This paper researches the system evaluations of the reconfigurable intelligent surface (RIS)-assisted satellite aerial terrestrial integrated systems. To ensure the stability of the regarded network, a link selection scheme is presented to get the balance between the system performance and the system efficiency. Besides, in order to build a practical environment of the transmission networks, the imperfect hardware, channel estimation errors and co-channel interference are both considered in the networks. Relied on the above considerations, the detailed analysis for the outage behaviors is shown along with the asymptotic outage probability in high signal-to-noise ratio scenarios. Moreover, the diversity order and coding gain are also provided to give fast methods to confirm the system evaluation. Finally, some re-presentative simulations are provided to confirm the efficiency and advantage of analytical results and the proposed link selection scheme.

The proliferation of IoT networks across various sectors necessitates robust Trust Management mechanisms for secure and reliable operations. This paper proposes a Multi-Attribute Decision Making (MADM)-based approach for trust score calculation in IoT Trust Management. This solution addresses limitations of existing methods by considering multiple attributes and providing a comprehensive evaluation of trustworthiness. The methodology computes a device's trust score by integrating factors such as Cyber Risk, Ease of Access, and Security Level using a weighted sum-based calculation. The Analytical Hierarchy Process (AHP) to determine the factors’ weights is utilized, contributing a novel approach to IoT Trust Management. Furthermore, this approach includes dynamic trust score updates throughout the device's lifetime, accommodating changes in the device's Cyber Risk for accurate trust assessment. A trust score penalization mechanism for devices below a predefined threshold is also introduced, enabling prompt risk mitigation. A simulated assessment, considering varying numbers of IoT devices, evaluates the effectiveness of the proposed methodology. By addressing limitations and introducing innovative components, the proposed MADM-based approach enhances security, reliability, and overall performance of IoT networks. This research advances trust management in IoT and provides valuable insights for developing secure and trustworthy IoT ecosystems.

This paper presents a comprehensive collection of reusable artifacts for addressing security and privacy issues in the context of flow-based programming in Function-as-a-Service (FaaS) environments. With the rapid adoption of FaaS platforms, it becomes important to guarantee the security and privacy of applications. The presented artifacts incorporate a wide variety of nodes and techniques into the popular Node-RED architecture. They intend to improve the security and privacy of applications by addressing critical aspects such as secure data flow management, code authenticity and validation, access control mechanisms, and runtime monitoring and anomaly detection. Using these artifacts, developers can construct more robust and resilient applications in FaaS environments while mitigating potential security and privacy risks.

ERATOSTHENES is an EC, co-funded, research project strongly considering modern security challenges in the domain of Internet of Things in mind of their huge penetration into our day to day lives. There are a series of recent challenges that recently have been converted into obstacles or risk points that could block the secure operation of IoT networks in all day to day activities, from home to office, to leisure and security. These include examples such as the highly increased number of connected devices (at all network levels) that are on top forming inhomogeneous networks and systems of systems. Different vendor characteristics further increase the attack surface that is expected to further rise in the upcoming years. Such, highly critical, characteristics, dramatically increase the needs for confidentiality access control, user and things’ privacy, devices’ trustworthiness and compliance that require lifecycle considerations. The ERATOSTHENES project orchestrates a novel distributed, automated, auditable, yet privacy-respectful, Trust and Identity Management Framework and Reference Architecture with the ultimate scope to dynamically and holistically manage IoT devices in a lifecycle approach, strengthening trust, identities, and resilience in the entire IoT ecosystem while supporting the enforcement of the NIS directive, GDPR and Cybersecurity Act. This publication describes the ERATOSTHENES technical concept and reference architecture as well as design considerations, architecture characteristics, connectivity and interoperability.

Digital transformation is a method where new technologies replace the old to meet essential organisational requirements and enhance the end-user experience. Technological transformation often improvises the manner in which a facility or resources are delivered to the recipient. Data is one of the key assets of every organisation which influences significantly reaching the long-term objective. Thus, the entities, as well as technologies involved in the data management process, have a significant role to play to secure different data types. However, the traditional data governance process often follows a centralised approach and thus resulting in various cyber attacks, whereas the distributed approaches are mostly research prototypes and often comprise various security challenges. Security incidents such as data theft fabricate the integrity of confidential data and thus the consequences are often disastrous. To address the challenges, we introduce TRUSTEE, a data-driven platform which aims to provide a secure and privacy-by-design framework to empower companies, organisations, and individuals to access different data domains, use and re-use the data and metadata to extract knowledge with trust and confidentiality. In this paper, we assess the effectiveness of the platform by reviewing the potential challenges and threats associated with the incorporated technologies. Our research emphasises the efficacy of distributed technologies to indicate their significance in data integrity and security.

