29 results on '"Grgić, Krešimir"'
Search Results
2. A Comparative Study of Machine Learning Models for Predicting Meteorological Data in Agricultural Applications.
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Šuljug, Jelena, Spišić, Josip, Grgić, Krešimir, and Žagar, Drago
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MACHINE learning ,SUSTAINABLE agriculture ,WIDE area networks ,METEOROLOGICAL databases ,ATMOSPHERIC models - Abstract
This study aims to address the challenges of climate change, which has led to extreme temperature events and reduced rainfall, using Internet of Things (IoT) technologies. Specifically, we monitored the effects of drought on maize crops in the Republic of Croatia. Our research involved analyzing an extensive dataset of 139,965 points of weather data collected during the summer of 2022 in different areas with 18 commercial sensor nodes using the Long-Range Wide Area Network (LoRaWAN) protocol. The measured parameters include temperature, humidity, solar irradiation, and air pressure. Newly developed maize-specific predictive models were created, taking into account the impact of urbanization on the agrometeorological parameters. We also categorized the data into urban, suburban, and rural segments to fill gaps in the existing literature. Our approach involved using 19 different regression models to analyze the data, resulting in four regional models per parameter and four general models that apply to all areas. This comprehensive analysis allowed us to select the most effective models for each area, improving the accuracy of our predictions of agrometeorological parameters and helping to optimize maize yields as weather patterns change. Our research contributes to the integration of machine learning and AI into the Internet of Things for agriculture and provides innovative solutions for predictive analytics in crop production. By focusing on solar irradiation in addition to traditional weather parameters and accounting for geographical differences, our models provide a tool to address the pressing issue of agricultural sustainability in the face of impending climate change. In addition, our results have practical implications for resource management and efficiency improvement in the agricultural sector. [ABSTRACT FROM AUTHOR]
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- 2024
- Full Text
- View/download PDF
3. An Advanced Energy-Efficient Environmental Monitoring in Precision Agriculture Using Lora-Based Wireless Sensor Networks
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Križanović, Višnja, primary, Grgić, Krešimir, additional, Spišić, Josip, additional, and Žagar, Drago, additional
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- 2023
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4. An Advanced Energy-Efficient Environmental Monitoring in Precision Agriculture Using LoRa-Based Wireless Sensor Networks.
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Križanović, Višnja, Grgić, Krešimir, Spišić, Josip, and Žagar, Drago
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WIRELESS sensor networks , *PRECISION farming , *ENVIRONMENTAL monitoring , *SENSOR networks , *ENERGY consumption , *ELECTRIC power distribution grids , *RADIO networks - Abstract
Sensor networks, as a special subtype of wireless networks, consist of sets of wirelessly connected sensor nodes often placed in hard-to-reach environments. Therefore, it is expected that sensor nodes will not be powered from the power grid. Instead, sensor nodes have their own power sources, the replacement of which is often impractical and requires additional costs, so it is necessary to ensure minimum energy consumption. For that reason, the energy efficiency of wireless sensor networks used for monitoring environmental parameters is essential, especially in remote networking scenarios. In this paper, an overview of the latest research progress on wireless sensor networks based on LoRa was provided. Furthermore, analyses of energy consumption of sensor nodes used in agriculture to observe environmental parameters were conducted using the results of real measurements in the field, as well as simulations carried out based on collected data about real equipment. Optimization methods of energy consumption, in terms of choosing the appropriate data collection processes from the conducted field measurements, as well as the settings of network radio parameters imitating real conditions used in conducted simulations were highlighted. In the analyses, special emphasis was placed on choosing the optimal packet size. Unlike in other papers analyzing energy efficiency of LoRa communication, in this paper, it was proven that the adjustment of the transmission speed to the actual size of the packet is important for better energy efficiency of communication and that it can reduce energy consumption considerably. Moreover, in the paper, the contents of a packet that can be used in precision agriculture is suggested in order to prove that the 6-bit packet is sufficient for energy-efficient collection of parameters from the environment, in contrast to the 11-bit packets used in standard commercially available equipment. [ABSTRACT FROM AUTHOR]
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- 2023
- Full Text
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5. Coding techniques for convolutional codes
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Cvenić, Damjan and Grgić, Krešimir
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encoders ,polynomial generator ,coding ,konvolucijski kodovi ,generatorski polinom ,decoding ,TECHNICAL SCIENCES. Electrical Engineering. Telecommunications and Informatics ,dekodiranje ,convolutional code ,kodiranje ,TEHNIČKE ZNANOSTI. Elektrotehnika. Telekomunikacije i informatika ,koderi - Abstract
Konvolucijsko kodiranje zaštitno je kodiranje podataka u prijenosu. Takva vrsta kodiranja potrebna je kako bi se informacija zaštitila, da i nakon dekodiranja ne gubi svoj smisao. Konvolucijsko kodiranje, za razliku od blok kodova, uzima struju informacija i kodira ju. Prema tome kodna riječ može biti beskonačne duljine, a razlog je tome što i ulazna poruka isto tako može biti neograničena. Konvolucijsko kodiranje objasnit će se na primjerima dijagram stanja, dijagrama stabla, dijagrama rešetke, kodiranjem s memorijskim elementima. Nadalje, u radu će se govoriti o postupcima dekodiranja konvolucijskim kodovima kako bi potpuno razumjeli način konvolucijskog utjecaja na informaciju. Objasnit će se dva postupka dekodiranja, serijsko dekodiranje i Viterbijevo dekodiranje. Kroz analizu četiri vrste kodera pokazat će se da postoje razlike bez obzira što se koriste koderi s istom kodnom brzinom. Pokazat će se da koderi s različitim brojem memorijskih elemenata imaju drukčije vrijeme kodiranja, a rade s istom duljinom ulaznog niza bitova. Dokazat će se da simulacija i ručno kodiranje putem generatorskog polinoma daju isti kodirani niz. Grafički će se prikazati rezultati analize te njihova usporedbu. Convolutional code is a protected encoding of data in transmission. This type of coding is needed for data protection so that it does not lose its meaning even after the decoding process. Unlike block codes, convolutional coding takes a stream of data and encodes it. That code can be of infinite length because the input message can also be of infinite length. Convolutional coding will be shown using the examples of tree diagrams, lattice diagrams and with coding using memory elements. Furthermore, the ways of decoding using convolutional codes will be discussed, to fully understand the way convolution affects information. Two ways of decoding, serial decoding, and Viterbi decoding will be explained. It will be shown whether there are any differences between four types of encoders with the same encoding rate. The encoders with different number of memory elements have different encoding times while encoding the same length of the input bit string. It will be proven that simulation and manual coding with a polynomial generator gives the same coded sequence. The results will be compared and graphically represented
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- 2022
6. Development of the NB-IoT device communication module for mobile network
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Liović, Hrvoje, Grgić, Krešimir, and Lišnjić, Anđelko
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Low Power Wide Area Network - LPWAN ,TECHNICAL SCIENCES. Electrical Engineering. Telecommunications and Informatics ,Internet of Things ,TEHNIČKE ZNANOSTI. Elektrotehnika. Telekomunikacije i informatika ,Narrowband - IoT - Abstract
U radu je obrađen NB-IoT, kao uskopojasni komunikacijski standard za Internet stvari, tehničke karakteristike, njegovi glavni dijelovi i razvoj sustava za mjerenje NB-IoT signala. Za potrebe ovog rada detaljno su opisani moduli, koji čine eksperimentalni sustav funkcionalnim. U praktičnom dijelu opisano je razvojno rješenje NB-IoT uređaja. U zadnjem dijelu rada izvršena su potrebna mjerenja te je prikazana analiza rezultata mjerenja izmjerenih s analizatorom spektra FSH8 i razvojnim NB-IoT uređajem. The paper deals with NB-IoT, as a narrowband communication standard for the Internet of Things, technical characteristics, its main parts and the development of a system for measuring NB-IoT signals. For the purposes of this paper, the modules that make the experimental system functional are described in detail. The practical part describes the development solution of NB-IoT devices. In the last part of the paper, the necessary measurements were performed and the analysis of the measurement results measured with the FSH8 spectrum analyzer and development NB-IoT devices was presented.
