Mobility Independent Secret Key Generation for Wearable Health-care Devices

Security in Wireless Body Area Networks (WBAN) is of major concern as the miniature personal health-care devices need to protect the sensitive health information transmitted in wireless medium. It is essential for these devices to generate the shared secret key used for data encryption periodically. Recent studies have exploited wireless channel characteristics, e.g., received signal strength indicator (RSSI) to derive the shared secret key during random body movement of subject wearing devices. However, in the absence of node mobility, these schemes have very low bit rate capacity, and fail to derive keys with good entropy, which is a big threat for security. In this work, we study the effectiveness of combining dual antennas and frequency diversity for obtaining uncorrelated channel samples to improve entropy of key and bit rate in static channel conditions. We propose a novel mobility independent RSSI based secret key generation protocol -- iARC for WBAN. We conduct an extensive set of experiments in real time environments on sensor platforms used in WBAN to validate the performance of iARC. iARC has 800 bps secrecy capacity and generates 128 bit key in only 160 ms.