Search

Authentication and integrity are the prerequisites for trustworthy and secure communication. Without unambiguous knowledge of who is being interacted with, no confidential content can be exchanged, no (remote) access to systems and equipment can be granted, and no trust can be established. This situation is further exacerbated by an increasing interconnection and globalization towards a hyperconnected world. (Communication) Participants are no longer necessarily in close physical and social proximity and do not need to know each other, but can have their source/destination anywhere in the world. An authentication process is used to verify that someone -whether human or machine-, is in fact who she claims to be: The process thus includes a validation step to evaluate an assertion. However, systems differ in terms of their requirements, for instance with regard to the authentication options available, the time period required for reauthentication and the frequency of re-authentication, as well as the level of security to be achieved with authentication. The latter particularly with regard to the cost/benefit ratio of the application. Additionally, there are efforts to finally abolish traditional passwords, passphrases and pin codes and render them obsolete. In this work, technologies and methods for authentication beyond passwords and trustworthy authentication will be examined, particularly with regard to future communication infrastructures such as Beyond 5G and Sixth Generation (6G) wireless systems. Thereby, the impact of Artificial Intelligence (AI) methods, but also the relevance to Quantum Key Distribution (QKD) and Post Quantum Cryptography, as well as the use of 6G-enabling technologies like Reconfigurable Intelligent Surfaces (RISs), Wireless Optical Communication (WOC) and Physical Layer Security (PhySec), for example as additional factors of a multi-factor authentication process, will be considered, along with Body Area Networks (BANs) and the integration of the human body relying on biometrics. The various concepts are compared with regard to their requirements, limitations and possible applications in order to provide the user with an orientation as to which authentication method is conceivable and useful in which specific scenarios. [ABSTRACT FROM AUTHOR]

Intelligent, comprehensive and, above all, secure wireless interconnection is the driving force behind technological progress. To ensure this, the development towards Sixth Generation (6G) Wireless Systems has been launched and is scheduled to be operational by 2030. This data technology of the future turns 6G into the infrastructure of a new generation of mobile, intelligent, and context-sensitive services, available everywhere and featuring high trustworthiness and performance, relying on both, network-side and off-network context sources. In addition, the networks themselves ought to become intelligent and thus more efficient and resource-saving, which requires a high degree of automated utilization of Artificial Intelligence (AI). Building upon the principles of information and communication theory for both the physical (bit)- transmission layer (PHY) and media access, new communication concepts for 6G will be developed providing the foundations for research into new single and multi-user operation, access and core networks. The flip side of this coin of opportunities: Sophisticated technology inevitably leads to additional security vulnerabilities, open access systems and Open-Radio Access Network (O-RAN) approaches imply new attack vectors. The holistic interconnection of everything renders it ever more attractive to attackers to harm systems, and create damage. Furthermore, enhanced computational power along with quantum computers make conventional systems more vulnerable than ever, and the value of the transmitted data increases tremendously: It is not only machine and sensor data, but also very personal and healthcare data transmitted with 6G. Therefore, the aim is to build a resilient and secure 6G system capable of recognizing attacks and uncertainties, flexibly absorbing them, recovering in a timely and sustainable manner, and compensating for impaired functionality through transformation. This holistic resilience-by-design approach is based, among other things, on technology such as Quantum Key Distribution (QKD) and Post Quantum-Crypto to achieve end-to-end security, Reconfigurable Intelligent Surfaces (RISs) to rely, control and manipulate the wireless transmission channel, Wireless Optical Communication (WOC), Physical Layer Security (PhySec), but also Body Area Networks (BANs), the integration of the human body relying on biometrics and the Tactile Internet (TI). These concepts will be discussed and shed light on in the scope of this work. [ABSTRACT FROM AUTHOR]

