autoCreateUser = autoCreateUser;
            }

+            public String getUseAsUsername() {
+                if (useAsUsername != null && useAsUsername.trim().length() > 0) {
+                    return useAsUsername;
+                }
+                return "email";
+            }
+
+            public void setUseAsUsername(String useAsUsername) {
+                this.useAsUsername = useAsUsername;
+            }
+
+            public String getProvider() {
+                return provider;
+            }
+
+            public void setProvider(String provider) {
+                this.provider = provider;
+            }
+
+            public Collection<String> getScopes() {
+                return scopes;
+            }
+
+            public void setScopes(String scpoes) {
+                List<String> scopesList =
+                        Arrays.stream(scpoes.split(","))
+                                .map(String::trim)
+                                .collect(Collectors.toList());
+                this.scopes.addAll(scopesList);
+            }
+
            @Override
            public String toString() {
                return "OAUTH2 [enabled="
@ -274,6 +313,12 @@ public class ApplicationProperties {
                        + (clientSecret != null && !clientSecret.isEmpty() ? "MASKED" : "NULL")
                        + ", autoCreateUser="
                        + autoCreateUser
+                        + ", useAsUsername="
+                        + useAsUsername
+                        + ", provider"
+                        + provider
+                        + ", scopes="
+                        + scopes
                        + "]";
            }
        }
--- a/src/main/java/stirling/software/SPDF/model/AuthenticationType.java
+++ b/src/main/java/stirling/software/SPDF/model/AuthenticationType.java
@ -0,0 +1,6 @@
+package stirling.software.SPDF.model;
+
+public enum AuthenticationType {
+    WEB,
+    OAUTH2
+}
--- a/src/main/java/stirling/software/SPDF/model/User.java
+++ b/src/main/java/stirling/software/SPDF/model/User.java
@ -47,6 +47,9 @@ public class User {
    @Column(name = "roleName")
    private String roleName;

+    @Column(name = "authenticationtype")
+    private String authenticationType;
+
    @OneToMany(fetch = FetchType.EAGER, cascade = CascadeType.ALL, mappedBy = "user")
    private Set<Authority> authorities = new HashSet<>();

@ -116,6 +119,14 @@ public class User {
        this.enabled = enabled;
    }

+    public void setAuthenticationType(AuthenticationType authenticationType) {
+        this.authenticationType = authenticationType.toString().toLowerCase();
+    }
+
+    public String getAuthenticationType() {
+        return authenticationType;
+    }
+
    public Set<Authority> getAuthorities() {
        return authorities;
    }
@ -137,4 +148,8 @@ public class User {
                .map(Authority::getAuthority)
                .collect(Collectors.joining(", "));
    }
+
+    public boolean hasPassword() {
+        return this.getPassword() != "" ? true : false;
+    }
 }
--- a/src/main/resources/messages_ar_AR.properties
+++ b/src/main/resources/messages_ar_AR.properties
@ -54,11 +54,12 @@ notAuthenticatedMessage=User not authenticated.
 userNotFoundMessage=User not found.
 incorrectPasswordMessage=Current password is incorrect.
 usernameExistsMessage=New Username already exists.
-invalidUsernameMessage=Invalid username, Username must only contain alphabet characters and numbers.
+invalidUsernameMessage=Invalid username, username can only contain letters, numbers and the following special characters @._+- or must be a valid email address.
 deleteCurrentUserMessage=Cannot delete currently logged in user.
 deleteUsernameExistsMessage=The username does not exist and cannot be deleted.
 downgradeCurrentUserMessage=لا يمكن خفض دور المستخدم الحالي
 downgradeCurrentUserLongMessage=لا يمكن تخفيض دور المستخدم الحالي. وبالتالي، لن يظهر المستخدم الحالي.
+userAlreadyExistsMessage=OAuth2: User already exists.
 error=Error
 oops=Oops!
 help=Help
@ -164,7 +165,7 @@ adminUserSettings.header=Admin User Control Settings
 adminUserSettings.admin=Admin
 adminUserSettings.user=User
 adminUserSettings.addUser=Add New User
-adminUserSettings.usernameInfo=Username must only contain letters and numbers, no spaces or special characters.
+adminUserSettings.usernameInfo=Username can only contain letters, numbers and the following special characters @._+- or must be a valid email address.
 adminUserSettings.roles=Roles
 adminUserSettings.role=Role
 adminUserSettings.actions=Actions
@ -176,6 +177,7 @@ adminUserSettings.internalApiUser=Internal API User
 adminUserSettings.forceChange=Force user to change password on login
 adminUserSettings.submit=Save User
 adminUserSettings.changeUserRole=تغيير دور المستخدم
+adminUserSettings.authenticated=Authentication type

 #############
 # HOME-PAGE #
--- a/src/main/resources/messages_bg_BG.properties
+++ b/src/main/resources/messages_bg_BG.properties
@ -54,11 +54,12 @@ notAuthenticatedMessage=Потребителят не е автентикира
 userNotFoundMessage=Потребителят не е намерен
 incorrectPasswordMessage=Текущата парола е неправилна.
 usernameExistsMessage=Новият потребител вече съществува.
-invalidUsernameMessage=Невалидно потребителско име, потребителското име трябва да съдържа само букви и цифри.
+invalidUsernameMessage=Невалидно потребителско име, потребителското име може да съдържа само букви, цифри и следните специални знаци @._+- или трябва да е валиден имейл адрес.
 deleteCurrentUserMessage=Не може да се изтрие вписания в момента потребител.
 deleteUsernameExistsMessage=Потребителското име не съществува и не може да бъде изтрито.
 downgradeCurrentUserMessage=Не може да се понижи ролята на текущия потребител
 downgradeCurrentUserLongMessage=Не може да се понижи ролята на текущия потребител. Следователно текущият потребител няма да бъде показан.
+userAlreadyExistsMessage=OAuth2: User already exists.
 error=Грешка
 oops=Опаа!
 help=Помощ
@ -164,7 +165,7 @@ adminUserSettings.header=Настройки за администраторск
 adminUserSettings.admin=Администратор
 adminUserSettings.user=Потребител
 adminUserSettings.addUser=Добавяне на нов потребител
-adminUserSettings.usernameInfo=Потребителското име трябва да съдържа само букви и цифри, без интервали или специални знаци.
+adminUserSettings.usernameInfo=Потребителското име може да съдържа само букви, цифри и следните специални символи @._+- или трябва да е валиден имейл адрес.
 adminUserSettings.roles=Роли
 adminUserSettings.role=Роля
 adminUserSettings.actions=Действия
@ -176,6 +177,7 @@ adminUserSettings.internalApiUser=Вътрешен API потребител
 adminUserSettings.forceChange=Принудете потребителя да промени потребителското име/парола при влизане
 adminUserSettings.submit=Съхранете потребителя
 adminUserSettings.changeUserRole=Промяна на ролята на потребителя
+adminUserSettings.authenticated=Authentication type

 #############
 # HOME-PAGE #
--- a/src/main/resources/messages_ca_CA.properties
+++ b/src/main/resources/messages_ca_CA.properties
@ -54,11 +54,12 @@ notAuthenticatedMessage=User not authenticated.
 userNotFoundMessage=User not found.
 incorrectPasswordMessage=Current password is incorrect.
 usernameExistsMessage=New Username already exists.
-invalidUsernameMessage=Invalid username, Username must only contain alphabet characters and numbers.
+invalidUsernameMessage=Invalid username, username can only contain letters, numbers and the following special characters @._+- or must be a valid email address.
 deleteCurrentUserMessage=Cannot delete currently logged in user.
 deleteUsernameExistsMessage=The username does not exist and cannot be deleted.
 downgradeCurrentUserMessage=No es pot reduir la funció de l'usuari actual
 downgradeCurrentUserLongMessage=No es pot baixar la funció de l'usuari actual. Per tant, no es mostrarà l'usuari actual.
+userAlreadyExistsMessage=OAuth2: User already exists.
 error=Error
 oops=Oops!
 help=Help
@ -164,7 +165,7 @@ adminUserSettings.header=Usuari Admin Opcions Control
 adminUserSettings.admin=Admin
 adminUserSettings.user=Usuari
 adminUserSettings.addUser=Afegir Usuari
-adminUserSettings.usernameInfo=Username must only contain letters and numbers, no spaces or special characters.
+adminUserSettings.usernameInfo=Username can only contain letters, numbers and the following special characters @._+- or must be a valid email address.
 adminUserSettings.roles=Rols
 adminUserSettings.role=Rol
 adminUserSettings.actions=Accions
@ -176,6 +177,7 @@ adminUserSettings.internalApiUser=Internal API User
 adminUserSettings.forceChange=Force user to change password on login
 adminUserSettings.submit=Desar Usuari
 adminUserSettings.changeUserRole=Canvia el rol de l'usuari
+adminUserSettings.authenticated=Authentication type