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- 2022
7. The application of Mikrotik firewall in local area network
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Kučenjak, Inoslav and Grgić, Krešimir
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prijetnje na Internetu ,MikroTik RouterOS ,TECHNICAL SCIENCES. Electrical Engineering. Telecommunications and Informatics ,filtriranje prometa ,network protection ,TEHNIČKE ZNANOSTI. Elektrotehnika. Telekomunikacije i informatika ,traffic filtering ,Internet threats ,vatrozid ,zaštita mreže ,firewall - Abstract
Kako Internet postaje sve bitniji dio svakodnevnog života, ali isto tako i života raznih organizacija, bitno je znati kakvim se opasnostima izlažemo, te kako se možemo zaštititi i osigurati od raznih prijetnji kojima se izlažemo korištenjem Interneta. Unutar organizacije veliku ulogu sigurnosti čini ograničenje pristupa neovlaštenim korisnicima mreže organizacije, radi zaštite podataka i uređaja koji su pod tom organizacijom. Vatrozid pruža mogućnost kontrole toka prometa mreže i pristup mreži organizacije. Mogućnosti vatrozida i neke od sposobnosti prikazane su korištenjem usmjerivača MikroTik RouterOS. Cilj rada je prikazati te mogućnosti u uporabi, te na koji način vatrozid može pomoći pri održavanju prometa mreže sigurnim. Usmjerivačem su provedena pravila koja obuhvaćaju filtriranje paketa prema listi IP adresa, protokolima i portovima. Uporabom postavljenih pravila korištenja mreže omogućeno je korištenje mreže samo određenim korisnicima, čime je postignuta sigurnost mreže. As the Internet is becoming an increasingly important part of everyday life, but also the life of various organizations, it is important to know what dangers we are exposed to and how we can protect ourselves and insure ourselves against various threats to which we are exposed using the Internet. Within the organization, security plays a major role in restricting access to unauthorized users of the organization's network, in order to protect data and devices under that organization. A firewall provides the ability to control the flow of network traffic and access to an organization's network. The firewall possibilities and some of the capabilities are demonstrated using the MikroTik RouterOS router. The goal of this thesis is to show these possibilities in use and how a firewall can help keep network traffic safe. The router implements rules that include packet filtering according to the list of IP addresses, protocols and ports. By using the set network usage rules, it is possible to use the network only for certain users, thus achieving network security.
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- 2022
8. Analysis of the impact of social engineering on computer security
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Ević, Ena and Grgić, Krešimir
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računalna sigurnost ,socijalni inženjering ,attacks ,cybersecurity ,TECHNICAL SCIENCES. Electrical Engineering. Telecommunications and Informatics ,napadi ,social engineering ,TEHNIČKE ZNANOSTI. Elektrotehnika. Telekomunikacije i informatika ,phishing - Abstract
Napredak digitalnih tehnologija je olakšao i ubrzao dijeljenje informacija. Danas otvoreno dijelimo privatne podatke putem društvenih mreža bez puno razmišljanja, kako javno tako i kroz privatnu komunikaciju. Problem je što metode digitalne komunikacije ne garantiraju sigurnost prilikom razmjene i objavljivanja takvih informacija, i ne mogu garantirati da ih netko drugi neće znati iskoristiti za zloćudne radnje. Upravo takve sigurnosne propuste i rizike napadači iskorištavaju kako bi došli do informacija koje smatraju korisnima. Taj pristup iskorištavanja ljudske ranjivosti, u kontekstu računalne sigurnosti, kako bi se dobila korisna informacija naziva se socijalnim inženjeringom. Ovaj rad opisuje vrste napada socijalnim inženjeringom i alate koji se koriste kako bi se isti mogli provesti. Advances in digital technologies have made it easier and faster to share information. Today, we openly share private information through social media without much thought, both publicly and through private communication. The problem is that digital communication methods do not guarantee security when exchanging and publishing such information, and cannot guarantee that someone else will not know how to use it for malicious actions. It is precisely such security flaws and risks that attackers take advantage of in order to obtain information that they consider useful. This approach of exploiting human vulnerability, in the context of computer security, to obtain useful information is called social engineering. This paper describes the types of social engineering attacks and the tools used to carry them out.
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- 2022
9. Secure hash algorithms and their applications
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Dubravac, Marko and Grgić, Krešimir
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sigurnost podataka ,TECHNICAL SCIENCES. Electrical Engineering. Telecommunications and Informatics ,cryptographic hash functions ,SHA ,TEHNIČKE ZNANOSTI. Elektrotehnika. Telekomunikacije i informatika ,algoritam ,algorithm. integrity ,kriptografska hash funkcija ,data security ,integritet - Abstract
U ovom radu je bilo potrebno navesti skupinu kriptografskih hash algoritama SHA, objasniti način rada i njihovu primjenu te izraditi algoritam u programskoj platformi MATLAB. U prvom dijelu rada objašnjena je skupina kriptografskih hash funkcija, kao i način rada SHA skupine algoritama. Naveden je proces izrade svakog algoritma te su uspoređeni. Na kraju se nalazi postupak izrade SHA-256 koristeći MATLAB-u. The goal of this thesis was to explain cryptographic hash functions SHA, explain their way of working and their application and to create algorithm using programming platform MATLAB. In the first part of the thesis, a group of cryptographic hash functions is explained, as well as the working method of the SHA group of algorithms. The process of creating each algorithm is listed and they are compared. Finally, there is a procedure for creating SHA-256 using MATLAB.
