  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.
