Progresses on Security and Attacking of Quantum Key Distribution | #IYQ2025 & #ThaiYQ2025 | Zhen-Qiang Yin (USTC, CN) | MAY 16, 2025 | (Q&A)

K Sripimanwat
19 ชั่วโมงที่ผ่านมา
ยาว 8 นาที

(May 2025) หัวข้อประจำเดือนพฤษภาคม ๒๕๖๘

สนทนา #IYQ2025 & #ThaiYQ2025

(Questions & Answers - บรรยายและคำถามคำตอบ)

#QuantumCommunications #QKD

(Zhen-Qiang Yin - USTC, Hefei, Anhui, China)

Welcome to #IYQ2025 & #ThaiYQ2025 on Q&A session. Thanks for your talk updating quantum cryptography from USTC, and we have a few questions. Please feel free to share your opinions.

Q1? : Quantum cryptography or QKD has seen impressive development in China, with significant achievements in publications, patents, and demonstrated projects. China is indeed a major global player in quantum communications, largely attributed to its successful human resource development strategy over the past decade. To provide context, could you please share some statistics or some insights on the scale of the QKD workforce ? Specifically, we are interested in the approximate number of researchers, students, and faculty members in the QKD field within your group, across all the USTC campuses, and nationwide.

Answer: Yes, human resource is very important to the development of QKD. There are thee professors, two associate researchers, three postdoctors, and over 20 students in our group. In USTC campus, I think there are several other groups working on QKD. Hence, approximately, there are around 10 professors focusing on QKD in USTC, and then you may estimate the number of students. As for the nationwide, it’s hard to estimate this number. As far as I know, there are groups working on QKD in many other universities, such as Shanghai Jiaotong University and Beijing University of Posts and Telecommunications. Besides, there are several companies developing QKD products. Hence, I think China may have the largest workforce in this field.

Q2?: While QKD products have been available for over two decades, widespread adoption by the core IT industry remains limited. Despite marketing efforts by companies in the EU and Japan, the primary market for QKD has been within education and R&D.

Another, QKD was initially invented in 1984 by researchers at IBM and the University of Montreal. However, IBM has not pursued QKD production or dedicated labs over the past forty years. Several QKD companies, including some in the US and Korea, have ceased operations. Current market promotion strategies, such as tie-in sales with the power industry found in Thailand or cross-selling with post-quantum cryptography (PQC) and quantum random number generators (QRNG), raise questions about QKD's market viability. Some might even describe QKD as existing in a “bubble market.”

Given these backgrounds, we are very interested in understanding the factors contributing to the growth and success of two major Chinese QKD companies, especially considering the challenges of the US-China trade war and the “entity list.” Could you please share insights into the key strategies behind the success of the QKD business in China ? "

Answer: Yes, you are absolutely correct. In reality, China's quantum key distribution (QKD) companies heavily rely on education and R&D markets, particularly government-led investments. As the only theoretically information-theoretic secure communication solution currently available, QKD receives substantial attention from the Chinese government. Central authorities have established specialized programs to support QKD research and application, which proves crucial for the success of Chinese QKD enterprises. Moreover, government initiatives have catalyzed commercial and private investments flowing into this sector, further consolidating the industry's growth.

The consumer end-market indeed struggles to sustain the entire QKD industry globally. This primarily stems from the limited urgency for information-theoretic security in current market demands. First, quantum computers capable of breaking classical cryptographic algorithms remain unrealized. Second, post-quantum cryptography (PQC) serves as an alternative solution against future quantum computing threats. As you noted, the United States prioritizes PQC development over QKD, resulting in weaker governmental support and consequently less robust QKD industrial progress there.

In summary, while both China and the U.S. face similar challenges in consumer market viability for QKD technologies, China's strategic emphasis on QKD through policy support and investment mobilization has fostered remarkable industry advancement. This approach mirrors China's broader technological development paradigm observed in other cutting-edge sectors.