 #############
 # HOME-PAGE #
--- a/src/main/resources/messages_de_DE.properties
+++ b/src/main/resources/messages_de_DE.properties
@ -54,11 +54,12 @@ notAuthenticatedMessage=Benutzer nicht authentifiziert.
 userNotFoundMessage=Benutzer nicht gefunden.
 incorrectPasswordMessage=Das Passwort ist falsch.
 usernameExistsMessage=Neuer Benutzername existiert bereits.
-invalidUsernameMessage=Ungültiger Benutzername. Der Benutzername darf nur Buchstaben und Zahlen enthalten.
+invalidUsernameMessage=Ungültiger Benutzername. Der Benutzername darf nur Buchstaben, Zahlen und die folgenden Sonderzeichen @._+- enthalten oder muss eine gültige E-Mail-Adresse sein.
 deleteCurrentUserMessage=Der aktuell angemeldete Benutzer kann nicht gelöscht werden.
 deleteUsernameExistsMessage=Der Benutzername existiert nicht und kann nicht gelöscht werden.
 downgradeCurrentUserMessage=Die Rolle des aktuellen Benutzers kann nicht herabgestuft werden
 downgradeCurrentUserLongMessage=Die Rolle des aktuellen Benutzers kann nicht herabgestuft werden. Daher wird der aktuelle Benutzer nicht angezeigt.
+userAlreadyExistsMessage=OAuth2: User already exists.
 error=Fehler
 oops=Hoppla!
 help=Hilfe
@ -164,7 +165,7 @@ adminUserSettings.header=Administrator-Benutzerkontrolle
 adminUserSettings.admin=Administrator
 adminUserSettings.user=Benutzer
 adminUserSettings.addUser=Neuen Benutzer hinzufügen
-adminUserSettings.usernameInfo=Der Benutzername darf nur Buchstaben und Zahlen enthalten, keine Leerzeichen oder Sonderzeichen.
+adminUserSettings.usernameInfo=Der Benutzername darf nur Buchstaben, Zahlen und die folgenden Sonderzeichen @._+- enthalten oder muss eine gültige E-Mail-Adresse sein.
 adminUserSettings.roles=Rollen
 adminUserSettings.role=Rolle
 adminUserSettings.actions=Aktion
@ -176,6 +177,7 @@ adminUserSettings.internalApiUser=Interner API-Benutzer
 adminUserSettings.forceChange=Benutzer dazu zwingen, Benutzernamen/Passwort bei der Anmeldung zu ändern
 adminUserSettings.submit=Benutzer speichern
 adminUserSettings.changeUserRole=Benutzerrolle ändern
+adminUserSettings.authenticated=Authentication type

 #############
 # HOME-PAGE #
--- a/src/main/resources/messages_el_GR.properties
+++ b/src/main/resources/messages_el_GR.properties
@ -54,11 +54,12 @@ notAuthenticatedMessage=Ο χρήστης δεν έχει αυθεντικοπο
 userNotFoundMessage=Ο χρήστης δεν βρέθηκε.
 incorrectPasswordMessage=Ο τρέχων κωδικός πρόσβασης είναι λανθασμένος.
 usernameExistsMessage=Το νέο όνομα χρήστη υπάρχει ήδη.
-invalidUsernameMessage=Μη έγκυρο όνομα χρήστη, το όνομα χρήστη πρέπει να περιέχει μόνο αλφαβητικούς χαρακτήρες και αριθμούς.
+invalidUsernameMessage=Μη έγκυρο όνομα χρήστη, όνομα χρήστη μπορεί να περιέχει μόνο γράμματα, αριθμούς και τους ακόλουθους ειδικούς χαρακτήρες @._+- ή πρέπει να είναι έγκυρη διεύθυνση email.
 deleteCurrentUserMessage=Δεν είναι δυνατή η διαγραφή του τρέχοντος συνδεδεμένου χρήστη.
 deleteUsernameExistsMessage=Το όνομα χρήστη δεν υπάρχει και δεν μπορεί να διαγραφεί.
 downgradeCurrentUserMessage=Δεν είναι δυνατή η υποβάθμιση του ρόλου του τρέχοντος χρήστη
 downgradeCurrentUserLongMessage=Δεν είναι δυνατή η υποβάθμιση του ρόλου του τρέχοντος χρήστη. Ως εκ τούτου, ο τρέχων χρήστης δεν θα εμφανίζεται.
+userAlreadyExistsMessage=OAuth2: User already exists.
 error=Σφάλμα
 oops=Ωχ!
 help=Βοήθεια
@ -164,7 +165,7 @@ adminUserSettings.header=Ρυθμίσεις ελέγχου Διαχειριστ
 adminUserSettings.admin=Διαχειριστής
 adminUserSettings.user=Χρήστης
 adminUserSettings.addUser=Προσθήκη νέου Χρήστη
-adminUserSettings.usernameInfo=Username must only contain letters and numbers, no spaces or special characters.
+adminUserSettings.usernameInfo=Username can only contain letters, numbers and the following special characters @._+- or must be a valid email address.
 adminUserSettings.roles=Ρόλοι
 adminUserSettings.role=Ρόλος
 adminUserSettings.actions=Ενέργειες
@ -176,6 +177,7 @@ adminUserSettings.internalApiUser=Εσωτερικός API χρήστης
 adminUserSettings.forceChange=Αναγκάστε τον χρήστη να αλλάξει το όνομα χρήστη/κωδικό πρόσβασης κατά τη σύνδεση
 adminUserSettings.submit=Αποθήκευση Χρήστη
 adminUserSettings.changeUserRole=Αλλαγή ρόλου χρήστη
+adminUserSettings.authenticated=Authentication type

 #############
 # HOME-PAGE #
--- a/src/main/resources/messages_en_GB.properties
+++ b/src/main/resources/messages_en_GB.properties
@ -54,11 +54,12 @@ notAuthenticatedMessage=User not authenticated.
 userNotFoundMessage=User not found.
 incorrectPasswordMessage=Current password is incorrect.
 usernameExistsMessage=New Username already exists.
-invalidUsernameMessage=Invalid username, Username must only contain alphabet characters and numbers.
+invalidUsernameMessage=Invalid username, username can only contain letters, numbers and the following special characters @._+- or must be a valid email address.
 deleteCurrentUserMessage=Cannot delete currently logged in user.
 deleteUsernameExistsMessage=The username does not exist and cannot be deleted.
 downgradeCurrentUserMessage=Cannot downgrade current user's role
 downgradeCurrentUserLongMessage=Cannot downgrade current user's role. Hence, current user will not be shown.
+userAlreadyExistsMessage=OAuth2: User already exists.
 error=Error
 oops=Oops!
 help=Help
@ -164,7 +165,7 @@ adminUserSettings.header=Admin User Control Settings
 adminUserSettings.admin=Admin
 adminUserSettings.user=User
 adminUserSettings.addUser=Add New User
-adminUserSettings.usernameInfo=Username must only contain letters and numbers, no spaces or special characters.
+adminUserSettings.usernameInfo=Username can only contain letters, numbers and the following special characters @._+- or must be a valid email address.
 adminUserSettings.roles=Roles
 adminUserSettings.role=Role
 adminUserSettings.actions=Actions
@ -176,6 +177,7 @@ adminUserSettings.internalApiUser=Internal API User
 adminUserSettings.forceChange=Force user to change password on login
 adminUserSettings.submit=Save User
 adminUserSettings.changeUserRole=Change User's Role
+adminUserSettings.authenticated=Authentication type

 #############
 # HOME-PAGE #
--- a/src/main/resources/messages_en_US.properties
+++ b/src/main/resources/messages_en_US.properties
@ -54,11 +54,12 @@ notAuthenticatedMessage=User not authenticated.
 userNotFoundMessage=User not found.
 incorrectPasswordMessage=Current password is incorrect.
 usernameExistsMessage=New Username already exists.
-invalidUsernameMessage=Invalid username, Username must only contain alphabet characters and numbers.
+invalidUsernameMessage=Invalid username, username can only contain letters, numbers and the following special characters @._+- or must be a valid email address.
 deleteCurrentUserMessage=Cannot delete currently logged in user.
 deleteUsernameExistsMessage=The username does not exist and cannot be deleted.
 downgradeCurrentUserMessage=Cannot downgrade current user's role
 downgradeCurrentUserLongMessage=Cannot downgrade current user's role. Hence, current user will not be shown.
+userAlreadyExistsMessage=OAuth2: User already exists.
 error=Error
 oops=Oops!
 help=Help
@ -164,7 +165,7 @@ adminUserSettings.header=Admin User Control Settings
 adminUserSettings.admin=Admin
 adminUserSettings.user=User
 adminUserSettings.addUser=Add New User
-adminUserSettings.usernameInfo=Username must only contain letters and numbers, no spaces or special characters.
+adminUserSettings.usernameInfo=Username can only contain letters, numbers and the following special characters @._+- or must be a valid email address.
 adminUserSettings.roles=Roles
 adminUserSettings.role=Role
 adminUserSettings.actions=Actions
@ -176,6 +177,7 @@ adminUserSettings.internalApiUser=Internal API User
 adminUserSettings.forceChange=Force user to change password on login
 adminUserSettings.submit=Save User
 adminUserSettings.changeUserRole=Change User's Role
+adminUserSettings.authenticated=Authentication type

