Weng Chen-Xun, Gao Rui-Qi, Bao Yu, Li Bing-Hong, Liu Wen-Bo, Xie Yuan-Mei, Lu Yu-Shuo, Yin Hua-Lei, Chen Zeng-Bing
National Laboratory of Solid State Microstructures and School of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China.
Department of Physics and Beijing Key Laboratory of Opto-electronic Functional Materials and Micro-nano Devices, Key Laboratory of Quantum State Construction and Manipulation (Ministry of Education), Renmin University of China, Beijing 100872, China.
Research (Wash D C). 2023 Nov 21;6:0272. doi: 10.34133/research.0272. eCollection 2023.
Byzantine agreement, the underlying core of blockchain, aims to make every node in a decentralized network reach consensus. Classical Byzantine agreements unavoidably face two major problems. One is 1/3 fault-tolerance bound, which means that the system to tolerate malicious players requires at least 3 + 1 players. The other is the security loopholes from its classical cryptography methods. Here, we propose a Byzantine agreement framework with unconditional security to break this bound with nearly 1/2 fault tolerance due to multiparty correlation provided by quantum digital signatures. It is intriguing that quantum entanglement is not necessary to break the 1/3 fault-tolerance bound, and we show that weaker correlation, such as asymmetric relationship of quantum digital signature, can also work. Our work strictly obeys two Byzantine conditions and can be extended to any number of players without requirements for multiparticle entanglement. We experimentally demonstrate three-party and five-party consensus for a digital ledger. Our work indicates the quantum advantage in terms of consensus problems and suggests an important avenue for quantum blockchain and quantum consensus networks.
拜占庭共识作为区块链的核心基础，旨在使去中心化网络中的每个节点达成共识。传统的拜占庭共识不可避免地面临两个主要问题。一个是1/3容错界限，这意味着系统要容忍恶意参与者至少需要3 + 1个参与者。另一个是其传统加密方法存在的安全漏洞。在此，我们提出了一个具有无条件安全性的拜占庭共识框架，由于量子数字签名提供的多方相关性，该框架以近1/2的容错能力打破了这一界限。有趣的是，打破1/3容错界限并不需要量子纠缠，我们证明了较弱的相关性，如量子数字签名的不对称关系，也能起到作用。我们的工作严格遵循两个拜占庭条件，并且可以扩展到任意数量的参与者，而无需多粒子纠缠。我们通过实验证明了数字账本的三方和五方共识。我们的工作表明了在共识问题方面的量子优势，并为量子区块链和量子共识网络指明了一条重要途径。