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- 2022
10. Ethical hacking and cybersecurity
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Mrganić, Stjepan and Grgić, Krešimir
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ethical hacking ,penetration testing ,penetracijsko testiranje ,system security analysis ,etičko hakiranje ,TECHNICAL SCIENCES. Electrical Engineering. Telecommunications and Informatics ,cyber security ,sigurnosna analiza ,kibernetička sigurnost ,TEHNIČKE ZNANOSTI. Elektrotehnika. Telekomunikacije i informatika ,risk management ,menadžment rizika - Abstract
Diplomski rad sažeto objašnjava ključne pojmove kibernetičke sigurnosti poput klasifikacije napada i napadača te njihovih motiva za napade. Opisano je značenje i važnost pojmova povjerljivosti, integriteta i dostupnosti za područje sigurnosti. Navedene su razine provedbe testiranja sustava i stadiji provedbe napada na sustav. Razjašnjeni su pojmovi rizika i ranjivosti. Objašnjeni su načini prepoznavanja rizika, analiziranja i rukovanja njime iz perspektive menadžmenta rizika. Definirani su postupci i mjere za ostvarivanje kibernetičke sigurnosti. Na praktičnom primjeru pokazano je korištenje alata za provođenje sigurnosnog testiranja i načini kojima je moguće ostvariti neovlašten administratorski pristup sustavu. Naposlijetku, opisani su problemi koji su nastali prilikom testiranja i načini njihovog rješavanja. The thesis briefly explains the key concepts of cyber security such as attack and attacker classification as well as their motives. The meaning and importance of confidentiality, integrity, and availability for the field of cyber security are described. The stages of testing system security are listed along with the stages of conducting a system attack. The distinction between risk and vulnerability is clarified. Risk recognition, analysis and governance are explained from the perspective of risk management. A practical example shows the use of tools for conducting security testing and the ways in which it is possible to gain an unauthorized administrator access to the system. Finally, the problems that arose during the testing period and respective resolutions are delineated.
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- 2022
11. The use of Zero Trust model for cloud security assessment
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Živković, Anastazija and Grgić, Krešimir
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oblak ,procjena ,assessment ,questionnaire method ,security ,NIST ,sigurnost u oblaku ,ISO ,cloud ,PaaS ,metoda upitnika ,savjetništvo ,TECHNICAL SCIENCES. Electrical Engineering. Telecommunications and Informatics ,sigurnosni okviri ,IaaS ,sigurnost ,TEHNIČKE ZNANOSTI. Elektrotehnika. Telekomunikacije i informatika ,sigurnosna rješenja ,cloud security ,SaaS ,security frameworks ,consulting ,network ,security solutions ,mreža ,Zero Trust - Abstract
Zero Trust je koncept koji je zasnovan na motu never trust, always verify. Upravo ova rečenica označava kako se Zero Trust princip koristi pri svakoj od komponenti oblaka za provjeru aplikacija, usluga, uređaja, podataka i mreže. Na taj način moguće je zaštititi sve dijelove oblaka i informacije pohranjene u oblaku. U Zero Trust modelu mijenja se dosadašnje poimanje sigurnosti računalstva u oblaku te se smatra kako se napadač mrežom može kretati lateralno. Upravo zato je potrebno stalno iznova provjeravati prava dodijeljena svakoj komponenti oblaka, koristeći autentifikaciju, verifikaciju i autorizaciju. Zero Trust is a concept whose motto is never trust, always verify. This sentence proves that Zero Trust principle has been used for every component of cloud, to check applications, services, devices, data and network. In this way it is possible to protect every cloud component, including information which is stored in cloud. Zero Trust model changes former understanding of cloud security and it considers that malicious attacker's lateral movement through the network is possible. This is the reason why it is necessary to circurarly check dedicated rights for every system component, by using authentication, verification and authorization.
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- 2022
12. Digital identities in cloud
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Klobučar, Dora and Grgić, Krešimir
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Cloud ,TECHNICAL SCIENCES. Electrical Engineering. Telecommunications and Informatics ,TEHNIČKE ZNANOSTI. Elektrotehnika. Telekomunikacije i informatika ,security ,sigurnost i digitalni identitet ,digital identity - Abstract
U ovom diplomskom radu detaljno je opisano upravljanje digitalnim identitetima u oblaku. U uvodu je nešto detaljnije rečeno o tehnologijama u oblaku. Nakon toga su definirani koncepti računalstva u oblaku, principi koji se koriste, modeli, svojstva i ostale karakteristike. Objašnjeno je sigurno računalstvo u oblaku, sigurni hipervizori i šifriranje podataka. Zadnja dva poglavlja objašnjavaju digitalno upravljanje u oblaku te standarde i nedostatke koji se javljaju prilikom upravljanja. Naveden je detaljan primjer sigurnosnog problema i prijedlog njegovog rješenja. This thesis describes in detail the management of digital identities in the cloud. In the introduction, something was said in more detail about cloud technologies. After that, the concepts of cloud computing, the principles used, models, properties and other characteristics are defined. Secure cloud computing, secure hypervisors and data encryption explained. The last two chapters explain digital management in the cloud and the standards and shortcomings that arise during management. A detailed example of a security problem and a proposal for its solution are given. The detailed example of security problem is given and solution for it.
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- 2022
13. Security of endpoint devices in corporative environment
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Lenić, Martina and Grgić, Krešimir
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threats ,cybersecurity ,TECHNICAL SCIENCES. Electrical Engineering. Telecommunications and Informatics ,endpoints ,kibernetička sigurnost ,TEHNIČKE ZNANOSTI. Elektrotehnika. Telekomunikacije i informatika ,krajnji uređaji ,ugroze ,EDR ,Crowdstrike Falcon - Abstract
U ovom diplomskom radu naglasak je bio na važnosti krajnjih uređaja u organizaciji te njihovoj ranjivosti, a što uvelike utječe na reduciranje kompletne sigurnosti korporacijskog okruženja. Krajnji uređaji kao ulazne točke i pritom najranjiviji dio organizacije predstavljaju važan dio okruženja kod procjene i primjene sigurnosnih kontrola. Od zlonamjernih programa koji kompromitiraju sustave i tehnika socijalnog inženjeringa za kompromitiranje korisničkih identiteta, danas se organizacije svakodnevno susreću i bore s raznoraznim prijetnjama koje za cilj imaju ugroziti sigurnost i poslovanje organizacija. Iz tog se razloga javlja potreba za povećanjem opsega kibernetičke sigurnosti u svim aspektima korporacijskog okruženja, a koji osim krajnjih uređaja uključuju mreže, osoblje i oblak. Osim implementacije vatrozida, proxyja, sustava detekcije i prevencije upada, VPN, segmentacije mreže, EDR rješenja i ostalih sigurnosnih kontrola postavljenih u svim dijelovima organizacije, važnost se stavlja i na procese oporavka te odgovora na incidente. To su dodatni obrambeni mehanizmi kojima se pokrivaju situacije u kojima dolazi do napada i ozbiljne kompromitiranosti uređaja, sustava i korisničkih identiteta. Aktivnosti, djelovanja, odgovori i implementacije unutar organizacije proizlaze iz posture i okvira kibernetičke sigurnosti kroz police, procedure, procese i smjernice kojima se definiraju pristupi sigurnosti unutar organizacije s naglaskom na identificiranje, zaštitu, detekciju, odgovor i oporavak. n this master's thesis the emphasis was on the importance of endpoint devices in organizations and their vulnerability which greatly affects the reduction of the complete security of the corporate environment. As entry points and with that the most vulnerable organization's asset endpoints represent an important part of the environment when assessing and applying security controls. From malicious programs (malwares) that compromise systems and social engineering techniques that compromise user's identities, organizations encounter and fight a variety of threats that aim to compromise the security and corporate operations on a daily basis. For this reason, there is a need to increase the scope of cybersecurity in all aspects of the corporate environment, which in addition to endpoints include networks, personnel and the cloud workloads. In addition to the implementation of firewalls, proxies, intrusion detection and prevention systems, VPN, network segmentation, EDR solutions and other security controls placed in all parts of the organization, importance is also placed on recovery processes and incident response. These are additional defense mechanisms to cover situations where attacks occur alongside serious compromise of devices, systems and user identities. Activities, actions, responses and implementations within the organization derive from the posture and framework of cybersecurity through policies, procedures, processes and guidelines that define security approaches within the organization with an emphasis on identification, protection, detection, response and recovery.
