Always specify Locale on toLowerCase and toUpperCase usages, fixes AuthMe not working correctly on machines with turkish locale. ('I'.toLowerCase() => 'ı')

src/main/java/fr/xephi/authme/api/v3/AuthMeApi.java

@@ -21,6 +21,7 @@ import java.time.Instant;
 import java.util.ArrayList;
 import java.util.Date;
 import java.util.List;
+import java.util.Locale;
 import java.util.Optional;
 
 /**
@@ -217,7 +218,7 @@ public class AuthMeApi {
      * @return true if player is registered, false otherwise
      */
     public boolean isRegistered(String playerName) {
-        String player = playerName.toLowerCase();
+        String player = playerName.toLowerCase(Locale.ROOT);
         return dataSource.isAuthAvailable(player);
     }
 
@@ -241,7 +242,7 @@ public class AuthMeApi {
      * @return true if the player was registered successfully
      */
     public boolean registerPlayer(String playerName, String password) {
-        String name = playerName.toLowerCase();
+        String name = playerName.toLowerCase(Locale.ROOT);
         if (isRegistered(name)) {
             return false;
         }

src/main/java/fr/xephi/authme/command/CommandMapper.java

@@ -11,6 +11,7 @@ import java.util.ArrayList;
 import java.util.Collection;
 import java.util.HashSet;
 import java.util.List;
+import java.util.Locale;
 import java.util.Set;
 
 import static fr.xephi.authme.command.FoundResultStatus.INCORRECT_ARGUMENTS;
@@ -130,7 +131,7 @@ public class CommandMapper {
     }
 
     private CommandDescription getBaseCommand(String label) {
-        String baseLabel = label.toLowerCase();
+        String baseLabel = label.toLowerCase(Locale.ROOT);
         if (baseLabel.startsWith("authme:")) {
             baseLabel = baseLabel.substring("authme:".length());
         }
@@ -157,7 +158,7 @@ public class CommandMapper {
             return null;
         }
 
-        final String label = parts.get(0).toLowerCase();
+        final String label = parts.get(0).toLowerCase(Locale.ROOT);
         final int argumentCount = parts.size() - 1;
 
         for (CommandDescription child : baseCommand.getChildren()) {

src/main/java/fr/xephi/authme/command/executable/authme/AccountsCommand.java

@@ -10,6 +10,7 @@ import org.bukkit.command.CommandSender;
 
 import javax.inject.Inject;
 import java.util.List;
+import java.util.Locale;
 
 /**
  * Shows all accounts registered by the same IP address for the given player name or IP address.
@@ -44,7 +45,7 @@ public class AccountsCommand implements ExecutableCommand {
             });
         } else {
             bukkitService.runTaskAsynchronously(() -> {
-                PlayerAuth auth = dataSource.getAuth(playerName.toLowerCase());
+                PlayerAuth auth = dataSource.getAuth(playerName.toLowerCase(Locale.ROOT));
                 if (auth == null) {
                     commonService.send(sender, MessageKey.UNKNOWN_USER);
                     return;

src/main/java/fr/xephi/authme/command/executable/authme/ConverterCommand.java

@@ -22,6 +22,7 @@ import org.bukkit.command.CommandSender;
 
 import javax.inject.Inject;
 import java.util.List;
+import java.util.Locale;
 import java.util.Map;
 
 /**
@@ -71,7 +72,7 @@ public class ConverterCommand implements ExecutableCommand {
     private static Class<? extends Converter> getConverterClassFromArgs(List<String> arguments) {
         return arguments.isEmpty()
             ? null
-            : CONVERTERS.get(arguments.get(0).toLowerCase());
+            : CONVERTERS.get(arguments.get(0).toLowerCase(Locale.ROOT));
     }
 
     /**

src/main/java/fr/xephi/authme/command/executable/authme/PurgeBannedPlayersCommand.java

@@ -9,6 +9,7 @@ import org.bukkit.command.CommandSender;
 import javax.inject.Inject;
 import java.util.HashSet;
 import java.util.List;
+import java.util.Locale;
 import java.util.Set;
 
 /**
@@ -29,7 +30,7 @@ public class PurgeBannedPlayersCommand implements ExecutableCommand {
         Set<OfflinePlayer> bannedPlayers = bukkitService.getBannedPlayers();
         Set<String> namedBanned = new HashSet<>(bannedPlayers.size());
         for (OfflinePlayer offlinePlayer : bannedPlayers) {
-            namedBanned.add(offlinePlayer.getName().toLowerCase());
+            namedBanned.add(offlinePlayer.getName().toLowerCase(Locale.ROOT));
         }
 
         purgeService.purgePlayers(sender, namedBanned, bannedPlayers.toArray(new OfflinePlayer[bannedPlayers.size()]));

src/main/java/fr/xephi/authme/command/executable/authme/PurgePlayerCommand.java

@@ -9,6 +9,7 @@ import org.bukkit.command.CommandSender;
 
 import javax.inject.Inject;
 import java.util.List;
+import java.util.Locale;
 
 import static java.util.Collections.singletonList;
 
@@ -36,7 +37,7 @@ public class PurgePlayerCommand implements ExecutableCommand {
     private void executeCommand(CommandSender sender, String name, String option) {
         if ("force".equals(option) || !dataSource.isAuthAvailable(name)) {
             OfflinePlayer offlinePlayer = bukkitService.getOfflinePlayer(name);
-            purgeExecutor.executePurge(singletonList(offlinePlayer), singletonList(name.toLowerCase()));
+            purgeExecutor.executePurge(singletonList(offlinePlayer), singletonList(name.toLowerCase(Locale.ROOT)));
             sender.sendMessage("Purged data for player " + name);
         } else {
             sender.sendMessage("This player is still registered! Are you sure you want to proceed? "

src/main/java/fr/xephi/authme/command/executable/authme/RegisterAdminCommand.java

@@ -17,6 +17,7 @@ import org.bukkit.entity.Player;
 
 import javax.inject.Inject;
 import java.util.List;
+import java.util.Locale;
 
 /**
  * Admin command to register a user.
@@ -45,7 +46,7 @@ public class RegisterAdminCommand implements ExecutableCommand {
         // Get the player name and password
         final String playerName = arguments.get(0);
         final String playerPass = arguments.get(1);
-        final String playerNameLowerCase = playerName.toLowerCase();
+        final String playerNameLowerCase = playerName.toLowerCase(Locale.ROOT);
 
         // Command logic
         ValidationResult passwordValidation = validationService.validatePassword(playerPass, playerName);

src/main/java/fr/xephi/authme/command/executable/authme/debug/DebugCommand.java

@@ -9,6 +9,7 @@ import org.bukkit.command.CommandSender;
 
 import javax.inject.Inject;
 import java.util.List;
+import java.util.Locale;
 import java.util.Map;
 import java.util.Set;
 import java.util.TreeMap;
@@ -45,7 +46,7 @@ public class DebugCommand implements ExecutableCommand {
         if (arguments.isEmpty()) {
             return null;
         }
-        return getSections().get(arguments.get(0).toLowerCase());
+        return getSections().get(arguments.get(0).toLowerCase(Locale.ROOT));
     }
 
     private void sendAvailableSections(CommandSender sender) {

src/main/java/fr/xephi/authme/command/executable/changepassword/ChangePasswordCommand.java

@@ -12,6 +12,7 @@ import org.bukkit.entity.Player;
 
 import javax.inject.Inject;
 import java.util.List;
+import java.util.Locale;
 
 /**
  * The command for a player to change his password with.
@@ -35,7 +36,7 @@ public class ChangePasswordCommand extends PlayerCommand {
 
     @Override
     public void runCommand(Player player, List<String> arguments) {
-        String name = player.getName().toLowerCase();
+        String name = player.getName().toLowerCase(Locale.ROOT);
 
         if (!playerCache.isAuthenticated(name)) {
             commonService.send(player, MessageKey.NOT_LOGGED_IN);

src/main/java/fr/xephi/authme/data/ProxySessionManager.java

@@ -4,6 +4,7 @@ import fr.xephi.authme.initialization.HasCleanup;
 import fr.xephi.authme.util.expiring.ExpiringSet;
 
 import javax.inject.Inject;
+import java.util.Locale;
 import java.util.concurrent.TimeUnit;
 
 public class ProxySessionManager implements HasCleanup {
@@ -21,7 +22,7 @@ public class ProxySessionManager implements HasCleanup {
      * @param name the player's name
      */
     private void setActiveSession(String name) {
-        activeProxySessions.add(name.toLowerCase());
+        activeProxySessions.add(name.toLowerCase(Locale.ROOT));
     }
 
     /**

src/main/java/fr/xephi/authme/data/VerificationCodeManager.java

@@ -16,6 +16,7 @@ import org.bukkit.entity.Player;
 
 import javax.inject.Inject;
 import java.util.HashSet;
+import java.util.Locale;
 import java.util.Set;
 import java.util.concurrent.TimeUnit;
 
@@ -82,7 +83,7 @@ public class VerificationCodeManager implements SettingsDependent, HasCleanup {
      * @return true if the player has been verified, false otherwise
      */
     private boolean isPlayerVerified(String name) {
-        return verifiedPlayers.contains(name.toLowerCase());
+        return verifiedPlayers.contains(name.toLowerCase(Locale.ROOT));
     }
 
     /**
@@ -92,7 +93,7 @@ public class VerificationCodeManager implements SettingsDependent, HasCleanup {
      * @return true if the code exists, false otherwise
      */
     public boolean hasCode(String name) {
-        return (verificationCodes.get(name.toLowerCase()) != null);
+        return (verificationCodes.get(name.toLowerCase(Locale.ROOT)) != null);
     }
 
     /**
@@ -135,7 +136,7 @@ public class VerificationCodeManager implements SettingsDependent, HasCleanup {
             final String email = emailResult.getValue();
             if (!Utils.isEmailEmpty(email)) {
                 String code = RandomStringUtils.generateNum(6); // 6 digits code
-                verificationCodes.put(name.toLowerCase(), code);
+                verificationCodes.put(name.toLowerCase(Locale.ROOT), code);
                 emailService.sendVerificationMail(name, email, code);
             }
         }
@@ -150,7 +151,7 @@ public class VerificationCodeManager implements SettingsDependent, HasCleanup {
      */
     public boolean checkCode(String name, String code) {
         boolean correct = false;
-        if (code.equals(verificationCodes.get(name.toLowerCase()))) {
+        if (code.equals(verificationCodes.get(name.toLowerCase(Locale.ROOT)))) {
             verify(name);
             correct = true;
         }
@@ -163,7 +164,7 @@ public class VerificationCodeManager implements SettingsDependent, HasCleanup {
      * @param name the name of the player to generate a code for
      */
     public void verify(String name) {
-        verifiedPlayers.add(name.toLowerCase());
+        verifiedPlayers.add(name.toLowerCase(Locale.ROOT));
     }
 
