Computer Engineering / Bilgisayar Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/10
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Conference Object Enhancing genomic data sharing with blockchain-enabled dynamic consent in beacon V2(Springernature, 2024) Binokay, Leman; Celik, Hamit Mervan; Gurdal, Gultekin; Ayav, Tolga; Tuglular, Tugkan; Oktay, Yavuz; Karakulah, GokhanConference Object Citation - Scopus: 1A Lightweight and Energy Efficient Secrecy Outage Probability-Based Friendly Jamming(IEEE, 2023) Yaman, Okan; Ayav, Tolga; Erten, Yusuf MuratThird 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 - Scopus: 3A Novel Countermeasure for Selective Forwarding Attacks in Iot Networks(IEEE, 2022) Yaman, Okan; Sokat, Barış; Ayav, Tolga; Erten, Yusuf MuratAs 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.Conference Object Citation - WoS: 2Citation - Scopus: 3Secure Iot Update Using Blockchain(IEEE, 2021) Kaptan, Melike; Tomur, Emrah; Ayav, Tolga; Erten, Yusuf MuratIn 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.Article Otomotiv Endüstrisinde Zamanlama Mimarilerinin Değerlendirilmesi(TMMOB Elektrik Mühendisleri Odası, 2021) Saydam, Berkay; Ayav, TolgaTeknolojik gelişmeler araçlara da yansırken güvenlikten ödün vermeden araçlara yeni işlevler ekleme zorluğunu da beraberinde getirmektedir. Araçlarda kullanılan çeşitli işlevleri yerine getiren görevler farklı karakteristiklere sahiptir. Güvenlik ve performans, bu görevlerin karakteristiğini belirlemek için kullanılan iki temel kriterdir. Görevlerin karakteristikleri, Otomotiv Güvenlik Bütünlük Seviyeleri olarak bilinen güvenlik seviyelerine göre sınıflandırılabilir. Donanım ve yazılım tasarımı ile ayrıca bunların doğrulanması ve testi otomotiv endüstrisinde uzun soluklu bir ilerlemedir. Bir Elektronik Kontrol Birimi sahada kullanılmaya başlandığında, donanım tasarımındaki herhangi bir değişiklik oldukça maliyetlidir. Makalede savunulan hipoteze göre, Merkezi İşlem Birimi tarafından görev yürütme sıralarını belirlemek için kullanılan zamanlama algoritmaları özenle seçilmelidir. Ayrıca donanım ve yazılım tasarımında bu karakteristik ve algoritmalar dikkate alınmalıdır. Aksi takdirde görevler, kritik bileşen için zaman kısıtının kaçırılması gibi güvenlik açısından ciddi sorunlara neden olabilmektedir. Bu makalede, zamanlama mimarileri değerlendirilerek hangi zamanlama mimarilerinin hangi amaçla kullanılması gerektiği belirtilmektedir. Algoritmaların avantaj ve dezavantajları sunulmaktadır.Conference Object Citation - WoS: 12Citation - Scopus: 20Loyalty Program Using Blockchain(IEEE, 2020) Sönmeztürk, Osman; Ayav, Tolga; Erten, Yusuf MuratThe traditional loyalty systems usually offer people benefits in a specific sector. The users usually need to stay within the loyalty system for a long time and accumulate points in order to win rewards which may not be very interesting for them most of the time. Additionally, users usually do not prefer to share their personal information to join these loyalty systems due to privacy concerns. It has, therefore, been observed that the number of customers in the loyalty systems is decreasing day by day. To reduce these drawbacks a loyalty program which complies with ERC20 standards was proposed in this study using tokens based on the Ethereum blockchain. Using this new generation loyalty system, users can convert their earned tokens to Ether in the market and they can receive services or products with the accumulated tokens according to their interests from any supplier that has been contracted by the manufacturer. Additionally, users in the designed system do not need to carry many different cards, it is adequate to have only one Ethereum wallet. Furthermore, users do not need to share any personal data to join the loyalty system. Suppliers can also request Ether from the manufacturer for the tokens they have accumulated from the members of the loyalty system. The proposed loyalty system has been implemented and presented in this study.Article Citation - WoS: 15Citation - Scopus: 18Achieving Query Performance in the Cloud Via a Cost-Effective Data Replication Strategy(Springer, 2021) Tos, Uras; Mokadem, Riad; Hameurlain, Abdelkader; Ayav, TolgaMeeting performance expectations of tenants without sacrificing economic benefit is a tough challenge for cloud providers. We propose a data replication strategy to simultaneously satisfy both the performance and provider profit. Response time of database queries is estimated with the consideration of parallel execution. If the estimated response time is not acceptable, bottlenecks are identified in the query plan. Data replication is realized to resolve the bottlenecks. Data placement is heuristically performed in a way to satisfy query response times at a minimal cost for the provider. We demonstrate the validity of our strategy in a performance evaluation study.Article Citation - WoS: 9Citation - Scopus: 11Test Input Generation From Cause-Effect Graphs(Springer, 2021) Kavzak Ufuktepe, Deniz; Ayav, Tolga; Belli, FevziCause-effect graphing is a well-known requirement-based and systematic testing method with a heuristic approach. Since it was introduced by Myers in 1979, there have not been any sufficiently comprehensive studies to generate test inputs from these graphs. However, there exist several methods for test input generation from Boolean expressions. Cause-effect graphs can be more convenient for a