Reliable symmetric key generation for body area networks using wireless physical layer security in the presence of an on-body eavesdropper

Abstract

Utilizing the randomness of the wireless channel for securing on-body communication in the presence of an on-body eavesdropper is considered. The feasibility of establishing a secure, unique and random key is investigated using a radio platform operating in the 2.4GHz ISM band. A low-complexity algorithm for establishing a symmetric encryption key tailored to the on-body propagation environment is proposed and justified. The algorithm uses the readily available radio signal strength indicator from existing packets going back and forth over the communication link and presents marginal system overheads. The secret bit sequences generated by the algorithm are evaluated for matching between the two communicating parties, mismatching with an eavesdropper placed on the body, and degree of randomness. It is shown that the algorithm generates long and highly random bit sequences which are perfectly matched between the legitimate communicating parties yet weakly matched with the eavesdropper's bit sequences.