Computer Engineering / Bilgisayar Mühendisliği

Permanent URI for this collectionhttps://hdl.handle.net/11147/10

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Now showing 1 - 10 of 36
  • Conference Object
    Kurt saldırıları için sentetik irislerde örnek seçilimi
    (IEEE, 2023) Akdeniz, Eyüp Kaan; Erdoğmuş, Nesli
    In this study, samples with higher potential to succeed in wolf attacks are picked among synthetically generated iris images, and the composed subset is shown to pose a more significant threat toward an iris recognition system backed by a Presentation Attack Detection (PAD) module with respect to randomly selected samples. Iris images generated by Deep Convolutional Generative Adversarial Networks (DCGAN) are firstly filtered by rejection sampling on PAD score distribution of real iris image PAD scores. Next, the probability of zero success in all attack attempts is calculated for each synthetic iris image, using real iris images in the training set, and match and non-match score distributions are calculated on those. Synthetic images with the lowest probabilities of zero success are included in the final set. Our hypothesis that this set would be more successful in wolf attacks is tested by comparing its spoofing performances with randomly selected sample sets.
  • Conference Object
    Citation - Scopus: 1
    A Lightweight and Energy Efficient Secrecy Outage Probability-Based Friendly Jamming
    (IEEE, 2023) Yaman, Okan; Ayav, Tolga; Erten, Yusuf Murat
    Third parties and legitimate entities can reach and process users' private data through most wireless networks. However, attackers such as intruders and eavesdroppers may also try to exploit this property in communication. Hence, wireless networks are intrinsically more vulnerable to threats, unlike their wired alternatives. Cryptographic techniques are the conventional approaches to deal with that weakness. Nevertheless, they still need to meet the requirements of contemporary technologies, including IoT nodes with energy and processing power constraints. In that respect, friendly jamming (FJ) is one of the encouraging countermeasures to overcome the mentioned susceptibility since it has an energy-efficient and computation-friendly nature. However, that promising approach brings another challenge, applicability. Although various models exist against this issue, a lightweight scheme compliant with novel technologies is needed. Hence, we propose a more straightforward FJ model evaluated on cellular network-based simulations in this study. Moreover, introducing a lightweight secrecy outage probability definition increases robustness and energy efficiency. © 2023 IEEE.
  • Conference Object
    Citation - WoS: 2
    Citation - Scopus: 2
    Effort Prediction With Limited Data: a Case Study for Data Warehouse Projects
    (IEEE, 2022) Unlu, Huseyin; Yildiz, Ali; Demirors, Onur
    Organizations may create a sustainable competitive advantage against competitors by using data warehouse systems with which they can assess the current status of their operations at any moment. They can analyze trends and connections using up-to-date data. However, data warehouse projects tend to fail more often than other projects as it can be tough to estimate the effort required to build a data warehouse system. Functional size measurement is one of the methods used as an input for estimating the amount of work in a software project. In this study, we formed a measurement basis for DWH projects in an organization based on the COSMIC Functional Size Measurement Method. We mapped COSMIC rules on two different architectures used for DWH projects in the organization and measured the size of the projects. We calculated the productivity of the projects and compared them with the organization's previous projects and DWH projects in the ISBSG repository. We could not create an organization-wide effort estimation model as we had a limited number of projects. As an alternative, we evaluated the success of effort estimation using DWH projects in the ISBSG repository. We also reported the challenges we faced during the size measurement process.
  • Conference Object
    Citation - WoS: 7
    Citation - Scopus: 12
    Utilization of Three Software Size Measures for Effort Estimation in Agile World: a Case Study
    (IEEE, 2022) Unlu, Huseyin; Hacaloglu, Tuna; Buber, Fatma; Berrak, Kivilcim; Leblebici, Onur; Demirors, Onur
    Functional size measurement (FSM) methods, by being systematic and repeatable, are beneficial in the early phases of the software life cycle for core project management activities such as effort, cost, and schedule estimation. However, in agile projects, requirements are kept minimal in the early phases and are detailed over time as the project progresses. This situation makes it challenging to identify measurement components of FSM methods from requirements in the early phases, hence complicates applying FSM in agile projects. In addition, the existing FSM methods are not fully compatible with today's architectural styles, which are evolving into event-driven decentralized structures. In this study, we present the results of a case study to compare the effectiveness of different size measures: functional -COSMIC Function Points (CFP)-, event-based - Event Points-, and code length-based - Line of Code (LOC)- on projects that were developed with agile methods and utilized a microservice- based architecture. For this purpose, we measured the size of the project and created effort estimation models based on three methods. It is found that the event-based method estimated effort with better accuracy than the CFP and LOC-based methods.
  • Conference Object
    Citation - Scopus: 3
    A Novel Countermeasure for Selective Forwarding Attacks in Iot Networks
    (IEEE, 2022) Yaman, Okan; Sokat, Barış; Ayav, Tolga; Erten, Yusuf Murat
    As the Internet of Things (IoT) devices become more widespread there are rising public concerns about whether or not IoT devices and their services are secure. One of the major threats they face is selective forwarding attacks performed by malicious nodes. Although packets can be lost inherently due to network conditions, malicious nodes, such as those performing blackhole attacks, may deliberately drop some, but not all of them. Therefore, distinguishing these nodes from legitimate ones is not so easy. This study has proposed a lightweight countermeasure to deal with this kind of attack in IoT networks, using the standard IPv6 Routing Protocol for Low Power and Lossy Networks (RPL). The mechanism is based on Mobile Trusted Nodes (MTNs). For the given threat model, we showed that our model has robust detection accuracy and brings no additional overhead to the network. © 2022 IEEE.
