core-bundle/src/Resources/contao/library/Contao/System.php
public static function getSessionHash($strCookie)
	{
		@trigger_error('Using System::getSessionHash() has been deprecated and will no longer work in Contao 5.0. Use Symfony authentication instead.', E_USER_DEPRECATED);

		$session = static::getContainer()->get('session');

		if (!$session->isStarted())
		{
			$session->start();
		}

		return sha1($session->getId().$strCookie);
	}
public static function getSessionHash($strCookie)
	{
		@trigger_error('Using System::getSessionHash() has been deprecated and will no longer work in Contao 5.0. Use Symfony authentication instead.', E_USER_DEPRECATED);

		$session = static::getContainer()->get('session');

		if (!$session->isStarted())
		{
			$session->start();
		}

		return sha1($session->getId().$strCookie);
	}
Return the session hash

@param string $strCookie The cookie name

@return string The session hash

@deprecated Deprecated since Contao 4.5, to be removed in Contao 5.0.
Use Symfony authentication instead.