Blockchain provides decentralization and trustlessness features for the Industrial Internet of Things (IIoT), which expands the application scenarios of IIoT. To address the problem that the blockchain cannot actively obtain off-chain data, the blockchain oracle is proposed as a bridge between the blockchain and external data. However, the existing oracle schemes are difficult to solve the problem of low quality of service caused by frequent data changes and heterogeneous devices in IIoT, and the current oracle node selection schemes are difficult to balance security and quality of service. To tackle these problems, this paper proposes a secure and reliable oracle scheme that can obtain high-quality off-chain data. Specifically, we first design an oracle node selection algorithm based on Verifiable Random Function (VRF) and reputation mechanism to securely select high-quality nodes. Second, we propose a data filtering algorithm based on a sliding window to further improve the consistency of the collected data. We verify the security of the proposed scheme through security analysis. The experimental results show that the proposed scheme can effectively improve the service quality of the oracle.

翻译：区块链为工业物联网（IIoT）提供了去中心化和无需信任的特性，从而扩展了IIoT的应用场景。为解决区块链无法主动获取链外数据的问题，区块链预言机被提出作为区块链与外部数据之间的桥梁。然而，现有预言机方案难以解决IIoT中因数据频繁变化和异构设备导致的低服务质量问题，且当前预言机节点选取方案难以平衡安全性与服务质量。针对这些问题，本文提出一种能够获取高质量链外数据的安全可靠的预言机方案。具体而言，我们首先设计了一种基于可验证随机函数（VRF）和信誉机制的预言机节点选择算法，以安全地选取高质量节点。其次，我们提出了一种基于滑动窗口的数据过滤算法，以进一步提升采集数据的一致性。通过安全性分析验证了所提方案的安全性。实验结果表明，所提方案能够有效提升预言机的服务质量。