diff --git a/extensions/elasticsearch/ActiveRecord.php b/extensions/elasticsearch/ActiveRecord.php
index d6ada20..e6e28b7 100644
--- a/extensions/elasticsearch/ActiveRecord.php
+++ b/extensions/elasticsearch/ActiveRecord.php
@@ -9,12 +9,10 @@ namespace yii\elasticsearch;
 
 use yii\base\InvalidCallException;
 use yii\base\InvalidConfigException;
-use yii\base\NotSupportedException;
-use yii\db\ActiveRecordInterface;
 use yii\db\BaseActiveRecord;
+use yii\helpers\FileHelper;
 use yii\helpers\Inflector;
 use yii\helpers\Json;
-use yii\helpers\StringHelper;
 
 /**
  * ActiveRecord is the base class for classes representing relational data in terms of objects.
@@ -228,7 +226,7 @@ class ActiveRecord extends BaseActiveRecord
 	 */
 	public static function index()
 	{
-		return Inflector::pluralize(Inflector::camel2id(StringHelper::basename(get_called_class()), '-'));
+		return Inflector::pluralize(Inflector::camel2id(FileHelper::basename(get_called_class()), '-'));
 	}
 
 	/**
@@ -236,7 +234,7 @@ class ActiveRecord extends BaseActiveRecord
 	 */
 	public static function type()
 	{
-		return Inflector::camel2id(StringHelper::basename(get_called_class()), '-');
+		return Inflector::camel2id(FileHelper::basename(get_called_class()), '-');
 	}
 
 	/**
diff --git a/extensions/gii/generators/crud/templates/controller.php b/extensions/gii/generators/crud/templates/controller.php
index bb5d3f4..c1ce71f 100644
--- a/extensions/gii/generators/crud/templates/controller.php
+++ b/extensions/gii/generators/crud/templates/controller.php
@@ -1,7 +1,7 @@
 <?php
 
 use yii\db\ActiveRecordInterface;
-use yii\helpers\StringHelper;
+use yii\helpers\FileHelper;
 
 /**
  * This is the template for generating a CRUD controller class file.
@@ -10,9 +10,9 @@ use yii\helpers\StringHelper;
  * @var yii\gii\generators\crud\Generator $generator
  */
 
-$controllerClass = StringHelper::basename($generator->controllerClass);
-$modelClass = StringHelper::basename($generator->modelClass);
-$searchModelClass = StringHelper::basename($generator->searchModelClass);
+$controllerClass = FileHelper::basename($generator->controllerClass);
+$modelClass = FileHelper::basename($generator->modelClass);
+$searchModelClass = FileHelper::basename($generator->searchModelClass);
 if ($modelClass === $searchModelClass) {
 	$searchModelAlias = $searchModelClass.'Search';
 }
@@ -27,7 +27,7 @@ $actionParamComments = $generator->generateActionParamComments();
 echo "<?php\n";
 ?>
 
-namespace <?= StringHelper::dirname(ltrim($generator->controllerClass, '\\')) ?>;
+namespace <?= FileHelper::dirname(ltrim($generator->controllerClass, '\\')) ?>;
 
 use <?= ltrim($generator->modelClass, '\\') ?>;
 use <?= ltrim($generator->searchModelClass, '\\') ?><?php if (isset($searchModelAlias)):?> as <?= $searchModelAlias ?><?php endif ?>;
@@ -38,7 +38,7 @@ use yii\web\VerbFilter;
 /**
  * <?= $controllerClass ?> implements the CRUD actions for <?= $modelClass ?> model.
  */
-class <?= $controllerClass ?> extends <?= StringHelper::basename($generator->baseControllerClass) . "\n" ?>
+class <?= $controllerClass ?> extends <?= FileHelper::basename($generator->baseControllerClass) . "\n" ?>
 {
 	public function behaviors()
 	{
diff --git a/extensions/gii/generators/crud/templates/search.php b/extensions/gii/generators/crud/templates/search.php
index 1411896..1a9da82 100644
--- a/extensions/gii/generators/crud/templates/search.php
+++ b/extensions/gii/generators/crud/templates/search.php
@@ -1,6 +1,6 @@
 <?php
 
-use yii\helpers\StringHelper;
+use yii\helpers\FileHelper;
 
 /**
  * This is the template for generating a CRUD controller class file.
@@ -9,8 +9,8 @@ use yii\helpers\StringHelper;
  * @var yii\gii\generators\crud\Generator $generator
  */
 
-$modelClass = StringHelper::basename($generator->modelClass);
-$searchModelClass = StringHelper::basename($generator->searchModelClass);
+$modelClass = FileHelper::basename($generator->modelClass);
+$searchModelClass = FileHelper::basename($generator->searchModelClass);
 $rules = $generator->generateSearchRules();
 $labels = $generator->generateSearchLabels();
 $searchAttributes = $generator->getSearchAttributes();
@@ -19,7 +19,7 @@ $searchConditions = $generator->generateSearchConditions();
 echo "<?php\n";
 ?>
 
