A Complete Circuit Model for the Key Distribution System Using Resistors and Noise Sources

A complete circuit model is developed for modeling the classical key distribution system based on resistors and band-limited noise sources. Theoretical analysis provides component values, including the mutual inductance. Circuit simulations are performed to obtain voltage and current as a function of frequency. Any imbalance between two sides of the communications link is identified. Results indicate that the current, especially, in the bootstrapping circuit, can be a potential security risk unless all signals are band-limited to a low frequency.