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：智能合约作为运行在区块链上的有状态程序，通常依赖于外部报告。发布者通过将报告发布至区块链而获得报酬。设计激励及时报告的协议是当前报告机制中的核心问题。然而，现有解决方案面临安全性与性能之间的权衡：依赖少数可信发布者会引入中心化风险，而允许开放发布则会导致区块链上报告数量过多。我们认为这一权衡的根本原因在于标准的对称奖励设计，即对所有报告给予同等对待。我们证明，任何对称奖励机制均无法克服这一权衡。本文提出面向报告的个人随机奖励协议（Prrr），该协议为报告分配随机异质价值。我们将这一新颖的机制设计概念称为“事前合成非对称性”。据我们所知，Prrr是首个（在任何场景下）有意构建参与者非对称性的博弈论机制。Prrr采用类第二价格结算方式分配奖励，确保激励相容性，同时实现安全性与效率。遵循该协议构成子博弈完美纳什均衡，能够抵御共谋与女巫攻击。Prrr可广泛应用于依赖及时报告的各类智能合约。