Sotiris Ioannidis

Technical University of Crete | TUC · Department of Electronic and Computer Engineering

Reconfigurable intelligent surfaces (RIS) can actively manipulate the wave propagation within a space, even in unconventional ways, enabling software-defined wireless propagation. Enabling real-time RIS operation requires a codebook, that is, a set of pre-calculated states of the RIS constituent elements that yield any of the supported macroscopic...

Providing security guarantees when executing application code in untrusted environments is vital, especially when handling sensitive data. To address this task, Trusted Execution Environments (TEEs) such as Intel's Software Guard eXtension (SGX), which implement hardware-based techniques by silicon manufacturers, have been introduced to provide con...

In the evolving landscape of sixth-generation (6G) wireless networks, unmanned aerial vehicles (UAVs) have emerged as transformative tools for dynamic and adaptive connectivity. However, dynamically adjusting their position to offer favorable communication channels introduces operational challenges in terms of energy consumption, especially when in...

Digitalization is continuing facilitating our daily lives. The world is interconnected as never before, bringing close people, businesses, or other organizations. However, hackers are also coming close. New business and operational models require the collection and processing of massive amounts of data in real-time, involving utilization of complex...

Lately a new approach to Extended Reality (XR), denoted as XR-RF, has been proposed which is realized by combining Radio Frequency (RF) Imaging and programmable wireless environments (PWEs). RF Imaging is a technique that aims to detect geometric and material features of an object through RF waves. On the other hand, the PWE focuses on the the conv...

In the evolving landscape of sixth-generation (6G) wireless networks, unmanned aerial vehicles (UAVs) have emerged as transformative tools for dynamic and adaptive connectivity. However, dynamically adjusting their position to offer favorable communication channels introduces operational challenges in terms of energy consumption, especially when in...

We introduce fuzzol, the first syntax-aware mutation fuzzer for systematically testing the security and reliability of solc, the standard Solidity compiler. fuzzol addresses a challenge of existing fuzzers when dealing with structured inputs: the generation of inputs that get past the parser checks of the system under test. To do so, fuzzol introdu...

Internet of Things (IoT) networks are expected to be a key enabler technology for smart cities, due to theirability to offer real-time monitoring. In this work, we propose a novel medium access control (MAC) protocol, inspired by the synergy of slotted ALOHA and hybrid automatic repeat request with code combining (HARQ-CC), termed as code combining...

In this work, we focus on the theoretical modeling and experimental evaluation of UAV-mounted absorbing metasurfaces as facilitators for secure wireless communication channels. Specifically, we present a network architecture based on UAV-mounted metasurfaces and conduct a comprehensive analysis of its components. Furthermore, by utilizing physical...

The growing adoption of network encryption protocols , like TLS, has altered the scene of monitoring network traffic. With the advent increase in network encryption, typical DPI systems that monitor network packet payload contents are becoming obsolete, while in the meantime, adversaries abuse the utilization of the TLS protocol to bypass them. In...

Sliding Window Random Linear Network Coding (RLNC) offers a clear path towards achieving ultra-high reliability and low latency at the same time. Such requirements are pivotal for a wide range of applications in the future Internet as well as in 5G and beyond networks. While traditional RLNC has been extensively used for some years now, its Sliding...

On 24 February 2022, Russia invaded Ukraine, starting what is now known as the Russo-Ukrainian War, initiating an online discourse on social media. Twitter as one of the most popular SNs, with an open and democratic character, enables a transparent discussion among its large user base. Unfortunately, this often leads to Twitter's policy violations,...

Twitter as one of the most popular social networks, offers a means for communication and online discourse, which unfortunately has been the target of bots and fake accounts, leading to the manipulation and spreading of false information. Towards this end, we gather a challenging, multilingual dataset of social discourse on Twitter, originating from...

A primary objective of the forthcoming sixth generation (6G) of wireless networking is to support demanding applications, while ensuring energy efficiency. Programmable wireless environments (PWEs) have emerged as a promising solution, leveraging reconfigurable intelligent surfaces (RISs), to control wireless propagation and deliver exceptional qua...

Providing enhanced quality of service (QoS) to support demanding applications in the most energy-efficient way has been identified as a primary objective of future 6G networks. Towards this direction, the concept of programmable wireless environments (PWEs) has emerged, wherein extremely high QoS can be ensured by controlling the wireless propagati...

Reconfigurable intelligent surfaces (RISs) are artificial planar structures able to offer a unique way of manipulating propagated wireless signals. Commonly composed of a number of reconfigurable passive cell components and basic electronic circuits, RISs can almost freely perform a set of wave modification functionalities, in order to realize prog...

The present study proposes the use of intelligent materials in the design of products, as enforcers of circular economy principles. Intelligent materials can tune their physical properties (electromagnetic, acoustic, mechanical and thermal) by receiving software commands. When incorporated within products and living spaces they can mitigate the res...

Honeypots have been proven to be a useful tool in the arsenal of defense solutions against cyber-attacks. Over time, various honeypot solutions have been proposed to lure attackers that target both conventional networks and Industrial Control Systems. However, the current approaches do not make the deployment and usability of honeypots more attract...