     /**
@@ -172,7 +173,7 @@ public class VerificationCodeManager implements SettingsDependent, HasCleanup {
      * @param name the name of the player to generate a code for
      */
     public void unverify(String name){
-        verifiedPlayers.remove(name.toLowerCase());
+        verifiedPlayers.remove(name.toLowerCase(Locale.ROOT));
     }
 
     @Override

src/main/java/fr/xephi/authme/data/auth/PlayerAuth.java

@@ -3,6 +3,7 @@ package fr.xephi.authme.data.auth;
 import fr.xephi.authme.security.crypts.HashedPassword;
 import org.bukkit.Location;
 
+import java.util.Locale;
 import java.util.Objects;
 import java.util.Optional;
 import java.util.UUID;
@@ -54,7 +55,7 @@ public class PlayerAuth {
 
 
     public void setNickname(String nickname) {
-        this.nickname = nickname.toLowerCase();
+        this.nickname = nickname.toLowerCase(Locale.ROOT);
     }
 
     public String getNickname() {
@@ -239,7 +240,7 @@ public class PlayerAuth {
          */
         public PlayerAuth build() {
             PlayerAuth auth = new PlayerAuth();
-            auth.nickname = checkNotNull(name).toLowerCase();
+            auth.nickname = checkNotNull(name).toLowerCase(Locale.ROOT);
             auth.realName = Optional.ofNullable(realName).orElse("Player");
             auth.password = Optional.ofNullable(password).orElse(new HashedPassword(""));
             auth.totpKey = totpKey;

src/main/java/fr/xephi/authme/data/auth/PlayerCache.java

@@ -1,6 +1,7 @@
 package fr.xephi.authme.data.auth;
 
 
+import java.util.Locale;
 import java.util.Map;
 import java.util.concurrent.ConcurrentHashMap;
 
@@ -20,7 +21,7 @@ public class PlayerCache {
      * @param auth the player auth object to save
      */
     public void updatePlayer(PlayerAuth auth) {
-        cache.put(auth.getNickname().toLowerCase(), auth);
+        cache.put(auth.getNickname().toLowerCase(Locale.ROOT), auth);
     }
 
     /**
@@ -29,7 +30,7 @@ public class PlayerCache {
      * @param user name of the player to remove
      */
     public void removePlayer(String user) {
-        cache.remove(user.toLowerCase());
+        cache.remove(user.toLowerCase(Locale.ROOT));
     }
 
     /**
@@ -40,7 +41,7 @@ public class PlayerCache {
      * @return true if player is logged in, false otherwise.
      */
     public boolean isAuthenticated(String user) {
-        return cache.containsKey(user.toLowerCase());
+        return cache.containsKey(user.toLowerCase(Locale.ROOT));
     }
 
     /**
@@ -51,7 +52,7 @@ public class PlayerCache {
      * @return the associated auth object, or null if not available
      */
     public PlayerAuth getAuth(String user) {
-        return cache.get(user.toLowerCase());
+        return cache.get(user.toLowerCase(Locale.ROOT));
     }
 
     /**

src/main/java/fr/xephi/authme/data/captcha/CaptchaCodeStorage.java

@@ -3,6 +3,7 @@ package fr.xephi.authme.data.captcha;
 import fr.xephi.authme.util.RandomStringUtils;
 import fr.xephi.authme.util.expiring.ExpiringMap;
 
+import java.util.Locale;
 import java.util.concurrent.TimeUnit;
 
 /**
@@ -51,7 +52,7 @@ public class CaptchaCodeStorage {
      * @return the code the player is required to enter
      */
     public String getCodeOrGenerateNew(String name) {
-        String code = captchaCodes.get(name.toLowerCase());
+        String code = captchaCodes.get(name.toLowerCase(Locale.ROOT));
         return code == null ? generateCode(name) : code;
     }
 
@@ -63,7 +64,7 @@ public class CaptchaCodeStorage {
      */
     private String generateCode(String name) {
         String code = RandomStringUtils.generate(captchaLength);
-        captchaCodes.put(name.toLowerCase(), code);
+        captchaCodes.put(name.toLowerCase(Locale.ROOT), code);
         return code;
     }
 
@@ -76,7 +77,7 @@ public class CaptchaCodeStorage {
      * @return true if the code matches, false otherwise
      */
     public boolean checkCode(String name, String code) {
-        String nameLowerCase = name.toLowerCase();
+        String nameLowerCase = name.toLowerCase(Locale.ROOT);
         String savedCode = captchaCodes.get(nameLowerCase);
         if (savedCode != null && savedCode.equalsIgnoreCase(code)) {
             captchaCodes.remove(nameLowerCase);

src/main/java/fr/xephi/authme/data/captcha/LoginCaptchaManager.java

@@ -8,6 +8,7 @@ import fr.xephi.authme.util.expiring.TimedCounter;
 import org.bukkit.entity.Player;
 
 import javax.inject.Inject;
+import java.util.Locale;
 import java.util.concurrent.TimeUnit;
 
 /**
@@ -36,14 +37,14 @@ public class LoginCaptchaManager implements CaptchaManager, SettingsDependent, H
      */
     public void increaseLoginFailureCount(String name) {
         if (isEnabled) {
-            String playerLower = name.toLowerCase();
+            String playerLower = name.toLowerCase(Locale.ROOT);
             playerCounts.increment(playerLower);
         }
     }
 
     @Override
     public boolean isCaptchaRequired(String playerName) {
-        return isEnabled && playerCounts.get(playerName.toLowerCase()) >= threshold;
+        return isEnabled && playerCounts.get(playerName.toLowerCase(Locale.ROOT)) >= threshold;
     }
 
     @Override
@@ -53,7 +54,7 @@ public class LoginCaptchaManager implements CaptchaManager, SettingsDependent, H
 
     @Override
     public boolean checkCode(Player player, String code) {
-        String nameLower = player.getName().toLowerCase();
+        String nameLower = player.getName().toLowerCase(Locale.ROOT);
         boolean isCodeCorrect = captchaCodeStorage.checkCode(nameLower, code);
         if (isCodeCorrect) {
             playerCounts.remove(nameLower);
@@ -68,7 +69,7 @@ public class LoginCaptchaManager implements CaptchaManager, SettingsDependent, H
      */
     public void resetLoginFailureCount(String name) {
         if (isEnabled) {
-            playerCounts.remove(name.toLowerCase());
+            playerCounts.remove(name.toLowerCase(Locale.ROOT));
         }
     }
 

src/main/java/fr/xephi/authme/data/captcha/RegistrationCaptchaManager.java

@@ -8,6 +8,7 @@ import fr.xephi.authme.util.expiring.ExpiringSet;
 import org.bukkit.entity.Player;
 
 import javax.inject.Inject;
+import java.util.Locale;
 import java.util.concurrent.TimeUnit;
 
 /**
@@ -31,7 +32,7 @@ public class RegistrationCaptchaManager implements CaptchaManager, SettingsDepen
 
     @Override
     public boolean isCaptchaRequired(String name) {
-        return isEnabled && !verifiedNamesForRegistration.contains(name.toLowerCase());
+        return isEnabled && !verifiedNamesForRegistration.contains(name.toLowerCase(Locale.ROOT));
     }
 
     @Override
@@ -41,7 +42,7 @@ public class RegistrationCaptchaManager implements CaptchaManager, SettingsDepen
 
     @Override
     public boolean checkCode(Player player, String code) {
-        String nameLower = player.getName().toLowerCase();
+        String nameLower = player.getName().toLowerCase(Locale.ROOT);
         boolean isCodeCorrect = captchaCodeStorage.checkCode(nameLower, code);
         if (isCodeCorrect) {
             verifiedNamesForRegistration.add(nameLower);

src/main/java/fr/xephi/authme/data/limbo/LimboService.java

@@ -9,6 +9,7 @@ import org.bukkit.Location;
 import org.bukkit.entity.Player;
 
 import javax.inject.Inject;
+import java.util.Locale;
 import java.util.Map;
 import java.util.Optional;
 import java.util.concurrent.ConcurrentHashMap;
@@ -55,7 +56,7 @@ public class LimboService {
      * @param isRegistered whether or not the player is registered
      */
     public void createLimboPlayer(Player player, boolean isRegistered) {
-        final String name = player.getName().toLowerCase();
+        final String name = player.getName().toLowerCase(Locale.ROOT);
 
         LimboPlayer limboFromDisk = persistence.getLimboPlayer(player);
         if (limboFromDisk != null) {
@@ -89,7 +90,7 @@ public class LimboService {
      * @return the associated limbo player, or null if none available
      */
     public LimboPlayer getLimboPlayer(String name) {
-        return entries.get(name.toLowerCase());
+        return entries.get(name.toLowerCase(Locale.ROOT));
     }
 
     /**
@@ -99,7 +100,7 @@ public class LimboService {
      * @return true if present, false otherwise
      */
     public boolean hasLimboPlayer(String name) {
-        return entries.containsKey(name.toLowerCase());
+        return entries.containsKey(name.toLowerCase(Locale.ROOT));
     }
 
     /**
@@ -111,7 +112,7 @@ public class LimboService {
      * @param player the player whose data should be restored
      */
     public void restoreData(Player player) {
-        String lowerName = player.getName().toLowerCase();
+        String lowerName = player.getName().toLowerCase(Locale.ROOT);
         LimboPlayer limbo = entries.remove(lowerName);
 
         if (limbo == null) {
@@ -178,7 +179,7 @@ public class LimboService {
      * @return Optional with the limbo player
      */
     private Optional<LimboPlayer> getLimboOrLogError(Player player, String context) {
-        LimboPlayer limbo = entries.get(player.getName().toLowerCase());
+        LimboPlayer limbo = entries.get(player.getName().toLowerCase(Locale.ROOT));
         if (limbo == null) {
             logger.debug("No LimboPlayer found for `{0}`. Action: {1}", player.getName(), context);
         }

src/main/java/fr/xephi/authme/datasource/CacheDataSource.java

@@ -18,6 +18,7 @@ import fr.xephi.authme.util.Utils;
 
 import java.util.Collection;
 import java.util.List;
+import java.util.Locale;
 import java.util.Optional;
 import java.util.Set;
 import java.util.concurrent.Executors;
@@ -86,7 +87,7 @@ public class CacheDataSource implements DataSource {
 