 #############
 # HOME-PAGE #
--- a/src/main/resources/messages_es_ES.properties
+++ b/src/main/resources/messages_es_ES.properties
@ -54,11 +54,12 @@ notAuthenticatedMessage=Usuario no autentificado.
 userNotFoundMessage=Usuario no encontrado.
 incorrectPasswordMessage=La contraseña actual no es correcta.
 usernameExistsMessage=El nuevo nombre de usuario está en uso.
-invalidUsernameMessage=Nombre de usuario no válido, El nombre de ususario debe contener únicamente números y caracteres alfabéticos.
+invalidUsernameMessage=Nombre de usuario no válido, el nombre de usuario solo puede contener letras, números y los siguientes caracteres especiales @._+- o debe ser una dirección de correo electrónico válida.
 deleteCurrentUserMessage=No puede eliminar el usuario que tiene la sesión actualmente en uso.
 deleteUsernameExistsMessage=El usuario no existe y no puede eliminarse.
 downgradeCurrentUserMessage=No se puede degradar el rol del usuario actual
 downgradeCurrentUserLongMessage=No se puede degradar el rol del usuario actual. Por lo tanto, el usuario actual no se mostrará.
+userAlreadyExistsMessage=OAuth2: User already exists.
 error=Error
 oops=Ups!
 help=Help
@ -164,7 +165,7 @@ adminUserSettings.header=Configuración de control de usuario administrador
 adminUserSettings.admin=Administrador
 adminUserSettings.user=Usuario
 adminUserSettings.addUser=Añadir Nuevo Usuario
-adminUserSettings.usernameInfo=El nombrede usuario debe contener únicamente letras y números, no espacios ni caracteres especiales.
+adminUserSettings.usernameInfo=El nombre de usuario solo puede contener letras, números y los siguientes caracteres especiales @._+- o debe ser una dirección de correo electrónico válida.
 adminUserSettings.roles=Roles
 adminUserSettings.role=Rol
 adminUserSettings.actions=Acciones
@ -176,6 +177,7 @@ adminUserSettings.internalApiUser=Usuario interno de API
 adminUserSettings.forceChange=Forzar usuario a cambiar usuario/contraseña en el acceso
 adminUserSettings.submit=Guardar Usuario
 adminUserSettings.changeUserRole=Cambiar rol de usuario
+adminUserSettings.authenticated=Authentication type

 #############
 # HOME-PAGE #
--- a/src/main/resources/messages_eu_ES.properties
+++ b/src/main/resources/messages_eu_ES.properties
@ -54,11 +54,12 @@ notAuthenticatedMessage=User not authenticated.
 userNotFoundMessage=User not found.
 incorrectPasswordMessage=Current password is incorrect.
 usernameExistsMessage=New Username already exists.
-invalidUsernameMessage=Invalid username, Username must only contain alphabet characters and numbers.
+invalidUsernameMessage=Invalid username, username can only contain letters, numbers and the following special characters @._+- or must be a valid email address.
 deleteCurrentUserMessage=Cannot delete currently logged in user.
 deleteUsernameExistsMessage=The username does not exist and cannot be deleted.
 downgradeCurrentUserMessage=Ezin da uneko erabiltzailearen rola jaitsi
 downgradeCurrentUserLongMessage=Ezin da uneko erabiltzailearen rola jaitsi. Beraz, oraingo erabiltzailea ez da erakutsiko.
+userAlreadyExistsMessage=OAuth2: User already exists.
 error=Error
 oops=Oops!
 help=Help
@ -164,7 +165,7 @@ adminUserSettings.header=Admin Erabiltzailearen Ezarpenen Kontrolak
 adminUserSettings.admin=Admin
 adminUserSettings.user=Erabiltzaile
 adminUserSettings.addUser=Erabiltzaile berria
-adminUserSettings.usernameInfo=Username must only contain letters and numbers, no spaces or special characters.
+adminUserSettings.usernameInfo=Username can only contain letters, numbers and the following special characters @._+- or must be a valid email address.
 adminUserSettings.roles=Rolak
 adminUserSettings.role=Rol
 adminUserSettings.actions=Ekintzak
@ -176,6 +177,7 @@ adminUserSettings.internalApiUser=Internal API User
 adminUserSettings.forceChange=Force user to change password on login
 adminUserSettings.submit=Gorde Erabiltzailea
 adminUserSettings.changeUserRole=Erabiltzailearen rola aldatu
+adminUserSettings.authenticated=Authentication type

 #############
 # HOME-PAGE #
--- a/src/main/resources/messages_fr_FR.properties
+++ b/src/main/resources/messages_fr_FR.properties
@ -54,11 +54,12 @@ notAuthenticatedMessage=Utilisateur non authentifié.
 userNotFoundMessage=Utilisateur non trouvé.
 incorrectPasswordMessage=Le mot de passe actuel est incorrect.
 usernameExistsMessage=Le nouveau nom d’utilisateur existe déjà.
-invalidUsernameMessage=Nom d’utilisateur invalide, le nom d’utilisateur ne peut contenir que des chiffres et des lettres.
+invalidUsernameMessage=Nom d’utilisateur invalide, le nom d’utilisateur ne peut contenir que des lettres, des chiffres et les caractères spéciaux suivants @._+- ou doit être une adresse e-mail valide.
 deleteCurrentUserMessage=Impossible de supprimer l’utilisateur actuellement connecté.
 deleteUsernameExistsMessage=Le nom d’utilisateur n’existe pas et ne peut pas être supprimé.
 downgradeCurrentUserMessage=Impossible de rétrograder le rôle de l'utilisateur actuel
 downgradeCurrentUserLongMessage=Impossible de rétrograder le rôle de l'utilisateur actuel. Par conséquent, l'utilisateur actuel ne sera pas affiché.
+userAlreadyExistsMessage=OAuth2: User already exists.
 error=Erreur
 oops=Oups !
 help=Aide
@ -164,7 +165,7 @@ adminUserSettings.header=Administration des paramètres des utilisateurs
 adminUserSettings.admin=Administateur
 adminUserSettings.user=Utilisateur
 adminUserSettings.addUser=Ajouter un utilisateur
-adminUserSettings.usernameInfo=Le nom d’utilisateur ne doit contenir que des lettres et des chiffres, sans espaces ni caractères spéciaux.
+adminUserSettings.usernameInfo=Le nom d'utilisateur ne peut contenir que des lettres, des chiffres et les caractères spéciaux suivants @._+- ou doit être une adresse e-mail valide.
 adminUserSettings.roles=Rôles
 adminUserSettings.role=Rôle
 adminUserSettings.actions=Actions
@ -176,6 +177,7 @@ adminUserSettings.internalApiUser=Internal API User
 adminUserSettings.forceChange=Forcer l’utilisateur à changer son nom d’utilisateur/mot de passe lors de la connexion
 adminUserSettings.submit=Ajouter
 adminUserSettings.changeUserRole=Changer le rôle de l'utilisateur
+adminUserSettings.authenticated=Authentication type

 #############
 # HOME-PAGE #
--- a/src/main/resources/messages_hi_IN.properties
+++ b/src/main/resources/messages_hi_IN.properties
@ -54,11 +54,12 @@ notAuthenticatedMessage=उपयोगकर्ता प्रमाणित
 userNotFoundMessage=उपयोगकर्ता नहीं मिला।
 incorrectPasswordMessage=वर्तमान पासवर्ड गलत है।
 usernameExistsMessage=नया उपयोगकर्ता नाम पहले से मौजूद है।
-invalidUsernameMessage=Invalid username, Username must only contain alphabet characters and numbers.
+invalidUsernameMessage=Invalid username, username can only contain letters, numbers and the following special characters @._+- or must be a valid email address.
 deleteCurrentUserMessage=Cannot delete currently logged in user.
 deleteUsernameExistsMessage=The username does not exist and cannot be deleted.
 downgradeCurrentUserMessage=मौजूदा यूज़र की भूमिका को डाउनग्रेड नहीं किया जा सकता
 downgradeCurrentUserLongMessage=मौजूदा यूज़र की भूमिका को डाउनग्रेड नहीं किया जा सकता। इसलिए, वर्तमान उपयोगकर्ता को नहीं दिखाया जाएगा।
+userAlreadyExistsMessage=OAuth2: User already exists.
 error=Error
 oops=Oops!
 help=Help
@ -164,7 +165,7 @@ adminUserSettings.header=व्यवस्थापक उपयोगकर्
 adminUserSettings.admin=व्यवस्थापक
 adminUserSettings.user=उपयोगकर्ता
 adminUserSettings.addUser=नया उपयोगकर्ता जोड़ें
-adminUserSettings.usernameInfo=Username must only contain letters and numbers, no spaces or special characters.
+adminUserSettings.usernameInfo=Username can only contain letters, numbers and the following special characters @._+- or must be a valid email address.
 adminUserSettings.roles=रोल्स
 adminUserSettings.role=रोल
 adminUserSettings.actions=क्रियाएँ
@ -176,6 +177,7 @@ adminUserSettings.internalApiUser=Internal API User
 adminUserSettings.forceChange=उपयोगकर्ता को लॉगिन पर उपयोगकर्ता नाम/पासवर्ड बदलने के लिए मजबूर करें
 adminUserSettings.submit=उपयोगकर्ता को सहेजें
 adminUserSettings.changeUserRole=यूज़र की भूमिका बदलें
+adminUserSettings.authenticated=Authentication type