Most studies analyzing political traffic on Social Networks focus on a single platform, while campaigns and reactions to political events produce interactions across different social media. Ignoring such cross-platform traffic may lead to analytical errors, missing important interactions across social media that e.g. explain the cause of trending o...

Traditional IoT setups are cloud-centric and typically focused around a centralized IoT platform to which data is uploaded for further processing. Next generation IoT applications are incorporating technologies such as artificial intelligence, augmented reality, and distributed ledgers to realize semi-autonomous behaviour of vehicles, guidance for...

The powerful capabilities of modern browsers have pushed the web application logic to the user side, in order to minimize latency, increase scalability of the service and improve users' quality of experience. What is more, browsers provide a rich toolchest for browser extensions to provide additional functionality, but at the same time enable them...

A primary objective of the forthcoming sixth generation (6G) of wireless networking is to support demanding applications, while ensuring energy efficiency. Programmable wireless environments (PWEs) have emerged as a promising solution, leveraging reconfigurable intelligent surfaces (RISs), to control wireless propagation and deliver exceptional qua...

With digital technologies now being part of the fabric of our societies, identifying and managing cybersecurity threats becomes imperative. Within the European Union, several initiatives are underway, aiming to motivate, regulate and eventually orchestrate the establishment of capacity and enhancement of situational awareness, incident response, an...

Reconfigurable intelligent surfaces (RISs) are artificial planar structures able to offer a unique way of manipulating propagated wireless signals. Commonly composed of a number of reconfigurable passive cell components and basic electronic circuits, RISs can almost freely perform a set of wave modification functionalities, in order to realize prog...

Reconfigurable Intelligent Surfaces (RIS) constitute a promising technology that could fulfill the extreme performance and capacity needs of the upcoming 6G wireless networks, by offering software-defined control over wireless propagation phenomena. Despite the existence of many theoretical models describing various aspects of RIS from the signal p...

This paper proposes a computationally efficient thermal study method that substitutes Computational Fluid Dynamics (CFD) with Finite Element Analysis (FEA) involving minimal loss of accuracy and omission of the increased computational load. The suggested technique contributes towards the realization of multiphysics optimization of high-speed electr...

We present a new approach to Extended Reality (XR), denoted as iCOPYWAVES, which seeks to offer naturally low-latency operation and cost-effectiveness, overcoming the critical scalability issues faced by existing solutions. iCOPYWAVES is enabled by emerging PWEs, a recently proposed technology in wireless communications. Empowered by intelligent (m...

Programmable wireless environments (PWEs) utilize internetworked intelligent metasurfaces to transform wireless propagation into a software-controlled resource. In this article, the interplay is explored between the user devices, the metasurfaces, and the PWE control system from the theory to the end-to-end implementation. This article first discus...

The rising use of FPGAs, in the context of cloud computing, has created security concerns. Previous works have shown that malicious users can implement voltage fluctuation sensors and mount successful power analysis attacks against cryptographic algorithms that share the same Power Distribution Network (PDN). So far, masking and hiding schemes are...

Wireless telecommunications are ubiquitously networking computers, from mobiles in our palms to datacentres in the arctic circle, enabling emerging and prospective systems, such as the Internet of Things (IoT), that build upon omnipresent mobile networks. Intelligent Reconfigurable Surfaces (IRS) are ultra‐thin, two‐dimensional electromagnetic devi...

Abstract—Healthcare ecosystems form a critical type of in-frasHealthcare ecosystems form a critical type of in-frastructures that provide valuable services in today societies.However, the underlying sensitive information is also of interest ofmalicious entities around the globe, with the attack volume beingcontinuously increasing. Safeguarding this...

Intensive care unit (ICU) patients with venous thromboembolism (VTE) and/or cancer suffer from high mortality rates. Mortality prediction in the ICU has been a major medical challenge for which several scoring systems exist but lack in specificity. This study focuses on two target groups, namely patients with thrombosis or cancer. The main goal is...

Traditional signature-based intrusion detection systems inspect packet headers and payloads to report any malicious or abnormal traffic behavior that is observed in the network. With the advent and rapid adoption of network encryption mechanisms, typical deep packet inspection systems that monitor network packet payload contents are becoming less e...

Despite the tremendous socioeconomic importance of supply chains (SCs), security officers and operators are faced with no easy and integrated way for protecting their critical, and interconnected, infrastructures from cyber-attacks. As a result, solutions and methodologies that support the detection of malicious activity on SCs are constantly resea...

Modern Internet of Things (IoT) environments are monitored via a large number of IoT enabled sensing devices, with the data acquisition and processing infrastructure setting restrictions in terms of computational power and energy resources. To alleviate this issue, sensors are often configured to operate at relatively low sampling frequencies, yiel...

This study introduces a novel, reproducible and reusable Twitter bot identification system. The system uses a machine learning (ML) pipeline, fed with hundreds of features extracted from a Twitter corpus. The main objective of the proposed ML pipeline is to train and validate different state-of-the-art machine learning models, where the eXtreme Gra...