     @Override
     public HashedPassword getPassword(String user) {
-        user = user.toLowerCase();
+        user = user.toLowerCase(Locale.ROOT);
         Optional<PlayerAuth> pAuthOpt = cachedAuths.getIfPresent(user);
         if (pAuthOpt != null && pAuthOpt.isPresent()) {
             return pAuthOpt.get().getPassword();
@@ -96,7 +97,7 @@ public class CacheDataSource implements DataSource {
 
     @Override
     public PlayerAuth getAuth(String user) {
-        user = user.toLowerCase();
+        user = user.toLowerCase(Locale.ROOT);
         return cachedAuths.getUnchecked(user).orElse(null);
     }
 
@@ -120,7 +121,7 @@ public class CacheDataSource implements DataSource {
 
     @Override
     public boolean updatePassword(String user, HashedPassword password) {
-        user = user.toLowerCase();
+        user = user.toLowerCase(Locale.ROOT);
         boolean result = source.updatePassword(user, password);
         if (result) {
             cachedAuths.refresh(user);
@@ -153,7 +154,7 @@ public class CacheDataSource implements DataSource {
 
     @Override
     public boolean removeAuth(String name) {
-        name = name.toLowerCase();
+        name = name.toLowerCase(Locale.ROOT);
         boolean result = source.removeAuth(name);
         if (result) {
             cachedAuths.invalidate(name);
@@ -210,12 +211,12 @@ public class CacheDataSource implements DataSource {
 
     @Override
     public void setLogged(final String user) {
-        source.setLogged(user.toLowerCase());
+        source.setLogged(user.toLowerCase(Locale.ROOT));
     }
 
     @Override
     public void setUnlogged(final String user) {
-        source.setUnlogged(user.toLowerCase());
+        source.setUnlogged(user.toLowerCase(Locale.ROOT));
     }
 
     @Override

src/main/java/fr/xephi/authme/datasource/MySQL.java

@@ -24,6 +24,7 @@ import java.util.ArrayList;
 import java.util.Collection;
 import java.util.HashSet;
 import java.util.List;
+import java.util.Locale;
 import java.util.Set;
 import java.util.UUID;
 
@@ -309,7 +310,7 @@ public class MySQL extends AbstractSqlDataSource {
         String sql = "SELECT * FROM " + tableName + " WHERE " + col.NAME + "=?;";
         PlayerAuth auth;
         try (Connection con = getConnection(); PreparedStatement pst = con.prepareStatement(sql)) {
-            pst.setString(1, user.toLowerCase());
+            pst.setString(1, user.toLowerCase(Locale.ROOT));
             try (ResultSet rs = pst.executeQuery()) {
                 if (rs.next()) {
                     int id = rs.getInt(col.ID);
@@ -377,11 +378,11 @@ public class MySQL extends AbstractSqlDataSource {
 
     @Override
     public boolean removeAuth(String user) {
-        user = user.toLowerCase();
+        user = user.toLowerCase(Locale.ROOT);
         String sql = "DELETE FROM " + tableName + " WHERE " + col.NAME + "=?;";
         try (Connection con = getConnection(); PreparedStatement pst = con.prepareStatement(sql)) {
             sqlExtension.removeAuth(user, con);
-            pst.setString(1, user.toLowerCase());
+            pst.setString(1, user.toLowerCase(Locale.ROOT));
             pst.executeUpdate();
             return true;
         } catch (SQLException ex) {
@@ -402,7 +403,7 @@ public class MySQL extends AbstractSqlDataSource {
         String sql = "DELETE FROM " + tableName + " WHERE " + col.NAME + "=?;";
         try (Connection con = getConnection(); PreparedStatement pst = con.prepareStatement(sql)) {
             for (String name : toPurge) {
-                pst.setString(1, name.toLowerCase());
+                pst.setString(1, name.toLowerCase(Locale.ROOT));
                 pst.executeUpdate();
             }
         } catch (SQLException ex) {
@@ -470,7 +471,7 @@ public class MySQL extends AbstractSqlDataSource {
         String sql = "UPDATE " + tableName + " SET " + col.TOTP_KEY + " = ? WHERE " + col.NAME + " = ?";
         try (Connection con = getConnection(); PreparedStatement pst = con.prepareStatement(sql)) {
             pst.setString(1, totpKey);
-            pst.setString(2, user.toLowerCase());
+            pst.setString(2, user.toLowerCase(Locale.ROOT));
             pst.executeUpdate();
             return true;
         } catch (SQLException e) {

src/main/java/fr/xephi/authme/datasource/PostgreSqlDataSource.java

@@ -23,6 +23,7 @@ import java.util.ArrayList;
 import java.util.Collection;
 import java.util.HashSet;
 import java.util.List;
+import java.util.Locale;
 import java.util.Set;
 
 import static fr.xephi.authme.datasource.SqlDataSourceUtils.getNullableLong;
@@ -257,7 +258,7 @@ public class PostgreSqlDataSource extends AbstractSqlDataSource {
     }
 
     private boolean isColumnMissing(DatabaseMetaData metaData, String columnName) throws SQLException {
-        try (ResultSet rs = metaData.getColumns(null, null, tableName, columnName.toLowerCase())) {
+        try (ResultSet rs = metaData.getColumns(null, null, tableName, columnName.toLowerCase(Locale.ROOT))) {
             return !rs.next();
         }
     }
@@ -267,7 +268,7 @@ public class PostgreSqlDataSource extends AbstractSqlDataSource {
         String sql = "SELECT * FROM " + tableName + " WHERE " + col.NAME + "=?;";
         PlayerAuth auth;
         try (Connection con = getConnection(); PreparedStatement pst = con.prepareStatement(sql)) {
-            pst.setString(1, user.toLowerCase());
+            pst.setString(1, user.toLowerCase(Locale.ROOT));
             try (ResultSet rs = pst.executeQuery()) {
                 if (rs.next()) {
                     int id = rs.getInt(col.ID);
@@ -335,11 +336,11 @@ public class PostgreSqlDataSource extends AbstractSqlDataSource {
 
     @Override
     public boolean removeAuth(String user) {
-        user = user.toLowerCase();
+        user = user.toLowerCase(Locale.ROOT);
         String sql = "DELETE FROM " + tableName + " WHERE " + col.NAME + "=?;";
         try (Connection con = getConnection(); PreparedStatement pst = con.prepareStatement(sql)) {
             sqlExtension.removeAuth(user, con);
-            pst.setString(1, user.toLowerCase());
+            pst.setString(1, user.toLowerCase(Locale.ROOT));
             pst.executeUpdate();
             return true;
         } catch (SQLException ex) {
@@ -360,7 +361,7 @@ public class PostgreSqlDataSource extends AbstractSqlDataSource {
         String sql = "DELETE FROM " + tableName + " WHERE " + col.NAME + "=?;";
         try (Connection con = getConnection(); PreparedStatement pst = con.prepareStatement(sql)) {
             for (String name : toPurge) {
-                pst.setString(1, name.toLowerCase());
+                pst.setString(1, name.toLowerCase(Locale.ROOT));
                 pst.executeUpdate();
             }
         } catch (SQLException ex) {
@@ -428,7 +429,7 @@ public class PostgreSqlDataSource extends AbstractSqlDataSource {
         String sql = "UPDATE " + tableName + " SET " + col.TOTP_KEY + " = ? WHERE " + col.NAME + " = ?";
         try (Connection con = getConnection(); PreparedStatement pst = con.prepareStatement(sql)) {
             pst.setString(1, totpKey);
-            pst.setString(2, user.toLowerCase());
+            pst.setString(2, user.toLowerCase(Locale.ROOT));
             pst.executeUpdate();
             return true;
         } catch (SQLException e) {

src/main/java/fr/xephi/authme/datasource/SQLite.java

@@ -20,6 +20,7 @@ import java.util.ArrayList;
 import java.util.Collection;
 import java.util.HashSet;
 import java.util.List;
+import java.util.Locale;
 import java.util.Set;
 
 import static fr.xephi.authme.datasource.SqlDataSourceUtils.getNullableLong;
@@ -268,7 +269,7 @@ public class SQLite extends AbstractSqlDataSource {
         String delete = "DELETE FROM " + tableName + " WHERE " + col.NAME + "=?;";
         try (PreparedStatement deletePst = con.prepareStatement(delete)) {
             for (String name : toPurge) {
-                deletePst.setString(1, name.toLowerCase());
+                deletePst.setString(1, name.toLowerCase(Locale.ROOT));
                 deletePst.executeUpdate();
             }
         } catch (SQLException ex) {
@@ -280,7 +281,7 @@ public class SQLite extends AbstractSqlDataSource {
     public boolean removeAuth(String user) {
         String sql = "DELETE FROM " + tableName + " WHERE " + col.NAME + "=?;";
         try (PreparedStatement pst = con.prepareStatement(sql)) {
-            pst.setString(1, user.toLowerCase());
+            pst.setString(1, user.toLowerCase(Locale.ROOT));
             pst.executeUpdate();
             return true;
         } catch (SQLException ex) {
@@ -355,7 +356,7 @@ public class SQLite extends AbstractSqlDataSource {
         String sql = "UPDATE " + tableName + " SET " + col.TOTP_KEY + " = ? WHERE " + col.NAME + " = ?";
         try (PreparedStatement pst = con.prepareStatement(sql)) {
             pst.setString(1, totpKey);
-            pst.setString(2, user.toLowerCase());
+            pst.setString(2, user.toLowerCase(Locale.ROOT));
             pst.executeUpdate();
             return true;
         } catch (SQLException e) {

src/main/java/fr/xephi/authme/datasource/columnshandler/AuthMeColumnsHandler.java

@@ -14,6 +14,7 @@ import fr.xephi.authme.settings.properties.DatabaseSettings;
 import java.sql.Connection;
 import java.sql.SQLException;
 import java.util.List;
+import java.util.Locale;
 
 import static ch.jalu.datasourcecolumns.sqlimplementation.SqlColumnsHandlerConfig.forConnectionPool;
 import static ch.jalu.datasourcecolumns.sqlimplementation.SqlColumnsHandlerConfig.forSingleConnection;
@@ -78,7 +79,7 @@ public final class AuthMeColumnsHandler {
      */
     public <T> boolean update(String name, DataSourceColumn<T> column, T value) {
         try {
-            return internalHandler.update(name.toLowerCase(), column, value);
+            return internalHandler.update(name.toLowerCase(Locale.ROOT), column, value);
         } catch (SQLException e) {
             logSqlException(e);
             return false;
@@ -110,7 +111,7 @@ public final class AuthMeColumnsHandler {
      */
     public boolean update(String name, UpdateValues<ColumnContext> updateValues) {
         try {
-            return internalHandler.update(name.toLowerCase(), updateValues);
+            return internalHandler.update(name.toLowerCase(Locale.ROOT), updateValues);
         } catch (SQLException e) {
             logSqlException(e);
             return false;
@@ -145,7 +146,7 @@ public final class AuthMeColumnsHandler {
      * @throws SQLException .
      */
     public <T> DataSourceValue<T> retrieve(String name, DataSourceColumn<T> column) throws SQLException {
-        return internalHandler.retrieve(name.toLowerCase(), column);
+        return internalHandler.retrieve(name.toLowerCase(Locale.ROOT), column);
     }
 