 #############
 # HOME-PAGE #
--- a/src/main/resources/messages_hu_HU.properties
+++ b/src/main/resources/messages_hu_HU.properties
@ -54,11 +54,12 @@ notAuthenticatedMessage=Felhasználó nincs hitelesítve.
 userNotFoundMessage=A felhasználó nem található.
 incorrectPasswordMessage=A jelenlegi jelszó helytelen.
 usernameExistsMessage=Az új felhasználónév már létezik.
-invalidUsernameMessage=Invalid username, Username must only contain alphabet characters and numbers.
+invalidUsernameMessage=Invalid username, username can only contain letters, numbers and the following special characters @._+- or must be a valid email address.
 deleteCurrentUserMessage=Cannot delete currently logged in user.
 deleteUsernameExistsMessage=The username does not exist and cannot be deleted.
 downgradeCurrentUserMessage=A jelenlegi felhasználó szerepkörét nem lehet visszaminősíteni
 downgradeCurrentUserLongMessage=Az aktuális felhasználó szerepkörét nem lehet visszaminősíteni. Ezért az aktuális felhasználó nem jelenik meg.
+userAlreadyExistsMessage=OAuth2: User already exists.
 error=Error
 oops=Oops!
 help=Help
@ -164,7 +165,7 @@ adminUserSettings.header=Adminisztrátori Felhasználói Vezérlési Beállítá
 adminUserSettings.admin=Adminisztrátor
 adminUserSettings.user=Felhasználó
 adminUserSettings.addUser=Új felhasználó hozzáadása
-adminUserSettings.usernameInfo=Username must only contain letters and numbers, no spaces or special characters.
+adminUserSettings.usernameInfo=Username can only contain letters, numbers and the following special characters @._+- or must be a valid email address.
 adminUserSettings.roles=Szerepek
 adminUserSettings.role=Szerep
 adminUserSettings.actions=Műveletek
@ -176,6 +177,7 @@ adminUserSettings.internalApiUser=Internal API User
 adminUserSettings.forceChange=Kényszerítse a felhasználót a felhasználónév/jelszó megváltoztatására bejelentkezéskor
 adminUserSettings.submit=Felhasználó mentése
 adminUserSettings.changeUserRole=Felhasználó szerepkörének módosítása
+adminUserSettings.authenticated=Authentication type

 #############
 # HOME-PAGE #
--- a/src/main/resources/messages_id_ID.properties
+++ b/src/main/resources/messages_id_ID.properties
@ -54,11 +54,12 @@ notAuthenticatedMessage=Pengguna tidak ter-autentikasi.
 userNotFoundMessage=Pengguna tidak ditemukan.
 incorrectPasswordMessage=Kata sandi saat ini salah.
 usernameExistsMessage=Nama pengguna baru sudah ada.
-invalidUsernameMessage=Invalid username, Username must only contain alphabet characters and numbers.
+invalidUsernameMessage=Invalid username, username can only contain letters, numbers and the following special characters @._+- or must be a valid email address.
 deleteCurrentUserMessage=Cannot delete currently logged in user.
 deleteUsernameExistsMessage=The username does not exist and cannot be deleted.
 downgradeCurrentUserMessage=Tidak dapat menurunkan peran pengguna saat ini
 downgradeCurrentUserLongMessage=Tidak dapat menurunkan peran pengguna saat ini. Oleh karena itu, pengguna saat ini tidak akan ditampilkan.
+userAlreadyExistsMessage=OAuth2: User already exists.
 error=Error
 oops=Oops!
 help=Help
@ -164,7 +165,7 @@ adminUserSettings.header=Pengaturan Kontrol Admin
 adminUserSettings.admin=Admin
 adminUserSettings.user=Pengguna
 adminUserSettings.addUser=Tambahkan Pengguna Baru
-adminUserSettings.usernameInfo=Username must only contain letters and numbers, no spaces or special characters.
+adminUserSettings.usernameInfo=Username can only contain letters, numbers and the following special characters @._+- or must be a valid email address.
 adminUserSettings.roles=Peran
 adminUserSettings.role=Peran
 adminUserSettings.actions=Tindakan
@ -176,6 +177,7 @@ adminUserSettings.internalApiUser=Internal API User
 adminUserSettings.forceChange=Memaksa pengguna untuk mengubah nama pengguna/kata sandi saat masuk
 adminUserSettings.submit=Simpan Pengguna
 adminUserSettings.changeUserRole=Ubah Peran Pengguna
+adminUserSettings.authenticated=Authentication type

 #############
 # HOME-PAGE #
--- a/src/main/resources/messages_it_IT.properties
+++ b/src/main/resources/messages_it_IT.properties
@ -54,11 +54,12 @@ notAuthenticatedMessage=Utente non autenticato.
 userNotFoundMessage=Utente non trovato.
 incorrectPasswordMessage=La password attuale non è corretta.
 usernameExistsMessage=Il nuovo nome utente esiste già.
-invalidUsernameMessage=Nome utente non valido, il nome utente deve contenere solo caratteri alfabetici e numeri.
+invalidUsernameMessage=Nome utente non valido, il nome utente può contenere solo lettere, numeri e i seguenti caratteri speciali @._+- o deve essere un indirizzo email valido.
 deleteCurrentUserMessage=Impossibile eliminare l'utente attualmente connesso.
 deleteUsernameExistsMessage=Il nome utente non esiste e non può essere eliminato.
 downgradeCurrentUserMessage=Impossibile declassare il ruolo dell'utente corrente
 downgradeCurrentUserLongMessage=Impossibile declassare il ruolo dell'utente corrente. Pertanto, l'utente corrente non verrà visualizzato.
+userAlreadyExistsMessage=OAuth2: User already exists.
 error=Errore
 oops=Oops!
 help=Aiuto
@ -164,7 +165,7 @@ adminUserSettings.header=Impostazioni di controllo utente amministratore
 adminUserSettings.admin=Amministratore
 adminUserSettings.user=Utente
 adminUserSettings.addUser=Aggiungi un nuovo Utente
-adminUserSettings.usernameInfo=Il nome utente deve contenere solo lettere e numeri, senza spazi o caratteri speciali.
+adminUserSettings.usernameInfo=Il nome utente può contenere solo lettere, numeri e i seguenti caratteri speciali @._+- oppure deve essere un indirizzo email valido.
 adminUserSettings.roles=Ruoli
 adminUserSettings.role=Ruolo
 adminUserSettings.actions=Azioni
@ -176,6 +177,7 @@ adminUserSettings.internalApiUser=API utente interna
 adminUserSettings.forceChange=Forza l'utente a cambiare nome username/password all'accesso
 adminUserSettings.submit=Salva utente
 adminUserSettings.changeUserRole=Cambia il ruolo dell'utente
+adminUserSettings.authenticated=Authentication type

 #############
 # HOME-PAGE #
--- a/src/main/resources/messages_ja_JP.properties
+++ b/src/main/resources/messages_ja_JP.properties
@ -54,11 +54,12 @@ notAuthenticatedMessage=ユーザーが認証されていません。
 userNotFoundMessage=ユーザーが見つかりません。
 incorrectPasswordMessage=現在のパスワードが正しくありません。
 usernameExistsMessage=新しいユーザー名はすでに存在します。
-invalidUsernameMessage=ユーザー名が無効です。ユーザー名にはアルファベットと数字のみを使用してください。
+invalidUsernameMessage=ユーザー名が無効です。ユーザー名には文字、数字、およびそれに続く特殊文字 @._+- のみを含めることができます。または、有効な電子メール アドレスである必要があります。
 deleteCurrentUserMessage=現在ログインしているユーザーは削除できません。
 deleteUsernameExistsMessage=そのユーザー名は存在しないため削除できません。
 downgradeCurrentUserMessage=現在のユーザーの役割をダウングレードできません
 downgradeCurrentUserLongMessage=現在のユーザーの役割をダウングレードできません。したがって、現在のユーザーは表示されません。
+userAlreadyExistsMessage=OAuth2: User already exists.
 error=エラー
 oops=おっと！
 help=ヘルプ
@ -164,7 +165,7 @@ adminUserSettings.header=管理者ユーザー制御設定
 adminUserSettings.admin=管理者
 adminUserSettings.user=ユーザー
 adminUserSettings.addUser=新しいユーザを追加
-adminUserSettings.usernameInfo=ユーザー名には文字と数字のみが使用でき、スペースや特殊文字は使用できません。
+adminUserSettings.usernameInfo=ユーザー名には、文字、数字、および次の特殊文字 @._+- のみを含めることができます。または、有効な電子メール アドレスである必要があります。
 adminUserSettings.roles=役割
 adminUserSettings.role=役割
 adminUserSettings.actions=アクション
@ -176,6 +177,7 @@ adminUserSettings.internalApiUser=内部APIユーザー
 adminUserSettings.forceChange=ログイン時にユーザー名/パスワードを強制的に変更する
 adminUserSettings.submit=ユーザーの保存
 adminUserSettings.changeUserRole=ユーザーの役割を変更する
+adminUserSettings.authenticated=Authentication type