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- 2022
14. Security attack analysis in network and application environment
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Kosić, Matej and Grgić, Krešimir
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TECHNICAL SCIENCES. Electrical Engineering ,Mrežni napad ,TEHNIČKE ZNANOSTI. Elektrotehnika. Telekomunikacije i informatika ,Aplikacijski napad ,Network attack ,DDoS ,Application attack - Abstract
Cilj rada bio je analizirati najpoznatiji sigurnosni napadi u aplikacijskoj i mrežnoj domeni pri čemu je poseban naglasak stavljen na analizu raspodijeljenih napada uskraćivanja usluge. U prvom dijelu rada predstavljeni su osnovni pojmovi vezani za sigurnosne napade nakon čega se pristupilo odvojenoj analizi napada najprije u aplikacijskoj, a zatim i u mrežnoj domeni. Potom se pobliže upoznalo s DDoS napadima i različitim metodama njegovog izvođenja ovisno o meti napada. Obavljen je pregled najnovijih statističkih izvještaja i najpoznatijih dosad zabilježenih DDoS napada. U posljednjem poglavlju opisane su različiti načini obrane te su predloženi preventivni koraci sprječavanja napada. The aim of this thesis was to analyse the most well-known security attacks in the application and network domains, focusing in particular on the analysis of distributed denial-of-service attacks. The first part of the work presents basic concepts related to security attacks, followed by a separate analysis of the attacks first in the application and then in the network domain. The DDoS attacks and the various methods of conducting it depending on the target of the attack were then made more familiar. A review of the latest statistical reports and the most well-known DDoS attacks recorded so far was carried out. The last chapter describes the different means of defence and proposes preventive steps to prevent attacks.
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- 2022
15. Implementation of artificial intelligence in smart cities
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Vučetić, Domagoj, Crnjac Milić, Dominika, and Grgić, Krešimir
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TEHNIČKE ZNANOSTI. Računarstvo. Umjetna inteligencija ,machine learning ,smart city ,umjetna inteligencija ,pametni grad ,artificial intelligence ,TECHNICAL SCIENCES. Computing. Artificial Intelligence ,strojno učenje - Abstract
Sve veća urbanizacija sa sobom je donijela brojne klimatske, ekološke, tehnološke i ekonomske probleme koji smanjuju kvalitetu života. Kako bi se ti problemi riješili nastao je koncept pametnog grada koji primjenom raznih tehnologija podiže kvalitetu života. Umjetna inteligencija jedna je od tih tehnologija. Implementacijom umjetne inteligencije u razna područja grada kvaliteta života drastično se podigla. Kvalitetnija medicinska pomoć, bolja prometna povezanost dijelova grada, manja potrošnja energije, bolje obrazovanje te smanjenje troškova života samo su neke od mnogih prednosti implementacije umjetne inteligencije u gradove. Naravno postoje i neke posljedice koje će s razvitkom umjetne inteligencije postajati sve manje i manje. Na kraju objašnjen je i plan grada Osijeka da postane pametni grad povezujući razne dijelove infrastrukture grada. Increasing urbanization has brought with itself numerous climatic, environmental, technological and economic problems that reduce the quality of life. In order to solve these problems, the concept of a smart city was created, which raises the quality of life by applying various technologies. Artificial intelligence is one of these technologies. With the implementation of artificial intelligence in various areas of the city, the quality of life has risen drastically. Better medical care, better transport connectivity of the city, lower energy consumption, better education and reduced cost of living are just some of the many benefits of implementing artificial intelligence in cities. Of course, there are also some consequences that will become smaller and smaller with the development of artificial intelligence. Finally, the plan of the city of Osijek to become a smart city by connecting various parts of the city's infrastructure was explained.
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- 2022
16. Mathematical background of the AES cryptosystem
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Doko, Dubravka, Katić, Anita, and Grgić, Krešimir
- Subjects
modular arithmetic ,decryption ,Byte Substitution layer ,Galois field ,NIST ,polje ,key ,group ,ShiftRow ,kriptografija ,encryption ,Diffusion layer ,linearna algebra ,AES ,cryptography ,modularna aritmetika ,TECHNICAL SCIENCES. Electrical Engineering. Telecommunications and Informatics ,Key Addition layer ,prsten ,TEHNIČKE ZNANOSTI. Elektrotehnika. Telekomunikacije i informatika ,National Institute of Standards and Technology ,Rijndaela ,DES ,field ,Galois polje ,Advanced Encryption Standard ,linear algebra ,deširiranje ,MixColumn ,ključ ,grupa ,ring ,šifriranje - Abstract
National Institute of Standards and Technology (NIST) je 1997. godine raspisao natječaj za novi napredni standard šifriranja, te je 2000. godine objavio da je odabrao Rijndaela kao AES. Rijndaela je naslijedio DES koji je postajao sve ranjiviji. Advanced Encryption Standard je 2001. godine odobren kao moderni standard za šifriranje podataka. Ima široku primjenu na raznim područjima, od povjerljivih državnih dokumenata do prometa putem Wi-Fi usmjerivača. AES koji koristimo su razvila dva belgijska kriptografa Joan Daemen i Vincent Rijmen. Razvili su šifru Rijandel kojoj veličina bloka varira od 128, 192 do 256 bita. Međutim AES koristi samo veličinu bloka od 128 bita. Vrlo bitno svojstvo AES-a je što koristi isti ključ za proces šifriranja i dešifriranja. Rijndael podržava tri duljine ključa 128, 192 i 256 bita. U procesu šifriranja i dešifriranja razlikujemo tri vrste slojeva: Sloj dodavanja ključa ( eng. Key Addition layer), Sloj zamjene bajtova (eng. Byte Substitution layer (S-Box)) i Difuzijski sloj (eng. Diffusion layer) koji se dijeli na dva podsloja (ShiftRow i MixColumn). U pozadini tih slojeva koristi se nekoliko ključnih matematičkih koncepata iz linearne algebre i teorije prstena. Algoritam uključuje 10 do 14 rundi u kojima se izmjenjuju navedeni slojevi s manjim razlikama u prvoj i zadnjoj rundi izvođenja. U svakom od navedenih koraka AES algoritma vrši se jednostavna radnja s matematičkim izračunima. In 1997, the National Institute of Standards and Technology (NIST) announced a competition for a new advanced encryption standard, and in 2000 announced that it had selected Rijndael as AES. Rijndael was succeeded by DES, which was becoming increasingly vulnerable. The Advanced Encryption Standard was approved in 2001 as the modern-standard for data-encryption. It is widely used in a variety of areas, from classified-government-documents to traffic-through Wi-Fi routers. The AES we use was-developed by two Belgian-cryptographers, Joan-Daemen and Vincent Rijmen. They developed the Rijandel cipher, whose block size varies from 128, 192 to 256 bits. However, AES only uses a block size of 128 bits. A very important property of AES is that it uses the same key for the encryption and decryption process. Rijndael supports three key lengths 128, 192 and 256 bits. In the encryption and decryption process, we distinguish three types of layers: Key Addition layer, Byte Substitution layer (S-Box) and Diffusion layer, which is divided into two sublayers (ShiftRow and MixColumn). In the background of these layers, several key mathematical concepts from linear algebra and ring theory are used. The algorithm includes 10 to 14 rounds in which the specified layers are alternated with minor differences in the first and last rounds of execution. In each of the mentioned steps of the AES algorithm, a simple action with mathematical calculations is performed.