     /**
@@ -157,7 +158,7 @@ public final class AuthMeColumnsHandler {
      * @throws SQLException .
      */
     public DataSourceValues retrieve(String name, DataSourceColumn<?>... columns) throws SQLException {
-        return internalHandler.retrieve(name.toLowerCase(), columns);
+        return internalHandler.retrieve(name.toLowerCase(Locale.ROOT), columns);
     }
 
     /**

src/main/java/fr/xephi/authme/datasource/converter/CrazyLoginConverter.java

@@ -14,6 +14,7 @@ import java.io.BufferedReader;
 import java.io.File;
 import java.io.FileReader;
 import java.io.IOException;
+import java.util.Locale;
 
 /**
  * Converter for CrazyLogin to AuthMe.
@@ -70,7 +71,7 @@ public class CrazyLoginConverter implements Converter {
         String password = args[1];
         if (password != null) {
             PlayerAuth auth = PlayerAuth.builder()
-                .name(playerName.toLowerCase())
+                .name(playerName.toLowerCase(Locale.ROOT))
                 .realName(playerName)
                 .password(password, null)
                 .build();

src/main/java/fr/xephi/authme/datasource/converter/RoyalAuthConverter.java

@@ -12,6 +12,7 @@ import org.bukkit.configuration.file.YamlConfiguration;
 
 import javax.inject.Inject;
 import java.io.File;
+import java.util.Locale;
 
 import static fr.xephi.authme.util.FileUtils.makePath;
 
@@ -35,7 +36,7 @@ public class RoyalAuthConverter implements Converter {
     public void execute(CommandSender sender) {
         for (OfflinePlayer player : plugin.getServer().getOfflinePlayers()) {
             try {
-                String name = player.getName().toLowerCase();
+                String name = player.getName().toLowerCase(Locale.ROOT);
                 File file = new File(makePath(".", "plugins", "RoyalAuth", "userdata", name + ".yml"));
 
                 if (dataSource.isAuthAvailable(name) || !file.exists()) {

src/main/java/fr/xephi/authme/datasource/converter/VAuthConverter.java

@@ -12,6 +12,7 @@ import org.bukkit.command.CommandSender;
 import javax.inject.Inject;
 import java.io.File;
 import java.io.IOException;
+import java.util.Locale;
 import java.util.Scanner;
 import java.util.UUID;
 
@@ -48,12 +49,12 @@ public class VAuthConverter implements Converter {
                         continue;
                     }
                     auth = PlayerAuth.builder()
-                        .name(pname.toLowerCase())
+                        .name(pname.toLowerCase(Locale.ROOT))
                         .realName(pname)
                         .password(password, null).build();
                 } else {
                     auth = PlayerAuth.builder()
-                        .name(name.toLowerCase())
+                        .name(name.toLowerCase(Locale.ROOT))
                         .realName(name)
                         .password(password, null).build();
                 }

src/main/java/fr/xephi/authme/datasource/converter/XAuthConverter.java

@@ -18,6 +18,7 @@ import java.sql.ResultSet;
 import java.sql.SQLException;
 import java.util.ArrayList;
 import java.util.List;
+import java.util.Locale;
 
 import static fr.xephi.authme.util.FileUtils.makePath;
 
@@ -66,7 +67,7 @@ public class XAuthConverter implements Converter {
             String psw = getPassword(id);
             if (psw != null && !psw.isEmpty() && pl != null) {
                 PlayerAuth auth = PlayerAuth.builder()
-                    .name(pl.toLowerCase())
+                    .name(pl.toLowerCase(Locale.ROOT))
                     .realName(pl)
                     .password(psw, null).build();
                 database.saveAuth(auth);
@@ -89,7 +90,7 @@ public class XAuthConverter implements Converter {
             if (!rs.next()) {
                 return null;
             }
-            realPass = rs.getString("playername").toLowerCase();
+            realPass = rs.getString("playername").toLowerCase(Locale.ROOT);
         } catch (SQLException e) {
             xAuthLog.severe("Failed to retrieve name for account: " + id, e);
             return null;

src/main/java/fr/xephi/authme/initialization/OnShutdownPlayerSaver.java

@@ -14,6 +14,7 @@ import org.bukkit.Location;
 import org.bukkit.entity.Player;
 
 import javax.inject.Inject;
+import java.util.Locale;
 
 /**
  * Saves all players' data when the plugin shuts down.
@@ -48,7 +49,7 @@ public class OnShutdownPlayerSaver {
     }
 
     private void savePlayer(Player player) {
-        String name = player.getName().toLowerCase();
+        String name = player.getName().toLowerCase(Locale.ROOT);
         if (PlayerUtils.isNpc(player) || validationService.isUnrestricted(name)) {
             return;
         }
@@ -64,7 +65,7 @@ public class OnShutdownPlayerSaver {
         if (settings.getProperty(RestrictionSettings.SAVE_QUIT_LOCATION)) {
             Location loc = spawnLoader.getPlayerLocationOrSpawn(player);
             PlayerAuth auth = PlayerAuth.builder()
-                .name(player.getName().toLowerCase())
+                .name(player.getName().toLowerCase(Locale.ROOT))
                 .realName(player.getName())
                 .location(loc).build();
             dataSource.updateQuitLoc(auth);

src/main/java/fr/xephi/authme/listener/OnJoinVerifier.java

@@ -25,6 +25,7 @@ import org.bukkit.event.player.PlayerLoginEvent;
 import javax.annotation.PostConstruct;
 import javax.inject.Inject;
 import java.util.Collection;
+import java.util.Locale;
 import java.util.regex.Pattern;
 
 /**
@@ -160,7 +161,7 @@ public class OnJoinVerifier implements Reloadable {
             String realName = auth.getRealName(); // might be null or "Player"
 
             if (StringUtils.isEmpty(realName) || "Player".equals(realName)) {
-                dataSource.updateRealName(connectingName.toLowerCase(), connectingName);
+                dataSource.updateRealName(connectingName.toLowerCase(Locale.ROOT), connectingName);
             } else if (!realName.equals(connectingName)) {
                 throw new FailedVerificationException(MessageKey.INVALID_NAME_CASE, realName, connectingName);
             }

src/main/java/fr/xephi/authme/listener/PlayerListener.java

@@ -52,6 +52,7 @@ import org.bukkit.event.player.PlayerShearEntityEvent;
 import org.bukkit.inventory.InventoryView;
 
 import javax.inject.Inject;
+import java.util.Locale;
 import java.util.Set;
 
 import static fr.xephi.authme.settings.properties.RestrictionSettings.ALLOWED_MOVEMENT_RADIUS;
@@ -214,7 +215,7 @@ public class PlayerListener implements Listener {
             return;
         }
 
-        String name = player.getName().toLowerCase();
+        String name = player.getName().toLowerCase(Locale.ROOT);
         String joinMsg = event.getJoinMessage();
 
         // Remove the join message while the player isn't logging in
@@ -292,7 +293,7 @@ public class PlayerListener implements Listener {
 
     @EventHandler(ignoreCancelled = true, priority = EventPriority.LOWEST)
     public void onPlayerCommandPreprocess(PlayerCommandPreprocessEvent event) {
-        String cmd = event.getMessage().split(" ")[0].toLowerCase();
+        String cmd = event.getMessage().split(" ")[0].toLowerCase(Locale.ROOT);
         if (settings.getProperty(HooksSettings.USE_ESSENTIALS_MOTD) && "/motd".equals(cmd)) {
             return;
         }
@@ -482,7 +483,7 @@ public class PlayerListener implements Listener {
             return false;
         }
         Set<String> whitelist = settings.getProperty(RestrictionSettings.UNRESTRICTED_INVENTORIES);
-        return whitelist.contains(ChatColor.stripColor(inventory.getTitle()).toLowerCase());
+        return whitelist.contains(ChatColor.stripColor(inventory.getTitle()).toLowerCase(Locale.ROOT));
     }
 
     @EventHandler(ignoreCancelled = true, priority = EventPriority.LOWEST)

src/main/java/fr/xephi/authme/output/LogFilterHelper.java

@@ -6,6 +6,7 @@ import fr.xephi.authme.util.StringUtils;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
+import java.util.Locale;
 
 /**
  * Service class for the log filters.
@@ -35,7 +36,7 @@ final class LogFilterHelper {
         if (message == null) {
             return false;
         }
-        String lowerMessage = message.toLowerCase();
+        String lowerMessage = message.toLowerCase(Locale.ROOT);
         return lowerMessage.contains(ISSUED_COMMAND_TEXT) && StringUtils.containsAny(lowerMessage, COMMANDS_TO_SKIP);
     }
 

src/main/java/fr/xephi/authme/process/changepassword/AsyncChangePassword.java

@@ -14,6 +14,7 @@ import org.bukkit.command.CommandSender;
 import org.bukkit.entity.Player;
 
 import javax.inject.Inject;
+import java.util.Locale;
 
 public class AsyncChangePassword implements AsynchronousProcess {
     
@@ -42,7 +43,7 @@ public class AsyncChangePassword implements AsynchronousProcess {
      * @param newPassword the new password chosen by the player
      */
     public void changePassword(Player player, String oldPassword, String newPassword) {
-        String name = player.getName().toLowerCase();
+        String name = player.getName().toLowerCase(Locale.ROOT);
         PlayerAuth auth = playerCache.getAuth(name);
         if (passwordSecurity.comparePassword(oldPassword, auth.getPassword(), player.getName())) {
             HashedPassword hashedPassword = passwordSecurity.computeHash(newPassword, name);
@@ -71,7 +72,7 @@ public class AsyncChangePassword implements AsynchronousProcess {
      * @param newPassword the new password chosen for the player
      */
     public void changePasswordAsAdmin(CommandSender sender, String playerName, String newPassword) {
-        String lowerCaseName = playerName.toLowerCase();
+        String lowerCaseName = playerName.toLowerCase(Locale.ROOT);
         if (!(playerCache.isAuthenticated(lowerCaseName) || dataSource.isAuthAvailable(lowerCaseName))) {
             if (sender == null) {
                 logger.warning("Tried to change password for user " + lowerCaseName + " but it doesn't exist!");

src/main/java/fr/xephi/authme/process/email/AsyncAddEmail.java

@@ -15,6 +15,7 @@ import fr.xephi.authme.util.Utils;
 import org.bukkit.entity.Player;
 
 import javax.inject.Inject;
+import java.util.Locale;
 