Dynamic Random-Access Memory (DRAM)-based Physically Unclonable Functions (PUFs) are a part of the Physical Layer Security (PhySec) domain. Those electrical PUFs are memory based and exhibit a high availability, Shannon Entropy, low energy consumption and high amount of Challenge Response Pairs (CRPs). Because of those properties, the DRAM PUF is a promising approach for security applications in the Industrial Internet of Things (IIoT) context as well as securing the Sixth-Generation (6G) Wireless Systems and edge computing. DRAM, with its most common one-Transistor one-Capacitor (1T1C) architecture, and as a volatile memory is embedded in almost every modern computing unit. Regarding the PUF security applications, four main types of applications are currently distinguished in the scientific community: Retention Error, Row Hammer, Startup and Latency PUFs. Thereby these differ in their procedure in how responses are generated as well as by the physical mechanisms. Each of them with varying properties in terms of availability, reliability, uniqueness and uniformity. To examine this, and to obtain comparable results, this work proposes to compare the four different DRAM-PUF types i) with the same metrics of evaluation and ii) implemented on the same DRAM cells. This represents both the difference with regard to the work done in the literature and the added value of this work presented. As far as known, there is no work to date that performs the intended evaluations using the same evaluation platform under the identical conditions. However, this is required for comparable results. This consistent comparison is ensured by a self-developed and implemented evaluation platform, which is accordingly equipped with a significant number of DRAMs. By an appropriate high volume of measurements, a corresponding resolution will be given. Monitoring the environmental conditions prevents from wrong interpretations caused by environmental influences but also provides useful context information. Furthermore, a detailed technical and physical background will be described. The results of this approach will assist by the consideration of which DRAM-PUF is appropriate in which (environmental) conditions and thereby provide a guideline for practitioners. [ABSTRACT FROM AUTHOR]

In an increasingly interconnected and globalized world in which the volume but also the confidentiality of transmitted content is becoming ever more important, trust, confidence and trustworthiness are of fundamental importance. Particularly in human societies, this trust is established, sustained and strengthened by personal relationships and experiences. But, in a globally connected world with Cyber-Physical Production Systems (CPPS), Industrial Internet of Things (IIoT) and Digital Twins (DTs), these personal relationships do not longer exist. (Remote) access to systems is possible from anywhere on the globe. However, this implies that there have to be technical solutions to detect, identify and acknowledge entities -people and machines-in the networks and thus to establish an initial level of trust. Especially since the proliferation of appropriate use-cases, Physical Layer Security (PhySec) is becoming increasingly popular in the scientific community. Using systems' intrinsic information for security applications provides a lightweight but secure alternative to traditional computationally intensive and complex cryptography. PhySec is therefore not only suitable for the IIoT and the multitude of resource-limited devices and sensors, it also opens up alternatives in terms of scalability and efficiency. Moreover, it provides security aspects regarding the entropy H and Perfect Forward Secrecy (PFS). Therefore, this work provides insight into three major branches of PhySec: i) Human - Physically Unclonable Functions (PUFs) ii) silicon/electrical - PUFs, and iii) Channel-PUFs. Based on the PUF operating principle, the silicon derivatives consider the electrical properties of semiconductors. Individual and uninfluenceable deviations during the manufacturing process result in component-specific behavior, which is described in particular for Static- and Dynamic Random Access Memory (S-/DRAM). Following this PUF principle, human characteristics -biological, physiological and behavioral features-, are used to recognize and authenticate them. With respect to the wireless channel, the characteristic properties of electromagnetic wave propagation and the influences on the wireless channel -diffraction, reflection, refraction and scattering-, are used to achieve symmetric encryption of the channel. In addition to the "conventional" wireless PhySec, especially the development of the Sixth Generation (6G) Wireless Systems, opens up a wide range of possibilities in terms of PhySec, for example in relation to Visible Light Communication (VLC), Reconfigurable Intelligent Surfaces (RIS) and in general the application of frequencies in the (sub)THz range. Thus, the work provides an overview of PhySec fields of application in all areas of the IIoT: in terms of humans, machines, and the transmission channel. [ABSTRACT FROM AUTHOR]