 #############
 # HOME-PAGE #
--- a/src/main/resources/messages_ko_KR.properties
+++ b/src/main/resources/messages_ko_KR.properties
@ -54,11 +54,12 @@ notAuthenticatedMessage=사용자가 인증되지 않았습니다.
 userNotFoundMessage=사용자를 찾을 수 없습니다.
 incorrectPasswordMessage=현재 비밀번호가 틀립니다.
 usernameExistsMessage=새 사용자명이 이미 존재합니다.
-invalidUsernameMessage=사용자 이름이 잘못되었습니다. 사용자 이름에는 알파벳 문자와 숫자만 포함되어야 합니다.
+invalidUsernameMessage=잘못된 사용자 이름입니다. 사용자 이름에는 문자, 숫자 및 다음 특수 문자(@._+-)만 포함할 수 있거나 유효한 이메일 주소여야 합니다.
 deleteCurrentUserMessage=현재 로그인한 사용자를 삭제할 수 없습니다.
 deleteUsernameExistsMessage=사용자 이름이 존재하지 않으며 삭제할 수 없습니다.
 downgradeCurrentUserMessage=현재 사용자의 역할을 다운그레이드할 수 없습니다
 downgradeCurrentUserLongMessage=현재 사용자의 역할을 다운그레이드할 수 없습니다. 따라서 현재 사용자는 표시되지 않습니다.
+userAlreadyExistsMessage=OAuth2: User already exists.
 error=오류
 oops=어머나!
 help=도움말
@ -164,7 +165,7 @@ adminUserSettings.header=사용자 관리
 adminUserSettings.admin=관리자
 adminUserSettings.user=사용자
 adminUserSettings.addUser=새 사용자 추가
-adminUserSettings.usernameInfo=사용자 이름은 문자와 숫자만 포함해야 하며 공백이나 특수 문자는 포함할 수 없습니다.
+adminUserSettings.usernameInfo=사용자 이름은 문자, 숫자, 특수 문자 @._+-만 포함할 수 있으며 유효한 이메일 주소여야 합니다.
 adminUserSettings.roles=역할
 adminUserSettings.role=역할
 adminUserSettings.actions=동작
@ -176,6 +177,7 @@ adminUserSettings.internalApiUser=내부 API 사용자
 adminUserSettings.forceChange=다음 로그인 때 사용자명과 비밀번호를 변경하도록 강제
 adminUserSettings.submit=사용자 저장
 adminUserSettings.changeUserRole=사용자의 역할 변경
+adminUserSettings.authenticated=Authentication type

 #############
 # HOME-PAGE #
--- a/src/main/resources/messages_nl_NL.properties
+++ b/src/main/resources/messages_nl_NL.properties
@ -54,11 +54,12 @@ notAuthenticatedMessage=Gebruiker niet ingelogd.
 userNotFoundMessage=Gebruiker niet gevonden.
 incorrectPasswordMessage=Huidige wachtwoord is onjuist.
 usernameExistsMessage=Nieuwe gebruikersnaam bestaat al.
-invalidUsernameMessage=Invalid username, Username must only contain alphabet characters and numbers.
+invalidUsernameMessage=Invalid username, username can only contain letters, numbers and the following special characters @._+- or must be a valid email address.
 deleteCurrentUserMessage=Cannot delete currently logged in user.
 deleteUsernameExistsMessage=The username does not exist and cannot be deleted.
 downgradeCurrentUserMessage=Kan de rol van de huidige gebruiker niet downgraden
 downgradeCurrentUserLongMessage=Kan de rol van de huidige gebruiker niet downgraden. Huidige gebruiker wordt dus niet weergegeven.
+userAlreadyExistsMessage=OAuth2: User already exists.
 error=Error
 oops=Oops!
 help=Help
@ -164,7 +165,7 @@ adminUserSettings.header=Beheer gebruikers
 adminUserSettings.admin=Beheerder
 adminUserSettings.user=Gebruiker
 adminUserSettings.addUser=Voeg nieuwe gebruiker toe
-adminUserSettings.usernameInfo=Username must only contain letters and numbers, no spaces or special characters.
+adminUserSettings.usernameInfo=Username can only contain letters, numbers and the following special characters @._+- or must be a valid email address.
 adminUserSettings.roles=Rollen
 adminUserSettings.role=Rol
 adminUserSettings.actions=Acties
@ -176,6 +177,7 @@ adminUserSettings.internalApiUser=Internal API User
 adminUserSettings.forceChange=Forceer gebruiker om gebruikersnaam/wachtwoord te wijzigen bij inloggen
 adminUserSettings.submit=Gebruiker opslaan
 adminUserSettings.changeUserRole=De rol van de gebruiker wijzigen
+adminUserSettings.authenticated=Authentication type

 #############
 # HOME-PAGE #
--- a/src/main/resources/messages_pl_PL.properties
+++ b/src/main/resources/messages_pl_PL.properties
@ -54,11 +54,12 @@ notAuthenticatedMessage=User not authenticated.
 userNotFoundMessage=User not found.
 incorrectPasswordMessage=Current password is incorrect.
 usernameExistsMessage=New Username already exists.
-invalidUsernameMessage=Invalid username, Username must only contain alphabet characters and numbers.
+invalidUsernameMessage=Invalid username, username can only contain letters, numbers and the following special characters @._+- or must be a valid email address.
 deleteCurrentUserMessage=Cannot delete currently logged in user.
 deleteUsernameExistsMessage=The username does not exist and cannot be deleted.
 downgradeCurrentUserMessage=Nie można obniżyć roli bieżącego użytkownika
 downgradeCurrentUserLongMessage=Nie można obniżyć roli bieżącego użytkownika. W związku z tym bieżący użytkownik nie zostanie wyświetlony.
+userAlreadyExistsMessage=OAuth2: User already exists.
 error=Error
 oops=Oops!
 help=Help
@ -164,7 +165,7 @@ adminUserSettings.header=Admin User Control Settings
 adminUserSettings.admin=Admin
 adminUserSettings.user=User
 adminUserSettings.addUser=Add New User
-adminUserSettings.usernameInfo=Username must only contain letters and numbers, no spaces or special characters.
+adminUserSettings.usernameInfo=Username can only contain letters, numbers and the following special characters @._+- or must be a valid email address.
 adminUserSettings.roles=Roles
 adminUserSettings.role=Role
 adminUserSettings.actions=Actions
@ -176,6 +177,7 @@ adminUserSettings.internalApiUser=Internal API User
 adminUserSettings.forceChange=Force user to change password on login
 adminUserSettings.submit=Save User
 adminUserSettings.changeUserRole=Zmień rolę użytkownika
+adminUserSettings.authenticated=Authentication type

 #############
 # HOME-PAGE #
--- a/src/main/resources/messages_pt_BR.properties
+++ b/src/main/resources/messages_pt_BR.properties
@ -54,11 +54,12 @@ notAuthenticatedMessage=User not authenticated.
 userNotFoundMessage=User not found.
 incorrectPasswordMessage=Current password is incorrect.
 usernameExistsMessage=New Username already exists.
-invalidUsernameMessage=Invalid username, Username must only contain alphabet characters and numbers.
+invalidUsernameMessage=Invalid username, username can only contain letters, numbers and the following special characters @._+- or must be a valid email address.
 deleteCurrentUserMessage=Cannot delete currently logged in user.
 deleteUsernameExistsMessage=The username does not exist and cannot be deleted.
 downgradeCurrentUserMessage=Não é possível fazer downgrade da função do usuário atual
 downgradeCurrentUserLongMessage=Não é possível fazer downgrade da função do usuário atual. Portanto, o usuário atual não será mostrado.
+userAlreadyExistsMessage=OAuth2: User already exists.
 error=Error
 oops=Oops!
 help=Help
@ -164,7 +165,7 @@ adminUserSettings.header=Admin User Control Settings
 adminUserSettings.admin=Admin
 adminUserSettings.user=User
 adminUserSettings.addUser=Add New User
-adminUserSettings.usernameInfo=Username must only contain letters and numbers, no spaces or special characters.
+adminUserSettings.usernameInfo=Username can only contain letters, numbers and the following special characters @._+- or must be a valid email address.
 adminUserSettings.roles=Roles
 adminUserSettings.role=Role
 adminUserSettings.actions=Actions
@ -176,6 +177,7 @@ adminUserSettings.internalApiUser=Internal API User
 adminUserSettings.forceChange=Force user to change password on login
 adminUserSettings.submit=Save User
 adminUserSettings.changeUserRole=Alterar Função de Usuário
+adminUserSettings.authenticated=Authentication type

