public static function saltTooShort(string $str)
    {
        $length = strlen($str);
        if ($length === 0) {
            return new self(sprintf(
                'The internal key salt must be at least 8 characters. You supplied an empty salt.'
            ));
        } else {
            return new self(sprintf(
                'The internal key salt must be at least 8 characters. You supplied a %s character salt: %s',
                $length,
                $str
            ));
        }
    }