A Channel Model of Transceivers for Multiterminal Secret Key Agreement
This work addresses a foundational problem in information-theoretic security for communication systems, offering a novel model that could impact secure key generation protocols.
The paper tackles the problem of secret key agreement in multiterminal settings by proposing a new channel model where each terminal acts as both a transmitter and receiver, and it provides upper and lower bounds for the secret key capacity, proving the capacity under specific conditions like noninteractive public communication and independent inputs.
Information theoretic secret key agreement is impossible without making initial assumptions. One type of initial assumption is correlated random variables that are generated by using a noisy channel that connects the terminals. Terminals use the correlated random variables and communication over a reliable public channel to arrive at a shared secret key. Previous channel models assume that each terminal either controls one input to the channel, or receives one output variable of the channel. In this paper, we propose a new channel model of transceivers where each terminal simultaneously controls an input variable and observes an output variable of the (noisy) channel. We give upper and lower bounds for the secret key capacity (i.e., highest achievable key rate) of this transceiver model, and prove the secret key capacity under the conditions that the public communication is noninteractive and input variables of the noisy channel are independent.