Smart contracts, the stateful programs running on blockchains, often rely on reports. Publishers are paid to publish these reports on the blockchain. Designing protocols that incentivize timely reporting is the prevalent reporting problem. But existing solutions face a security-performance trade-off: Relying on a small set of trusted publishers introduces centralization risks, while allowing open publication results in an excessive number of reports on the blockchain. We identify the root cause of this trade-off to be the standard symmetric reward design, which treats all reports equally. We prove that no symmetric-reward mechanism can overcome the trade-off. We present Personal Random Rewards for Reporting (Prrr), a protocol that assigns random heterogeneous values to reports. We call this novel mechanism-design concept Ex-Ante Synthetic Asymmetry. To the best of our knowledge, Prrr is the first game-theoretic mechanism (in any context) that deliberately forms participant asymmetry. Prrr employs a second-price-style settlement to allocate rewards, ensuring incentive compatibility and achieving both security and efficiency. Following the protocol constitutes a Subgame-Perfect Nash Equilibrium, robust against collusion and Sybil attacks. Prrr is applicable to numerous smart contracts that rely on timely reports.

翻译：摘要：智能合约作为运行在区块链上的有状态程序，通常依赖于各类报告。发布者通过将报告上链获取报酬。设计激励及时报告的协议是当前报告领域面临的核心问题。然而现有解决方案面临安全性与性能的权衡：若依赖少量可信发布者则存在中心化风险，若允许开放发布则会导致链上报告数量激增。我们识别出这种权衡的根本原因在于标准的对称奖励设计——所有报告获得同等对待。我们证明了没有任何对称奖励机制能够突破这一权衡。本文提出面向报告的个人随机奖励机制（Prrr），该协议为报告分配随机异质值，我们称这种机制设计概念为事前合成非对称性。据我们所知，Prrr是首个（在任何领域）通过刻意构建参与者非对称性的博弈论机制。Prrr采用二价结算方式分配奖励，在保证激励兼容性的同时实现了安全性与效率的平衡。遵循该协议构成子博弈完美纳什均衡，且对合谋攻击与女巫攻击具有鲁棒性。Prrr可广泛应用于依赖及时报告的各类智能合约场景。