Key-sharing via channel randomness in body area networks: Is everyday movement sufficient?
We consider secure communication for Body-Area-Networks (BAN's). We examine the near-body radio channel of BAN's as a source of common randomness between two sensors. The movement of the subject and associated fading is used to hide a secure key from Eve. We examine recently approved radio channel models of the IEEE 802.15.6 Task Group, and show that the common randomness is too low rate for unconditional encoding. We find a key-generation rate around 2bits/second. We suggest the channel randomness may be better used in generating perpetually new keys for an AES-style encryption -- eg, a 128bits key every minute -- via a randomness scavenging procedure.