-namespace <?= StringHelper::dirname(ltrim($generator->searchModelClass, '\\')) ?>;
+namespace <?= FileHelper::dirname(ltrim($generator->searchModelClass, '\\')) ?>;
 
 use yii\base\Model;
 use yii\data\ActiveDataProvider;
diff --git a/extensions/gii/generators/crud/templates/views/_form.php b/extensions/gii/generators/crud/templates/views/_form.php
index 52538d5..4ac7971 100644
--- a/extensions/gii/generators/crud/templates/views/_form.php
+++ b/extensions/gii/generators/crud/templates/views/_form.php
@@ -1,7 +1,7 @@
 <?php
 
+use yii\helpers\FileHelper;
 use yii\helpers\Inflector;
-use yii\helpers\StringHelper;
 
 /**
  * @var yii\web\View $this
@@ -28,7 +28,7 @@ use yii\widgets\ActiveForm;
  */
 ?>
 
-<div class="<?= Inflector::camel2id(StringHelper::basename($generator->modelClass)) ?>-form">
+<div class="<?= Inflector::camel2id(FileHelper::basename($generator->modelClass)) ?>-form">
 
 	<?= "<?php " ?>$form = ActiveForm::begin(); ?>
 
diff --git a/extensions/gii/generators/crud/templates/views/_search.php b/extensions/gii/generators/crud/templates/views/_search.php
index af2f948..6ba9ee0 100644
--- a/extensions/gii/generators/crud/templates/views/_search.php
+++ b/extensions/gii/generators/crud/templates/views/_search.php
@@ -1,7 +1,7 @@
 <?php
 
+use yii\helpers\FileHelper;
 use yii\helpers\Inflector;
-use yii\helpers\StringHelper;
 
 /**
  * @var yii\web\View $this
@@ -21,7 +21,7 @@ use yii\widgets\ActiveForm;
  */
 ?>
 
-<div class="<?= Inflector::camel2id(StringHelper::basename($generator->modelClass)) ?>-search">
+<div class="<?= Inflector::camel2id(FileHelper::basename($generator->modelClass)) ?>-search">
 
 	<?= "<?php " ?>$form = ActiveForm::begin([
 		'action' => ['index'],
diff --git a/extensions/gii/generators/crud/templates/views/create.php b/extensions/gii/generators/crud/templates/views/create.php
index 68d08ba..71d5049 100644
--- a/extensions/gii/generators/crud/templates/views/create.php
+++ b/extensions/gii/generators/crud/templates/views/create.php
@@ -1,7 +1,7 @@
 <?php
 
+use yii\helpers\FileHelper;
 use yii\helpers\Inflector;
-use yii\helpers\StringHelper;
 
 /**
  * @var yii\web\View $this
@@ -18,11 +18,11 @@ use yii\helpers\Html;
  * @var <?= ltrim($generator->modelClass, '\\') ?> $model
  */
 
-$this->title = 'Create <?= Inflector::camel2words(StringHelper::basename($generator->modelClass)) ?>';
-$this->params['breadcrumbs'][] = ['label' => '<?= Inflector::pluralize(Inflector::camel2words(StringHelper::basename($generator->modelClass))) ?>', 'url' => ['index']];
+$this->title = 'Create <?= Inflector::camel2words(FileHelper::basename($generator->modelClass)) ?>';
+$this->params['breadcrumbs'][] = ['label' => '<?= Inflector::pluralize(Inflector::camel2words(BaseFileHelper::basename($generator->modelClass))) ?>', 'url' => ['index']];
 $this->params['breadcrumbs'][] = $this->title;
 ?>
-<div class="<?= Inflector::camel2id(StringHelper::basename($generator->modelClass)) ?>-create">
+<div class="<?= Inflector::camel2id(FileHelper::basename($generator->modelClass)) ?>-create">
 
 	<h1><?= "<?= " ?>Html::encode($this->title) ?></h1>
 
diff --git a/extensions/gii/generators/crud/templates/views/index.php b/extensions/gii/generators/crud/templates/views/index.php
index 3ad2138..31f9e58 100644
--- a/extensions/gii/generators/crud/templates/views/index.php
+++ b/extensions/gii/generators/crud/templates/views/index.php
@@ -1,7 +1,7 @@
 <?php
 
+use yii\helpers\FileHelper;
 use yii\helpers\Inflector;
-use yii\helpers\StringHelper;
 
 /**
  * @var yii\web\View $this
@@ -23,17 +23,17 @@ use <?= $generator->indexWidgetType === 'grid' ? "yii\\grid\\GridView" : "yii\\w
  * @var <?= ltrim($generator->searchModelClass, '\\') ?> $searchModel
  */
 