wide variety of users compared to Boolean expressions. Moreover, they can be used to enforce common constraints and rules on the system variables of different expressions of the system. This study proposes a new mutant-based test input generation method, Spectral Testing for Boolean specification models based on spectral analysis of Boolean expressions using mutations of the original expression. Unlike Myers' method, Spectral Testing is an algorithmic and deterministic method, in which we model the possible faults systematically. Furthermore, the conversion of cause-effect graphs between Boolean expressions is explored so that the existing test input generation methods for Boolean expressions can be exploited for cause-effect graphing. A software is developed as an open-source extendable tool for generating test inputs from cause-effect graphs by using different methods and performing mutation analysis for quantitative evaluation on these methods for further analysis and comparison. Selected methods, MI, MAX-A, MUTP, MNFP, CUTPNFP, MUMCUT, Unique MC/DC, and Masking MC/DC are implemented together with Myers' technique and the proposed Spectral Testing in the developed tool. For mutation testing, 9 common fault types of Boolean expressions are modeled, implemented, and generated in the tool. An XML-based standard on top of GraphML representing a cause-effect graph is proposed and is used as the input type to the approach. An empirical study is performed by a case study on 5 different systems with various requirements, including the benchmark set from the TCAS-II system. Our results show that the proposed XML-based cause-effect graph model can be used to represent system requirements. The developed tool can be used for test input generation from proposed cause-effect graph models and can perform mutation analysis to distinguish between the methods with respect to the effectiveness of test inputs and their mutant kill scores. The proposed Spectral Testing method outperforms the state-of-the-art methods in the context of critical systems, regarding both the effectiveness and mutant kill scores of the generated test inputs, and increasing the chances of revealing faults in the system and reducing the cost of testing. Moreover, the proposed method can be used as a separate or complementary method to other well-performing test input generation methods for covering specific fault types.Article Citation - WoS: 6Citation - Scopus: 7Human-Robot Interfaces of the Neuroboscope: a Minimally Invasive Endoscopic Pituitary Tumor Surgery Robotic Assistance System(ASME, 2021) Dede, Mehmet İsmet Can; Kiper, Gökhan; Ayav, Tolga; Özdemirel, Barbaros; Tatlıcıoğlu, Enver; Hanalioğlu, Şahin; Işıkay, İlkayEndoscopic endonasal surgery is a commonly practiced minimally invasive neurosurgical operation for the treatment of a wide range of skull base pathologies including pituitary tumors. A common shortcoming of this surgery is the necessity of a third hand when the endoscope has to be handled to allow active use of both hands of the main surgeon. The robot surgery assistant NeuRoboScope system has been developed to take over the endoscope from the main surgeon's hand while providing the surgeon with the necessary means of controlling the location and direction of the endoscope. One of the main novelties of the NeuRoboScope system is its human-robot interface designs which regulate and facilitate the interaction between the surgeon and the robot assistant. The human-robot interaction design of the NeuRoboScope system is investigated in two domains: direct physical interaction (DPI) and master-slave teleoperation (MST). The user study indicating the learning curve and ease of use of the MST is given and this paper is concluded via providing the reader with an outlook of possible new human-robot interfaces for the robot assisted surgery systems.Article Citation - WoS: 2Citation - Scopus: 1Mutant Selection by Using Fourier Expansion(Türkiye Klinikleri Journal of Medical Sciences, 2020) Takan, Savaş; Ayav, TolgaMutation analysis is a widely used technique to evaluate the effectiveness of test cases in both hardware and software testing. The original model is mutated systematically under certain fault assumptions and test cases are checked against the mutants created to see whether the test cases can detect the faults or not. Mutation analysis is usually a computationally intensive task, particularly in finite state machine (FSM) testing due to a possibly huge amount of mutants. Random selection could be a practical reduction method under the assumption that each mutant is identical in terms of the probability of occurrence of its associating fault. The present study proposes a mutant selection method based on Fourier analysis of Boolean functions. Fourier helps to identify the most effective transitions on the output so that the mutants related to those transitions can be selected. Such mutants are considered more important since they are more likely to be killed. To evaluate the method, test cases are generated by the well-known W method, which has the capability of detecting every potential fault. The original and reduced sets of mutants are compared with respect to their importance values. Evaluations show that the mutants selected by the proposed technique are more effective, which reduces the cost of mutation analysis without sacrificing the performance of the mutation analysis.