Implementation of Quantum Key Distribution With Multiple Eavesdroppers

Abstract

Quantum Key Distribution (QKD), a type of quantum cryptography in which two parties generate and share a highly secure secret key, is a novel computational technique that can ensure high data security in modern quantum computers. It is based on the laws of quantum mechanics such as superposition, the Heisenberg Uncertainty Principle (HUP), and the No- Cloning theorem, as opposed to integer factorization and discrete logarithmic problems used in conventional classic computers. Although proposed in the 1970’s by Stephen Wiesner at Columbia University via introduction of the idea of quantum conjugate coding, and further improved on by Charles H. Bennett through his concept of secure communication, the very first successful attempt to implement this technique was in the 1980’s when Charles H. Bennett proposed the first quantum cryptography protocol – the BB84 based on nonorthogonal states. At around the same time Artur Ekert proposed a QKD method based on the idea of quantum entanglement. Since then, there has been remarkable progress in research aimed at the adoption of technologies to ensure highly secure quantum computers with the most notable work being the 2021 study by Hamish Johnston on implementation of the Beijing-Shanghai QKD network over 4600 km. However, despite the wide ongoing adoption of QKD technologies in commercial applications, research on new technologies to ensure high data rates and data security is still at its infancy. This research work is an effort in that direction. Data obtained through simulations implemented using the publicly available IBM’s Qiskit (see https://www.ibm.com/quantum) is used to study, test and implement a BB84-based QKD protocol for the case of multiple eavesdroppers, using the Intercept-Resend (IR) attack on a secure QKD system. Associated Quantum Bit Error Rates (QBERs) for the cases of (i) no eavesdropper, (ii) single eavesdropper and (iii) multiple eavesdroppers are computed and presented. Our results show that the QBERs are independent of the number of eavesdroppers, hence providing evidence that our QKD system remains secure even with an increased number of eavesdroppers.