The Internet of Things (IoT) is leaving its mark on an ever-increasing number of domains. Sensors embedded in everyday objects (e.g., smart watches) enable the continuous capture of a large amount of data. Since such IoT devices feature connectivity to other IoT devices and cloud services, the captured data can be shared for processing and analyzing. Blockchain technologies are often applied to ensure the immutability and temper-resistance of the shared data. Actuators are able to react automatically to patterns found in these data. This enables a variety of innovative smart services, e.g., in the eHealth or Industry 4.0 domain.

However, the data required for smart services are highly sensitive. For instance, health data contain a lot of private information, while industrial data have a high economic value. Therefore, novel privacy and security mechanisms are required that are tailored to the IoT and blockchain technologies. When designing such mechanisms, it is important to consider applicable data protection laws, such as the EU General Data Protection Regulation (GRPR).

The goal of this Special Issue is to provide an overview of the latest developments regarding security and privacy in blockchains and the IoT. Both theoretical and technical aspects are of interest. Interdisciplinary approaches are also highly welcome.