-$this->title = '<?= Inflector::pluralize(Inflector::camel2words(StringHelper::basename($generator->modelClass))) ?>';
+$this->title = '<?= Inflector::pluralize(Inflector::camel2words(FileHelper::basename($generator->modelClass))) ?>';
 $this->params['breadcrumbs'][] = $this->title;
 ?>
-<div class="<?= Inflector::camel2id(StringHelper::basename($generator->modelClass)) ?>-index">
+<div class="<?= Inflector::camel2id(FileHelper::basename($generator->modelClass)) ?>-index">
 
 	<h1><?= "<?= " ?>Html::encode($this->title) ?></h1>
 
 	<?= "<?php " . ($generator->indexWidgetType === 'grid' ? "// " : "") ?>echo $this->render('_search', ['model' => $searchModel]); ?>
 
 	<p>
-		<?= "<?= " ?>Html::a('Create <?= StringHelper::basename($generator->modelClass) ?>', ['create'], ['class' => 'btn btn-success']) ?>
+		<?= "<?= " ?>Html::a('Create <?= FileHelper::basename($generator->modelClass) ?>', ['create'], ['class' => 'btn btn-success']) ?>
 	</p>
 
 <?php if ($generator->indexWidgetType === 'grid'): ?>
diff --git a/extensions/gii/generators/crud/templates/views/update.php b/extensions/gii/generators/crud/templates/views/update.php
index 2fbbecf..e095bbc 100644
--- a/extensions/gii/generators/crud/templates/views/update.php
+++ b/extensions/gii/generators/crud/templates/views/update.php
@@ -1,7 +1,7 @@
 <?php
 
+use yii\helpers\FileHelper;
 use yii\helpers\Inflector;
-use yii\helpers\StringHelper;
 
 /**
  * @var yii\web\View $this
@@ -20,12 +20,12 @@ use yii\helpers\Html;
  * @var <?= ltrim($generator->modelClass, '\\') ?> $model
  */
 
-$this->title = 'Update <?= Inflector::camel2words(StringHelper::basename($generator->modelClass)) ?>: ' . $model-><?= $generator->getNameAttribute() ?>;
-$this->params['breadcrumbs'][] = ['label' => '<?= Inflector::pluralize(Inflector::camel2words(StringHelper::basename($generator->modelClass))) ?>', 'url' => ['index']];
+$this->title = 'Update <?= Inflector::camel2words(FileHelper::basename($generator->modelClass)) ?>: ' . $model-><?= $generator->getNameAttribute() ?>;
+$this->params['breadcrumbs'][] = ['label' => '<?= Inflector::pluralize(Inflector::camel2words(BaseFileHelper::basename($generator->modelClass))) ?>', 'url' => ['index']];
 $this->params['breadcrumbs'][] = ['label' => $model-><?= $generator->getNameAttribute() ?>, 'url' => ['view', <?= $urlParams ?>]];
 $this->params['breadcrumbs'][] = 'Update';
 ?>
-<div class="<?= Inflector::camel2id(StringHelper::basename($generator->modelClass)) ?>-update">
+<div class="<?= Inflector::camel2id(FileHelper::basename($generator->modelClass)) ?>-update">
 
 	<h1><?= "<?= " ?>Html::encode($this->title) ?></h1>
 
diff --git a/extensions/gii/generators/crud/templates/views/view.php b/extensions/gii/generators/crud/templates/views/view.php
index 9e74aff..7087d48 100644
--- a/extensions/gii/generators/crud/templates/views/view.php
+++ b/extensions/gii/generators/crud/templates/views/view.php
@@ -1,7 +1,7 @@
 <?php
 
+use yii\helpers\FileHelper;
 use yii\helpers\Inflector;
-use yii\helpers\StringHelper;
 
 /**
  * @var yii\web\View $this
@@ -22,10 +22,10 @@ use yii\widgets\DetailView;
  */
 
 $this->title = $model-><?= $generator->getNameAttribute() ?>;
-$this->params['breadcrumbs'][] = ['label' => '<?= Inflector::pluralize(Inflector::camel2words(StringHelper::basename($generator->modelClass))) ?>', 'url' => ['index']];
+$this->params['breadcrumbs'][] = ['label' => '<?= Inflector::pluralize(Inflector::camel2words(FileHelper::basename($generator->modelClass))) ?>', 'url' => ['index']];
 $this->params['breadcrumbs'][] = $this->title;
 ?>
-<div class="<?= Inflector::camel2id(StringHelper::basename($generator->modelClass)) ?>-view">
+<div class="<?= Inflector::camel2id(FileHelper::basename($generator->modelClass)) ?>-view">
 
