Chongfan Technology
News
09
2025
-
04
Light | Highly efficient quantum digital signature with embedded chip
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Introduction
As the cornerstone of modern cryptography, encryption and digital signatures safeguard the four fundamental elements of information security: confidentiality, integrity, authenticity, and non-repudiation. Unlike classical cryptography, quantum cryptography leverages the fundamental principles of quantum mechanics to provide a "quantum cryptographic toolbox" that does not rely on assumptions about the eavesdropper's computational capabilities. Among these, quantum key distribution (QKD) ensures the confidentiality of information transmission, while quantum digital signature (QDS) guarantees the integrity, authenticity, and non-repudiation of information transmission. Since the proposal of the first QDS protocol in 2001, scholars worldwide have conducted extensive research on QDS theory and experiments, striving to advance the practical application of QDS.
Recently, a collaboration between Guangxi University, the National Innovation Center for Information Photonics, Renmin University of China, and Nanjing University successfully overcame the challenges of large device size, high cost, and low system signing rate in practical QDS applications by utilizing silicon photonic integrated technology and a single decoy-state one-time global hash QDS protocol. The research team proposed and verified a high-efficiency quantum digital signature network with on-chip integration. At a communication distance of 200 km, signing a 1 Mbit file achieved a signing rate of 0.04 times per second. This achievement was published in the top international optics journal Chip-integrated quantum signature network over 200 km as 'Light: Science & Applications' ， Dr. Yongqiang Du (Guangxi University) 、 Dr. Binghong Li (Nanjing University) 、 Dr. Xiaoyu Cao (Nanjing University) and the National Innovation Center for Information Photonics Dr. Xin Hua are the co-first authors of this paper, and Professor Kejin Wei (Guangxi University) Professor Kejin Wei (Guangxi University) the National Innovation Center for Information Photonics General Manager Xi Xiao and Renmin University of China Associate Professor Hualei Yin are the co-corresponding authors.
Against the backdrop of traditional encryption technology facing threats from quantum computing, quantum communication has attracted significant attention due to its unique advantages in information security. Among them, quantum digital signature (QDS), as an important cryptographic tool, has important application value in e-business, digital currency, and blockchain due to its ability to guarantee the integrity, authenticity, and non-repudiation of information transmission. Currently, QDS has rapidly evolved from proof-of-concept to mature system demonstrations and is expected to become the next commercially available quantum cryptographic technology. However, all previous QDS systems relied on expensive and complex fiber optic equipment, posing challenges in large-scale deployment and seamless integration with existing communication infrastructure. Therefore, the development of low-cost, high-efficiency, and scalable chip-based QDS networks has significant research value and broad application prospects.
Professor Kejin Wei from Guangxi University and Dr. Xi Xiao's team at the National Innovation Center for Information Photonics have long been committed to developing chip-level quantum secure communication systems that guarantee all elements of information security. This collaborative team has previously reported on polarization-encoding quantum key distribution decoder chips with polarization tracking capability [Chip 2, 100039 (2023)], resource-saving chip quantum key distribution systems [Photon. Res. 11, 1364-1372 (2023)], and source-independent chip quantum random number generators [Opt. Express 32, 38793-38804 (2024), Commun. Phys. 8, 9 (2025)]. Recently, this research team, in collaboration with Associate Professor Hualei Yin's team at Renmin University of China, proposed a novel star topology QDS network architecture and developed a single decoy-state one-time global hash QDS protocol, which significantly improves system performance while greatly reducing the complexity of system hardware and data post-processing. A three-node quantum digital signature network demonstration was completed based on silicon-based encoder and decoder chips.
Figure 1 shows the chip-embedded star-shaped QDS network architecture proposed by the collaborative team. Complex and difficult-to-integrate measurement devices are centrally deployed at the central node of the network. Each user only needs to have a miniaturized and low-cost transmitter chip to perform digital signature tasks between different users. In addition, this network architecture can be integrated into existing communication infrastructure, and by flexibly configuring the integrated measurement unit (IMU), it can be adapted to measurement device-independent protocols, thus improving network performance.
Figure 1: Schematic diagram of a star topology chip QDS network
In order to improve the performance of the above integrated QDS network while enhancing its compatibility with silicon-based chips, the research team also developed a single decoy-state one-time global hash QDS protocol ( Figure 2 ). The operation of this protocol is mainly divided into a distribution phase and a message phase. Its advantages are: 1. It does not require the preparation of vacuum states, thus reducing the requirements for the extinction ratio of the intensity modulator on the silicon-based chip, thereby reducing the complexity of manufacturing the transmitter chip; 2. In the message phase, imperfect keys that have not undergone privacy amplification can be directly used, thus greatly reducing the computational resources required for data post-processing and reducing system latency.
Figure 2: Schematic diagram of the operation of the efficient QDS protocol
Figure 3: Experimental setup. (a) Chip-based three-node quantum network. (b) Microscopic image of the silicon-based encoder chip. (c) Microscopic image of the silicon-based decoder chip
To verify Figure 1 the chip-based QDS network shown in Figure 3 the research team built a three-node chip quantum network as shown in the figure. This network includes a central node assigned to the signer Alice, and two sub-nodes assigned to the receiver Bob and the verifier Charlie. Bob and Charlie each have a silicon-based encoder chip, while Alice has a silicon-based decoder chip. The research team used the developed new QDS protocol to conduct experiments based on this network configuration. To showcase the breakthrough achieved in this work, the researchers summarized the results obtained from QDS experiments at different distances in Figure 4. It is worth mentioning that the proposed chip-based QDS scheme achieved a signing rate of 0.04 times per second for signing a 1 Mbit file at a fiber distance of 200 km.
Figure 4: Signing rate at different transmission distances
Summary and Outlook
In this study, the research team proposes a chip-based QDS network and improves the network performance while reducing system complexity by developing a single decoy-state one-time global hash QDS protocol. Subsequently, a three-node QDS network was built using a silicon-based codec chip for experimental verification. Experimental results show that at a communication distance of 200 km, the signature rate for a 1 Mbit file reached 0.04 times per second. The research team stated that this research not only promotes the practical application of QDS technology but also has broad application value in other quantum communication fields such as quantum E-Business and quantum blockchain.
Paper Information
Du, Y., Li, BH., Hua, X. et al. Chip-integrated quantum signature network over 200 km. Light Sci Appl 14, 108 (2025).
https://doi.org/10.1038/s41377-025-01775-4
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