 #############
 # HOME-PAGE #
--- a/src/main/resources/messages_pt_PT.properties
+++ b/src/main/resources/messages_pt_PT.properties
@ -54,11 +54,12 @@ notAuthenticatedMessage=Utilizador não autenticado.
 userNotFoundMessage=Utilizador inexistente.
 incorrectPasswordMessage=Senha incorreta.
 usernameExistsMessage=Esse utilizador já existe.
-invalidUsernameMessage=Invalid username, Username must only contain alphabet characters and numbers.
+invalidUsernameMessage=Invalid username, username can only contain letters, numbers and the following special characters @._+- or must be a valid email address.
 deleteCurrentUserMessage=Cannot delete currently logged in user.
 deleteUsernameExistsMessage=The username does not exist and cannot be deleted.
 downgradeCurrentUserMessage=Não é possível fazer downgrade da função do utilizador atual
 downgradeCurrentUserLongMessage=Não é possível fazer downgrade da função do utilizador atual. Portanto, o utilizador atual não será mostrado.
+userAlreadyExistsMessage=OAuth2: User already exists.
 error=Error
 oops=Oops!
 help=Help
@ -164,7 +165,7 @@ adminUserSettings.header=Admin User Control Settings
 adminUserSettings.admin=Admin
 adminUserSettings.user=User
 adminUserSettings.addUser=Add New User
-adminUserSettings.usernameInfo=Username must only contain letters and numbers, no spaces or special characters.
+adminUserSettings.usernameInfo=Username can only contain letters, numbers and the following special characters @._+- or must be a valid email address.
 adminUserSettings.roles=Roles
 adminUserSettings.role=Role
 adminUserSettings.actions=Actions
@ -176,6 +177,7 @@ adminUserSettings.internalApiUser=Internal API User
 adminUserSettings.forceChange=Force user to change password on login
 adminUserSettings.submit=Save User
 adminUserSettings.changeUserRole=Alterar usuário
+adminUserSettings.authenticated=Authentication type

 #############
 # HOME-PAGE #
--- a/src/main/resources/messages_ro_RO.properties
+++ b/src/main/resources/messages_ro_RO.properties
@ -54,11 +54,12 @@ notAuthenticatedMessage=User not authenticated.
 userNotFoundMessage=User not found.
 incorrectPasswordMessage=Current password is incorrect.
 usernameExistsMessage=New Username already exists.
-invalidUsernameMessage=Invalid username, Username must only contain alphabet characters and numbers.
+invalidUsernameMessage=Invalid username, username can only contain letters, numbers and the following special characters @._+- or must be a valid email address.
 deleteCurrentUserMessage=Cannot delete currently logged in user.
 deleteUsernameExistsMessage=The username does not exist and cannot be deleted.
 downgradeCurrentUserMessage=Rolul utilizatorului curent nu poate fi retrogradat
 downgradeCurrentUserLongMessage=Rolul utilizatorului curent nu poate fi retrogradat. Prin urmare, utilizatorul curent nu va fi afișat.
+userAlreadyExistsMessage=OAuth2: User already exists.
 error=Error
 oops=Oops!
 help=Help
@ -164,7 +165,7 @@ adminUserSettings.header=Admin User Control Settings
 adminUserSettings.admin=Admin
 adminUserSettings.user=User
 adminUserSettings.addUser=Add New User
-adminUserSettings.usernameInfo=Username must only contain letters and numbers, no spaces or special characters.
+adminUserSettings.usernameInfo=Username can only contain letters, numbers and the following special characters @._+- or must be a valid email address.
 adminUserSettings.roles=Roles
 adminUserSettings.role=Role
 adminUserSettings.actions=Actions
@ -176,6 +177,7 @@ adminUserSettings.internalApiUser=Internal API User
 adminUserSettings.forceChange=Force user to change password on login
 adminUserSettings.submit=Save User
 adminUserSettings.changeUserRole=Schimbați rolul utilizatorului
+adminUserSettings.authenticated=Authentication type

 #############
 # HOME-PAGE #
--- a/src/main/resources/messages_ru_RU.properties
+++ b/src/main/resources/messages_ru_RU.properties
@ -54,11 +54,12 @@ notAuthenticatedMessage=Пользователь не прошел провер
 userNotFoundMessage=Пользователь не найден.
 incorrectPasswordMessage=Текущий пароль неверен.
 usernameExistsMessage=Новое имя пользователя уже существует.
-invalidUsernameMessage=Недопустимое имя пользователя, Имя пользователя должно содержать только буквы алфавита и цифры.
+invalidUsernameMessage=Неверное имя пользователя. Имя пользователя может содержать только буквы, цифры и следующие специальные символы @._+- или должно быть действительным адресом электронной почты.
 deleteCurrentUserMessage=Невозможно удалить пользователя, вошедшего в систему.
 deleteUsernameExistsMessage=Имя пользователя не существует и не может быть удалено.
 downgradeCurrentUserMessage=Невозможно понизить роль текущего пользователя
 downgradeCurrentUserLongMessage=Невозможно понизить роль текущего пользователя. Следовательно, текущий пользователь не будет отображаться.
+userAlreadyExistsMessage=OAuth2: User already exists.
 error=Ошибка
 oops=Ой!
 help=Помощь
@ -164,7 +165,7 @@ adminUserSettings.header=Настройки контроля пользоват
 adminUserSettings.admin=Администратор
 adminUserSettings.user=Пользователь
 adminUserSettings.addUser=Добавить нового пользователя
-adminUserSettings.usernameInfo=Имя пользователя должно содержать только буквы и цифры, без пробелов и специальных символов.
+adminUserSettings.usernameInfo=Имя пользователя может содержать только буквы, цифры и следующие специальные символы @._+- или должно быть действительным адресом электронной почты.
 adminUserSettings.roles=Роли
 adminUserSettings.role=Роль
 adminUserSettings.actions=Действия
@ -176,6 +177,7 @@ adminUserSettings.internalApiUser=Внутренний пользователь
 adminUserSettings.forceChange=Просить пользователя изменить пароль при входе в систему
 adminUserSettings.submit=Сохранить пользователя
 adminUserSettings.changeUserRole=Изменить роль пользователя
+adminUserSettings.authenticated=Authentication type

 #############
 # HOME-PAGE #
--- a/src/main/resources/messages_sr_LATN_RS.properties
+++ b/src/main/resources/messages_sr_LATN_RS.properties
@ -54,11 +54,12 @@ notAuthenticatedMessage=Korisnik nije autentifikovan.
 userNotFoundMessage=Korisnik nije pronađen.
 incorrectPasswordMessage=Trenutna šifra je netačna.
 usernameExistsMessage=Novi korisnik već postoji
-invalidUsernameMessage=Invalid username, Username must only contain alphabet characters and numbers.
+invalidUsernameMessage=Invalid username, username can only contain letters, numbers and the following special characters @._+- or must be a valid email address.
 deleteCurrentUserMessage=Cannot delete currently logged in user.
 deleteUsernameExistsMessage=The username does not exist and cannot be deleted.
 downgradeCurrentUserMessage=Nije moguće degradirati ulogu trenutnog korisnika
 downgradeCurrentUserLongMessage=Nije moguće unazaditi ulogu trenutnog korisnika. Dakle, trenutni korisnik neće biti prikazan.
+userAlreadyExistsMessage=OAuth2: User already exists.
 error=Error
 oops=Oops!
 help=Help
@ -164,7 +165,7 @@ adminUserSettings.header=Podešavanja kontrole korisnika za administratora
 adminUserSettings.admin=Administrator
 adminUserSettings.user=Korisnik
 adminUserSettings.addUser=Dodaj novog korisnika
-adminUserSettings.usernameInfo=Username must only contain letters and numbers, no spaces or special characters.
+adminUserSettings.usernameInfo=Username can only contain letters, numbers and the following special characters @._+- or must be a valid email address.
 adminUserSettings.roles=Uloge
 adminUserSettings.role=Uloga
 adminUserSettings.actions=Akcije
@ -176,6 +177,7 @@ adminUserSettings.internalApiUser=Internal API User
 adminUserSettings.forceChange=Prisili korisnika da promeni korisničko ime/lozinku pri prijavi
 adminUserSettings.submit=Sačuvaj korisnika
 adminUserSettings.changeUserRole=Promenite ulogu korisnika
+adminUserSettings.authenticated=Authentication type