 	<h1><?= "<?= " ?>Html::encode($this->title) ?></h1>
 
diff --git a/extensions/gii/generators/module/Generator.php b/extensions/gii/generators/module/Generator.php
index 5946e07..2209ace 100644
--- a/extensions/gii/generators/module/Generator.php
+++ b/extensions/gii/generators/module/Generator.php
@@ -10,7 +10,7 @@ namespace yii\gii\generators\module;
 use Yii;
 use yii\gii\CodeFile;
 use yii\helpers\Html;
-use yii\helpers\StringHelper;
+use yii\helpers\FileHelper;
 
 /**
  * This generator will generate the skeleton code needed by a module.
@@ -119,7 +119,7 @@ EOD;
 		$files = [];
 		$modulePath = $this->getModulePath();
 		$files[] = new CodeFile(
-			$modulePath . '/' . StringHelper::basename($this->moduleClass) . '.php',
+			$modulePath . '/' . FileHelper::basename($this->moduleClass) . '.php',
 			$this->render("module.php")
 		);
 		$files[] = new CodeFile(
diff --git a/extensions/redis/ActiveRecord.php b/extensions/redis/ActiveRecord.php
index f227ed1..9de9f6c 100644
--- a/extensions/redis/ActiveRecord.php
+++ b/extensions/redis/ActiveRecord.php
@@ -8,8 +8,8 @@
 namespace yii\redis;
 
 use yii\base\InvalidConfigException;
-use yii\base\NotSupportedException;
 use yii\db\BaseActiveRecord;
+use yii\helpers\FileHelper;
 use yii\helpers\Inflector;
 use yii\helpers\StringHelper;
 
@@ -97,7 +97,7 @@ class ActiveRecord extends BaseActiveRecord
 	 */
 	public static function keyPrefix()
 	{
-		return Inflector::camel2id(StringHelper::basename(get_called_class()), '_');
+		return Inflector::camel2id(FileHelper::basename(get_called_class()), '_');
 	}
 
 	/**
@@ -288,7 +288,7 @@ class ActiveRecord extends BaseActiveRecord
 		if (is_numeric($key)) {
 			return $key;
 		} elseif (is_string($key)) {
-			return ctype_alnum($key) && StringHelper::strlen($key) <= 32 ? $key : md5($key);
+			return ctype_alnum($key) && StringHelper::byteLen($key) <= 32 ? $key : md5($key);
 		} elseif (is_array($key)) {
 			if (count($key) == 1) {
 				return self::buildKey(reset($key));
diff --git a/extensions/sphinx/ActiveRecord.php b/extensions/sphinx/ActiveRecord.php
index 7128b79..9831cbd 100644
--- a/extensions/sphinx/ActiveRecord.php
+++ b/extensions/sphinx/ActiveRecord.php
@@ -12,8 +12,8 @@ use yii\db\BaseActiveRecord;
 use yii\base\NotSupportedException;
 use yii\db\ActiveRelationInterface;
 use yii\db\StaleObjectException;
+use yii\helpers\FileHelper;
 use yii\helpers\Inflector;
-use yii\helpers\StringHelper;
 use Yii;
 
 /**
@@ -166,7 +166,7 @@ abstract class ActiveRecord extends BaseActiveRecord
 	 */
 	public static function indexName()
 	{
-		return Inflector::camel2id(StringHelper::basename(get_called_class()), '_');
+		return Inflector::camel2id(FileHelper::basename(get_called_class()), '_');
 	}
 
 	/**
diff --git a/framework/yii/caching/Cache.php b/framework/yii/caching/Cache.php
index 371f91a..ee471b3 100644
--- a/framework/yii/caching/Cache.php
+++ b/framework/yii/caching/Cache.php
@@ -100,7 +100,7 @@ abstract class Cache extends Component implements \ArrayAccess
 	protected function buildKey($key)
 	{
 		if (is_string($key)) {
-			$key = ctype_alnum($key) && StringHelper::strlen($key) <= 32 ? $key : md5($key);
+			$key = ctype_alnum($key) && StringHelper::byteLen($key) <= 32 ? $key : md5($key);
 		} else {
 			$key = md5(json_encode($key));
 		}
diff --git a/framework/yii/db/ActiveRecord.php b/framework/yii/db/ActiveRecord.php
index adcf508..ada79b6 100644
--- a/framework/yii/db/ActiveRecord.php
+++ b/framework/yii/db/ActiveRecord.php
@@ -9,12 +9,7 @@
 namespace yii\db;
 
 use yii\base\InvalidConfigException;
-use yii\base\Model;
-use yii\base\InvalidParamException;
-use yii\base\ModelEvent;
-use yii\base\UnknownMethodException;
-use yii\base\InvalidCallException;
-use yii\helpers\StringHelper;
+use yii\helpers\FileHelper;
 use yii\helpers\Inflector;
 
 /**
@@ -174,7 +169,7 @@ class ActiveRecord extends BaseActiveRecord
 	 */
 	public static function tableName()
 	{
-		return 'tbl_' . Inflector::camel2id(StringHelper::basename(get_called_class()), '_');
+		return 'tbl_' . Inflector::camel2id(FileHelper::basename(get_called_class()), '_');
 	}
 