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- 2022
17. RTP and RTCP protocol analysis using network analyzer
- Author
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Vračić, Josip and Grgić, Krešimir
- Subjects
RTCP ,Jitsi ,RTP ,Wireshark ,VoIP ,TECHNICAL SCIENCES. Electrical Engineering. Telecommunications and Informatics ,TEHNIČKE ZNANOSTI. Elektrotehnika. Telekomunikacije i informatika - Abstract
Kontinuirani razvoj tehnologije imao je velik utjecaj na način današnje komunikacije i razmjene informacija, stoga se kroz rad nastojalo analizirati RTP (engl. Real Time Transport Protocol) i RTCP protokole (engl: Real Time Control Protocol). U prošlosti su prve mreže omogućavale prenošenje samo jedne vrste informacija, dok je danas situacija znatno drugačija, stoga je današnjom tehnologijom moguće istovremeno obaviti prijenos više različitih vrsta informacija. RTP protokol je tako razvijen kako bi bio standardizirana podrška prilikom prijenosa isporuke audio-vizualnog sadržaja, u stvarnom vremenu i sa što manje kašnjenja, a uvijek se koristi u korelaciji sa RTCP protokolom. Za potrebe izrade ovog rada korišten je mrežni analizator Wireshark, pomoću kojega su analizirani podatkovni tokovi radi analize RTP i RTCP protokola. Dakle, pomoću istog programa analizirana je audio sjednica, video sjednica te video konferencija, a promet navedenih sjednica odvijao se putem aplikacije Jitsi. Continuous development of technology has had a great impact on the way of today's communication and information exchange, so the paper sought to analyze RTP (Real-Time Transmission Protocol) and RTCP Protocol (Real-Time Control Protocol). In the past, the first networks allowed the transmission of only one type of information, while today the situation is much different, so with today's technology it is possible to transmit several different types of information at the same time. The RTP protocol has been developed to be a standardized support for the transmission of audio-visual content delivery, in real time and with as few delays as possible, and is always used in correlation with the RTCP protocol. For the purposes of this paper, the Wireshark network analyzer was used, which was used to analyze data flows for the analysis of RTP and RTCP protocols. Accordingly, with the help of the same program, the audio session, video session and video conference were analyzed, and the traffic of these sessions took place via Jitsi applications.
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- 2022
18. Network scanning and vulnerabilities
- Author
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Marek, Ana and Grgić, Krešimir
- Subjects
Mrežna ranjivost ,Computer network ,Network vulnerability ,Skeniranje mreže ,TECHNICAL SCIENCES. Electrical Engineering. Telecommunications and Informatics ,Ključni principi sigurnosti ,Vulnerability scanning ,TEHNIČKE ZNANOSTI. Elektrotehnika. Telekomunikacije i informatika ,Računalne mreže ,Skeniranje ranjivosti ,Network scanning ,Key security principles - Abstract
Završni rad podijeljen je na pet cjelina. U prvoj cjelini definirane su računalne mreže, kako upravljati računalnim mrežama i održavati ih. Druga cjelina definira što je mrežna ranjivosti, koji su ciljevi potencijalnih napada i opis zlonamjernih softvera. Treća cjelina sadrži ključne principe sigurnosti, smjernice kako uspostaviti računalnu sigurnost te prijedloge rukovanja propustima. U četvrtoj cjelini prikazani su programi za skeniranje računalne mreže i skeniranje ranjivosti. U zaključku su istaknute neke smjernice za bolje razumijevanje sigurnosti mreže i time povećanje razine zaštite sustava. The final paper is divided into five parts. In the first part, computer networks are defined, how to manage and maintain computer networks. The second unit defines what network vulnerabilities are, what the targets of potential attacks are, and the description of malware. The third section contains key security principles, guidelines on how to establish computer security, and suggestions for handling vulnerabilities. The fourth part presents programs for computer network scanning and vulnerability scanning. In conclusion, there are listed some guidelines for better understanding of network security and thus increading the level of system preotection.
- Published
- 2022
19. Wireless positioning using Wi-Fi networks
- Author
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Balić, Luka and Grgić, Krešimir
- Subjects
WLAN ,bežično pozicioniranje ,TECHNICAL SCIENCES. Electrical Engineering. Telecommunications and Informatics ,IPS ,TEHNIČKE ZNANOSTI. Elektrotehnika. Telekomunikacije i informatika ,Wi-Fi ,AP ,Cell-ID ,wireless positioning - Abstract
Tema ovog rada je bežično pozicioniranje pomoću Wi-Fi mreže. Prvi dio rada se bavi teorijskim dijelom opisivanja razvoja Wi-Fi-a, WLAN arhitekture i njezinih komponenata. Također, opisuje se problematika i funkcioniranje pozicioniranja u zatvorenim prostorima te IPS sustava. Zatim, slijedi usporedba različitih tehnologija, tehnika i algoritama za pozicioniranje u zatvorenom prostoru. Zadnji dio rada se odnosi na provedbu mjerenja snage signala pet AP-ova postavljenih na hodniku u zgradi Fakulteta elektrotehnike, računarstva i informacijskih tehnologija Osijek – FERIT. Svrha mjerenja je bila izmjeriti mobilnom aplikacijom u odabranim referentnim točkama duž cijelog hodnika snagu signala svakog pojedinog AP-a u datoj točki. Na temelju prikupljenih podataka i uz pomoć Cell-ID metode pokušala se procijeniti lokacija odabranih točaka i usporediti sa stvarnom lokacijom koja je poznata. Prikupljeni podaci su prikazani tablično i pomoću grafova, te su opisana zapažanja i zaključci. The topic of this thesis is wireless positioning using a Wi-Fi network. The first part of the paper deals with the theoretical part of describing the development of Wi-Fi, WLAN architecture and its components. Also, the problems and functioning of positioning indoors and IPS system are described. Then, a comparison of different technologies, techniques and algorithms for indoor positioning follows. The last part of the paper refers to the implementation of signal strength measurements of five APs installed in the hallway in the building of the Faculty of Electrical Engineering, Computing and Information Technology Osijek - FERIT. The purpose of the measurement was to measure the signal strength of each individual AP at a given point with a mobile application at selected reference points along the entire corridor. Based on the collected data and using the Cell-ID method, an attempt was made to estimate the location of the selected points and compare them with the actual location known. The collected data are presented in tables and graphs, and observations and conclusions are described.
