Published in a Nature Portfolio Journal! Saisi Time Synchronization Servers Support a Domestic Chinese Team in Realizing the World’s First Information-Theoretically Secure Relativistic

Zero-Knowledge ProofWith the rapid advancement of quantum computing, the gradual deployment of large-scale quantum computers exposes core data including personal privacy, financial transactions and identity authentication across cyberspace to unprecedented leakage risks. Delivering truly unconditionally secure privacy protection in the post-quantum era has become an urgent research priority for the global information security community.A groundbreaking joint research effort has recently yielded a transformative solution, led by Professor Zengbing Chen and Professor Shengjun Wu from the School of Physics, National Laboratory of Solid State Microstructures, and Collaborative Innovation Center of Advanced Microstructures at Nanjing University, alongside Associate Professor Hualei Yin’s research group from the School of Physics, Key Laboratory of Quantum State Construction and Manipulation under the Ministry of Education, Renmin University of China (hereinafter referred to as “the research team”).The team pioneered an asymmetric relativistic zero-knowledge proof (RZKP) protocol with information-theoretic security. Even if adversaries possess exponential-scale quantum entanglement resources, the protocol retains unconditional security while delivering high practical efficiency. The corresponding research paper, titled Experimental asymmetric relativistic zero-knowledge proofs with unconditional security, was published in Nature Communications, a top-tier international journal under the Nature Portfolio. This work lays a foundational security framework for privacy computation and trusted communication in the post-quantum era.For this landmark experimental study, high-precision time synchronization servers supplied by Zhejiang Saisi Electronic Technology Co., Ltd. provided a unified global timing reference for the entire experiment via nanosecond-level time dissemination and exceptional holdover performance.1. Groundbreaking Original Innovation: Asymmetric Relativistic Zero-Knowledge Proof (RZKP) ProtocolZero-Knowledge Proof (ZKP) serves as a core cryptographic primitive for blockchains, anonymous voting, identity verification and private financial transactions. Its core principle: a prover can prove the truth of a mathematical statement without disclosing any extra confidential information to the verifier — analogous to an ATM withdrawal system, which only verifies that you hold the correct PIN without revealing the PIN itself.Conventional ZKPs, however, rely on computational complexity assumptions and cannot withstand quantum computing attacks. Early symmetric relativistic zero-knowledge proofs, while capable of unconditional security grounded in the speed-of-light principle, remain vulnerable to circumvention via quantum entanglement resources. They also suffer severe performance drawbacks: a round complexity of \(\mathcal{O}(|E|^4)\), randomness overhead reaching nearly 6 billion gigabytes, and a single proof computation requiring 60,000 years to complete, confining such schemes purely to theoretical research.To construct an unconditionally secure cryptosystem resilient to quantum attacks, the research team designed a novel asymmetric RZKP protocol built upon relativistic bit commitment, cutting the round complexity from \(\mathcal{O}(|E|^4)\) down to \(\mathcal{O}(|E|)\). The protocol adopts an asymmetric two-prover architecture where two proving devices \(P_1\) and \(P_2\) perform distinct tasks:

\(P_1\) commits to a graph three-coloring assignment;

The verifier randomly selects graph edges to issue cryptographic challenges;

\(P_2\) responds within a spacelike-separated time window, physically prohibiting any communication between the two provers.

The verifier subsequently validates two conditions across multiple rounds: consistency of all commitments and distinct color assignments for each challenged edge. Repeated iterations exponentially suppress the maximum cheating probability of adversarial participants.

The protocol’s binding property holds for arbitrary quantum correlations, founded on the no-superluminal-signaling principle of special relativity. Its zero-knowledge property stems from the hiding characteristic of relativistic commitments: in each round, the verifier may only open the two color boxes associated with one single edge, with colors randomly permuted. The verifier merely observes a pair of random distinct labels and gains no additional secret information.Experimental Setup & Quantitative Performance MetricsTo validate the protocol’s practicality and stability, the team built an outdoor field testbed for physical experimental verification. The two proving devices were placed 300 meters apart, corresponding to a 1000 ns spacelike separation, which strictly enforces all per-round operations to finish within the secure causal time window.In a graph three-coloring test featuring 588 vertices and 1097 edges, the system completed approximately \(2.2\times10^5\) interactive rounds in just 0.22 seconds, with a total randomness consumption of only 430.81 MB. This scheme requires no dedicated quantum hardware, featuring low deployment barriers and broad compatibility, with promising deployment prospects for privacy-sensitive scenarios including blockchains, smart contracts and anonymous government administrative services.2. Saisi Time Synchronization Servers Underpin 220,000 Ultra-Fast Interactive RoundsThe security guarantee of relativistic zero-knowledge proofs fundamentally rests on the physical law that no signal can propagate faster than the speed of light. The full-stack global timing benchmark enabling the completion of 220,000 interaction rounds within 0.22 seconds was fully sustained by Saisi high-precision time synchronization servers.

Key device specifications: absolute time accuracy ≤ 30 ns (including all link latency), integrated onboard atomic clock; even with complete loss of GPS satellite signals, the equipment maintains time drift below 1 μs per 24 hours.Performance Validation of Saisi High-Precision Time Synchronization ServersThroughout the entire experiment, the average measured values of device time differences \(|t_1-t_4|\) and \(|t_2-t_3|\) stabilized at roughly 700 ns with a standard deviation of merely ~16 ns. Even under the worst-case error superposition with bidirectional GPS precision offset (\(2\Delta=60\) ns), the maximum measured time difference remained below 940 ns, consistently staying under the 1000 ns safety threshold. Zero verification failures occurred across all experimental runs, and all recorded timestamps maintained full authenticity and credibility.