Blockchain technology has created an excitement that was last seen two decades ago when the Internet was entering the mainstream. An appealing feature of blockchain technology is smart contracts. A smart contract is an executable code. It runs on top of the blockchain facilitating an agreement between untrusted parties. These smart contracts have a major limitation, namely they cannot operate on information external to the blockchain. The inability to query such information has paved the need for trusted entities called “oracles.” These oracles attest to facts without the robust security guarantees that blockchains generally provide. This can potentially harm the integrity of the network and lead to centralized points-of-failure. To address this concern, this article proposes a decentralized oracle which is based on a voting-based game that decides the truth or falsity of queries. In the context of this article, we are only interested in binary markets, i.e., queries which can be $\text{True}$, $\text{False}$, or $\text{Unknown}$. When requesting facts from an oracle, a user submits binary queries. Reporters (or certifiers) respond to the queries by placing monetary stake. A formal analysis of the system parameters is presented, which shows that the proposed platform incentivizes a Nash equilibrium for truthful reporting. An extension to the base protocol is also described and profiled against the original framework. Finally, we discuss a prototype architecture, along with additional features to be considered during implementation.

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基于公共众包的去中心化区块链 Oracle 机制

区块链技术创造了一种兴奋，这种兴奋是在二十年前互联网进入主流时出现的。区块链技术的一个吸引人的特点是智能合约。智能合约是可执行代码。它运行在区块链之上，促进了不受信任方之间的协议。这些智能合约有一个主要限制，即它们不能对区块链外部的信息进行操作。由于无法查询此类信息，因此需要称为“oracles”的可信实体。这些预言机在没有区块链通常提供的强大安全保证的情况下证明了事实。这可能会损害网络的完整性并导致集中式故障点。为了解决这个问题，本文提出了一个去中心化的预言机，它基于一个基于投票的游戏来决定查询的真假。在本文的上下文中，我们只对二元市场, 即查询可以是 $\text{真}$, $\text{假}$， 或者 $\text{未知}$. 当从预言机请求事实时，用户提交二进制查询。报告者（或验证者）通过放置货币来回应查询。对系统参数进行了正式分析，表明所提出的平台激励了纳什均衡以进行真实报告。对基本协议的扩展也针对原始框架进行了描述和概要分析。最后，我们讨论原型架构，以及在实现过程中要考虑的附加功能。