 	/**
diff --git a/framework/yii/helpers/BaseFileHelper.php b/framework/yii/helpers/BaseFileHelper.php
index 325cc8a..7994773 100644
--- a/framework/yii/helpers/BaseFileHelper.php
+++ b/framework/yii/helpers/BaseFileHelper.php
@@ -292,11 +292,11 @@ class BaseFileHelper
 		if ($isDir = is_dir($path)) {
 			$path .= '/';
 		}
-		$n = StringHelper::strlen($path);
+		$n = StringHelper::byteLen($path);
 
 		if (!empty($options['except'])) {
 			foreach ($options['except'] as $name) {
-				if (StringHelper::substr($path, -StringHelper::strlen($name), $n) === $name) {
+				if (StringHelper::byteSubstr($path, -StringHelper::byteLen($name), $n) === $name) {
 					return false;
 				}
 			}
@@ -304,7 +304,7 @@ class BaseFileHelper
 
 		if (!$isDir && !empty($options['only'])) {
 			foreach ($options['only'] as $name) {
-				if (StringHelper::substr($path, -StringHelper::strlen($name), $n) === $name) {
+				if (StringHelper::byteSubstr($path, -StringHelper::byteLen($name), $n) === $name) {
 					return true;
 				}
 			}
@@ -338,4 +338,48 @@ class BaseFileHelper
 		chmod($path, $mode);
 		return $result;
 	}
+
+	/**
+	 * Returns the trailing name component of a path.
+	 * This method is similar to the php function `basename()` except that it will
+	 * treat both \ and / as directory separators, independent of the operating system.
+	 * This method was mainly created to work on php namespaces. When working with real
+	 * file paths, php's `basename()` should work fine for you.
+	 * Note: this method is not aware of the actual filesystem, or path components such as "..".
+	 *
+	 * @param string $path A path string.
+	 * @param string $suffix If the name component ends in suffix this will also be cut off.
+	 * @return string the trailing name component of the given path.
+	 * @see http://www.php.net/manual/en/function.basename.php
+	 */
+	public static function basename($path, $suffix = '')
+	{
+		if (($len = mb_strlen($suffix)) > 0 && mb_substr($path, -$len) == $suffix) {
+			$path = mb_substr($path, 0, -$len);
+		}
+		$path = rtrim(str_replace('\\', '/', $path), '/\\');
+		if (($pos = mb_strrpos($path, '/')) !== false) {
+			return mb_substr($path, $pos + 1);
+		}
+		return $path;
+	}
+
+	/**
+	 * Returns parent directory's path.
+	 * This method is similar to `dirname()` except that it will treat
+	 * both \ and / as directory separators, independent of the operating system.
+	 *
+	 * @param string $path A path string.
+	 * @return string the parent directory's path.
+	 * @see http://www.php.net/manual/en/function.basename.php
+	 */
+	public static function dirname($path)
+	{
+		$pos = mb_strrpos(str_replace('\\', '/', $path), '/');
+		if ($pos !== false) {
+			return mb_substr($path, 0, $pos);
+		} else {
+			return $path;
+		}
+	}
 }
diff --git a/framework/yii/helpers/BaseSecurity.php b/framework/yii/helpers/BaseSecurity.php
index 03af81d..6abdd04 100644
--- a/framework/yii/helpers/BaseSecurity.php
+++ b/framework/yii/helpers/BaseSecurity.php
@@ -80,10 +80,10 @@ class BaseSecurity
 		}
 		$module = static::openCryptModule();
 		$ivSize = mcrypt_enc_get_iv_size($module);
-		$iv = StringHelper::substr($data, 0, $ivSize);
+		$iv = StringHelper::byteSubstr($data, 0, $ivSize);
 		$key = static::deriveKey($password, $iv);
 		mcrypt_generic_init($module, $key, $iv);
-		$decrypted = mdecrypt_generic($module, StringHelper::substr($data, $ivSize, StringHelper::strlen($data)));
+		$decrypted = mdecrypt_generic($module, StringHelper::byteSubstr($data, $ivSize, StringHelper::byteLen($data)));
 		mcrypt_generic_deinit($module);
 		mcrypt_module_close($module);
 		return static::stripPadding($decrypted);
@@ -96,7 +96,7 @@ class BaseSecurity
 	*/
 	protected static function addPadding($data)
 	{
-		$pad = self::CRYPT_BLOCK_SIZE - (StringHelper::strlen($data) % self::CRYPT_BLOCK_SIZE);
+		$pad = self::CRYPT_BLOCK_SIZE - (StringHelper::byteLen($data) % self::CRYPT_BLOCK_SIZE);
 		return $data . str_repeat(chr($pad), $pad);
 	}
 