- Published
- 2021
20. Bluetooth Low Energy (BLE) and its applications
- Author
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Flisar, Stjepan and Grgić, Krešimir
- Subjects
skeniranje ,scanning ,periferni uređaj ,TECHNICAL SCIENCES. Electrical Engineering. Telecommunications and Informatics ,peripheral device ,central device ,TEHNIČKE ZNANOSTI. Elektrotehnika. Telekomunikacije i informatika ,advertising ,Bluetooth Low Energy (BLE) ,centralni uređaj ,oglašavanje - Abstract
Bluetooth Low Energy (BLE) predstavljen je u inačici Bluetooth 4.0., sa svojstvom smanjene potrošnje energije uređaja koji međusobno komuniciraju. BLE radi u pojasu širine 2.4 GHz (ISM) koji je segmentiran u 40 radio frekvencijskih kanala, svaki širine po 2 MHz gdje se tri posljednja kanala koriste za oglašavanje a preostalih 37 za prijenos podataka. Arhitektura protokolnog stoga BLE-a čine slojevi kontroler, host i aplikacijski sloj sa pripadajućima slojevima. U komunikaciji mogu sudjelovati uređaji kao što su periferni uređaja, emiter, centralni uređaj i promatrač. Prije uspostave komunikacije uređaji se oglašavaju i skeniraju kako bi mogli prenositi međusobno podatke. U stanju oglašavanja, uređaj šalje pakete koji sadrže korisne podatke drugima koji ih primaju i obrađuju. Nakon uspostavljene veze definira se način na koji će jedan od uređaja, poslužitelj, predočiti svoje podatke klijentu što predstavlja ATT i format servisa i njihove karakteristike što predstavlja GATT. Sigurnost u BLE tehnologiji upravlja Security Manager (SM) koji definira protokole i algoritme za generiranje i razmjenu ključeva između dva uređaja. 2017. godine Bluetooth SIG predstavio je Bluetooth mrežni standard (eng. Bluetooth mesh) gdje više uređaja mogu međusobno slati poruke. Bluetooth Low Energy (BLE) is introduced in Bluetooth version 4.0, with the property of reduced power consumption of devices that communicate with each other. The BLE operates in the 2.4 GHz band (ISM) which is segmented into 40 radio frequency channels, each 2 MHz wide where the last three channels are used for advertising and the remaining 37 for data transmission. The BLE protocol stack architecture consists of a controller, host, and an application layer with associated layers. Devices such as a peripheral device, emitter, central device, and an observer can participate in communication. Before establishing communication, the devices are advertised and scanned so that they can transmit data. In the advertising state, the device sends packets containing useful data to others who receive and process it. Once the connection is established, the way in which one of the devices, the server, presents its data to the client, which is ATT and the format of the service, and their characteristics, which is GATT, is defined. Security in BLE technology is managed by Security Manager (SM) which defines protocols and algorithms for generating and exchanging keys between two devices. In 2017, the Bluetooth SIG introduced the Bluetooth mesh standard, where multiple devices can send messages to each other.
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- 2021
21. Transmission and reflection parameters of a composite building block for the frequency range from 600 to 6000 MHz
- Author
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Sudar, Adam, Rupčić, Slavko, and Grgić, Krešimir
- Subjects
betonski blok ,TECHNICAL SCIENCES. Electrical Engineering. Radio Communications ,S12 parameter ,TEHNIČKE ZNANOSTI. Elektrotehnika. Radiokomunikacije ,Antene ,Računalna simulacija ,ANSYS HFSS ,Antennas ,S12 parametar ,slabljenje signala ,concrete block ,Computer simulation ,signal attenuation - Abstract
U radu se provodi simulacija nad različitim vrstama bentoskog bloka da se vidi njegov utjecaj na transmisijske parametre antena. Antene imaju široku primjenu sve od komunikacije sa satelitima sve do wi-fi signala u kući, beton kao najkorišteniji građevinski materijal ima velik utjecaj na signal koji antene emitiraju. U uvodnom poglavlju opisane su korištene tehnologije i traženi parametri simulacije. Drugo poglavlje opisuje proces kreiranja modela simulacije te izmjene koje su rađenje na modelu bloka. U četvrtom poglavlju su dobiveni rezultati različitih simulacija, koji se uspoređuju. The parer carried out simulation of different types of concrete block to see its effect on the transmission parameters of the antenna. Antennas have a wide application from communication with satellites to wi-fi signals in the house, concrete as the most used building material has a great influence on the signal that the antennas emit. The introductory chapter describes the technologies used and the required results parameters. The second chapter describes the process of creating a simulation model and the changes that are made to the block model. In the fourth chapter, the results of different simulations are obtained, which are compared.
- Published
- 2021
22. Ethical hacking - tools and examples
- Author
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Šimić, Mihovil and Grgić, Krešimir
- Subjects
ethical hacking ,stages of ethical hacking ,etičko hakiranje ,TECHNICAL SCIENCES. Electrical Engineering. Telecommunications and Informatics ,alati ,faze etičkog hakiranja ,tools ,TEHNIČKE ZNANOSTI. Elektrotehnika. Telekomunikacije i informatika ,uređaji ,devices - Abstract
Cilj ovog rada bio je definirati i objasniti pojam etičkog hakiranja, definirati razlike u odnosu na neetičko te istaknuti relevantnost istoga u današnjem društvu. Objašnjeni su najčešći sigurnosni propusti i ishodi ako se isti ne otkriju na vrijeme. Kroz demonstraciju alata prikazan je postupak sigurnosnog testiranja u svrhu pronalaska određenih propusta te su predloženi postupci za popravljanje i buduće izbjegavanje istih. Za svaki je alat detaljno objašnjena teorija područja na kojemu se alat koristi, opisane su značajke te su praktičnim primjerom prikazane mogućnosti i važnost alata. Zatim su objašnjeni uređaji koji poboljšavaju rad alata i olakšavaju sigurnosno testiranje. Za svaki uređaj objašnjeno je područje primjene i opisane su najvažnije značajke. Na kraju su objašnjene i opisane faze etičkog hakiranja. Za svaku je fazu istaknuto koji se prethodno objašnjeni alati i uređaji koriste, što je cilj provođenja faze te važnost pravilnog izvođenja zbog uspješnog provođenja postupka sigurnosnog testiranja. The aim of this paper was to define and elaborate on the concept of ethical hacking, differentiate it from the unethical hacking and emphasize its relevance in today's society. The most common security vulnerabilities along with consequences of their late detection are listed. Demonstrating the tools, the security testing procedure for finding certain vulnerabilities accompanied by procedures for fixing and avoiding them in the future is explained. The field of use and tool features are elaborated on and exemplified. Furthermore, devices which enhance or replace the tools are explained. Each device’s main features and usages are analyzed. Finally, the phases of ethical hacking are described relating each phase with previously described tools and devices. Each phase aim and the importance of proper execution for the purpose of successful security testing procedure implementation is clarified.