 /**
  * Async task to add an email to an account.
@@ -48,7 +49,7 @@ public class AsyncAddEmail implements AsynchronousProcess {
      * @param email the email to add
      */
     public void addEmail(Player player, String email) {
-        String playerName = player.getName().toLowerCase();
+        String playerName = player.getName().toLowerCase(Locale.ROOT);
 
         if (playerCache.isAuthenticated(playerName)) {
             PlayerAuth auth = playerCache.getAuth(playerName);

src/main/java/fr/xephi/authme/process/email/AsyncChangeEmail.java

@@ -14,6 +14,7 @@ import fr.xephi.authme.service.ValidationService;
 import org.bukkit.entity.Player;
 
 import javax.inject.Inject;
+import java.util.Locale;
 
 /**
  * Async task for changing the email.
@@ -48,7 +49,7 @@ public class AsyncChangeEmail implements AsynchronousProcess {
      * @param newEmail provided new email
      */
     public void changeEmail(Player player, String oldEmail, String newEmail) {
-        String playerName = player.getName().toLowerCase();
+        String playerName = player.getName().toLowerCase(Locale.ROOT);
         if (playerCache.isAuthenticated(playerName)) {
             PlayerAuth auth = playerCache.getAuth(playerName);
             String currentEmail = auth.getEmail();

src/main/java/fr/xephi/authme/process/join/AsynchronousJoin.java

@@ -32,6 +32,8 @@ import org.bukkit.potion.PotionEffectType;
 
 import javax.inject.Inject;
 
+import java.util.Locale;
+
 import static fr.xephi.authme.service.BukkitService.TICKS_PER_SECOND;
 import static fr.xephi.authme.settings.properties.RestrictionSettings.PROTECT_INVENTORY_BEFORE_LOGIN;
 
@@ -90,7 +92,7 @@ public class AsynchronousJoin implements AsynchronousProcess {
      * @param player the player to process
      */
     public void processJoin(Player player) {
-        String name = player.getName().toLowerCase();
+        String name = player.getName().toLowerCase(Locale.ROOT);
         String ip = PlayerUtils.getPlayerIp(player);
 
         if (!validationService.fulfillsNameRestrictions(player)) {

src/main/java/fr/xephi/authme/process/login/AsynchronousLogin.java

@@ -40,6 +40,7 @@ import org.bukkit.entity.Player;
 import javax.inject.Inject;
 import java.util.ArrayList;
 import java.util.List;
+import java.util.Locale;
 
 /**
  * Asynchronous task for a player login.
@@ -153,7 +154,7 @@ public class AsynchronousLogin implements AsynchronousProcess {
      *         (e.g. because he is already logged in)
      */
     private PlayerAuth getPlayerAuth(Player player, boolean quiet) {
-        String name = player.getName().toLowerCase();
+        String name = player.getName().toLowerCase(Locale.ROOT);
         if (playerCache.isAuthenticated(name)) {
             if (!quiet) {
                 service.send(player, MessageKey.ALREADY_LOGGED_IN_ERROR);
@@ -206,7 +207,7 @@ public class AsynchronousLogin implements AsynchronousProcess {
      *         false otherwise
      */
     private boolean checkPlayerInfo(Player player, PlayerAuth auth, String password) {
-        String name = player.getName().toLowerCase();
+        String name = player.getName().toLowerCase(Locale.ROOT);
 
         // If captcha is required send a message to the player and deny to log in
         if (loginCaptchaManager.isCaptchaRequired(name)) {
@@ -380,7 +381,7 @@ public class AsynchronousLogin implements AsynchronousProcess {
         for (Player onlinePlayer : bukkitService.getOnlinePlayers()) {
             if (ip.equalsIgnoreCase(PlayerUtils.getPlayerIp(onlinePlayer))
                 && !onlinePlayer.getName().equals(name)
-                && dataSource.isLogged(onlinePlayer.getName().toLowerCase())) {
+                && dataSource.isLogged(onlinePlayer.getName().toLowerCase(Locale.ROOT))) {
                 ++count;
             }
         }

src/main/java/fr/xephi/authme/process/login/ProcessSyncPlayerLogin.java

@@ -22,6 +22,7 @@ import org.bukkit.potion.PotionEffectType;
 
 import javax.inject.Inject;
 import java.util.List;
+import java.util.Locale;
 
 import static fr.xephi.authme.settings.properties.RestrictionSettings.PROTECT_INVENTORY_BEFORE_LOGIN;
 
@@ -76,7 +77,7 @@ public class ProcessSyncPlayerLogin implements SynchronousProcess {
      * @param authsWithSameIp registered names with the same IP address as the player's
      */
     public void processPlayerLogin(Player player, boolean isFirstLogin, List<String> authsWithSameIp) {
-        final String name = player.getName().toLowerCase();
+        final String name = player.getName().toLowerCase(Locale.ROOT);
         final LimboPlayer limbo = limboService.getLimboPlayer(name);
 
         // Limbo contains the State of the Player before /login

src/main/java/fr/xephi/authme/process/logout/AsynchronousLogout.java

@@ -15,6 +15,7 @@ import fr.xephi.authme.settings.properties.RestrictionSettings;
 import org.bukkit.entity.Player;
 
 import javax.inject.Inject;
+import java.util.Locale;
 
 /**
  * Async task when a player wants to log out.
@@ -51,7 +52,7 @@ public class AsynchronousLogout implements AsynchronousProcess {
      * @param player the player wanting to log out
      */
     public void logout(Player player) {
-        String name = player.getName().toLowerCase();
+        String name = player.getName().toLowerCase(Locale.ROOT);
         if (!playerCache.isAuthenticated(name)) {
             service.send(player, MessageKey.NOT_LOGGED_IN);
             return;

src/main/java/fr/xephi/authme/process/quit/AsynchronousQuit.java

@@ -18,6 +18,7 @@ import org.bukkit.Location;
 import org.bukkit.entity.Player;
 
 import javax.inject.Inject;
+import java.util.Locale;
 
 /**
  * Async process called when a player quits the server.
@@ -63,7 +64,7 @@ public class AsynchronousQuit implements AsynchronousProcess {
         if (player == null || validationService.isUnrestricted(player.getName())) {
             return;
         }
-        String name = player.getName().toLowerCase();
+        String name = player.getName().toLowerCase(Locale.ROOT);
         boolean wasLoggedIn = playerCache.isAuthenticated(name);
 
         if (wasLoggedIn) {

src/main/java/fr/xephi/authme/process/register/AsyncRegister.java

@@ -20,6 +20,7 @@ import org.bukkit.entity.Player;
 
 import javax.inject.Inject;
 import java.util.List;
+import java.util.Locale;
 
 import static fr.xephi.authme.permission.PlayerStatePermission.ALLOW_MULTIPLE_ACCOUNTS;
 
@@ -67,7 +68,7 @@ public class AsyncRegister implements AsynchronousProcess {
      * @return true if the checks are successful and the event hasn't marked the action as denied, false otherwise.
      */
     private boolean preRegisterCheck(RegistrationMethod<?> variant, Player player) {
-        String name = player.getName().toLowerCase();
+        String name = player.getName().toLowerCase(Locale.ROOT);
         if (playerCache.isAuthenticated(name)) {
             service.send(player, MessageKey.ALREADY_LOGGED_IN_ERROR);
             return false;

src/main/java/fr/xephi/authme/process/register/executors/PlayerAuthBuilderHelper.java

@@ -5,6 +5,8 @@ import fr.xephi.authme.security.crypts.HashedPassword;
 import fr.xephi.authme.util.PlayerUtils;
 import org.bukkit.entity.Player;
 
+import java.util.Locale;
+
 /**
  * Helper for constructing PlayerAuth objects.
  */
@@ -23,7 +25,7 @@ final class PlayerAuthBuilderHelper {
      */
     static PlayerAuth createPlayerAuth(Player player, HashedPassword hashedPassword, String email) {
         return PlayerAuth.builder()
-            .name(player.getName().toLowerCase())
+            .name(player.getName().toLowerCase(Locale.ROOT))
             .realName(player.getName())
             .password(hashedPassword)
             .email(email)

src/main/java/fr/xephi/authme/security/PasswordSecurity.java

@@ -13,6 +13,7 @@ import org.bukkit.plugin.PluginManager;
 import javax.annotation.PostConstruct;
 import javax.inject.Inject;
 import java.util.Collection;
+import java.util.Locale;
 
 /**
  * Manager class for password-related operations.
@@ -54,7 +55,7 @@ public class PasswordSecurity implements Reloadable {
      * @return The password hash
      */
     public HashedPassword computeHash(String password, String playerName) {
-        String playerLowerCase = playerName.toLowerCase();
+        String playerLowerCase = playerName.toLowerCase(Locale.ROOT);
         return encryptionMethod.computeHash(password, playerLowerCase);
     }
 
@@ -81,7 +82,7 @@ public class PasswordSecurity implements Reloadable {
      * @return True if the password matches, false otherwise
      */
     public boolean comparePassword(String password, HashedPassword hashedPassword, String playerName) {
-        String playerLowerCase = playerName.toLowerCase();
+        String playerLowerCase = playerName.toLowerCase(Locale.ROOT);
         return methodMatches(encryptionMethod, password, hashedPassword, playerLowerCase)
             || compareWithLegacyHashes(password, hashedPassword, playerLowerCase);
     }

src/main/java/fr/xephi/authme/security/crypts/Smf.java

@@ -7,6 +7,8 @@ import fr.xephi.authme.security.crypts.description.SaltType;
 import fr.xephi.authme.security.crypts.description.Usage;
 import fr.xephi.authme.util.RandomStringUtils;
 
+import java.util.Locale;
+
 import static fr.xephi.authme.security.HashUtils.isEqual;
 
 /**
@@ -29,7 +31,7 @@ public class Smf implements EncryptionMethod {
 
     @Override
     public String computeHash(String password, String salt, String name) {
-        return HashUtils.sha1(name.toLowerCase() + password);
+        return HashUtils.sha1(name.toLowerCase(Locale.ROOT) + password);
     }
 
