Secure Opportunistic Contextual Logging for Wearable Healthcare Sensing Devices

Wearable technology is increasingly being used for medical applications such as continuous monitoring of chronically ill patients in homes and hospitals. The various stakeholders (patients, doctors, insurers) have an interest in ensuring not only that the data is untampered, but also that the context is verifiable (e.g., correct time and location can be associated with the data collected). Prior works have studied these aspects in isolation, typically using cryptographic techniques. In this paper, we develop a new solution that leverages the density of wireless devices in the vicinity of the transaction to create witness records ensuring data is tamper-protected and bound to its time and location context. Our first contribution is to develop a secure logging architecture that compacts witness records using Bloom filters and hash-chains them to bind them to the data, allowing fast and reliable forensic verification. Our second contribution is to identify the various configuration parameters influencing the performance of our scheme in terms of storage, processing, and transmission efficiency, and to quantify their effect on verification accuracy. Our third contribution implements and demonstrates the feasibility of our scheme, and quantifies its efficacy via simulation using real trace data from a multi-storey building representing a hospital environment.