- Published
- 2021
23. Creating multiple service set identifiers
- Author
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Kuna, Renato and Grgić, Krešimir
- Subjects
Pristupna točka ,Skeniranje ,TECHNICAL SCIENCES. Electrical Engineering. Telecommunications and Informatics ,Beacon Management Frame ,TEHNIČKE ZNANOSTI. Elektrotehnika. Telekomunikacije i informatika ,Bežična mreža ,Scanning ,Service set identifier ,Beacon okvir ,Wireless network ,Identifikator postavljenog servisa ,Access point - Abstract
U okviru ovog završnog rada obavljena je simulacija i konfiguracija identifikatora postavljenog servisa na opremi MikroTik RouterBOARD 951Ui 2HnD koja je dodijeljena od strane fakulteta. Prije obavljanja same simulacije provedeno je istraživanje WLAN mreža u kojima se koriste identifikatori postavljanog servisa. Opisane su prednosti WLAN mreža naspram žičnih mreža, način njihove implementacije te načini kojima se mogu detektirati. Definiran je pojam identifikatora postavljenog servisa i njegov utjecaj na sigurnost bežičnih mreža. Naposlijetku, kratko je opisana korištena oprema i svi popratni programi koji su bili potrebni za ostvarivanje simulacije. Simulacija je pokrivala i početnu konfiguraciju opreme koja je bila potrebna za daljnji postupak. As part of this final paper, a simulation and configuration of service set identifiers was performed on MikroTik RouterBOARD 951Ui 2HnD equpment which was provided by the college. Before performing the simulation, a research of WLAN networks was conducted in which the service set identifiers are used. The advantages of WLAN networks over wired networks, their implementation and the ways in which they are detected are described. The notion of service set identifier and its impact on wireless network security is defined. Finally, the used equipment and all the accompanying programs that were needed to perform the simulation are briefly described. The simulation also covered the initial configuration of the equipment needed for the further procedure.
- Published
- 2021
24. Challenges of 4G to 5G mobile network transition
- Author
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Mandić, Mihaela and Grgić, Krešimir
- Subjects
izazovi ,karakteristike mreže ,network characteristics ,5G mreža ,TECHNICAL SCIENCES. Electrical Engineering. Telecommunications and Informatics ,4G LTE network ,5G network ,TEHNIČKE ZNANOSTI. Elektrotehnika. Telekomunikacije i informatika ,challenges ,4G LTE mreža - Abstract
U ovom završnom radu objašnjene su generacije mobilnih mreža prije 5G mreže s naglaskom na 4G mrežu i 5G mrežu. Objašenjene su karakteristike 4G LTE mreže kako bi se vidjele razlike u odnosu na 5G mrežu. Objašnjeni su izazovi prijelaska s 4G LTE mreže na 5G mrežu te je detaljno objašnjena 5G mreža. In this bachelor thesis are explained generations of mobile network before 5G network with an emphasis on the 4G network and 5G network. The characteristics of the 4G LTE network are explained in order to see the differences between 4G and 5G network. The challenges of the transition from 4G LTE network to 5G network are explained and the 5G network is explained in detail.
- Published
- 2021
25. Rehoming in mobile networks
- Author
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Staković, Ivan and Grgić, Krešimir
- Subjects
TECHNICAL SCIENCES. Electrical Engineering. Telecommunications and Informatics ,network ,ćelija ,TEHNIČKE ZNANOSTI. Elektrotehnika. Telekomunikacije i informatika ,mreža ,okruženje ,rehoming ,rollback ,cell ,environment - Abstract
U ovom završnom radu prikazan je proces rada rehominga u 2G mreži. Najprije je objašnjeno što je rehoming kao pojam. Nakon toga, prikazani su parametri koji karakteriziraju mrežu. Slikovno su prikazane strukture mreža, od koliko ćelija se okruženje sastoji i kakvog je okruženje tipa. Za skiciranje mreže korišten je Google alat za crtanje. Sve naredbe dobivene postupkom rehominga i rollbacka detaljno su objašnjene. In this final paper, the rehoming process in a 2G network is presented. It is first explained what rehoming is as a term. After that, the parameters that characterize the network are displayed. The structures of the networks are shown with pictures, how many cells the environment consists of and what type of environment it is. The Google drawing tool was used to sketch the grid. All commands obtained by the rehoming and rollback procedure are explained with details.
- Published
- 2021
26. Wireless network security analysis
- Author
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Skočibušić, Davor, Martinović, Goran, and Grgić, Krešimir
- Subjects
sigurnost ,TEHNIČKE ZNANOSTI. Računarstvo. Informacijski sustavi ,wireless network ,čovjek u sredini ,neovlašteni pristup ,bežična mreža ,security ,man in the middle ,brute-force attack ,TECHNICAL SCIENCES. Computing. Information Systems ,napad sirovom snagom ,unauthorized access - Abstract
Cilj ovog rada bio je opisati probleme bežičnog načina rada WI-FI mreže te teoretski i primjerom pokazati slabosti koje ista koristi. Jedan sigurnosni protokol koji se danas još uvijek u ne znanju koristi među širom populacijom predstavlja primjer lošeg načina zaštite. Na druga dva su prikazani mogući napadi kako bi se ostvario pristup mreži u obliku napada sirovom snagom na uhvaćeni proces rukovanja, te oblik napada društvenog inženjerstva gdje se korisnika navodi na otkrivanje pristupnog ključa mreže. Opisani su procesi neovlaštenog nadziranja korisnika i podvaljivanja korisniku, ostvarivanju neovlaštenog pristupa računalu, te uvođenju preporuka za povećanje razine sigurnosti u bežičnoj mreži. Prikazano je korištenje alata Metasploit Framework i nmap kako bi se ostvario daljinski pristup računalu koje se nalazi na istoj mreži kao i napadač. Modelom je prikazan napada čovjek u sredini gdje se pomoću Wiresharka nadzire promet korisnika, te pomoću alata ettercap podvaljuje se lažni sadržaj korisniku u obliku lažnih DNS adresa. Na posljetku su dane preporuke zaštite koje napadačima mogu otežati pristup WI-FI mreži i zlonamjernoj aktivnosti na istoj. The aim of this final work was to describe the problems of wireless operation of the WI-FI network and to show theoretically and by example the weaknesses that it has. One security protocol that is still unknowingly used today among the general population is an example of poor protection. The other two show possible attacks to gain access to the network in the form of a bruteforce attack on the captured handshake process, and a form of social engineering attack where the user is instructed to give the network access key. The processes of unauthorized monitoring of the user and cheating the user, gaining unauthorized access to the computer, and introducing recommendations for increasing the level of security in the wireless network are described. The use of the Metasploit Framework and nmap tools to gain remote access to a computer on the same network as the attacker is shown. The model shows a human attack in the middle where Wireshark monitors user traffic, and uses the ettercap tool to trick fake content into fake user DNS addresses. Finally, protection recommendations were given that could make it difficult for attackers to access the WI-FI network and malicious activity on it.