     @Override

src/main/java/fr/xephi/authme/security/crypts/XAuth.java

@@ -3,6 +3,8 @@ package fr.xephi.authme.security.crypts;
 import fr.xephi.authme.security.crypts.description.Recommendation;
 import fr.xephi.authme.security.crypts.description.Usage;
 
+import java.util.Locale;
+
 import static fr.xephi.authme.security.HashUtils.isEqual;
 
 @Recommendation(Usage.RECOMMENDED)
@@ -19,7 +21,7 @@ public class XAuth extends HexSaltedMethod {
 
     @Override
     public String computeHash(String password, String salt, String name) {
-        String hash = getWhirlpool(salt + password).toLowerCase();
+        String hash = getWhirlpool(salt + password).toLowerCase(Locale.ROOT);
         int saltPos = password.length() >= hash.length() ? hash.length() - 1 : password.length();
         return hash.substring(0, saltPos) + salt + hash.substring(saltPos);
     }

src/main/java/fr/xephi/authme/security/totp/GenerateTotpService.java

@@ -6,6 +6,7 @@ import fr.xephi.authme.util.expiring.ExpiringMap;
 import org.bukkit.entity.Player;
 
 import javax.inject.Inject;
+import java.util.Locale;
 import java.util.concurrent.TimeUnit;
 
 /**
@@ -32,7 +33,7 @@ public class GenerateTotpService implements HasCleanup {
      */
     public TotpGenerationResult generateTotpKey(Player player) {
         TotpGenerationResult credentials = totpAuthenticator.generateTotpKey(player);
-        totpKeys.put(player.getName().toLowerCase(), credentials);
+        totpKeys.put(player.getName().toLowerCase(Locale.ROOT), credentials);
         return credentials;
     }
 
@@ -43,11 +44,11 @@ public class GenerateTotpService implements HasCleanup {
      * @return TOTP generation result
      */
     public TotpGenerationResult getGeneratedTotpKey(Player player) {
-        return totpKeys.get(player.getName().toLowerCase());
+        return totpKeys.get(player.getName().toLowerCase(Locale.ROOT));
     }
 
     public void removeGenerateTotpKey(Player player) {
-        totpKeys.remove(player.getName().toLowerCase());
+        totpKeys.remove(player.getName().toLowerCase(Locale.ROOT));
     }
 
     /**
@@ -58,7 +59,7 @@ public class GenerateTotpService implements HasCleanup {
      * @return true if the input code is correct, false if the code is invalid or no unexpired totp key is available
      */
     public boolean isTotpCodeCorrectForGeneratedTotpKey(Player player, String totpCode) {
-        TotpGenerationResult totpDetails = totpKeys.get(player.getName().toLowerCase());
+        TotpGenerationResult totpDetails = totpKeys.get(player.getName().toLowerCase(Locale.ROOT));
         return totpDetails != null && totpAuthenticator.checkCode(player.getName(), totpDetails.getTotpKey(), totpCode);
     }
 

src/main/java/fr/xephi/authme/security/totp/TotpAuthenticator.java

@@ -15,6 +15,8 @@ import org.bukkit.entity.Player;
 
 import javax.inject.Inject;
 
+import java.util.Locale;
+
 import static fr.xephi.authme.util.Utils.MILLIS_PER_MINUTE;
 
 /**
@@ -54,7 +56,7 @@ public class TotpAuthenticator implements HasCleanup {
      * @return true if code is valid, false otherwise
      */
     public boolean checkCode(String playerName, String totpKey, String inputCode) {
-        String nameLower = playerName.toLowerCase();
+        String nameLower = playerName.toLowerCase(Locale.ROOT);
         Integer totpCode = Ints.tryParse(inputCode);
         if (totpCode != null && !usedCodes.contains(nameLower, totpCode)
             && authenticator.authorize(totpKey, totpCode)) {

src/main/java/fr/xephi/authme/service/AntiBotService.java

@@ -11,6 +11,7 @@ import fr.xephi.authme.util.AtomicIntervalCounter;
 import org.bukkit.scheduler.BukkitTask;
 
 import javax.inject.Inject;
+import java.util.Locale;
 import java.util.concurrent.CopyOnWriteArrayList;
 
 import static fr.xephi.authme.service.BukkitService.TICKS_PER_MINUTE;
@@ -176,7 +177,7 @@ public class AntiBotService implements SettingsDependent {
      * @return true if the given name has been kicked because of Antibot
      */
     public boolean wasPlayerKicked(String name) {
-        return antibotKicked.contains(name.toLowerCase());
+        return antibotKicked.contains(name.toLowerCase(Locale.ROOT));
     }
 
     /**
@@ -186,7 +187,7 @@ public class AntiBotService implements SettingsDependent {
      * @param name the name to add
      */
     public void addPlayerKick(String name) {
-        antibotKicked.addIfAbsent(name.toLowerCase());
+        antibotKicked.addIfAbsent(name.toLowerCase(Locale.ROOT));
     }
 
     public enum AntiBotStatus {

src/main/java/fr/xephi/authme/service/BackupService.java

@@ -18,6 +18,7 @@ import java.io.FileOutputStream;
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.OutputStream;
+import java.util.Locale;
 
 import static fr.xephi.authme.util.Utils.logAndSendMessage;
 import static fr.xephi.authme.util.Utils.logAndSendWarning;
@@ -151,7 +152,7 @@ public class BackupService {
      * @return True if the path is correct, false if it is incorrect or the OS is not Windows
      */
     private boolean useWindowsCommand(String windowsPath) {
-        String isWin = System.getProperty("os.name").toLowerCase();
+        String isWin = System.getProperty("os.name").toLowerCase(Locale.ROOT);
         if (isWin.contains("win")) {
             if (new File(windowsPath + "\\bin\\mysqldump.exe").exists()) {
                 return true;

src/main/java/fr/xephi/authme/service/PasswordRecoveryService.java

@@ -20,6 +20,7 @@ import org.bukkit.entity.Player;
 
 import javax.annotation.PostConstruct;
 import javax.inject.Inject;
+import java.util.Locale;
 import java.util.concurrent.TimeUnit;
 
 import static fr.xephi.authme.settings.properties.EmailSettings.RECOVERY_PASSWORD_LENGTH;
@@ -76,7 +77,7 @@ public class PasswordRecoveryService implements Reloadable, HasCleanup {
         boolean couldSendMail = emailService.sendRecoveryCode(player.getName(), email, recoveryCode);
         if (couldSendMail) {
             commonService.send(player, MessageKey.RECOVERY_CODE_SENT);
-            emailCooldown.add(player.getName().toLowerCase());
+            emailCooldown.add(player.getName().toLowerCase(Locale.ROOT));
         } else {
             commonService.send(player, MessageKey.EMAIL_SEND_FAILURE);
         }
@@ -104,7 +105,7 @@ public class PasswordRecoveryService implements Reloadable, HasCleanup {
         boolean couldSendMail = emailService.sendPasswordMail(name, email, thePass);
         if (couldSendMail) {
             commonService.send(player, MessageKey.RECOVERY_EMAIL_SENT_MESSAGE);
-            emailCooldown.add(player.getName().toLowerCase());
+            emailCooldown.add(player.getName().toLowerCase(Locale.ROOT));
         } else {
             commonService.send(player, MessageKey.EMAIL_SEND_FAILURE);
         }
@@ -141,7 +142,7 @@ public class PasswordRecoveryService implements Reloadable, HasCleanup {
      * @return True if the player is not on cooldown.
      */
     private boolean checkEmailCooldown(Player player) {
-        Duration waitDuration = emailCooldown.getExpiration(player.getName().toLowerCase());
+        Duration waitDuration = emailCooldown.getExpiration(player.getName().toLowerCase(Locale.ROOT));
         if (waitDuration.getDuration() > 0) {
             String durationText = messages.formatDuration(waitDuration);
             messages.send(player, MessageKey.EMAIL_COOLDOWN_ERROR, durationText);

src/main/java/fr/xephi/authme/service/ValidationService.java

@@ -25,6 +25,7 @@ import javax.annotation.PostConstruct;
 import javax.inject.Inject;
 import java.util.Collection;
 import java.util.List;
+import java.util.Locale;
 import java.util.Set;
 import java.util.regex.Pattern;
 
@@ -69,7 +70,7 @@ public class ValidationService implements Reloadable {
      * @return the validation result
      */
     public ValidationResult validatePassword(String password, String username) {
-        String passLow = password.toLowerCase();
+        String passLow = password.toLowerCase(Locale.ROOT);
         if (!passwordRegex.matcher(passLow).matches()) {
             return new ValidationResult(MessageKey.PASSWORD_CHARACTERS_ERROR, passwordRegex.pattern());
         } else if (passLow.equalsIgnoreCase(username)) {
@@ -139,7 +140,7 @@ public class ValidationService implements Reloadable {
      * @return true if unrestricted, false otherwise
      */
     public boolean isUnrestricted(String name) {
-        return settings.getProperty(RestrictionSettings.UNRESTRICTED_NAMES).contains(name.toLowerCase());
+        return settings.getProperty(RestrictionSettings.UNRESTRICTED_NAMES).contains(name.toLowerCase(Locale.ROOT));
     }
 
     /**
@@ -149,7 +150,7 @@ public class ValidationService implements Reloadable {
      * @return true if the player may join, false if the player does not satisfy the name restrictions
      */
     public boolean fulfillsNameRestrictions(Player player) {
-        Collection<String> restrictions = restrictedNames.get(player.getName().toLowerCase());
+        Collection<String> restrictions = restrictedNames.get(player.getName().toLowerCase(Locale.ROOT));
         if (Utils.isCollectionEmpty(restrictions)) {
             return true;
         }
@@ -212,7 +213,7 @@ public class ValidationService implements Reloadable {
         for (String restriction : configuredRestrictions) {
             if (isInsideString(';', restriction)) {
                 String[] data = restriction.split(";");
-                restrictions.put(data[0].toLowerCase(), data[1]);
+                restrictions.put(data[0].toLowerCase(Locale.ROOT), data[1]);
             } else {
                 logger.warning("Restricted user rule must have a ';' separating name from restriction,"
                     + " but found: '" + restriction + "'");

src/main/java/fr/xephi/authme/service/bungeecord/BungeeSender.java

@@ -13,6 +13,7 @@ import org.bukkit.entity.Player;
 import org.bukkit.plugin.messaging.Messenger;
 
 import javax.inject.Inject;
+import java.util.Locale;
 
 public class BungeeSender implements SettingsDependent {
 
@@ -103,9 +104,9 @@ public class BungeeSender implements SettingsDependent {
             return;
         }
         if (type.isBroadcast()) {
-            sendForwardedBungeecordMessage(player, "AuthMe.v2.Broadcast", type.getId(), player.getName().toLowerCase());
+            sendForwardedBungeecordMessage(player, "AuthMe.v2.Broadcast", type.getId(), player.getName().toLowerCase(Locale.ROOT));
         } else {
-            sendBungeecordMessage(player, "AuthMe.v2", type.getId(), player.getName().toLowerCase());
+            sendBungeecordMessage(player, "AuthMe.v2", type.getId(), player.getName().toLowerCase(Locale.ROOT));
         }
     }
 

src/main/java/fr/xephi/authme/settings/SpawnLoader.java

@@ -19,6 +19,7 @@ import org.bukkit.entity.Player;
 import javax.inject.Inject;
 import java.io.File;
 import java.io.IOException;
+import java.util.Locale;
 
