Performance Analysis and Optimization of the Winnow Secret Key Reconciliation Protocol

Abstract : Currently, private communications in public and government sectors rely on methods of cryptographic key distribution that will likely be rendered obsolete the moment a full-scale quantum computer is realized, or efficient classical methods of factoring are discovered. There are alternative methods for distributing secret key material in a "post-quantum" era. One example of a system capable of securely distributing cryptographic key material, known as Quantum Key Distribution (QKD), is secure against quantum factorization techniques as its security rests on generally accepted laws of quantum physics. QKD protocols typically include a phase called "Error Reconciliation", a clear-text classical-channel discussion between legitimate parties of a QKD protocol by which errors introduced in the quantum channel are corrected and the legitimate parties ensure they share identical key material. This work improves one such reconciliation protocol, called Winnow, by examining block-size choices for Winnow and thus increasing QKD key rate. Block sizes are chosen to maximize the probability that each block contains exactly one error. Further analyses of Winnow are provided to characterize the effects of different error distributions on protocol operation and shed light on the time and communication complexities of the Winnow secret key reconciliation protocol.