 #############
 # HOME-PAGE #
--- a/src/main/resources/messages_sv_SE.properties
+++ b/src/main/resources/messages_sv_SE.properties
@ -54,11 +54,12 @@ notAuthenticatedMessage=User not authenticated.
 userNotFoundMessage=User not found.
 incorrectPasswordMessage=Current password is incorrect.
 usernameExistsMessage=New Username already exists.
-invalidUsernameMessage=Invalid username, Username must only contain alphabet characters and numbers.
+invalidUsernameMessage=Invalid username, username can only contain letters, numbers and the following special characters @._+- or must be a valid email address.
 deleteCurrentUserMessage=Cannot delete currently logged in user.
 deleteUsernameExistsMessage=The username does not exist and cannot be deleted.
 downgradeCurrentUserMessage=Kan inte nedgradera nuvarande användares roll
 downgradeCurrentUserLongMessage=Kan inte nedgradera nuvarande användares roll. Därför kommer den aktuella användaren inte att visas.
+userAlreadyExistsMessage=OAuth2: User already exists.
 error=Error
 oops=Oops!
 help=Help
@ -164,7 +165,7 @@ adminUserSettings.header=Admin User Control Settings
 adminUserSettings.admin=Admin
 adminUserSettings.user=User
 adminUserSettings.addUser=Add New User
-adminUserSettings.usernameInfo=Username must only contain letters and numbers, no spaces or special characters.
+adminUserSettings.usernameInfo=Username can only contain letters, numbers and the following special characters @._+- or must be a valid email address.
 adminUserSettings.roles=Roles
 adminUserSettings.role=Role
 adminUserSettings.actions=Actions
@ -176,6 +177,7 @@ adminUserSettings.internalApiUser=Internal API User
 adminUserSettings.forceChange=Force user to change password on login
 adminUserSettings.submit=Save User
 adminUserSettings.changeUserRole=Ändra användarens roll
+adminUserSettings.authenticated=Authentication type

 #############
 # HOME-PAGE #
--- a/src/main/resources/messages_tr_TR.properties
+++ b/src/main/resources/messages_tr_TR.properties
@ -54,11 +54,12 @@ notAuthenticatedMessage=Kullanıcı doğrulanmadı.
 userNotFoundMessage=Kullanıcı bulunamadı.
 incorrectPasswordMessage=Mevcut şifre yanlış.
 usernameExistsMessage=Yeni Kullanıcı Adı zaten var.
-invalidUsernameMessage=Geçersiz kullanıcı adı, Kullanıcı adı yalnızca alfabe karakterleri ve sayılar içermelidir.
+invalidUsernameMessage=Geçersiz kullanıcı adı, kullanıcı adı yalnızca harf, rakam ve aşağıdaki özel karakterleri @._+- içerebilir veya geçerli bir e-posta adresi olmalıdır.
 deleteCurrentUserMessage=Şu anda oturum açmış olan kullanıcı silinemiyor.
 deleteUsernameExistsMessage=Kullanıcı adı mevcut değil ve silinemez.
 downgradeCurrentUserMessage=Mevcut kullanıcının rolü düşürülemiyor
 downgradeCurrentUserLongMessage=Mevcut kullanıcının rolü düşürülemiyor. Bu nedenle, mevcut kullanıcı gösterilmeyecektir.
+userAlreadyExistsMessage=OAuth2: User already exists.
 error=Hata
 oops=Tüh!
 help=Yardım
@ -164,7 +165,7 @@ adminUserSettings.header=Yönetici Kullanıcı Kontrol Ayarları
 adminUserSettings.admin=Yönetici
 adminUserSettings.user=Kullanıcı
 adminUserSettings.addUser=Yeni Kullanıcı Ekle
-adminUserSettings.usernameInfo=Kullanıcı adı yalnızca harf ve rakamlardan oluşmalı, boşluk veya özel karakter içermemelidir.
+adminUserSettings.usernameInfo=Kullanıcı adı yalnızca harf, rakam ve aşağıdaki özel karakterleri @._+- içerebilir veya geçerli bir e-posta adresi olmalıdır.
 adminUserSettings.roles=Roller
 adminUserSettings.role=Rol
 adminUserSettings.actions=Eylemler
@ -176,6 +177,7 @@ adminUserSettings.internalApiUser=Dahili API Kullanıcısı
 adminUserSettings.forceChange=Kullanıcının girişte kullanıcı adı/şifre değiştirmesini zorla
 adminUserSettings.submit=Kullanıcıyı Kaydet
 adminUserSettings.changeUserRole=Kullanıcı rolünü değiştir
+adminUserSettings.authenticated=Authentication type

 #############
 # HOME-PAGE #
--- a/src/main/resources/messages_uk_UA.properties
+++ b/src/main/resources/messages_uk_UA.properties
@ -54,11 +54,12 @@ notAuthenticatedMessage=Користувач не пройшов перевір
 userNotFoundMessage=Користувача не знайдено.
 incorrectPasswordMessage=Поточний пароль невірний.
 usernameExistsMessage=Нове ім'я користувача вже існує.
-invalidUsernameMessage=Недійсне ім'я користувача, Ім'я користувача повинно містити тільки літери алфавіту та цифри.
+invalidUsernameMessage=Недійсне ім’я користувача, ім’я користувача може містити лише літери, цифри та наступні спеціальні символи @._+- або має бути дійсною електронною адресою.
 deleteCurrentUserMessage=Неможливо видалити користувача, який увійшов в систему.
 deleteUsernameExistsMessage=Ім'я користувача не існує і не може бути видалено.
 downgradeCurrentUserMessage=Неможливо понизити роль поточного користувача
 downgradeCurrentUserLongMessage=Неможливо понизити роль поточного користувача. Отже, поточний користувач не відображатиметься.
+userAlreadyExistsMessage=OAuth2: User already exists.
 error=Error
 oops=Oops!
 help=Help
@ -164,7 +165,7 @@ adminUserSettings.header=Налаштування контролю корист
 adminUserSettings.admin=Адміністратор
 adminUserSettings.user=Користувач
 adminUserSettings.addUser=Додати нового користувача
-adminUserSettings.usernameInfo=Ім'я користувача має містити тільки літери та цифри, без пробілів та спеціальних символів.
+adminUserSettings.usernameInfo=Ім’я користувача може містити лише літери, цифри та наступні спеціальні символи @._+- або має бути дійсною електронною адресою.
 adminUserSettings.roles=Ролі
 adminUserSettings.role=Роль
 adminUserSettings.actions=Дії
@ -176,6 +177,7 @@ adminUserSettings.internalApiUser=Внутрішній користувач API
 adminUserSettings.forceChange=Примусити користувача змінити пароль при вході в систему
 adminUserSettings.submit=Зберегти користувача
 adminUserSettings.changeUserRole=Змінити роль користувача
+adminUserSettings.authenticated=Authentication type

 #############
 # HOME-PAGE #
--- a/src/main/resources/messages_zh_CN.properties
+++ b/src/main/resources/messages_zh_CN.properties
@ -54,11 +54,12 @@ notAuthenticatedMessage=用户未经过身份验证。
 userNotFoundMessage=未找到用户。
 incorrectPasswordMessage=当前密码不正确。
 usernameExistsMessage=新用户名已存在。
-invalidUsernameMessage=用户名无效，用户名只能由字母字符和数字组成。
+invalidUsernameMessage=用户名无效，用户名只能包含字母、数字和以下特殊字符@._+- 或必须是有效的电子邮件地址。
 deleteCurrentUserMessage=无法删除当前登录的用户。
 deleteUsernameExistsMessage=用户名不存在，无法删除。
 downgradeCurrentUserMessage=无法降级当前用户的角色
 downgradeCurrentUserLongMessage=无法降级当前用户的角色。因此，当前用户将不会显示。
+userAlreadyExistsMessage=OAuth2: User already exists.
 error=错误
 oops=哎呀！
 help=帮助
@ -164,7 +165,7 @@ adminUserSettings.header=管理员用户控制设置
 adminUserSettings.admin=管理员
 adminUserSettings.user=用户
 adminUserSettings.addUser=添加新用户
-adminUserSettings.usernameInfo=用户名只能由字母和数字组成，不能包含空格或特殊字符。
+adminUserSettings.usernameInfo=用户名只能包含字母、数字和以下特殊字符@._+-，或者必须是有效的电子邮件地址。
 adminUserSettings.roles=角色
 adminUserSettings.role=角色
 adminUserSettings.actions=操作
@ -176,6 +177,7 @@ adminUserSettings.internalApiUser=内部API用户
 adminUserSettings.forceChange=强制用户在登录时更改用户名/密码
 adminUserSettings.submit=保存用户
 adminUserSettings.changeUserRole=更改用户角色
+adminUserSettings.authenticated=Authentication type