A key enabler for vertical businesses to adopt the 5G networking paradigm is the introduction of Network Applications as the horizontal middleware layer between 5G operators and vertical applications. The Network Application ecosystem allows reliable and secure interaction between the control plane of mobile operators and the various vertical businesses, in a standardised way defined by the Common API Framework. Although the framework's security features and mechanisms ensure robust communication between mobile operators and vertical applications, they cannot sustain the rapidly evolving Network Application marketplaces, which require seamless onboarding, authentication and authorization of Network Applications across multiple mobile operators. The paper investigates the security enhancements of incorporating the OpenID Connect protocol in the Common API Framework standard and supporting the single sign-on authentication scheme for Network Applications across different Common API Framework instances. The work, which builds on top of the EU funded EVOLVED-5G, aims on a robust and distributed solution using open-source protocols for authentication and authorization, incorporating security-as- a-service features for 5G and beyond network implementations.

Digitization, in terms of online services, work environment and other day-to-day procedures, has lead to the wide adoption and use of the respective digital identities. Users utilize their digital personas and their corresponding attributes on a daily basis, in order to gain access to resources and services. This is achieved through the use of numerous identity management schemes, which often suffer from multiple vulnerabilities and are susceptible to threats. This results in the compromise of user privacy and data security. In the recent years, new technologies related to identity management, like the Self-Sovereign Identity (SSI) and eIDAS concepts, are employed to mitigate these issues. This paper presents an architecture that combines state-of-the-art technologies regarding identity management, authentication and secure storage. More specifically, the proposed framework utilizes IOTA-based SSI, the eIDAS framework, FIDO protocol and Trusted Execution Environment (TEE), resulting in a trusted and secure identity management framework. Our solution is thoroughly presented via scenarios, showcasing its robustness and how well it copes in relation to our threat model.

The evolution of Information and Communications Technology and Cloud Computing, combined with the advent of novel telecommunication frameworks such as 5G, have introduced the notion of ubiquitous connectivity combined with a seemingly vast pool of resources, storage and services. This immense transformation introduced new types of security threats mostly due to the significant increase of the attack surface, which can now be compromised by malicious users. Despite the fact that malicious attacks constantly become more and more sophisticated, SMEs and public administrations remain reluctant to invest in cybersecurity since they operate on a limited budget and are mostly focused in time to market and cost minimization. The purpose of this book chapter is to provide an overview on how the most common network-related cybersecurity attacks are orchestrated, which are the systems and services they affect the most as well as present specific design principles and guidelines for crafting platforms and frameworks capable of mitigating such attacks and ensure a certain level of secure operation.

In secret sharing, a dealer knows the secret it shares. In a distributed key generation (DKG) protocol, a shared secret is collectively generated in a group in a completely distributed way such that any subset of size greater than a threshold can reveal or use the shared secret, while smaller subsets do not have any knowledge about it. The most important aspect is that there is no dealer or trusted party. The core idea of secret sharing schemes is Shamir’s secret sharing method, which uses Lagrange’s interpolation to reconstruct the shared secret key. This paper investigates an alternative method, called Newton’s interpolation and it cites the probability of implementing it on current DKG protocols.

Service providers, 5G network operators and, more generally, vertical industries face today a dangerous shortage of highly skilled cybersecurity experts. Along with the escalation and growing sophistication of cyber-attacks, 5G networks require the training of skilled and highly competent cyber forces. To meet these requirements, the SPIDER cyber range focuses specifically on 5G, and is based on three pillars, (i) cyber security assessment, (ii) training cyber security teams to defend against complex cyber-attack scenarios, and (iii) evaluation of cyber risk. The SPIDER cyber range replicates a customized 5G network, enabling the execution of cyber-exercises that take advantage of hands-on interaction in real time, the sharing of information between participants, and the gathering of feedback from network equipment, as well as the development and adaptation of advanced operational procedures. This aims to help 5G security professionals improve their ability to collaboratively manage and predict security incidents, complex attacks, and propagated vulnerabilities. The SPIDER cyber range is validated in two relevant use case scenarios aimed at demonstrating, in a realistic, measurable, and replicable way the transformations SPIDER will bring to the cybersecurity industry.