 /**
  * Manager for spawn points. It loads spawn definitions from AuthMe and third-party plugins
@@ -177,7 +178,7 @@ public class SpawnLoader implements Reloadable {
         World world = player.getWorld();
         Location spawnLoc = null;
         for (String priority : spawnPriority) {
-            switch (priority.toLowerCase().trim()) {
+            switch (priority.toLowerCase(Locale.ROOT).trim()) {
                 case "default":
                     if (world.getSpawnLocation() != null) {
                         if (!isValidSpawnPoint(world.getSpawnLocation())) {

src/main/java/fr/xephi/authme/task/purge/PurgeExecutor.java

@@ -15,6 +15,7 @@ import org.bukkit.Server;
 import javax.inject.Inject;
 import java.io.File;
 import java.util.Collection;
+import java.util.Locale;
 
 import static fr.xephi.authme.util.FileUtils.makePath;
 
@@ -80,7 +81,7 @@ public class PurgeExecutor {
         }
 
         for (String file : dataFolder.list()) {
-            if (cleared.contains(file.toLowerCase())) {
+            if (cleared.contains(file.toLowerCase(Locale.ROOT))) {
                 File playerFile = new File(dataFolder, file);
                 if (playerFile.exists() && playerFile.delete()) {
                     i++;
@@ -137,7 +138,7 @@ public class PurgeExecutor {
             if (name.equals(file)) {
                 continue;
             }
-            if (cleared.contains(name.toLowerCase())) {
+            if (cleared.contains(name.toLowerCase(Locale.ROOT))) {
                 File dataFile = new File(dataFolder, file);
                 if (dataFile.exists() && dataFile.delete()) {
                     i++;

src/main/java/fr/xephi/authme/task/purge/PurgeTask.java

@@ -12,6 +12,7 @@ import org.bukkit.entity.Player;
 import org.bukkit.scheduler.BukkitRunnable;
 
 import java.util.HashSet;
+import java.util.Locale;
 import java.util.Set;
 import java.util.UUID;
 
@@ -74,7 +75,7 @@ class PurgeTask extends BukkitRunnable {
             }
 
             OfflinePlayer offlinePlayer = offlinePlayers[nextPosition];
-            if (offlinePlayer.getName() != null && toPurge.remove(offlinePlayer.getName().toLowerCase())) {
+            if (offlinePlayer.getName() != null && toPurge.remove(offlinePlayer.getName().toLowerCase(Locale.ROOT))) {
                 if (!permissionsManager.loadUserData(offlinePlayer)) {
                     logger.warning("Unable to check if the user " + offlinePlayer.getName() + " can be purged!");
                     continue;

src/test/java/fr/xephi/authme/api/v3/AuthMeApiTest.java

@@ -28,6 +28,7 @@ import java.time.Instant;
 import java.util.Arrays;
 import java.util.Date;
 import java.util.List;
+import java.util.Locale;
 import java.util.Optional;
 import java.util.stream.Collectors;
 
@@ -457,7 +458,7 @@ public class AuthMeApiTest {
         String name = "Marco";
         String password = "myP4ss";
         HashedPassword hashedPassword = new HashedPassword("0395872SLKDFJOWEIUTEJSD");
-        given(passwordSecurity.computeHash(password, name.toLowerCase())).willReturn(hashedPassword);
+        given(passwordSecurity.computeHash(password, name.toLowerCase(Locale.ROOT))).willReturn(hashedPassword);
         given(dataSource.saveAuth(any(PlayerAuth.class))).willReturn(true);
 
         // when
@@ -465,10 +466,10 @@ public class AuthMeApiTest {
 
         // then
         assertThat(result, equalTo(true));
-        verify(passwordSecurity).computeHash(password, name.toLowerCase());
+        verify(passwordSecurity).computeHash(password, name.toLowerCase(Locale.ROOT));
         ArgumentCaptor<PlayerAuth> authCaptor = ArgumentCaptor.forClass(PlayerAuth.class);
         verify(dataSource).saveAuth(authCaptor.capture());
-        assertThat(authCaptor.getValue().getNickname(), equalTo(name.toLowerCase()));
+        assertThat(authCaptor.getValue().getNickname(), equalTo(name.toLowerCase(Locale.ROOT)));
         assertThat(authCaptor.getValue().getRealName(), equalTo(name));
         assertThat(authCaptor.getValue().getPassword(), equalTo(hashedPassword));
     }

src/test/java/fr/xephi/authme/command/CommandInitializerTest.java

@@ -9,6 +9,7 @@ import java.util.Collection;
 import java.util.HashMap;
 import java.util.HashSet;
 import java.util.List;
+import java.util.Locale;
 import java.util.Map;
 import java.util.Set;
 import java.util.function.BiConsumer;
@@ -90,7 +91,7 @@ public class CommandInitializerTest {
             @Override
             public void accept(CommandDescription command, Integer depth) {
                 for (String label : command.getLabels()) {
-                    if (!label.equals(label.toLowerCase())) {
+                    if (!label.equals(label.toLowerCase(Locale.ROOT))) {
                         fail("Label '" + label + "' should be lowercase");
                     } else if (invalidPattern.matcher(label).matches()) {
                         fail("Label '" + label + "' has whitespace");

src/test/java/fr/xephi/authme/command/executable/authme/ConverterCommandTest.java

@@ -17,6 +17,7 @@ import org.mockito.junit.MockitoJUnitRunner;
 
 import java.util.Collections;
 import java.util.HashSet;
+import java.util.Locale;
 import java.util.Map;
 import java.util.Set;
 
@@ -129,7 +130,7 @@ public class ConverterCommandTest {
         setBukkitServiceToRunTaskAsynchronously(bukkitService);
 
         // when
-        command.executeCommand(sender, Collections.singletonList(converterName.toUpperCase()));
+        command.executeCommand(sender, Collections.singletonList(converterName.toUpperCase(Locale.ROOT)));
 
         // then
         verify(converter).execute(sender);

src/test/java/fr/xephi/authme/command/executable/authme/PurgeBannedPlayersCommandTest.java

@@ -12,6 +12,7 @@ import org.mockito.junit.MockitoJUnitRunner;
 
 import java.util.Collections;
 import java.util.HashSet;
+import java.util.Locale;
 import java.util.Set;
 
 import static com.google.common.collect.Sets.newHashSet;
@@ -67,7 +68,7 @@ public class PurgeBannedPlayersCommandTest {
     private static Set<String> asLowerCaseSet(String... items) {
         Set<String> result = new HashSet<>(items.length);
         for (String item : items) {
-            result.add(item.toLowerCase());
+            result.add(item.toLowerCase(Locale.ROOT));
         }
         return result;
     }

src/test/java/fr/xephi/authme/command/executable/authme/PurgePlayerCommandTest.java

@@ -11,6 +11,8 @@ import org.mockito.InjectMocks;
 import org.mockito.Mock;
 import org.mockito.junit.MockitoJUnitRunner;
 
+import java.util.Locale;
+
 import static fr.xephi.authme.service.BukkitServiceTestHelper.setBukkitServiceToRunTaskAsynchronously;
 import static fr.xephi.authme.service.BukkitServiceTestHelper.setBukkitServiceToRunTaskOptionallyAsync;
 import static java.util.Arrays.asList;
@@ -71,7 +73,7 @@ public class PurgePlayerCommandTest {
 
         // then
         verify(dataSource).isAuthAvailable(name);
-        verify(purgeExecutor).executePurge(singletonList(player), singletonList(name.toLowerCase()));
+        verify(purgeExecutor).executePurge(singletonList(player), singletonList(name.toLowerCase(Locale.ROOT)));
     }
 
     @Test
@@ -87,6 +89,6 @@ public class PurgePlayerCommandTest {
         command.executeCommand(sender, asList(name, "force"));
 
         // then
-        verify(purgeExecutor).executePurge(singletonList(player), singletonList(name.toLowerCase()));
+        verify(purgeExecutor).executePurge(singletonList(player), singletonList(name.toLowerCase(Locale.ROOT)));
     }
 }

src/test/java/fr/xephi/authme/command/executable/authme/RegisterAdminCommandTest.java

@@ -21,6 +21,7 @@ import org.mockito.Mock;
 import org.mockito.junit.MockitoJUnitRunner;
 
 import java.util.Arrays;
+import java.util.Locale;
 
 import static fr.xephi.authme.service.BukkitServiceTestHelper.setBukkitServiceToRunTaskOptionallyAsync;
 import static fr.xephi.authme.service.BukkitServiceTestHelper.setBukkitServiceToScheduleSyncTaskFromOptionallyAsyncTask;
@@ -179,7 +180,7 @@ public class RegisterAdminCommandTest {
 
     private void assertAuthHasInfo(PlayerAuth auth, String name, HashedPassword hashedPassword) {
         assertThat(auth.getRealName(), equalTo(name));
-        assertThat(auth.getNickname(), equalTo(name.toLowerCase()));
+        assertThat(auth.getNickname(), equalTo(name.toLowerCase(Locale.ROOT)));
         assertThat(auth.getPassword(), equalTo(hashedPassword));
     }
 }

src/test/java/fr/xephi/authme/command/executable/authme/debug/DebugCommandTest.java

@@ -16,6 +16,7 @@ import org.mockito.junit.MockitoJUnitRunner;
 
 import java.util.Arrays;
 import java.util.List;
+import java.util.Locale;
 
 import static com.google.common.base.Preconditions.checkArgument;
 import static java.util.Collections.emptyList;
@@ -125,7 +126,7 @@ public class DebugCommandTest {
 