  • Editorial
    Message From the Symposium Chairs: Isssr 2022
    (IEEE, 2022) Wong, W. Eric; Wotawa, Franz; Zheng, Liwei; Tuğlular, Tuğkan
    Security, safety, and reliability are the three most important attributes of a system. This is especially the case for mission-critical and life-threatening systems. As the complexity of many systems continues to grow, ensuring security, safety, and reliability has become very critical. Not only does existing technology and tool support need to be enhanced, but we also need new strategies and approaches to satisfy more strict requirements on system security, safety, and reliability. In response to this challenge, the Steering Committee of ISSSR has decided to change its conference name from International Symposium on System and Software Reliability to International Symposium on System Security, Safety, and Reliability. The acronym ISSSR is still the same, but the full name has been slightly modified to emphasize the importance of security, safety, and reliability of many systems.
  • Conference Object
    Citation - WoS: 2
    Citation - Scopus: 3
    Secure Iot Update Using Blockchain
    (IEEE, 2021) Kaptan, Melike; Tomur, Emrah; Ayav, Tolga; Erten, Yusuf Murat
    In this study a platform is devised to send automatic remote updates for embedded devices. In this scenario there are Original Equipment Manufacturers (OEMs), Software suppliers, blockchain nodes, Gateways and embedded devices. OEMs and software suppliers are there to keep their software on Inter Planetary File System (IPFS) and send the meta-data and hashes of their software to the blockchain nodes in order to keep this information distributed and ready to be requested and used. There are also gateways which are the members of the blockchain and the IPFS network. Gateways are responsible for asking for a specific update for specific devices from IPFS database using the meta-data kept on the blockchain, and they will send those hashed secure updates to the devices. In order to provide a traceable data keeping platform, gateway update operations are handled as transactions in a second blockchain network which is the clockchain of the gateways. The system was implemented as of the two separate blockchain networks and it has been shown that, despite the calculation overhead of the member devices, by separating the functions between the two blockchain networks a more reliable and secure platform can be achieved.
  • Conference Object
    Citation - Scopus: 5
    Nfa Based Regular Expression Matching on Fpga
    (IEEE, 2021) Sert, Kamil; Bazlamaçcı, Cüneyt
    String matching is about finding all occurrences of a string within a given text. String matching algorithms have important roles in various real world areas such as web and security applications. In this work, we are interested in solving regular expression matching hence a more general form of string matching problem targeting especially the field of network intrusion detection systems (NIDS). In our work, we enhance a non-deterministic finite automata (NFA) based method on FPGA considerably. We propose to use a matching structure that processes two consecutive characters instead of one in order to yield better memory utilization and provide a novel mapping of this new architecture onto FPGA. The amount of digital circuitry needed to represent the NFA is reduced due to having less number of states and less number of LUTs in the devised 2-character regex matching process. An evaluation study is performed using the well-known Snort rule set and a sizable performance improvement is demonstrated.
  • Conference Object
    Citation - Scopus: 2
    Workload Distribution on Heterogeneous Platforms
    (IEEE, 2021) Alasmar, Mahmoud; Bazlamaçcı, Cüneyt
    This paper targets the problem of finding an efficient distribution of a computational task on a heterogeneous computing platform. The heterogeneity of the processing elements arise due to differences in computation speed and memory capacity of the processors. We first consider using a discrete functional performance model that integrates processing speed and capacity of processing elements and then develop a mathematical model and propose a heuristic mapping algorithm for distributing a given total workload of size N on p processing elements such that the total computation time is minimized. Computational results show that the proposed method provides a significant improvement in reducing the computation time in comparison to equal distribution approach.
  • Conference Object
    Citation - WoS: 3
    Citation - Scopus: 3
    Assessment of Human-Robot Interaction Between Householders and Robotic Vacuum Cleaners
    (IEEE, 2022) Yapıcı, Nur Beril; Tuğlular, Tuğkan; Başoğlu, Ahmet Nuri
    The study presented in this paper investigates the application of the Hybrid Model, which is the combination of the two strategies of the Built-to-Order Model and the Dynamic Eco-strategy Explorer Model, to robotic vacuum cleaners. The Hybrid Model aims to switch the market power from seller-driven perception to buyer-driven one by creating an individual perspective from the eye of users rather than traditional customer segmentation. The human-centered approach established theoretically has been tested with a determined procedure that includes prototyping, testing, and evaluating the proposed customization system for robotic vacuum cleaners to increase the interaction degree with purchasers. In this case, robotic vacuum cleaners have been chosen to implement and assess the hypothesis. Firstly, the successful prototyping of the Hybrid Model requires well customer analysis and habits determination to build well-constructed and coherent interaction between the purchaser and the robot. We utilized a content analysis of robotic vacuum cleaners and elaborative, conventional interviews with early adopters and early majority of this technology in Turkey to establish credible scenarios and product options during the phases of the Hybrid Model practice. The results of the interview were discussed, and the evaluations have been reported.