@@ -107,11 +107,11 @@ class BaseSecurity
 	*/
 	protected static function stripPadding($data)
 	{
-		$end = StringHelper::substr($data, -1, NULL);
+		$end = StringHelper::byteSubstr($data, -1, NULL);
 		$last = ord($end);
-		$n = StringHelper::strlen($data) - $last;
-		if (StringHelper::substr($data, $n, NULL) == str_repeat($end, $last)) {
-			return StringHelper::substr($data, 0, $n);
+		$n = StringHelper::byteLen($data) - $last;
+		if (StringHelper::byteSubstr($data, $n, NULL) == str_repeat($end, $last)) {
+			return StringHelper::byteSubstr($data, 0, $n);
 		}
 		return false;
 	}
@@ -164,11 +164,11 @@ class BaseSecurity
 	 */
 	public static function validateData($data, $key, $algorithm = 'sha256')
 	{
-		$hashSize = StringHelper::strlen(hash_hmac($algorithm, 'test', $key));
-		$n = StringHelper::strlen($data);
+		$hashSize = StringHelper::byteLen(hash_hmac($algorithm, 'test', $key));
+		$n = StringHelper::byteLen($data);
 		if ($n >= $hashSize) {
-			$hash = StringHelper::substr($data, 0, $hashSize);
-			$data2 = StringHelper::substr($data, $hashSize, $n - $hashSize);
+			$hash = StringHelper::byteSubstr($data, 0, $hashSize);
+			$data2 = StringHelper::byteSubstr($data, $hashSize, $n - $hashSize);
 			return $hash === hash_hmac($algorithm, $data2, $key) ? $data2 : false;
 		} else {
 			return false;
diff --git a/framework/yii/helpers/BaseStringHelper.php b/framework/yii/helpers/BaseStringHelper.php
index e1622b9..8f6c002 100644
--- a/framework/yii/helpers/BaseStringHelper.php
+++ b/framework/yii/helpers/BaseStringHelper.php
@@ -26,7 +26,7 @@ class BaseStringHelper
 	 * @param string $string the string being measured for length
 	 * @return integer the number of bytes in the given string.
 	 */
-	public static function strlen($string)
+	public static function byteLen($string)
 	{
 		return mb_strlen($string, '8bit');
 	}
@@ -40,52 +40,11 @@ class BaseStringHelper
 	 * @return string the extracted part of string, or FALSE on failure or an empty string.
 	 * @see http://www.php.net/manual/en/function.substr.php
 	 */
-	public static function substr($string, $start, $length)
+	public static function byteSubstr($string, $start, $length)
 	{
 		return mb_substr($string, $start, $length, '8bit');
 	}
 
-	/**
-	 * Returns the trailing name component of a path.
-	 * This method is similar to the php function `basename()` except that it will
-	 * treat both \ and / as directory separators, independent of the operating system.
-	 * This method was mainly created to work on php namespaces. When working with real
-	 * file paths, php's `basename()` should work fine for you.
-	 * Note: this method is not aware of the actual filesystem, or path components such as "..".
-	 * @param string $path A path string.
-	 * @param string $suffix If the name component ends in suffix this will also be cut off.
-	 * @return string the trailing name component of the given path.
-	 * @see http://www.php.net/manual/en/function.basename.php
-	 */
-	public static function basename($path, $suffix = '')
-	{
-		if (($len = mb_strlen($suffix)) > 0 && mb_substr($path, -$len) == $suffix) {
-			$path = mb_substr($path, 0, -$len);
-		}
-		$path = rtrim(str_replace('\\', '/', $path), '/\\');
-		if (($pos = mb_strrpos($path, '/')) !== false) {
-			return mb_substr($path, $pos + 1);
-		}
-		return $path;
-	}
-
-	/**
-	 * Returns parent directory's path.
-	 * This method is similar to `dirname()` except that it will treat
-	 * both \ and / as directory separators, independent of the operating system.
-	 * @param string $path A path string.
-	 * @return string the parent directory's path.
-	 * @see http://www.php.net/manual/en/function.basename.php
-	 */
-	public static function dirname($path)
-	{
-		$pos = mb_strrpos(str_replace('\\', '/', $path), '/');
-		if ($pos !== false) {
-			return mb_substr($path, 0, $pos);
-		} else {
-			return $path;
-		}
-	}
 