Internet of Things has a profound effect on everyday life and critical vertical services including healthcare, factories of the future and intelligent transport systems. The highly distributed nature of such networks and the heterogeneity of the devices, which constitute them, necessitates that their users should be able to trust them at all times. A method to determine the device's service trustworthiness is Trust Management (TM), which assigns scores to devices according to their trustworthiness level, based on evaluations from other entities that interacted with it. Often Internet of Things devices that just joined the network, have not interacted with any other entity of this network before, hence there is no way to determine its trustworthiness. Such an event is referred to as the cold start trust score or initial trust score problem. The majority of the trust management approaches address this problem by setting an arbitrary initial trust score, while others will ignore it. Assigning arbitrary trust scores for devices connected to the network for the first time has the potential to disrupt the operation of the entire system, when a high trust score is assigned to a non-trusted malicious device, or lead to unfair policies, when trusted devices are assumed as potential intruders, which also deteriorates the performance of the system. This paper proposes a mechanism, which combines the blockchain based BARRETT remote attestation protocol with a set of device's properties and communication and operational context parameters, in order to determine accurately and assign the initial trust score to each device. Through a set of extensive simulations over different experimental setups, the proposed scheme is achieving to safely distribute initial trust scores to one thousand devices over less than 6ms, while minimising the risk of computational denial of service attacks due to the inherent characteristics of the BARRETT remote attestation protocol.

Passwords are a problem in today's digital world. FIDO2, through WebAuthn, brought alternative password-less authentication that is more usable and secure than classic password-based systems, for web applications and services. In this work, we give a brief overview of FIDO2, and we present WebDevAuthn, a novel FIDO2/WebAuthn requests and responses analyser web tool. This tool can be used to help developers understand how FIDO2 works, aid in the development processes by speeding debugging using the WebAuthn traffic analyser and to test the security of an application through penetration testing by editing the WebAuhn requests or responses.

Network coding can be considered as a key enabler to achieve high throughput at low energy requirements in the 5G and beyond networks. Enabling the intermediate nodes to code and transmit the packets, network coding improves the resiliency against packet losses, but also introduce several security challenges in a non-trusted environment. A malicious intermediate user can pollute the information flow and such pollution attacks can significantly reduce the efficiency of the network if goes undetected. Integrity schemes with homomorphic properties are proposed to detect pollution attacks at the earliest. This paper proposes a bandwidth efficient, SDN-based integrity scheme suitable for the small cell environment. The proposed approach uses the secure control channel with the central controller for all security signalling and allows the participating nodes to process the packets verifying the integrity of received packets without any additional overhead on the communication channel. The proposed scheme is analyzed for the security against pollution attack, bandwidth efficiency, and scalability against the increasing number of users and varying coding parameters.

Future wireless communication systems will see the exponential growth in number of mobile devices and services. Quality of service (QoS) requirement is another aspect of the evolution of wireless communications and the explosive increase in number of devices, makes the fulfillment of this QoS requirement extremely challenging. Hyper dense small cell networks are an integral part of 5G environment. However, they can suffer from high interference and imbalanced distribution of users. Identifying weak users and helping them to achieve standard QoS requirement is a critical issue and challenge to handle. In this work, various technologies namely as joint transmission coordinated multi-point (JT-CoMP), non-orthogonal multiple access (NOMA), multi-user multiple-input multiple-output (MD-MIMO) and zero-forcing beamforming (ZFB) are used along with a cooperative coalition formation game. A static user scenario is developed in simulation environment, and a cooperative coalition game scenario with JT-CoMP is compared with No JT-CoMP, and results indicate the significant overall improvement over it.

Reliable communication over the wireless network with high throughput is a major target for the next generation communication technologies. Network coding can significantly improve the throughput efficiency of the network in a cooperative environment. The small cell technology and device to device communication make network coding an ideal candidate for improved performance in the fifth generation of communication networks. However, the security concerns associated with network coding needs to be addressed before any practical implementations. Pollution attacks are considered one of the most threatening attacks in the network coding environment. Although there are different integrity schemes to detect polluted packets, identifying the exact adversary in a network coding environment is a less addressed challenge. This paper proposes a scheme for identifying and locating adversaries in a dense, network coding enabled environment of mobile nodes. It also discusses a non-repudiation protocol that will prevent adversaries from deceiving the network.

