With the development of the Internet of Things (IoT) field, more and more data are generated by IoT devices and transferred over the network. However, a large amount of IoT data is sensitive, and the leakage of such data is a privacy breach. The security of sensitive IoT data is a big issue, as the data is shared over an insecure network channel. Current solutions include symmetric encryption and access controls to secure the data transfer, but they have some drawbacks such as a single point of failure. Blockchain is a promising distributed ledger technology that can prevent the malicious tampering of data, offering reliable data storage. This paper proposes a distributed access control system based on blockchain technology to secure IoT data. The proposed mechanism is based on fog computing and the concept of the alliance chain. This method uses mixed linear and nonlinear spatiotemporal chaotic systems (MLNCML) and the least significant bit (LSB) to encrypt the IoT data on an edge node and then upload the encrypted data to the cloud. The proposed mechanism can solve the problem of a single point of failure of access control by providing the dynamic and fine-grained access control for IoT data. The experimental results of this method demonstrated that it can protect the privacy of IoT data efficiently.

随着物联网（IoT）领域的发展，越来越多的数据由IoT设备生成并通过网络传输。但是，大量的物联网数据是敏感的，并且此类数据的泄漏是违反隐私的。敏感物联网数据的安全性是一个大问题，因为数据是通过不安全的网络通道共享的。当前的解决方案包括对称加密和访问控制以确保数据传输的安全，但是它们具有一些缺陷，例如单点故障。区块链是一种有前途的分布式账本技术，可以防止恶意篡改数据，提供可靠的数据存储。本文提出了一种基于区块链技术的分布式访问控制系统来保护物联网数据。所提出的机制基于雾计算和联盟链的概念。该方法使用混合线性和非线性时空混沌系统（MLNCML）和最低有效位（LSB）对边缘节点上的IoT数据进行加密，然后将加密的数据上传到云中。通过为物联网数据提供动态且细粒度的访问控制，该机制可以解决访问控制单点故障的问题。该方法的实验结果表明，该方法可以有效地保护物联网数据的隐私。