A novel quantum key distribution resistant against large-pulse attacks

Quantum key distribution (QKD) offers information-theoretic security by leveraging the principles of quantum mechanics. This means the security is independent of all future advances in algorithm or computational power. However, due to the non-availability of single-photon sources, most traditional QKD protocols are vulnerable to various attacks, such as photon number-splitting (PNS) attacks. Also, the imperfections in the measuring devices open a loophole for side channels that an eavesdropper may exploit to launch attacks such as large-pulse attacks. As a result, this compromises the security of transmitted information. To address these challenges, the authors present a QKD protocol that is secure against both large-pulse attacks and PNS attacks at zero-error, in which the eavesdropper does not introduce any error, but still, the legitimate users of the system cannot distil a secure key. A notable feature of the proposed protocol is that it promotes greater robustness against both attacks than the Bennett-Brassard 1984 (BB84) protocol or the Scarani-Acin-Ribordy-Gisin 2004 (SARG04) protocol.