With ten years of development, cloud computing has been widely used in more and more field. As a part of cloud computing, cloud storage has earned more and more attentions. It becomes a new trend that users employ cloud storage to outsource their data. Instead of the traditional approach to store data in a local server, users' data cannot be controlled once data outsourcing in cloud storage. At the same time, as the cloud service provider is honest‐but‐curious, it becomes a challenge to make sure that cloud service provider can provide storage service with high quantity. In this paper, we focus on the issue of cloud storage security audit. In particular, we propose a novel public audit scheme, which employs chameleon authentication tree in the third‐party audit model to significantly reduce the huge computation cost of data dynamic operation. Meanwhile, our scheme can effectively prevent the fraud of dishonest cloud service provider, with supporting dynamic data update and batch audit. The experimental results show that the proposed scheme is more secure and efficient compared with the existing schemes.

With the increase in network transmission rates, the Internet of Things (IoT) has gradually become a trend. Users can upload the data generated by the device to the cloud database to save local storage space, thereby reducing local storage costs. Because uploading data to the cloud loses physical control of the data, an audit is required. Traditional audit protocols are not completely suitable for lightweight devices in the IoT. This paper proposes a new type of audit protocol suitable for lightweight devices with weak computing power. This protocol transfers part of the computation of data tags to a cloud storage provider (CSP) with strong computing power, thereby reducing the introduction of computing entities. Our scheme supports the dynamic operation of data and guarantees the effectiveness of challenge response by blockchain. Compared with existing schemes, our scheme is more secure and effective.

No abstract