 	/**
 	 * Compares two strings or string arrays, and return their differences.
diff --git a/framework/yii/web/Response.php b/framework/yii/web/Response.php
index bb77848..9fe8ed4 100644
--- a/framework/yii/web/Response.php
+++ b/framework/yii/web/Response.php
@@ -382,7 +382,7 @@ class Response extends \yii\base\Response
 	public function sendContentAsFile($content, $attachmentName, $mimeType = 'application/octet-stream')
 	{
 		$headers = $this->getHeaders();
-		$contentLength = StringHelper::strlen($content);
+		$contentLength = StringHelper::byteLen($content);
 		$range = $this->getHttpRange($contentLength);
 		if ($range === false) {
 			$headers->set('Content-Range', "bytes */$contentLength");
@@ -395,14 +395,14 @@ class Response extends \yii\base\Response
 			->setDefault('Content-Type', $mimeType)
 			->setDefault('Cache-Control', 'must-revalidate, post-check=0, pre-check=0')
 			->setDefault('Content-Transfer-Encoding', 'binary')
-			->setDefault('Content-Length', StringHelper::strlen($content))
+			->setDefault('Content-Length', StringHelper::byteLen($content))
 			->setDefault('Content-Disposition', "attachment; filename=\"$attachmentName\"");
 
 		list($begin, $end) = $range;
 		if ($begin !=0 || $end != $contentLength - 1) {
 			$this->setStatusCode(206);
 			$headers->set('Content-Range', "bytes $begin-$end/$contentLength");
-			$this->content = StringHelper::substr($content, $begin, $end - $begin + 1);
+			$this->content = StringHelper::byteSubstr($content, $begin, $end - $begin + 1);
 		} else {
 			$this->setStatusCode(200);
 			$this->content = $content;
diff --git a/framework/yii/web/XmlResponseFormatter.php b/framework/yii/web/XmlResponseFormatter.php
index 292424a..c072ee6 100644
--- a/framework/yii/web/XmlResponseFormatter.php
+++ b/framework/yii/web/XmlResponseFormatter.php
@@ -12,7 +12,7 @@ use DOMElement;
 use DOMText;
 use yii\base\Arrayable;
 use yii\base\Component;
-use yii\helpers\StringHelper;
+use yii\helpers\FileHelper;
 
 /**
  * XmlResponseFormatter formats the given data into an XML response content.
@@ -66,7 +66,7 @@ class XmlResponseFormatter extends Component implements ResponseFormatterInterfa
 	protected function buildXml($element, $data)
 	{
 		if (is_object($data)) {
-			$child = new DOMElement(StringHelper::basename(get_class($data)));
+			$child = new DOMElement(FileHelper::basename(get_class($data)));
 			$element->appendChild($child);
 			if ($data instanceof Arrayable) {
 				$this->buildXml($child, $data->toArray());
diff --git a/tests/unit/framework/helpers/StringHelperTest.php b/tests/unit/framework/helpers/StringHelperTest.php
index 2f1fb06..125386d 100644
--- a/tests/unit/framework/helpers/StringHelperTest.php
+++ b/tests/unit/framework/helpers/StringHelperTest.php
@@ -1,6 +1,7 @@
 <?php
 namespace yiiunit\framework\helpers;
 
+use yii\helpers\FileHelper;
 use yii\helpers\StringHelper;
 use yiiunit\TestCase;
 
@@ -12,57 +13,57 @@ class StringHelperTest extends TestCase
 {
 	public function testStrlen()
 	{
-		$this->assertEquals(4, StringHelper::strlen('this'));
-		$this->assertEquals(6, StringHelper::strlen('это'));
+		$this->assertEquals(4, StringHelper::byteLen('this'));
+		$this->assertEquals(6, StringHelper::byteLen('это'));
 	}
 
 	public function testSubstr()
 	{
-		$this->assertEquals('th', StringHelper::substr('this', 0, 2));
-		$this->assertEquals('э', StringHelper::substr('это', 0, 2));
+		$this->assertEquals('th', StringHelper::byteSubstr('this', 0, 2));
+		$this->assertEquals('э', StringHelper::byteSubstr('это', 0, 2));
 	}
 
 	public function testBasename()
 	{
-		$this->assertEquals('', StringHelper::basename(''));
+		$this->assertEquals('', FileHelper::basename(''));
 
-		$this->assertEquals('file', StringHelper::basename('file'));
-		$this->assertEquals('file.test', StringHelper::basename('file.test', '.test2'));
-		$this->assertEquals('file', StringHelper::basename('file.test', '.test'));
+		$this->assertEquals('file', FileHelper::basename('file'));
+		$this->assertEquals('file.test', FileHelper::basename('file.test', '.test2'));
+		$this->assertEquals('file', FileHelper::basename('file.test', '.test'));
 
-		$this->assertEquals('file', StringHelper::basename('/file'));
-		$this->assertEquals('file.test', StringHelper::basename('/file.test', '.test2'));
-		$this->assertEquals('file', StringHelper::basename('/file.test', '.test'));
+		$this->assertEquals('file', FileHelper::basename('/file'));
+		$this->assertEquals('file.test', FileHelper::basename('/file.test', '.test2'));
+		$this->assertEquals('file', FileHelper::basename('/file.test', '.test'));
 
