On secret-key generation using wideband channels in mobile networks

Wireless networks are subject to security vulnerability due to the broadcasting nature of radio transmission. Information-theoretic approaches for secure communication propose to generate secret keys from a common source, such as reciprocal channels, available to the transmitter and receiver. However, such approaches assume the probability distribution of the sources, which may not be available in many realistic scenarios. In this paper, we establish an information-theoretic framework for secret-key generation (SKG) using noisy observations of unknown deterministic parameters (UDPs). Based on an axiomatic definition of UDPs, we derive a new metric called intrinsic information between the UDP and its observation, characterizing the rate of the secret key that can be generated from the observation. This metric is then applied to quantify the use of wideband channels in mobile networks for SKG. Our results provide a non-Bayesian perspective for SKG as well as its practical implications.