Filip Rezac

Bio: Filip Rezac is an academic researcher from Technical University of Ostrava. The author has contributed to research in topics: Voice over IP & Quality of service. The author has an hindex of 9, co-authored 50 publications receiving 174 citations. Previous affiliations of Filip Rezac include CESNET & University of Ostrava.

Analysis of the Public Channel of Quantum Key Distribution Link

Abstract: Quantum key distribution (QKD) relies on the laws of physics to establish a symmetric binary key between remote parties. A QKD link involves the realization of a quantum channel for the transmission of quantum key material encoded in certain photon properties, as well as a public channel for verification of the exchanged key material. This paper deals with the mutual dependence of these channels and analyzes the impact of performance of both channels on the overall key material establishment process. This paper presents measurement data obtained under laboratory conditions as well as the results obtained by establishing a virtual QKD link. Despite the common beliefs that increased quantum bit error rate implies a larger amount of traffic on the public channel, our measurements prove the opposite. The obtained data clearly show that the public channel has a major impact on the overall performance of the QKD link.

Security analysis system to detect threats on a SIP VoIP infrasctructure elements

Abstract: SIP PBX is definitely the alpha and omega of any IP telephony infrastructure and frequently also provides other services than those related to VoIP traffic. These exchanges are, however, very often the target of attacks by external actors. The article describes a system that was developed on VSB-TU Ostrava as a testing tool to verify if the target VoIP PBX is adequately secured and protected against any real threats. The system tests the SIP element for several usually occurring attacks and it compiles evaluation of its overall security on the basis of successfully or unsuccessfully penetrations. The article describes the applications and algorithms that are used by system and the conclusion consists recommendations and guidelines to ensure effective protection against VoIP PBX threats. The system is designed as an open-source web application, thus allowing independent access and is fully extensible to other test modules.

Security Risks in IP Telephony

Abstract: This paper deals with VoIP communication security and various techniques of VoIP attacks. We divided these threats in several categories according to their specific behaviour and their impact on the affected system. We also tried to find effective methods to prevent or mitigate these attacks. We focused our work on Spam over Internet Telephony (SPIT) as a real threat for the future. We have developed both a tool generating SPIT attacks and AntiSPIT tool defending communication systems against SPIT attacks. AntiSPIT represents an effective protection based on statistical blacklist and works without participation of the called party which is a significant advantage.

Threats to voice over IP communications systems

Abstract: This article deals with various techniques of VoIP attacks and VoIP communication security. These threats are divided in several categories according to their specific behaviour and their impact on the affected system. We describe effective methods to prevent or mitigate these attacks. Our work was especially focused on Spam over Internet Telephony (SPIT) as a real threat for the future and we consider spam in IP telephony to be very serious due to situation we face in e-mail communication. We have developed both an AntiSPIT tool defending communication systems against SPIT attacks and a tool generating SPIT attacks. AntiSPIT represents an effective protection based on statistical blacklist and works without participation of the called party which is significant advantage, AntiSPIT was implemented into Asterisk open-source platform and became one way of protection against the voice spam expected in near future.

Automatic Classification of Attacks on IP Telephony

Abstract: This article proposes an algorithm for automatic analysis of attack data in IP telephony network with a neural network. Data for the analysis is gathered from variable monitoring application running in the network. These monitoring systems are a typical part of nowadays network. Information from them is usually used after attack. It is possible to use an automatic classification of IP telephony attacks for nearly real-time classification and counter attack or mitigation of potential attacks. The classification use proposed neural network, and the article covers design of a neural network and its practical implementation. It contains also methods for neural network learning and data gathering functions from honeypot application.