-		$this->assertEquals('file', StringHelper::basename('/path/to/file'));
-		$this->assertEquals('file.test', StringHelper::basename('/path/to/file.test', '.test2'));
-		$this->assertEquals('file', StringHelper::basename('/path/to/file.test', '.test'));
+		$this->assertEquals('file', FileHelper::basename('/path/to/file'));
+		$this->assertEquals('file.test', FileHelper::basename('/path/to/file.test', '.test2'));
+		$this->assertEquals('file', FileHelper::basename('/path/to/file.test', '.test'));
 
-		$this->assertEquals('file', StringHelper::basename('\file'));
-		$this->assertEquals('file.test', StringHelper::basename('\file.test', '.test2'));
-		$this->assertEquals('file', StringHelper::basename('\file.test', '.test'));
+		$this->assertEquals('file', FileHelper::basename('\file'));
+		$this->assertEquals('file.test', FileHelper::basename('\file.test', '.test2'));
+		$this->assertEquals('file', FileHelper::basename('\file.test', '.test'));
 
-		$this->assertEquals('file', StringHelper::basename('C:\file'));
-		$this->assertEquals('file.test', StringHelper::basename('C:\file.test', '.test2'));
-		$this->assertEquals('file', StringHelper::basename('C:\file.test', '.test'));
+		$this->assertEquals('file', FileHelper::basename('C:\file'));
+		$this->assertEquals('file.test', FileHelper::basename('C:\file.test', '.test2'));
+		$this->assertEquals('file', FileHelper::basename('C:\file.test', '.test'));
 
-		$this->assertEquals('file', StringHelper::basename('C:\path\to\file'));
-		$this->assertEquals('file.test', StringHelper::basename('C:\path\to\file.test', '.test2'));
-		$this->assertEquals('file', StringHelper::basename('C:\path\to\file.test', '.test'));
+		$this->assertEquals('file', FileHelper::basename('C:\path\to\file'));
+		$this->assertEquals('file.test', FileHelper::basename('C:\path\to\file.test', '.test2'));
+		$this->assertEquals('file', FileHelper::basename('C:\path\to\file.test', '.test'));
 
 		// mixed paths
-		$this->assertEquals('file.test', StringHelper::basename('/path\to/file.test'));
-		$this->assertEquals('file.test', StringHelper::basename('/path/to\file.test'));
-		$this->assertEquals('file.test', StringHelper::basename('\path/to\file.test'));
+		$this->assertEquals('file.test', FileHelper::basename('/path\to/file.test'));
+		$this->assertEquals('file.test', FileHelper::basename('/path/to\file.test'));
+		$this->assertEquals('file.test', FileHelper::basename('\path/to\file.test'));
 
 		// \ and / in suffix
-		$this->assertEquals('file', StringHelper::basename('/path/to/filete/st', 'te/st'));
-		$this->assertEquals('st', StringHelper::basename('/path/to/filete/st', 'te\st'));
-		$this->assertEquals('file', StringHelper::basename('/path/to/filete\st', 'te\st'));
-		$this->assertEquals('st', StringHelper::basename('/path/to/filete\st', 'te/st'));
+		$this->assertEquals('file', FileHelper::basename('/path/to/filete/st', 'te/st'));
+		$this->assertEquals('st', FileHelper::basename('/path/to/filete/st', 'te\st'));
+		$this->assertEquals('file', FileHelper::basename('/path/to/filete\st', 'te\st'));
+		$this->assertEquals('st', FileHelper::basename('/path/to/filete\st', 'te/st'));
 
 		// http://www.php.net/manual/en/function.basename.php#72254
-		$this->assertEquals('foo', StringHelper::basename('/bar/foo/'));
-		$this->assertEquals('foo', StringHelper::basename('\\bar\\foo\\'));
+		$this->assertEquals('foo', FileHelper::basename('/bar/foo/'));
+		$this->assertEquals('foo', FileHelper::basename('\\bar\\foo\\'));
 	}
 }
diff --git a/tests/unit/framework/web/ResponseTest.php b/tests/unit/framework/web/ResponseTest.php
index 6077945..69fb60d 100644
--- a/tests/unit/framework/web/ResponseTest.php
+++ b/tests/unit/framework/web/ResponseTest.php
@@ -57,7 +57,7 @@ class ResponseTest extends \yiiunit\TestCase
 		$this->assertEquals(206, $this->response->statusCode);
 		$headers = $this->response->headers;
 		$this->assertEquals("bytes", $headers->get('Accept-Ranges'));
-		$this->assertEquals("bytes " . $expectedHeader . '/' . StringHelper::strlen($fullContent), $headers->get('Content-Range'));
+		$this->assertEquals("bytes " . $expectedHeader . '/' . StringHelper::byteLen($fullContent), $headers->get('Content-Range'));
 		$this->assertEquals('text/plain', $headers->get('Content-Type'));
 		$this->assertEquals("$length", $headers->get('Content-Length'));
 	}