 #############
 # HOME-PAGE #
--- a/src/main/resources/messages_zh_TW.properties
+++ b/src/main/resources/messages_zh_TW.properties
@ -54,11 +54,12 @@ notAuthenticatedMessage=使用者未認證。
 userNotFoundMessage=找不到使用者。
 incorrectPasswordMessage=目前密碼不正確。
 usernameExistsMessage=新使用者名稱已存在。
-invalidUsernameMessage=使用者名無效，使用者名只能包含字母字元和數位。
+invalidUsernameMessage=使用者名稱無效，使用者名稱只能包含字母、數字和以下特殊字元@._+- 或必須是有效的電子郵件地址。
 deleteCurrentUserMessage=無法刪除目前登錄的使用者。
 deleteUsernameExistsMessage=使用者名不存在，無法刪除。
 downgradeCurrentUserMessage=無法降級目前使用者的角色
 downgradeCurrentUserLongMessage=無法降級目前使用者的角色。因此，不會顯示目前的使用者。
+userAlreadyExistsMessage=OAuth2: User already exists.
 error=錯誤
 oops=哎呀！
 help=幫助
@ -164,7 +165,7 @@ adminUserSettings.header=管理使用者控制設定
 adminUserSettings.admin=管理員
 adminUserSettings.user=使用者
 adminUserSettings.addUser=新增使用者
-adminUserSettings.usernameInfo=使用者名只能包含字母和數位，不能包含空格或特殊字元。
+adminUserSettings.usernameInfo=使用者名稱只能包含字母、數字和以下特殊字元@._+-，或必須是有效的電子郵件地址。
 adminUserSettings.roles=角色
 adminUserSettings.role=角色
 adminUserSettings.actions=操作
@ -176,6 +177,7 @@ adminUserSettings.internalApiUser=內部 API 使用者
 adminUserSettings.forceChange=強制使用者在登入時修改使用者名稱/密碼
 adminUserSettings.submit=儲存
 adminUserSettings.changeUserRole=更改使用者身份
+adminUserSettings.authenticated=Authentication type

 #############
 # HOME-PAGE #
--- a/src/main/resources/settings.yml.template
+++ b/src/main/resources/settings.yml.template
@ -7,12 +7,16 @@ security:
  csrfDisabled: true
  loginAttemptCount: 5 # lock user account after 5 tries
  loginResetTimeMinutes : 120 # lock account for 2 hours after x attempts
-  #oauth2:
-  #  enabled: false # set to 'true' to enable login (Note: enableLogin must also be 'true' for this to work)
-  #  issuer: "" # set to any provider that supports OpenID Connect Discovery (/.well-known/openid-configuration) end-point
-  #  clientId: "" # Client ID from your provider
-  #  clientSecret: "" # Client Secret from your provider
-  #  autoCreateUser: false # set to 'true' to allow auto-creation of non-existing users
+  # oauth2:
+  #   enabled: true # set to 'true' to enable login (Note: enableLogin must also be 'true' for this to work)
+  #   issuer: "" # set to any provider that supports OpenID Connect Discovery (/.well-known/openid-configuration) end-point
+  #   clientId: "" # Client ID from your provider
+  #   clientSecret: "" # Client Secret from your provider
+  #   autoCreateUser: true # set to 'true' to allow auto-creation of non-existing users
+  #   autoCreateUser: true # Set to 'true' to automatically create users who do not already exist in the system
+  #   useAsUsername: "email" # Default is 'email'; custom fields can be used as the username
+  #   scopes: "openid, profile, email" # Specify the scopes for which the application will request permissions
+  #   provider: "google" # Set this to your OAuth provider's name, e.g., 'google' or 'keycloak'

 system:
  defaultLocale: 'en-US' # Set the default language (e.g. 'de-DE', 'fr-FR', etc)
--- a/src/main/resources/templates/addUsers.html
+++ b/src/main/resources/templates/addUsers.html
@ -26,6 +26,7 @@
                    <th th:text="#{username}">Username</th>
                    <th th:text="#{adminUserSettings.roles}">Roles</th>
                    <th th:text="#{adminUserSettings.actions}">Actions</th>
+                    <th th:text="#{adminUserSettings.authenticated}">Authentication type</th>
                  </tr>
                </thead>
                <tbody>
@ -37,6 +38,7 @@
                        <button type="submit" th:text="#{delete}">Delete</button>
                      </form>
                    </td>
+                    <td th:text="${user.authenticationType}"></td>
                  </tr>
                </tbody>
              </table>
@ -46,10 +48,11 @@
                <span th:if="${param.messageType[0] == 'usernameExists'}" th:text="#{usernameExistsMessage}">Default message if not found</span>
                <span th:if="${param.messageType[0] == 'invalidUsername'}" th:text="#{invalidUsernameMessage}">Default message if not found</span>
              </div>
+              <button class="btn btn-outline-info" data-toggle="tooltip" data-placement="auto" th:title="#{adminUserSettings.usernameInfo}" th:text="#{help}">Help</button>
              <form action="/api/v1/user/admin/saveUser" method="post">
                <div class="mb-3">
                  <label for="username" th:text="#{username}">Username</label>
-                  <input type="text" class="form-control" name="username" pattern="[a-zA-Z0-9]+" th:title="#{adminUserSettings.usernameInfo}" required>
+                  <input type="text" class="form-control" name="username" id="username" th:title="#{adminUserSettings.usernameInfo}" required>
                </div>
                <div class="mb-3">
                  <label for="password" th:text="#{password}">Password</label>
--- a/src/main/resources/templates/login.html
+++ b/src/main/resources/templates/login.html
@ -132,22 +132,34 @@
            }
          }
        </script>
-        <div th:if="${logoutMessage}" class="alert alert-success" th:text="${logoutMessage}"></div>
-        <div th:if="${param.messageType != null and param.messageType.size() > 0 and param.messageType[0] == 'credsUpdated'}" class="alert alert-success">
-          <span th:text="#{changedCredsMessage}">Default message if not found</span>
+        <img class="mb-4" src="favicon.svg?v=2" alt="" width="144" height="144">
+        <h1 class="h1 mb-3 fw-normal" th:text="${@appName}">Stirling-PDF</h1>
+        <div th:if="${oAuth2Enabled}">
+          <a href="oauth2/authorization/oidc" class="w-100 btn btn-lg btn-primary" th:text="#{login.ssoSignIn}">Login Via SSO</a>
+          <br>
+          <div th:if="${error}" class="alert alert-danger text-danger text-center">
+            <!-- oauth2AutoCreateDisabled -->
+            <div th:if="${error == 'oauth2AutoCreateDisabled'}" th:text="#{login.oauth2AutoCreateDisabled}">OAuth2: Auto-Create User Disabled.</div>
+            <!-- oauth2AuthenticationError -->
+            <div th:if="${error == 'oauth2AuthenticationError'}" th:text="#{userAlreadyExistsMessage}">OAuth2: User already exists.</div>
+            <!-- invalidUsername -->
+            <div th:if="${error == 'invalidUsername'}" th:text="#{invalidUsernameMessage}">OAUTH2: Invalid username.</div>
+            <!-- badcredentials -->
+            <div th:if="${error == 'badcredentials'}" th:text="#{login.invalid}">Invalid username or password.</div>
+            <!-- locked -->
+            <div th:if="${error == 'locked'}" th:text="#{login.locked}">Your account has been locked. </div>
+          </div>
+          <hr />
+        </div>
+          
+        <h2 class="h5 mb-3 fw-normal" th:text="#{login.signinTitle}">Please sign in</h2>
+        <div class="text-danger text-center">
+          <div th:if="${logoutMessage}" class="alert alert-success" th:text="${logoutMessage}"></div>
+          <div th:if="${param.messageType != null and param.messageType.size() > 0 and param.messageType[0] == 'credsUpdated'}" class="alert alert-success">
+            <span th:text="#{changedCredsMessage}">Default message if not found</span>
+          </div>
        </div>
        <form th:action="@{login}" method="post">
-          <img class="mb-4" src="favicon.svg?v=2" alt="" width="144" height="144">
-          <h1 class="h1 mb-3 fw-normal" th:text="${@appName}">Stirling-PDF</h1>
-          <div th:if="${oAuth2Enabled}">
-            <a href="oauth2/authorization/oidc" class="w-100 btn btn-lg btn-primary" th:text="#{login.ssoSignIn}">Login Via SSO</a>
-            <div class="text-danger text-center">
-              <div th:if="${error == 'oauth2AutoCreateDisabled'}" th:text="#{login.oauth2AutoCreateDisabled}">OAUTH2 Auto-Create User Disabled.</div>
-            </div>
-            <hr />
-          </div>
-          <h2 class="h5 mb-3 fw-normal" th:text="#{login.signinTitle}">Please sign in</h2>
-
          <div class="form-floating">
            <input type="text" class="form-control bg-dark text-light" id="username" name="username" placeholder="admin">
            <label for="username" th:text="#{username}">Username</label>
@ -175,10 +187,6 @@
            </div>
          </div>
        </div>
-        <div class="text-danger text-center">
-          <div th:if="${error == 'badcredentials'}" th:text="#{login.invalid}">Invalid username or password.</div>
-          <div th:if="${error == 'locked'}" th:text="#{login.locked}">Your account has been locked. </div>
-        </div>
      </main>
      <th:block th:insert="~{fragments/footer.html :: footer}"></th:block>
    </div>