Exploiting the randomness of the measurement basis in quantum cryptography: Secure Quantum Key Growing without Privacy Amplification

TL;DR

This paper introduces a quantum key distribution protocol that leverages the randomness of measurement basis choices to enhance security, eliminating the need for privacy amplification and enabling secure key growth.

Contribution

A novel QKD protocol that encrypts classical communication during key sifting, preventing eavesdropper replication and allowing secure key expansion without privacy amplification.

Findings

Prevents eavesdropper from reproducing the sifting process

Reduces information gain for eavesdroppers on the sifted key

Enables secure quantum key growth without privacy amplification

Abstract

We suggest that the randomness of the choices of measurement basis by Alice and Bob provides an additional important resource for quantum cryptography. As a specific application, we present a novel protocol for quantum key distribution (QKD) which enhances the BB84 scheme by encrypting the information sent over the classical channel during key sifting. We show that, in the limit of long keys, this process prevents an eavesdropper from reproducing the sifting process carried out by the legitimate users. The inability of the eavesdropper to sift the information gathered by tapping the quantum channel reduces the amount of information that an eavesdropper can gain on the sifted key. We further show that the protocol proposed is self sustaining, and thus allows the growing of a secret key.