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(Q&A) - Proof of concept of QKD (quantum key distribution) - use cases in Tokyo QKD Network

Q& A session: for Q-Thai SEM2021 #5 - November 30, 2022
Event: IEEE Communications Society - Thailand section & annual meeting

| Q-Thai forum | IEEE Communications society - Thailand chapter |

| Interviewed by Keattisak Sripimanwat | Published - November 10, 2022 |

(Director’s TALK) - Updated quantum cryptography project from quantum ICT laboratory, the National Institute of Information and Communications Technology (NICT) - Japan by its director, Dr.Mikio Fujiwara. This Q-Thai forum's annual seminar #5 (Q-Thai SEM 2022) is organized jointly with the annual meeting of IEEE Thailand section on November 30, 2022. Dr.Fujiwara gives us about thirty minutes online talk that focuses on QKD from the most update through various applications around the world, to the recent roadmap in Japan. That amazing plan would be started on the year 2023 from QKD network around Tokyo reaching to the global QKD network in 2035. This talk is good for all technology management & policy makers, researchers, as well as students (more detail).

Q-Thai forum organizes another session, in deep, to convey more specific information via Q & A. Dr.Fujiwara provides his answers at below including the latest progresses, hype & confusion and controversial regarding QKD, related science communications, and a few others. Those are important for the public understanding. Let’s update !

Q1: Japan’s activities on quantum key distribution (QKD) is highly impressive as the world pioneer since early 2000s. What are important lesson learns during 2010-2022, and what is about the future target of NICT in Japan's QKD society ?

Mikio Fujiwara: The following three points were considered important for the widespread use of QKD.

(1) Improvement of the performance of QKD systems

(2) Construction of QKD networks and design of interfaces with existing infrastructure

(3) Improvement of the functionality of the QKD network

We believe that we were the first in the world to research and develop these points and were able to apply them to various POCs (proof of concept). Therefore, we believe that it is important to incorporate a design with excellent role-sharing and connectivity with existing communication and cryptographic infrastructures. We aim to promote QKD as one of the cryptographic infrastructures.

Q2: There are confusions of the actual QKD applications around the world. It seems that testbed was done with specific conditions also with “quantum channel” for delivering quantum key those not existing in the real life (24 Hr/7 Days) infrastructure. However, researchers usually mentioned their R&D demonstrations as the practical uses cases. Many of them also claimed doubtedly that QKD has been using for nuclear power plant, electricity grid network, financial infrastructure or even for 5G mobile phone. While there is no any user review, nor public independent report till date. What is exactly happened in QKD community ?

Mikio Fujiwara: QKD certainly requires dark fiber, but this condition can be prepared without any problem, at least in Japan. QKD works well even with aerial lines, which are widely used in Japan due to the country's unique circumstances. Therefore, there is no problem in applying QKD to power lines. Even with any communication infrastructures, QKD can work as the method of sharing key at the endpoints, which is the basis of communication confidentiality. At least in Japan, long-term usage evaluations have been conducted by users, but it is undeniable that such evaluations are rarely made public due to the nature of cryptographic technology.

Q3: QKD researchers have defined many new technical words using on quantum communication field. However, those are yet available in the communication engineering society (for examples, quantum trusted relay/node or quantum hack). Also they claimed theoretically that QKD is an unhackable - unbreakable or absolute secure network. How engineering or IT society should adapt for ?

Mikio Fujiwara: The technologies and terms specific to QKD technology are defined in ITU-T Y3800, etc., so that confusion with ordinary carriers can be avoided. We believe that there will be no confusion in the future, as guidelines for the implementation safety of QKD systems will be developed.

Q4: Many leading firms for information security such as, NCSC (National Cyber Security Centre - UK 2018), NSA (National Security Agency - US 2020), ANSS (Agence nationale de la sécurité des systèmes d’information - France 2022), and BSI (Federal Office for Information Security - Germany 2022), did not recommend QKD as the cyber security solution. What is exactly the problem and what about the final feedback from QKD community ?

Mikio Fujiwara: It is up to them and we are not involved. We consider it unfortunate that there are more than a few people who criticize QKD without understanding the technology.

Q5: Recently, post-quantum cryptography (PQC) or quantum resistant cryptography is convinced as being the real solution worldwide once quantum computer is functioned. Please tell us about the situation of QKD regarding the same issue ?

Mikio Fujiwara: PQC is considered to have quantum computer resistant properties, but a serious problem was discovered in a scheme that was selected advanced to the fourth round of NIST. Mathematical cryptography, which is based on computational security, always has this risk, and QKD is important as a complement to PQC because of its physical security guarantees.

Q6: Due to various and serious limitations of QKD in the real world then there are important quotes as “seems like a solution to a problem that we don’t really have” or “boutique security product”, can we consider QKD as the “future solution” or a practical security scheme ONLY when all-quantum communication network or full quantum internet available ?

Mikio Fujiwara: Cannot be discussed because it is a difference of opinion. A business model is being formed.

Q7: Regarding future four step of NICT’s QKD plan (2023 - 2035), is there any possibility of collaboration with other countries and new comers in ASEAN countries and what they should prepare for ?

Mikio Fujiwara: Satellite QKD is essential for the formation of a global network, and it is necessary to enhance the peripheral technologies that enable satellite communications.

Q8: Last question, while QKD has been developing for over three decades. Its progress has been achieved impressively from terrestrial optical fiber though free space to satellite network. One of QKD community people, Prof.Anton Zeilinger, has just been awarded the Nobel prize in physics 2022. QKD is certainly one of the most successful technical field recently. However, its related science communication to the public is still quite far behind. What would you recommend to all concerns in order to advance QKD understanding publicly ?

Mikio Fujiwara: It is important to start by recognizing that quantum technology is also important in the cryptographic aspect: a random number generator is needed in PQC, and quantum technology is essential to achieve a secure physical random number generator; the essence of the security of QKD is quantum noise, and this benefit again plays an important role in other cryptographic techniques It is important to recognize that the essence of QKD security is quantum noise, and that this benefit plays an important role in other cryptographic techniques.


Full talk video [ Q-Thai SEM2022 #5 will be on Nov 30, 2022]

(more details)

NICT: Quantum ICT Laboratory

Q-Thai SEM#5: Q-Thai Annual SEMINAR

Quantum Cryptography: Background & Community


(1st announcement)




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