Recovering Error-Free Cryptographic Keys from Noisy Quantum Key Distribution and Independent Eavesdropper Detection on the Receiving End

In this paper we study the performance and feasibility of integrating a novel key encapsulation protocol into Quantum Key Distribution (QKD). The key encapsulation protocol includes a challenge-response pair (CRP). In our design, Alice and Bob derive identical cryptographic tables from shared challenges, allowing the ephemeral key to be encoded and recovered without disclosing helper data. Software simulations show error-free key recovery for quantum channel bit error rates up to 40% when using longer response lengths. Additionally, we designed the protocol to detect eavesdropping solely from the statistics of the received quantum stream, without sacrificing key bits for public comparison. We formalize the encoding and decoding model, analyze trade-offs between response length and latency, and report key recovery and error detection performance across different noise levels. The results indicate that this CRP-based multi-wavelength QKD protocol can reduce the reliance on classical reconciliation while preserving security in noisy settings.