C-RAN presents an advanced mobile networking architecture that promises to tackle various challenging aspects of 5G such as increasing energy efficiency and providing high capacity. Indeed, C-RAN paves the way toward better energy efficiency by centralizing the baseband processing at cloud computing based servers (BBU pool). In this paper, we propose an RRH group based mapping (RGBM) that aims to minimize the power consumption at the BBU pool, while considering users' QoS and BBU capacity constraints. To achieve this, the proposed scheme uses two key steps: i) the formation of RRH groups aimed at improving the QoS of weak users, ii) the formation of RRH cluster to be mapped for minimal number of BBUs requirement. The proposed scheme uses an efficient greedy heuristic to solve the optimization problem. The performance of the proposed approach was evaluated using simulations, which indicate a significant gain in terms of BBU minimization, power reduction and energy efficiency, while preserving QoS constraints, against well studied legacy solutions.

As the validation and trials of fifth generation communication architectures are maturing, it becomes evident that efficient bandwidth utilization, security, and seamless cooperation among heterogeneous small cell access networks are among the vital requirements that the future wireless networks must satisfy. A potential candidate technology that can ensure bandwidth efficiency and high resilient communications, especially in the adverse wireless networking conditions is network coding. However, without a security strategy for protecting the data and the identity of the communication entities, network coding can be proved as a factor of severely degrading networking performance. Although several cryptography based schemes have been used over the recent years to ensure secure communications over network coding enabled networks, none was specifically designed to address the mobile small cell access network of the forthcoming fifth- generation paradigm. This paper proposes a secure network coding architecture for mobile small cells, which due to their unpredictable topology, render the most encryption key management schemes unsuitable and costly in terms of signaling. The proposed secure network coding architecture incorporates blockchains in an effort to ensure efficient key distribution and reduced signaling overhead.

The fifth generation of mobile networks is rapidly evolving, fueled by the ever-growing mobile traffic over recent years. Ultra-reliable and low latency provisioning of services with ranging contextual parameters mapped to highly fluctuating levels of quality of service and quality of user experience, render the optimum operation point of the future networks unsustainable. Network coding is emerging once more as a potential key enabler for optimizing bandwidth requirements and energy consumption in highly dense mobile network environments. Nonetheless, network coding deployments still need to consider security vulnerabilities and their countermeasures, before they can be adapted as part of the emerging mobile network deployments. This paper studies the performance of random linear network coding for wireless mobile networks with an emphasis on pollution attacks while proposing a novel blockchain based message authentication scheme in order to minimize delays and signalling costs.

Over the last few year, operators have migrate to broadband IP infrastructures offering a broad range of rich-media content to mobile users, anywhere and anytime. Nevertheless, this is not true for the emergency communications, which until now are relying on legacy telecommunication technologies, unable to fulfill the next generation regulatory requirements. For the emergency communication platforms and services to cope with the cataclysmic changes that the 5G era is bringing along, a swift change is required in terms of incorporating mission critical IoT communications, massive machine-type communication and Gigabit mobile connectivity. In particularly, remote health care and sensor-triggered emergency communications are proposed as prominent enablers for next generation emergency platforms. In this paper a test-bed evaluation of the next generation emergency communication platform, part of the EU funded "EMYNOS" project is presented and discussed. Specifically, the study focuses on the efficiency of the SIP SUBSCRIBE/NOTIFY methods across the "EMYNOS" emergency services IP network, when applied for updating the sensory data provided through an API, which handles sensor-based health monitoring data to the first responders and emergency services (i.e, ambulance, fire-brigade, police, etc.) The black-box and white-box testing reveals promising results, placing the proposed architecture among the candidates for the next generation emergency communications platforms.

The sovereignty of cloud-deployed media applications and services is improbable to be disrupted in the foreseeable future. This paper aims to provide an overview of the most essential technologies utilized by this constantly evolving cloud ecosystem, identify the design principles of a media-aware cloud and present an architectural position based on the research conclusions. An end-to-end quality-aware optimization framework is evaluated, where path selection mechanisms are exploited in conjunction with media optimization in order to support cloud based multimedia delivery in a quality-aware manner. This position intends to be simplistic yet outright enough to be employed for mobile cloud deployment in the upcoming fifth generation network era.

The explosive growth of new multimedia applications over mobile networks has attracted intensive research over the years. The main problem in this area is posed by the immense data rate required for multimedia applications in conjunction with the scarcity of wireless resources. To alleviate this shortcoming, this paper proposes combining mobility management and application layer filtering in order to optimize and maintain video quality. The design of the proposed solution is described in depth, as well as the integration of this approach within the LTE Evolved Packet Core architecture. Finally, experimental results are presented to demonstrate the performance of the proposed mechanism.

