Quantum key distribution with hacking countermeasures and long term field trial

Abstract

Quantum key distribution’s (QKD’s) central and unique claim is information theoretic security. However there is an increasing understanding that the security of a QKD system relies not only on theoretical security proofs, but also on how closely the physical system matches the theoretical models and prevents attacks due to discrepancies. These side channel or hacking attacks exploit physical devices which do not necessarily behave precisely as the theory expects. As such there is a need for QKD systems to be demonstrated to provide security both in the theoretical and physical implementation. We report here a QKD system designed with this goal in mind, providing a more resilient target against possible hacking attacks including Trojan horse, detector blinding, phase randomisation and photon number splitting attacks. The QKD system was installed into a 45 km link of a metropolitan telecom network for a 2.5 month period, during which time the system operated continuously and distributed 1.33 Tbits of secure key data with a stable secure key rate over 200 kbit/s. In addition security is demonstrated against coherent attacks that are more general than the collective class of attacks usually considered.

Boosting the secret key rate in a shared quantum and classical fibre communication system

“…We also demonstrate, with off-the-shelf equipment, the robustness of the system by co-propagating a classical signal at 370 Gbit s −1 , paving the way for a shared quantum and classical communication network. * dabac@fotonik.dtu.dk, bdali@fotonik.dtu.dk These authors contributed equally to this work 1 arXiv:1911.05360v1 [quant-ph] 13 Nov 2019 of integration with the bright signals used in classical communications [17][18][19][20][21][22][23]. In this work, we show how to overcome the low rate and compatibility limitations by exploiting a 37-core multicore fibre (MCF) as a technology for quantum communications [24].…”

Experimental measurement-device-independent quantum digital signatures

“…Our quantum network features a majority of QKD links, used to distil information-theoretically secure encryption keys and digital signatures for the network’s users. This would ease the transition to a real-world system, as QKD offers excellent stability 37 and has already been implemented in field trials 38 – 40 . The polarisation encoding used in our setup has been used in previous quantum communications experiments and is controllable with high accuracy 41 .…”

Protecting fiber-optic quantum key distribution sources against light-injection attacks

“…A fiber-optic isolator or circulator, which is often placed as the last component in the source unit [34][35][36][37][38][39][40], is believed to protect a fiber-based QKD system from the adversary's injecting light through a quantum channel. For example, Ref.…”