Blockchain is a decentralized, distributed ledger technology that ensures transparency, security, and immutability through cryptographic techniques. However, advancements in quantum computing threaten the security of classical cryptographic schemes, jeopardizing blockchain integrity once cryptographic quantum supremacy is achieved. This milestone, defined here as the realization of quantum computers to solve practical cryptographic problems, would render existing security standards vulnerable, exposing blockchain assets (currency, data, etc.) to fraud and theft. To address this risk, we propose and implement a smart contract deployable on the Ethereum blockchain, having the ability to run applications on its blockchain, that generates classically intractable puzzles by probabilistically generating large, hard-to-factor numbers without requiring secret information. This contract then serves two purposes: to establish a mechanism (1) for a trustless, unbiased proof of cryptographic quantum supremacy by verifying solutions to these puzzles, and (2) to protect user funds on Ethereum by triggering quantum-secure fallback protocols upon detecting cryptographic quantum supremacy, since it is desirable to wait as long as possible to fall back to a quantum-secure scheme because of its inherent additional cost and complexity. These mechanisms demonstrate the ability to identify cryptographic vulnerabilities and ensure a smooth transition to quantum-secure standards, safeguarding blockchain assets in a post-quantum era.

翻译：区块链是一种去中心化的分布式账本技术，通过密码学方法确保透明度、安全性与不可篡改性。然而，量子计算的发展威胁着经典密码方案的安全性，一旦实现密码学意义上的量子霸权，将危及区块链的完整性。这一里程碑事件——本文将其定义为量子计算机能够解决实际密码学问题——将使现有安全标准变得脆弱，导致区块链资产（货币、数据等）面临欺诈与窃取风险。为应对此风险，我们设计并实现了一种可部署于以太坊区块链的智能合约（该合约具备在区块链上运行应用程序的能力），通过概率性生成无需秘密信息的大规模难分解数来构造经典计算不可解的难题。该合约随后实现双重功能：（1）通过验证这些难题的解，建立一种无需信任且无偏的密码学量子霸权证明机制；（2）在检测到密码学量子霸权时，触发量子安全备用协议以保护用户在以太坊上的资产——鉴于量子安全方案固有的额外成本与复杂性，尽可能延迟切换至此类方案是符合需求的。这些机制展示了识别密码学漏洞的能力，并确保向量子安全标准的平稳过渡，从而在后量子时代保障区块链资产安全。