         CommandSender sender = mock(CommandSender.class);
         given(permissionsManager.hasPermission(sender, section.getRequiredPermission())).willReturn(true);
-        List<String> arguments = Arrays.asList(section.getName().toUpperCase(), "test", "toast");
+        List<String> arguments = Arrays.asList(section.getName().toUpperCase(Locale.ROOT), "test", "toast");
 
         // when
         command.executeCommand(sender, arguments);
@@ -144,7 +145,7 @@ public class DebugCommandTest {
 
         CommandSender sender = mock(CommandSender.class);
         given(permissionsManager.hasPermission(sender, section.getRequiredPermission())).willReturn(false);
-        List<String> arguments = Arrays.asList(section.getName().toUpperCase(), "test");
+        List<String> arguments = Arrays.asList(section.getName().toUpperCase(Locale.ROOT), "test");
 
         // when
         command.executeCommand(sender, arguments);

src/test/java/fr/xephi/authme/command/executable/email/RecoverEmailCommandTest.java

@@ -22,6 +22,7 @@ import org.junit.runner.RunWith;
 import org.mockito.Mock;
 
 import java.util.Collections;
+import java.util.Locale;
 
 import static fr.xephi.authme.service.BukkitServiceTestHelper.setBukkitServiceToRunTaskAsynchronously;
 import static org.hamcrest.Matchers.equalTo;
@@ -187,7 +188,7 @@ public class RecoverEmailCommandTest {
         setBukkitServiceToRunTaskAsynchronously(bukkitService);
 
         // when
-        command.executeCommand(sender, Collections.singletonList(email.toUpperCase()));
+        command.executeCommand(sender, Collections.singletonList(email.toUpperCase(Locale.ROOT)));
 
         // then
         verify(emailService).hasAllInformation();

src/test/java/fr/xephi/authme/command/help/HelpProviderTest.java

@@ -23,6 +23,7 @@ import java.util.Arrays;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.List;
+import java.util.Locale;
 import java.util.stream.Collectors;
 
 import static fr.xephi.authme.command.TestCommandsUtil.getCommandWithLabel;
@@ -446,19 +447,19 @@ public class HelpProviderTest {
         given(helpMessagesService.buildLocalizedDescription(any(CommandDescription.class)))
             .willAnswer(new ReturnsArgumentAt(0));
         for (HelpMessage key : HelpMessage.values()) {
-            String text = key.name().replace("_", " ").toLowerCase();
+            String text = key.name().replace("_", " ").toLowerCase(Locale.ROOT);
             given(helpMessagesService.getMessage(key))
-                .willReturn(text.substring(0, 1).toUpperCase() + text.substring(1));
+                .willReturn(text.substring(0, 1).toUpperCase(Locale.ROOT) + text.substring(1));
         }
         for (DefaultPermission permission : DefaultPermission.values()) {
-            String text = permission.name().replace("_", " ").toLowerCase();
+            String text = permission.name().replace("_", " ").toLowerCase(Locale.ROOT);
             given(helpMessagesService.getMessage(permission))
-                .willReturn(text.substring(0, 1).toUpperCase() + text.substring(1));
+                .willReturn(text.substring(0, 1).toUpperCase(Locale.ROOT) + text.substring(1));
         }
         for (HelpSection section : HelpSection.values()) {
-            String text = section.name().replace("_", " ").toLowerCase();
+            String text = section.name().replace("_", " ").toLowerCase(Locale.ROOT);
             given(helpMessagesService.getMessage(section))
-                .willReturn(text.substring(0, 1).toUpperCase() + text.substring(1));
+                .willReturn(text.substring(0, 1).toUpperCase(Locale.ROOT) + text.substring(1));
         }
     }
 

src/test/java/fr/xephi/authme/data/captcha/LoginCaptchaManagerTest.java

@@ -7,6 +7,8 @@ import fr.xephi.authme.util.expiring.TimedCounter;
 import org.bukkit.entity.Player;
 import org.junit.Test;
 
+import java.util.Locale;
+
 import static fr.xephi.authme.AuthMeMatchers.stringWithLength;
 import static org.hamcrest.Matchers.equalTo;
 import static org.hamcrest.Matchers.not;
@@ -34,7 +36,7 @@ public class LoginCaptchaManagerTest {
         // then
         assertThat(manager.isCaptchaRequired(player), equalTo(false));
         manager.increaseLoginFailureCount(player);
-        assertThat(manager.isCaptchaRequired(player.toUpperCase()), equalTo(true));
+        assertThat(manager.isCaptchaRequired(player.toUpperCase(Locale.ROOT)), equalTo(true));
         assertThat(manager.isCaptchaRequired("otherPlayer"), equalTo(false));
     }
 
@@ -167,6 +169,6 @@ public class LoginCaptchaManagerTest {
     private static void assertHasCount(LoginCaptchaManager manager, String player, Integer count) {
         TimedCounter<String> playerCounts = ReflectionTestUtils
             .getFieldValue(LoginCaptchaManager.class, manager, "playerCounts");
-        assertThat(playerCounts.get(player.toLowerCase()), equalTo(count));
+        assertThat(playerCounts.get(player.toLowerCase(Locale.ROOT)), equalTo(count));
     }
 }

src/test/java/fr/xephi/authme/security/PasswordSecurityTest.java

@@ -27,6 +27,7 @@ import org.mockito.invocation.InvocationOnMock;
 import org.mockito.stubbing.Answer;
 
 import java.util.Collections;
+import java.util.Locale;
 import java.util.Set;
 
 import static com.google.common.collect.Sets.newHashSet;
@@ -118,7 +119,7 @@ public class PasswordSecurityTest {
         HashedPassword password = new HashedPassword("$TEST$10$SOME_HASH", null);
         String playerName = "Tester";
         // Calls to EncryptionMethod are always with the lower-case version of the name
-        String playerLowerCase = playerName.toLowerCase();
+        String playerLowerCase = playerName.toLowerCase(Locale.ROOT);
         String clearTextPass = "myPassTest";
 
         given(dataSource.getPassword(playerName)).willReturn(password);
@@ -139,7 +140,7 @@ public class PasswordSecurityTest {
         // given
         HashedPassword password = new HashedPassword("$TEST$10$SOME_HASH", null);
         String playerName = "My_PLayer";
-        String playerLowerCase = playerName.toLowerCase();
+        String playerLowerCase = playerName.toLowerCase(Locale.ROOT);
         String clearTextPass = "passw0Rd1";
 
         given(dataSource.getPassword(playerName)).willReturn(password);
@@ -178,7 +179,7 @@ public class PasswordSecurityTest {
         HashedPassword password =
             new HashedPassword("$2y$10$2e6d2193f43501c926e25elvWlPmWczmrfrnbZV0dUZGITjYjnkkW");
         String playerName = "somePlayer";
-        String playerLowerCase = playerName.toLowerCase();
+        String playerLowerCase = playerName.toLowerCase(Locale.ROOT);
         String clearTextPass = "Test";
         // MD5 hash for "Test"
         HashedPassword newPassword = new HashedPassword("0cbc6611f5540bd0809a388dc95a615b");
@@ -230,7 +231,7 @@ public class PasswordSecurityTest {
         // given
         String password = "MyP@ssword";
         String username = "theUserInTest";
-        String usernameLowerCase = username.toLowerCase();
+        String usernameLowerCase = username.toLowerCase(Locale.ROOT);
         HashedPassword hashedPassword = new HashedPassword("$T$est#Hash", "__someSalt__");
         given(method.computeHash(password, usernameLowerCase)).willReturn(hashedPassword);
         given(settings.getProperty(SecuritySettings.PASSWORD_HASH)).willReturn(HashAlgorithm.JOOMLA);

src/test/java/fr/xephi/authme/security/crypts/AbstractEncryptionMethodTest.java

@@ -8,6 +8,7 @@ import org.junit.BeforeClass;
 import org.junit.Test;
 
 import java.util.List;
+import java.util.Locale;
 import java.util.Map;
 
 import static org.hamcrest.Matchers.equalTo;
@@ -154,13 +155,13 @@ public abstract class AbstractEncryptionMethodTest {
                 method.comparePassword(password, hashedPassword, USERNAME));
             assumeThat(SKIP_LONG_TESTS, equalTo(false));
 
-            if (!password.equals(password.toLowerCase())) {
+            if (!password.equals(password.toLowerCase(Locale.ROOT))) {
                 assertFalse("Lower-case of '" + password + "' should not match generated hash '" + hash + "'",
-                    method.comparePassword(password.toLowerCase(), hashedPassword, USERNAME));
+                    method.comparePassword(password.toLowerCase(Locale.ROOT), hashedPassword, USERNAME));
             }
-            if (!password.equals(password.toUpperCase())) {
+            if (!password.equals(password.toUpperCase(Locale.ROOT))) {
                 assertFalse("Upper-case of '" + password + "' should not match generated hash '" + hash + "'",
-                    method.comparePassword(password.toUpperCase(), hashedPassword, USERNAME));
+                    method.comparePassword(password.toUpperCase(Locale.ROOT), hashedPassword, USERNAME));
             }
         }
     }

src/test/java/fr/xephi/authme/service/MigrationServiceTest.java

@@ -15,6 +15,7 @@ import org.mockito.Mock;
 import org.mockito.junit.MockitoJUnitRunner;
 
 import java.util.Arrays;
+import java.util.Locale;
 
 import static fr.xephi.authme.AuthMeMatchers.equalToHash;
 import static org.hamcrest.Matchers.equalToIgnoringCase;
@@ -118,7 +119,7 @@ public class MigrationServiceTest {
     private static void setSha256MockToUppercase(Sha256 sha256) {
         given(sha256.computeHash(anyString(), anyString())).willAnswer(invocation -> {
             String plainPassword = invocation.getArgument(0);
-            return new HashedPassword(plainPassword.toUpperCase(), null);
+            return new HashedPassword(plainPassword.toUpperCase(Locale.ROOT), null);
         });
     }
 }

src/test/java/tools/docs/hashmethods/HashAlgorithmsDescriptionTask.java

@@ -7,6 +7,7 @@ import tools.utils.TagValue.NestedTagValue;
 import tools.utils.TagValueHolder;
 import tools.utils.ToolsConstants;
 
+import java.util.Locale;
 import java.util.Map;
 
 /**
@@ -83,7 +84,7 @@ public class HashAlgorithmsDescriptionTask implements AutoToolTask {
         // Get the enum name and replace something like "DO_NOT_USE" to "Do not use"
         String enumName = value.toString().replace("_", " ");
         return enumName.length() > 2
-            ? enumName.substring(0, 1) + enumName.substring(1).toLowerCase()
+            ? enumName.substring(0, 1) + enumName.substring(1).toLowerCase(Locale.ROOT)
             : enumName;
     }