"I don't know how to protect myself": Understanding Privacy Perceptions Resulting from the Presence of Bystanders in Smart Environments

IoT devices no longer affect single users only because others like visitors or family members - denoted as bystanders - might be in the device's vicinity. Thus, data about bystanders can be collected by IoT devices and bystanders can observe what IoT devices output. To better understand how this affects the privacy of IoT device owners and bystanders and how their privacy can be protected better, we interviewed 42 young adults. Our results include that owners of IoT devices wish to adjust the device output when visitors are present. Visitors wish to be made aware of the data collected about them, to express their privacy needs, and to take measures. Based on our results, we show demand for scalable solutions that address the tension that arises between the increasing discreetness of IoT devices, their increase in numbers and the requirement to preserve the self-determination of owners and bystanders at the same time.