core-bundle/src/Resources/contao/library/Contao/Input.php
public static function cookie($strKey, $blnDecodeEntities=false)
	{
		if (!isset($_COOKIE[$strKey]))
		{
			return null;
		}

		$strCacheKey = $blnDecodeEntities ? 'cookieDecoded' : 'cookieEncoded';

		if (!isset(static::$arrCache[$strCacheKey][$strKey]))
		{
			$varValue = $_COOKIE[$strKey];

			$varValue = static::decodeEntities($varValue);
			$varValue = static::xssClean($varValue, true);
			$varValue = static::stripTags($varValue);

			if (!$blnDecodeEntities)
			{
				$varValue = static::encodeSpecialChars($varValue);
			}

			$varValue = static::encodeInsertTags($varValue);

			static::$arrCache[$strCacheKey][$strKey] = $varValue;
		}

		return static::$arrCache[$strCacheKey][$strKey];
	}
public static function cookie($strKey, $blnDecodeEntities=false)
	{
		if (!isset($_COOKIE[$strKey]))
		{
			return null;
		}

		$strCacheKey = $blnDecodeEntities ? 'cookieDecoded' : 'cookieEncoded';

		if (!isset(static::$arrCache[$strCacheKey][$strKey]))
		{
			$varValue = $_COOKIE[$strKey];

			$varValue = static::decodeEntities($varValue);
			$varValue = static::xssClean($varValue, true);
			$varValue = static::stripTags($varValue);

			if (!$blnDecodeEntities)
			{
				$varValue = static::encodeSpecialChars($varValue);
			}

			$varValue = static::encodeInsertTags($varValue);

			static::$arrCache[$strCacheKey][$strKey] = $varValue;
		}

		return static::$arrCache[$strCacheKey][$strKey];
	}
Return a $_COOKIE variable

@param string  $strKey            The variable name
@param boolean $blnDecodeEntities If true, all entities will be decoded

@return mixed The cleaned variable value