This paper studies the evaluation of the video streaming over Mobile Peer-to-Peer (MP2P) networks using Scalable Video Coding. The proposed research framework exploits the MP2P diversity characteristics where each node acts as a Mobile Peer for every neighboring node in a relay-based communicating path. Mobile Peers use a common look-up table to request video streaming resources in order to estimate the video packets transfer duration in the end-to-end path. The collaborative streaming is achieved through the data packets replication policy, which uses a bounded upper time limitation for the video packets of each layer (Use of Scalable Video). Each node/device utilizes a specified amount of capacity for both channel and storage purposes. Different scenarios have been introduced in this paper towards evaluating the video streaming policy in the MP2P system, using a real-time probabilistic Fractional Brownian Motion (FBM) and a Random Waypoint (RWP) Mobility model. In both models, nodes move according to certain probabilities, location and time. Intermittent connectivity occurs while nodes claim video streams, whereas promiscuous caching policy enables -where possible- recoverability of lost packets offering priority to packets from the base layer. The simulation results show that FBM provides better objective and subjective quality results for two video sequences resolution, in the MP2P network configuration.

Multiple description coding and path diversity is known to improve the perceptual quality of the received video. This paper considers a machine learning based technique to predict the perceived video quality, in terms of Mean Opinion Score for MDC Stereoscopic video. The perceived experience is expressed as a function of the three-dimensional video representation (color-plus-depth and left-right), the path diversity characterized by asymmetric packet losses between two available paths and the interpolation using a single description delivered over a reliable link as opposed to using multiple unreliable delivered descriptions.

This paper presents a stereo client within an end-to-end video communication ecosystem. The key characteristics of the stereo 3D Client are the following: “Open SVC Decoder” extensions to handle and parse on-the-fly RTP flows for both streams (Left-Right View), dynamic jitter buffer management, 3D Synchronization between the two views and Error concealment. QoE measurements have been carried out to evaluate the robustness of the Client within an end-to-end video communication platform. It is shown that stereo video quality is substantially higher when using the error concealment techniques.

Real-time rate control techniques are necessary to applications such as video streaming in order to adapt video sending rate to network conditions so that the perceived video quality is optimised. In this paper two realtime rate control schemes, are presented. The first one uses the currently available bandwidth in order to perform rate control by selecting the optimum QP (Quantization Parameter). The second rate control scheme is based on measurements of the current packet loss in order to select the optimum QP parameter. Through extensive simulations on a test-bed environment both schemes are studied under diverse network conditions and are compared against the commonly used Rate-Distortion optimization scheme, which is embedded on a video encoder.

This paper proposes an efficient packet scheduling scheme for minimizing perceived video distortion and power consumption over multipath wireless multimedia sensor networks. The proposed scheduling algorithm is responsible for transmitting the video packets over selected multipaths according to their importance (high priority packets over high bandwidth paths). Moreover, whenever the aggregate transmission rate available at the network cannot support the required transmission rate due to high packet loss probability, the scheduling algorithm can selectively drop combinations of video packets prior to transmission to adapt the rate of the sender to the limitations of the wireless channel capacity. The video packets that will be dropped prior to transmission are selected based on a recursive distortion prediction model that has been customized for H.264/AVC coding scheme and counts for isolated losses, burst of losses and losses separated with small lag. Two scheduling algorithms are proposed. The baseline scheme utilizes a novel distortion prediction model and decides upon which packet can be dropped prior to transmission based on the packets impact on the video distortion. Moreover, the power aware packet scheduling is an extension of the baseline capable of estimating the power that will be consumed by each node during the transmission; hence it can control the power consumption by selectively drop the least significant video packets prior to transmission. Simulation results indicate the efficiency of the proposed scheduling scheme in terms of received video distortion (PSNR) and power consumption.

The paper presents the future trends in network evolution and multimedia services provision and delivery. In the context of Next Generation Networks vision, Mobile and Fixed access networks converge over the IP Multimedia Subsystem (IMS) platform that will control the delivery of user-centric secure broadband quad-play services. The IMS has been well defined for the mobile world; however its integration with fixed line networks requires extended functionalities in the architecture, application and security planes. This study is concerned with the research efforts for extending IMS in order to become the common control architecture that will support the convergence of heterogeneous networks and the integration of quad-play services. Furthermore, the most up-to-date open source code IMS platforms and testing scenarios are presented.