ISSN 1213-1539
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Datum publikování: 31.08.2022
Autoři: Marek Sikora, Václav Zeman, Petr Číka, Vlastimil Člupek, Petr Blažek, Zdeněk Martinásek
Rubrika: Komunikační technologie
Jazyk (Language): CZ
Abstrakt (Abstract): As part of the design and optimization of information and communication technology (ICT) systems, one of the steps is to test systems under extreme load using so-called Denial of Service (DoS) or Distributed DoS (DDoS) attacks. Tests are done either using specialized hardware (HW) devices or by creating workloads using software (SW) distributed systems. In addition to the above tests, it is also often necessary to verify the behavior of the ICT infrastructure under predefined transmission conditions. Specialized HW and SW network emulators are used for this purpose, which allow defining the properties of the transmission network. The paper describes an innovative system, based on open-source technologies, which represents an alternative to closed-source commercial solutions, combines both functions, i.e. a load tester and a network emulator in one device, and the advantages of such a system are shown.
Datum publikování: 30.08.2022
Autoři: Karel Burda
Rubrika: Komunikační technologie
Jazyk (Language): CZ
Abstrakt (Abstract): The paper extends Shannon's classical theory of secrecy cryptosystems. This extension is based on the representation of ciphers by Latin rectangles. Based on this representation, a model is derived that uses the so-called valence of cryptograms, which is the number of all meaningful messages produced by decrypting a given cryptogram with all possible keys. Furthermore, the paper derives a lower guaranteed bound on the valence of any cipher with K keys and N inputs, of which M inputs are messages. That parameter allows quantifying the resistance of ciphers to brute force attack. The model is general, illustrative and uses a simpler mathematical apparatus than existing theory. It can thus be used as an introduction to the theory of secrecy cryptosystems.
Datum publikování: 30.06.2022
Autoři: Willi Lazarov, Antonín Bohačík
Rubrika: Komunikační technologie
Jazyk (Language): CZ
Abstrakt (Abstract): The paper deals with the security of the Kerberos network authentication protocol. The basic principles and the detailed flow of communication between a client and a system using the Kerberos protocol are explained in the introduction. The paper also points out the existing security threats in the form of ticket attacks and presents the method of their execution including predispositions. Post-exploitation attacks are problematic to detect, and thus administrators of systems that use the Kerberos protocol should be more familiar with the protection options. Particular ticket attacks are analyzed, and the paper concludes by describing security measures that can detect attacks presented and prevent or minimize their impact.
Datum publikování: 30.06.2022
Autoři: Petr Musil, Tomáš Roško, Stanislav Fučík
Rubrika: Komunikační technologie
Jazyk (Language): EN
Abstrakt (Abstract): Increasing complexity of international transport leads to higher requirements and expectations of shipping container tracking. However shipping transport faces specific technical challenges, such as the need to send accurate data, often and with low energy consumption. This article deals with the specific design of a tracking device, which addresses current requirements. The gateway offers Multi RAT (Multiple Radio Access Technology) which combines benefits of satellite and mobile networks to monitor shipping containers and its inner conditions with high energy efficiency.
Datum publikování: 23.05.2022
Autoři: Pavel Záviška, Petr Dejdar, Petr Münster, Tomáš Horváth
Rubrika: Komunikační technologie
Jazyk (Language): CZ
Abstrakt (Abstract): A comparison of two-dimensional edge detection approaches in a phase OTDR (Φ-OTDR) sensor system for perimeter disturbance detection is presented in this paper. To locate vibrations on the sensing fiber, Sobel and Prewitt operators are used to detect vertical edges in the processed image, which consists of consecutive Rayleigh backscattering traces. The perimeter disturbance is simulated using three different scenarios (loudspeaker, walk, and climbing over the fence) and the results of presented methods are evaluated using signal-to-noise ratio (SNR) and spatial resolution.
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