Uploader::getGuidFromToken

private function getGuidFromToken(string $token): ?string
{
	$parts = explode('.', $token, 2);
	if (count($parts) !== 2)
	{
		return null;
	}

	[$guid, $signature] = $parts;
	if (empty($guid) || empty($signature))
	{
		return null;
	}

	$salt = $this->getTokenSalt([$guid]);
	$signer = new Signer();

	if (!$signer->validate($guid, $signature, $salt))
	{
		return null;
	}

	return $guid;
}