Q3?: We are curious about the adoption rates of QKD and related quantum products in the Chinese market. For instance, we have observed a publicly listed company on the stock exchanges promoting various quantum-related products, including quantum security chips and quantum memory cards for 5G and walkie-talkie radio communications, including teleconferencing and many other wonder applications ! However, we have found no user product reviews or detailed information in their annual reports. Could you elaborate on the current market dynamics for QKD and related products in real life at China ?"

Answer: In reality, only several Chinese companies currently provide comprehensive QKD products. Most other domestic offerings are limited to ‌peripheral components‌ or technologies tangentially related to QKD systems. For instance:

Quantum random number generators (QRNG)‌:

Core security modules applicable beyond QKD, such as in cryptographic systems and IoT authentication

Single-photon detectors‌:

Critical quantum sensing devices also used in biomedical imaging and laser radar applications

These peripheral technologies hold significant market value due to their broader adaptability. However, certain products marketed as "quantum" lack substantive connections to QKD infrastructure—many appear to capitalize on the ‌quantum hype cycle‌ without genuine technical relevance. Industry analysts estimate that ~30% of China’s claimed "quantum technology" products fall into this speculative category.

This stratification reflects the industry’s developmental stage: while core QKD systems remain niche, auxiliary quantum-enabled components are achieving faster commercialization.

Q4?: In 2008, famous cryptographer Bruce Schneier described quantum cryptography as “unbelievably cool in theory, but nearly useless in real life.” More recently, cybersecurity agencies like the NCSC (UK 2018), NSA (US 2020), ANSS (France 2022), and BSI (Germany 2022), have not endorsed QKD, creating challenges for the industry. How has the Chinese QKD community responded to such skepticism, and what is your perspective on balancing theoretical promise with practical applications ?

Answer: Let me first clarify ‌QKD's fundamental advantage‌: Its ‌information-theoretic security‌ is mathematically proven, meaning its safety cannot be compromised by advances in computing power—even with quantum computers. This contrasts sharply with classical cryptographic solutions like ‌post-quantum cryptography (PQC)‌, whose theoretical security remains unproven. While PQC resists attacks from existing quantum algorithms, future breakthroughs could expose vulnerabilities. For example, a novel quantum algorithm might suddenly render certain PQC schemes obsolete, a risk absent in QKD due to its foundational security guarantees

Practical Security Considerations‌：

Both QKD and classical cryptography face ‌real-world implementation risks‌:

QKD‌: Device imperfections (e.g., flawed single-photon sources or detectors) may degrade its theoretical security

Classical Cryptography‌: Side-channel attacks (e.g., power analysis) or hardware vulnerabilities can compromise even mathematically sound algorithms

Despite these challenges, QKD retains an ‌inherent security edge‌ due to its provable theoretical foundation.

Cost vs. Use Case Analysis‌

QKD‌ suits ‌high-value, long-term secrecy needs‌ (e.g., government/military communications) where users prioritize security over cost. Its deployment is justified for scenarios like transferring classified documents requiring decades of protection

Classical Cryptography‌ (including PQC) excels in ‌short-term data protection‌ or ‌cost-sensitive applications‌ (e.g., consumer IoT, commercial transactions)

Market Outlook‌

The future will likely see ‌coexistence and hybridization‌ of QKD and classical cryptography:

QKD‌ dominates ‌niche high-security sectors‌ (e.g., national infrastructure, financial backbones)

Hybrid Systems‌ integrate QKD-generated keys with classical encryption, balancing cost and robustness

China’s “‌QKD+PQC‌” pilot networks exemplify this trend Classical Cryptography‌ remains mainstream for most applications due to maturity and scalability

In essence, QKD’s ‌unconditional security‌ carves a critical niche, while classical methods retain broad applicability—a duality reflecting the evolving cybersecurity landscape.

Q5?: This question is for those with a non-technical background, we would like to explore two key aspects of QKD systems:

a) The “quantum channel,” referring to the point-to-point QKD connection via fiber optic, appears to shift the security focus to the physical security of the fiber link itself. This raises the question of whether an adversary could compromise the QKD system by targeting to disconnect this infrastructure instead of tapping information as the purpose. The whole system is then unsecured !

b) The concept of “trusted relays/nodes” is primarily seen in R&D and demonstrations. This technical part is not typically found in communication engineering textbooks or commercially available standard IT equipment.

