Optimal parameter selection for a QKD protocol in noisy channels

Quantum Key Distribution (QKD) is a technology within the field of Information-Theoretic Security (ITS) that leverages the principles of Quantum Mechanics (QM) to distribute cryptographic keys between A and B. QKD ensures that any potential attacker, E, cannot gain any information about the key without being detected by the legitimate parties. To achieve this, QKD establishes a physical, point-to-point quantum link between Alice and Bob. However, this link is not perfect and can be affected by various physical imperfections, including attenuation, polarization drift and background noise. These imperfections can introduce errors in the transmitted quantum states. To obtain a secure and identical key between A and B, some additional steps are performed after transmission, such as sifting, error estimation, error correction and privacy amplification. For the optimization of the entire process, some parameters, like hold-off time, filter time window and raw key block length, can be adjusted to provide the best trade-off between security, correctness and speed in the generation of the key. The aim of this work is to analyze the three-state QKD protocol implemented by ThinkQuantum and to extend their QUKY software by developing a prototypal version that evaluates the channel imperfections and automatically selects the optimal parameters for a given level of attenuation and noise. This prototypal implementation serves as a proof of concept for automating parameter selection and enhancing the adaptability of ThinkQuantum devices under real operating conditions.