Twitter is one of the most popular social networks attracting millions of users, while a considerable proportion of online discourse is captured. It provides a simple usage framework with short messages and an efficient application programming interface (API) enabling the research community to study and analyze several aspects of this social networ...

Online social networks (OSN) are used by millions of users, daily. This user-base shares and discovers different opinions on popular topics. The social influence of large groups may be affected by user beliefs or be attracted by the interest in particular news or products. A large number of users, gathered in a single group or number of followers,...

Modern commodity computing systems are composed by a number of different heterogeneous processing units, each of which has its own unique performance and energy characteristics. However, the majority of current network packet processing frameworks targets only a specific processing unit (either the CPU or accelerator), leaving the remaining computa...

On 24 February 2022, Russia invaded Ukraine, also known now as Russo-Ukrainian War. We have initiated an ongoing dataset acquisition from Twitter API. Until the day this paper was written the dataset has reached the amount of 57.3 million tweets, originating from 7.7 million users. We apply an initial volume and sentiment analysis, while the datase...

A large number of EU organisations already leverage Big Data pools to drive value and investments. This trend also applies to the banking sector. As a specific example, CaixaBank currently manages more than 300 different data sources (more than 4 PetaBytes of data and increasing), and more than 700 internal and external active users and services ar...

The adoption of Internet of Things (IoT) devices, applications and services gradually transform our everyday lives. In parallel, the transition from linear to circular economic (CE) models provide an even more fertile ground for novel types of services, and the update and enrichment of legacy ones. To fully realize the potential of the interplay be...

Modern commodity computing systems are composed by a number of different heterogeneous processing units, each of which has its own unique performance and energy characteristics. However, the majority of current network packet processing frameworks targets only a specific processing unit (either the CPU or accelerator), leaving the remaining computa...

Control-Flow Integrity (CFI) is a popular technique to defend against State-of-the-Art exploits, by ensuring that every (indirect) control-flow transfer points to a legitimate address and it is part of the Control-flow Graph (CFG) of a program. Enabling CFI in real systems is not straightforward, since in many cases the actual CFG of a program can...

Manufacturing processes are highly complex. Production lines have several robots and digital tools, generating massive amounts of data. Unstructured, noisy and incomplete data have to be collected, aggregated, pre-processed and transformed into structured messages of a common, unified format in order to be analysed not only for the monitoring of th...

We present a new approach to Extended Reality (XR), denoted as iCOPYWAVES, which seeks to offer naturally low-latency operation and cost effectiveness, overcoming the critical scalability issues faced by existing solutions. iCOPYWAVES is enabled by emerging PWEs, a recently proposed technology in wireless communications. Empowered by intelligent (m...

Twitter is one of the most popular social networks attracting millions of users, while a considerable proportion of online discourse is captured. It provides a simple usage framework with short messages and an efficient application programming interface (API) enabling the research community to study and analyze several aspects of this social networ...

The Android OS is currently used in a plethora of devices that play a core part of our everyday life, such as mobile phones, tablets, smart home appliances, entertainment systems and embedded devices. The majority of these devices typically process and store a vast amount of security-critical and privacy-sensitive data, including personal contacts,...

This article studies the prospects of combining two promising wireless technologies for 6G wireless systems, namely ambient backscatter communications and Programmable Wireless Environments (PWEs). Ambient backscattering carries the promise of battery-less and perpetually operating IoT devices that "surf" ambient electromagnetic waves rather than g...

Eco-friendly systems are necessitated nowadays, as the global consumption is increasing. A data-driven aspect is prominent, involving the Internet of Things (IoT) as the main enabler of a Circular Economy (CE). Henceforth, IoT equipment records the system’s functionality, with machine learning (ML) optimizing green computing operations. Entities ex...

Exerting cyber-control over any natural resource and process has seen explosive growth, yielding technological breakthroughs in recent years. This impressive growth has so far stemmed from a horizontal expansion of control across application sectors, such as industrial, business, and household task automations. This article proposes cyber-control v...

Emerging technologies are facilitating our daily activities and drive the digital transformation. The Internet of Things (IoT) and 5G communications will provide a wide range of new applications and business opportunities, but with a wide and quite complex attack surface. Several users are not aware of the underlying threats and most of them do not...

The adoption of network traffic encryption is continually growing. Popular applications use encryption protocols to secure communications and protect the privacy of users. In addition, a large portion of malware is spread through the network traffic taking advantage of encryption protocols to hide its presence and activity. Entering into the era of...

Digital technologies are facilitating our daily activities, and thus leading to the social transformation with the upcoming 5G communications and the Internet of Things. However, mainstream and sophisticated attacks are remaining a threat, both for individuals and organisations. Cyber Range emerges as a promising solution to effectively train peopl...

Structured approaches to the definition of service orchestrations facilitate the composition of components and services and allow for more capable and powerful applications, while introducing many advantages such as service reusability, cost reduction, and simplification of organization alliances. A variety of such approaches exist in the literatur...