Given these technical considerations and challenges, how does QKD ensure security in real-world scenarios ?

Answer:

a) ‌Definitions of Security Across Disciplines‌

In cryptography, including QKD, ‌security‌ specifically refers to ‌preventing unauthorized disclosure of secrets‌ (e.g., encrypted data) rather than ensuring uninterrupted communication. For example: Classic encryption algorithms (e.g., AES) guarantee that intercepted ciphertext cannot be decrypted by eavesdroppers, but they do ‌nothing‌ to prevent internet outages or physical disruptions.

Similarly, QKD focuses on ‌information-theoretic secrecy‌ for key distribution but cannot address channel availability issues like fiber cuts or jamming. Criticisms claiming QKD is "meaningless" due to its inability to prevent channel disruption misunderstand its purpose. ‌Cryptography as a field‌—whether classical or quantum—is tasked with mitigating eavesdropping, not ensuring network reliability. In short, cryptographic security ≠ network reliability.

b) ‌Trusted Relays in QKD‌

Trusted relays address QKD’s ‌distance limitations‌ (e.g., enabling 200 km key distribution between users via an intermediate node at 100 km). However, this introduces a ‌security assumption‌:

If the relay operator is compromised (e.g., bribed), the entire protocol becomes vulnerable.

This mirrors ‌trusted authorities‌ in classical cryptography (e.g., certificate authorities in PKI), where users rely on pre-vetted entities (e.g., government agencies) to manage critical operations.

While trusted relays introduce risks, they remain ‌pragmatically acceptable‌ if managed by authoritative institutions, as seen in existing security infrastructures.

Q6?: As you mentioned in the talk on “unconditional secure communications” of QKD, and also impractical QKD could be occurred due to loopholes or gap between theoretical concept vs in practice. They remind us of the “quantum hack”, a weird news from a decade ago where Eves’s focus was on stealing “photons” rather than data nor other properties at Bob’s venue ! While these reports alarming generated significant attention, they were often perceived by those outside the QKD community as being disconnected from real-world data leakage concerns. That quantum hack was also later seen as a popular R&D topic rather than a real-world IT security threat, widening the gap between the QKD community and the public larger and larger.

How can the QKD community improve “science communication” to address such misconceptions and build trust with broader audiences ?

Answer:

In an era of free information flow, combating the spread of rumors and misinformation poses a significant challenge. While this is not a problem unique to QKD (Quantum Key Distribution) but rather a broader societal issue, the internet is rife with scientifically unfounded claims, such as global warming conspiracy theories, especially around trending scientific topics. The scientific community must actively counter these false narratives.

QKD research institutions and development teams, among others, should take responsibility for ‌public education‌, disseminating accurate information, and debunking myths. For instance, in China, many scientists and organizations leverage social media platforms like WeChat official accounts to promote verified facts and engage with the public. Such efforts are critical for ‌dispelling misconceptions‌ and fostering trust in science and technology.

Q7?: Your team’s success in human resource development is remarkable. Could this model be extended to international collaborations, particularly with ASEAN countries or others? For instance, are there opportunities to establish joint QKD training programs, technology transfer initiatives, or an international QKD network & hubs ? Could China’s terrestrial QKD network connect with satellite-based networks, such as those in Singapore or Japan?

Answer:

In terms of academic research, our team maintains an open stance toward international collaboration. We actively cooperate with QKD research groups abroad, demonstrating that transnational academic partnerships operate smoothly and effectively. For large-scale engineering projects, such as satellite-based QKD systems, government-led initiatives may play a pivotal role in facilitating cross-border cooperation. While academic exchanges thrive under existing frameworks, the feasibility of international collaboration in such specialized infrastructure projects remains subject to geopolitical and institutional considerations.

Thank you so much for your contribution to #IYQ2025 & #ThaiYQ2025.

— end of Q&A session