Quantum Key Distribution Based on BB84 Protocol

Abstract

Classical cryptosystem, which is based on mathematical complexity and irrationally time-consuming to decode, is endangered with the inception of quantum computers empowered with unprecedented computational processing along with sophisticated quantum algorithms. Thus requiring quantum cryptography and Quantum Key Distribution (QDK) protocol for secured key distribution. This thesis work contributes to the field of cryptography. First of all, it shows unconditionally secured QKD which is bound by quantum mechanics laws. It is minimal or moreover almost negligible chances of escaping the eavesdropper i.e. almost zero probability. Next, it shows the modified existing QKD protocol named BB84 protocol. The main drawback of the existing protocol is that it is less efficient concerning photon utilization as we know perfect single-photon generation is still challenging to current technology. In this work, the modified protocol has been presented and it is shown the simulated output using the Aer Provider backend ‘aer_simulator’ provided by Qiskit. With the generated key, message is encoded, transmitted and decoded in real quantum computer with backend ‘ibmq_manila’. The errors generated and analyzed and found that without interference in the channel, maximum only upto 15% errors have been generated from the noise of quantum circuit and are in acceptable range but in presence of interference, error rates surpass the acceptable range i.e. 20% error margin and hence the interference in the channel is detected.