A Study of a Variation of BB84 Quantum Cryptography Protocol for Improving Key Rate and Information Security

In the modern world, information security relies on encryption via key distribution, ensuring that only a sender and receiver can decrypt a transmission. Despite the implementation of such classical encryption, many algorithms still leave transmitted information susceptible to eavesdropping. To mitigate the effectiveness of eavesdropping, quantum techniques such as BB84 have been developed in the new age of quantum key distribution (QKD). The BB84 protocol allows one to generate a secure key by randomly changing quantum state bases between a sender (Alice) and receiver (Bob). Making use of quantum random number generators (QRNG), the protocol ensures true randomness of key generation. Additionally, eavesdropping (by Eve) is hindered by the probabilistic nature of photonic superposition at the point of measurement. We simulated biasing the choice of basis for a sender and receiver in the BB84 protocol (variation to original BB84) to determine the improvement of key generation rate and information security. Additionally, we also analyzed the effects of an eavesdropper biasing their choice of basis. We found that a varied BB84 protocol utilizing biased basis can improve key generation rate while retaining information security. Additionally, we found that there exists a bias region where, even with ideal performance of Eve, she is not able to obtain more mutual information than shared by Alice and Bob. Starting spring 2024, we will implement the findings on a quantum network test bed via a quantum node lab on UTC campus that provides access to a software-programable quantum network in the Chattanooga metropolitan area.