Mobile devices continuously beacon Bluetooth Low Energy (BLE) advertisement packets. This has created the threat of attackers identifying and tracking a device by sniffing its BLE signals. To mitigate this threat, MAC address randomization has been deployed at the link-layer in most BLE transmitters. However, attackers can bypass MAC address randomization using lower-level physical-layer fingerprints resulting from manufacturing imperfections of radios. In this work, we demonstrate a practical and effective method of obfuscating physical-layer hardware imperfection fingerprints. Through theoretical analysis, simulations, and field evaluations, we design and evaluate our approach to hardware imperfection obfuscation. By analyzing data from thousands of BLE devices, we demonstrate obfuscation significantly reduces the accuracy of identifying a target device. This makes an attack impractical, even if a target is continuously observed for 24 hours. Furthermore, we demonstrate the practicality of this defense by implementing it by making firmware changes to commodity BLE chipsets.

Wearables are a potentially vital mechanism for individuals to monitor their health, track behaviors, and stay connected. Unfortunately, both price and a lack of consideration of the needs of low-SES communities have made these devices inaccessible and unusable for communities that would most substantially benefit from their affordances. To address this gap and better understand how members of low-SES communities perceive the potential benefits and barriers to using wearable devices, we conducted 19 semi-structured interviews with people from minority, high crime rate, low-SES communities. Participants emphasized a critical need for safety-related wearable devices in their communities. Still, existing tools do not yet address the specific needs of this community and are out of reach due to several barriers. We distill themes on perceived useful features and ongoing obstacles to guide a much-needed research agenda we term ’Equityware’: building wearable devices based on low-SES communities’ needs, comfortability, and limitations.