The team of Professor Zeng-Bing Chen and Associate Professor Hua-Lei Yin from National Laboratory of Solid State Microstructures and School of Physics, Collaborative Innovation Center of Advanced Microstructures at Nanjing University, recently proposed the first quantum electronic commerce scheme based on one-time universal hashing quantum digital signature theory. They demonstrated, for the first time, a quantum e-commerce application scenario involving five users, providing unconditional security for the entire e-commerce transaction process.
E-commerce encompasses various online business activities such as online payments, online banking, electronic ticketing, and online auctions, as illustrated in Figure 1. The development of e-commerce has made commercial activities more convenient and efficient, allowing consumers to easily purchase a variety of goods and services through the internet. It has also provided opportunities for businesses to expand their markets and increase profits. The current annual transaction volume of e-commerce in China exceeds 40 trillion yuan, becoming a key factor in driving economic growth and enhancing economic vitality.
Existing e-commerce schemes utilize public-key encryption algorithms to protect the authenticity, integrity, and non-repudiation of information. The security of these schemes relies on assumptions about computational complexity and may face serious threats from advanced computing powers like quantum computers in the future. In order to achieve unconditional security for digital payments, Austrian scientists recently ensured identity authentication and payment information anti-counterfeiting through the development of a quantum digital payment protocol [Nat. Commun. 14, 3849 (2023)]. However, to provide complete security for the entire e-commerce transaction process, addressing non-repudiation as a specific information security element is necessary. Currently, there is no feasible quantum solution proposed for this aspect of the problem.
Figure 1 Diagram illustrating quantum e-commerce.
Based on the fundamental principles of quantum mechanics, quantum information science is considered an ideal approach to providing all aspects of information security. Quantum secure communication based on quantum key distribution can ensure unconditional security for message confidentiality. Meanwhile, quantum digital signatures based on quantum state transmission can simultaneously provide unconditional security for the authenticity, integrity, and non-repudiation of information processing. The research team has been studying how to construct efficient and secure quantum digital signatures for nearly a decade. In particular, in the last two years, the team has made significant progress by developing a one-time universal hash quantum digital signature [Natl. Sci. Rev. 10, nwac228 (2023); Phys. Rev. Applied 20, 044011 (2023)], improving the efficiency of signing long messages by more than eight orders of magnitude. In this research, the team treats quantum digital signatures as a fundamental technology and constructs an unconditionally secure quantum electronic commerce protocol based on the privacy properties introduced by noisy quantum states, the one-way properties of one-time universal hash function, and the asymmetric properties of secret sharing, as illustrated in Figure 2.
Figure 2 A schematic diagram of Quantum e-commerce network and its transaction process.
This quantum electronic commerce protocol can tolerate partial privacy leakage of quantum keys, eliminating the need for complex privacy purification operations in the post-processing stage. This feature can save significant computing resources, network bandwidth, and data processing time in scenarios involving large-scale networks and massive data transmission. The scheme successfully achieved a processing rate of 0.82 transactions per second for a transaction file size of 0.428 Mb under a transmission loss of 25 dB (approximately 150 km optical fiber attenuation), as shown in Figure 3(A). Compared to previous quantum digital payment schemes [Nat. Commun. 14, 3849 (2023)], both processing speed and transmission distance have been greatly improved. Additionally, the scheme demonstrates outstanding performance when dealing with large files. With the increase in signature length, under the same failure probability, the size of the signature file grows exponentially. Under 20 dB of transmission attenuation, the processing speed for a gigabyte-sized file exceeds 10 times per second, as shown in Figure 3(B), offering hope for achieving real-time transactions in metropolitan areas.
Furthermore, the research team proved the robustness of the scheme against imperfect devices. Through quantifying the preparation defects and transmission deviations of quantum states in experiments, they precisely estimated the information leakage caused by factors such as optical intensity fluctuations, pattern effects, the extinction ratio of polarization, phase shift, and Trojan horse attacks. The research team provided the maximum probability of protocol failure under these conditions. Moreover, the network structure established in this research does not require the prior specification of a trusted third party for payment verification, eliminating the need for a fixed central node. In the future, by leveraging advanced quantum communication technologies used in current quantum key distribution, the modulation rate, preparation precision, and transmission stability of quantum states in the quantum electronic commerce protocol can be further improved. This enhancement is expected to lead to a multi-order-of-magnitude increase in the processing rate of transaction files guaranteed within metropolitan areas.
Figure 3 (A) Signature rate, (B) Failure probability
The related research findings, titled "Experimental quantum e-commerce," were published on January 12, 2024, in Science Advances. The research has garnered widespread attention from both domestic and international media and has been reported by Nature magazine as a research highlight, New Scientist, Xinhua News Agency, People's Daily Overseas Edition, Guangming Daily, and other news media. Xiao-Yu Cao and Bing-Hong Li, Ph. D. candidates at School of Physics, Nanjing University, are co-first authors of the paper. Associate Professor Hua-Lei Yin (formerly Associate Professor at the School of Physics, Nanjing University) and Professor Zeng-Bing Chen from School of Physics, Nanjing University, are corresponding authors. The work was supported by the National Natural Science Foundation of China, the Natural Science Foundation of Jiangsu Province, and the Fundamental Research Funds for the Central Universities.
Paper Link:
https://www.science.org/doi/10.1126/sciadv.adk3258
Nature Research Highlights Link:
https://www.nature.com/articles/d41586-024-00128-2
New Scientist News Link:
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People's Daily Overseas Edition Front Page:
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Guangming Daily:
https://epaper.gmw.cn/gmrb/html/2024-01/14/nw.D110000gmrb_20240114_5-02.htm