- Published
- 2021
27. FIREWALLS AND EXAMPLES OF THEIR APPLICATION
- Author
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Gudelj, Ivan and Grgić, Krešimir
- Subjects
TECHNICAL SCIENCES. Electrical Engineering. Telecommunications and Informatics ,network ,mrežni napadi ,network security ,mrežna sigurnost ,Oracle VirtualBox ,TEHNIČKE ZNANOSTI. Elektrotehnika. Telekomunikacije i informatika ,mreža ,cyber-attacks ,vatrozid ,firewall - Abstract
Korištenje uređaja koji je povezan na internet korisnike automatski izlaže mogućem napadu i gubitku osobnih podataka koji su pohranjeni na tom uređaju. Potrebno je implementirati metode zaštite protiv mogućih napada. U radu je opisan postupak implementacije vatrozida u običnu korisničku mrežu te podešavanje njegovih mogućnosti. Vatrozid je najbolje sigurnosno rješenje budući da ima mogućnosti prijavljivanja uljeza i/ili zlonamjernog softvera u sustavu kao i mogućnost njihovog zaustavljanja. Implementacijom vatrozida je admnisnitrator dobio nadzor nad cjelokupnom mrežom. Usage of devices that have the ability to connect to the internet automatically puts users in danger by exposing them to cyber-attacks. It is necessary to implement security methods against possible cyber-attacks. This paper explains the firewall implementation procedure as well as modification of its services. Firewall is the best security solution because of its ability to locate and stop attackers and their malware. By implementing the firewall, administrator gains control of the entire network.
- Published
- 2021
28. Differential cryptanalysis
- Author
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Uršan, Josip and Grgić, Krešimir
- Subjects
supstitution-permutation networks ,diferencijalna kriptoanaliza ,TECHNICAL SCIENCES. Electrical Engineering. Telecommunications and Informatics ,S-kutije ,supstitucijsko-permutacijske mreže ,TEHNIČKE ZNANOSTI. Elektrotehnika. Telekomunikacije i informatika ,S-box ,differential cryptanalysis - Abstract
U ovom diplomskom radu opisana je temeljna ideja diferencijalne kriptoanalize na općenitom primjeru. Implementirana je jednostavna, proizvoljna, 4-bitna šifra sa dvije runde, jednom S-kutijom u svakoj rundu, te jednim potključem u svakoj rundi. Za ovu šifru provedena je potrebna analiza koju zahtijeva diferencijalna kriptoanaliza, a uključuje analizu karakteristike šifre do R-1 rundi i analizu frekvencija ulaza i izlaza šifre za karakteristiku do R-1 rundi. Nakon obavljene analize implementiran je napad kojeg opisuje diferencijalna kriptoanaliza na 4-bitnu šifru. Potključevi su uspješno dohvaćeni, a nad S-kutijom su provedeni daljnji testovi kako bi se uočio utjecaj konfiguracije S-kutije na ulazno-izlazne odnose. Sav programski kod realiziran je u python programskom jeziku. The fundamental idea of differential cryptanalysis is described in this thesis on a general example. A simple, arbitrary, 4-bit cipher has been implemented. This cipher consists of two rounds, one S-box in each round, and one subkey in each round. Necessary analysis dictated by differential cryptanalysis has been conducted for this 4-bit cipher, which includes analysing cipher characteristic to R-1 rounds and analysing input and output frequencies for cipher's R-1 round characteristic. After analysis, differential cryptanalysis attack on the 4-bit cipher has been implemented. Subkeys were successfully retrieved, and further analyses of S-boxes have been conducted to test out the S-box configuration influence on the input and output relations. All code was implemented using python programming language.
- Published
- 2021
29. Indoor positioning systems
- Author
-
Mendelski, Miran and Grgić, Krešimir
- Subjects
primjena sustava ,problems with positioning ,pozicioniranje ,TECHNICAL SCIENCES. Electrical Engineering. Telecommunications and Informatics ,tehnologije ,IPS ,TEHNIČKE ZNANOSTI. Elektrotehnika. Telekomunikacije i informatika ,mode of operations ,problematika pozicioniranja ,positioning ,BLE ,use of systems ,način rada ,technologies - Abstract
Samim napretkom i razvitkom tehnologije dolazi do sve većeg razvoja i korištenja sustava za pozicioniranje u zatvorenim prostorima. U radu se navode glavni problemi pozicioniranja u globalu te pozicioniranja u prostorima gdje GPS sustav nije moguće koristiti. Nadalje, prikazana su rješenja koja se koriste u smanjivanju i potpunom rješavanju problematike pozicioniranja. Opisan je pojam IPS sustava i prikazani su razlozi i uvjeti njegovog korištenja. Prikazane su glavne dostupne tehnologije s kojima je omogućeno lakše snalaženje i lociranje pozicije. Navedeni su najzastupljeniji IPS sustavi dostupni na tržištu te je prikazan način rada svakog od njih. Analizirane su glavne karakteristike i svojstva dostupnih uređaja i tehnologija te su uspoređene glavne metode kojima se koriste. Primjena sustava za unutarnje pozicioniranje je veoma široka te se razlikuje od potreba korisnika odnosno velikih kompanija s kojim uvjetuju korištenje različitih tehnologija i kombinacije istih. Svaki sustav ima svojih prednosti i mana te niti jedan nije savršen u svim kategorijama, no općenito najrašireniji i najpouzdaniji se pokazao BLE sustav zbog svoje preciznosti, jednostavnosti i sigurnosti. With an advancement and development of technology, there is a growth in using Indoor Positioning Systems. In this paper are listed the major problems in positioning and major problems for positioning in places where GPS system is not working properly. Further, the solutions, that are being used for reducing and completely solving problems in positioning, are shown. The term IPS system is described, as well as reasons and conditions of useing IPS. The most common IPS systems, that are available on market, are listed, as well as theirs operating system and theirs mode of operation. The main characteristics and properties of available devices and technologies are analyzed and the main methods are compared. Use of IPS is very wide and differs from the needs of users or large companies with which they require the use of different technologies. Each system has its advantages and disadvantages and none of the technologies are perfect in all categories, but in general the most widespread and the most reliable is BLE system due to his precision, simplicity and safety.
- Published
- 2021
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