The Evolution of Quantum Key Distribution Networks: On the Road to the Qinternet

Abstract: Quantum key distribution (QKD) constitutes a symmetric secret key negotiation protocol capable of maintaining information-theoretic security. Given the recent advances in QKD networks, they have evolved from academic research to some preliminary applications. A QKD network consists of two or more QKD nodes interconnected by optical fiber or free space links. The secret keys are negotiated between any pair of QKD nodes, and then they can be delivered to multiple users in various areas for ensuring long-term protection and forward secrecy. We commence by introducing the QKD basics, followed by reviewing the development of QKD networks and their implementation in practice. Subsequently, we describe the general QKD network architecture, its elements, as well as its interfaces and protocols. Next, we provide an in-depth overview of the associated physical layer and network layer solutions, followed by the standardization efforts as well as the application scenarios associated with QKD networks. Finally, we discuss the potential future research directions and provide design guidelines for QKD networks.

Quantum Key Distribution: A Networking Perspective

Abstract: The convergence of quantum cryptography with applications used in everyday life is a topic drawing attention from the industrial and academic worlds. The development of quantum electronics has led to the practical achievement of quantum devices that are already available on the market and waiting for their first application on a broader scale. A major aspect of quantum cryptography is the methodology of Quantum Key Distribution (QKD), which is used to generate and distribute symmetric cryptographic keys between two geographically separate users using the principles of quantum physics. In previous years, several successful QKD networks have been created to test the implementation and interoperability of different practical solutions. This article surveys previously applied methods, showing techniques for deploying QKD networks and current challenges of QKD networking. Unlike studies focusing on optical channels and optical equipment, this survey focuses on the network aspect by considering network organization, routing and signaling protocols, simulation techniques, and a software-defined QKD networking approach.

Vibration-Based Fault Diagnosis of Commutator Motor

Abstract: This paper presents a study on vibration-based fault diagnosis techniques of a commutator motor (CM). Proposed techniques used vibration signals and signal processing methods. The authors analysed recognition efficiency for 3 states of the CM: healthy CM, CM with broken tooth on sprocket, CM with broken rotor coil. Feature extraction methods called MSAF-RATIO-50-SFC (method of selection of amplitudes of frequencies ratio 50 second frequency coefficient), MSAF-RATIO-50-SFC-EXPANDED were implemented and used for an analysis. Feature vectors were obtained using MSAF-RATIO-50-SFC, MSAF-RATIO-50-SFC-EXPANDED, and sum of RSoV. Classification methods such as nearest mean (NM) classifier, linear discriminant analysis (LDA), and backpropagation neural network (BNN) were used for the analysis. A total efficiency of recognition was in the range of 79.16%–93.75% ( ). The proposed methods have practical application in industries.

Implementation of quantum key distribution network simulation module in the network simulator NS-3

Abstract: As the research in quantum key distribution (QKD) technology grows larger and becomes more complex, the need for highly accurate and scalable simulation technologies becomes important to assess the practical feasibility and foresee difficulties in the practical implementation of theoretical achievements. Due to the specificity of the QKD link which requires optical and Internet connection between the network nodes, to deploy a complete testbed containing multiple network hosts and links to validate and verify a certain network algorithm or protocol would be very costly. Network simulators in these circumstances save vast amounts of money and time in accomplishing such a task. The simulation environment offers the creation of complex network topologies, a high degree of control and repeatable experiments, which in turn allows researchers to conduct experiments and confirm their results. In this paper, we described the design of the QKD network simulation module which was developed in the network simulator of version 3 (NS-3). The module supports simulation of the QKD network in an overlay mode or in a single TCP/IP mode. Therefore, it can be used to simulate other network technologies regardless of QKD.

A review of cyber threats and defence approaches in emergency management

Abstract: Emergency planners, first responders and relief workers increasingly rely on computational and communication systems that support all aspects of emergency management, from mitigation and preparedness to response and recovery. Failure of these systems, whether accidental or because of malicious action, can have severe implications for emergency management. Accidental failures have been extensively documented in the past and significant effort has been put into the development and introduction of more resilient technologies. At the same time researchers have been raising concerns about the potential of cyber attacks to cause physical disasters or to maximise the impact of one by intentionally impeding the work of the emergency services. Here, we provide a review of current research on the cyber threats to communication, sensing, information management and vehicular technologies used in emergency management. We emphasise on open issues for research, which are the cyber threats that have the potential to affect emergency management severely and for which solutions have not yet been proposed in the literature.