# Special Issue on Security and Privacy in Blockchains and the IoT Volume II
###### Abstract
The seventeen papers in Volume II are outlined in the following. **Articles. ** In the opening research article, [PERSON] [2] highlights the similarities and differences between physical goods, such as oil, and virtual goods, such as data, in terms of handling and processing. Here, it becomes apparent that raw data, just like crude oil, needs to be refined in order to be useful. Therefore, an end-to-end data platform called REFINERY Platform is designed to enable effective and efficient data handling. The work focuses on the special characteristics of data and their implications for modern data management, covering challenges in data acquisition, refinement, storage, and delivery. In data processing, specific attention is paid to protection goals such as confidentiality, integrity, availability, and authenticity, as well as compliance with data protection laws such as the European General Data Protection Regulation (GDPR). In this way, the REFINERY Platform represents an information retrieval and provision platform that enables data to be handled in a trustworthy manner. Any data-heavy application benefits from such a platform. One example of such a data-heavy application is presented by [PERSON] et al. [3] in the form of the Internet of Battlefield Things (IoBT). This relatively novel application domain is about a concept in which various devices on the battlefield--both smart military equipment that makes autonomous decisions and conventional human-controlled military devices--are interconnected. The work focuses on a fundamental problem in IoBT networks, namely the routing of information and the calculation of a backbone network. To overcome these issues, the authors model the IoBT network as a multilayer network and adopt the concept of dominance to select a set of nodes as a backbone for the IoBT network. However, the domination concept of single-layer networks cannot be transferred straightforwardly to the more complex IoBT networks. To this end, the authors introduce the Cross-layer Connected Dominating Set (CCDS) algorithm, which is specifically designed for IoBT networks. Compared to state-of-the-art approaches, CCDS achieves more compact network spanners, while still ensuring network-wide flow of information. It is evident that confidential communication between devices is mandatory in a setting such as the IoBT. Virtual Private Network (VPN) technology allows us to establish private and secure communication channels over the Internet. [PERSON] et al. [4] therefore analyze in their paper the performance of different open-source firmware and operating systems for deploying VPNs in outdoor locations with poor network connectivity. For this purpose, they compare the performance of OpenWrt 21.x, Debian 11 x64, and Mikrotik 7.x as server-side operating systems, and various client-side operating systems, including Windows 10/11, iOS 15, and Android 11. As VPNs establish secure connections between client devices and remote endpoints by encrypting traffic, the applied VPN protocol also has an effect on the achievable level of security and performance parameters such as latency and throughput. The main goals of the research are therefore to identify algorithms that ensure efficient data transmission and encryption, achieve compatibility with existing VPN infrastructure, and enable the use of open firmware on constrained routers. In addition to secure communications, it is also essential to monitor the IoT devices in terms of the software running on them. In this regard, the early detection of cyberattacks plays a key role. Therefore, [PERSON] et al. [5] study whether malicious behavior of IoT devices can be detected based on their power consumption behavior. To this end, they identify unique power usage patterns for typical operations performed on an IoT device. A Raspberry Pi 3 model B and a DragonBoard 410c, two of the most common IoT systems today, are used for this purpose. If the energy consumption of an operation deviates noticeably from the expected pattern, this is an indication of an attack.