Quantum Resistant Authentication Methods for Quantum Key Distribution

Abstract

Quantum Key Distribution (QKD) can distribute keys securely, even in the era of quantum computers, only if the classical channel has been authenticated. This master thesis investigates several methods and optimal parameters for authenticating the classical channel as quickly as possible in the QKD protocol BB84. We utilized quantum-resistant signature algorithms for authentication as they withstand attacks from quantum adversaries. We introduce a novel authentication approach, mono-authentication, which comprises authenticating only at the end rather than the traditional multi-authentication after each stage of communication. We first simulated a simile of what would be performed in classical cryptography to distribute a key, where we ask the QKD for a determined number of security bits. Next, we studied how four different signature algorithms performed in a noisy quantum channel and found the optimal cases for implementing these algorithms. Then, we obtained a frequency of authentications for three payloads. Finally, we used the previous results to calculate the minimum period for each post-quantum algorithm needs for authentication in terms of the key rate. Results show that the mono-authentication style is at least twice faster than the multi-authentication case. We conclude that in noisy channels, the mono-case reduces its cost significantly. Regarding the performance of the signatures, CRYSTALS-DILITHIUM is shown to be the fastest overall, and in contrast to the other algorithms, its number of signatures per second fluctuates with the key rate while being consistently low for the others.