Secret Key Establishment over Noisy Channels

This paper provides a reflective overview of the research published in [3,4], which introduces a new realistic scenario for information theoretically secure key establishment. The scenario is when two parties are communicating over "noisy" channels that are eavesdropped by other parties in the environment. We define the secret key capacity as the highest achievable secret key rate, i.e., the highest number of secret key bits that the two parties can share on average per use of the channel. We study the above problem in two settings when the two parties have, or do not have, access to sources of local randomness. In each case, we derive lower and upper bounds on the SK capacity and derive the capacity for special cases. We also compare the bounds in the two settings and discuss the role of local randomness in increasing key rate.