Yazar "Dalkilic, Gokhan" seçeneğine göre listele

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    CoMAD: Context-Aware Mutual Authentication Protocol for Drone Networks
    (Ieee-Inst Electrical Electronics Engineers Inc, 2021) Cabuk, Umut Can; Dalkilic, Gokhan; Dagdeviren, Orhan
    Drone technology is developing very rapidly. Flying devices accomplishing various applications are becoming an integral part of our daily life undoubtedly. Drones are characterized by extreme mobility, decent computing power, scalability, and a very short lifetime due to energy constraints. The rise of drones inevitably enabled swarms and drone networking applications. Drone networks is a path-breaking subclass of flying ad-hoc networks with unique capabilities and specific requirements. One very important challenge with swarms is the device authentication problem, in other words, proving the identity of a single or a group of drones that request to join the swarm. In this paper, we tackle this emerging problem and propose a novel context-aware mutual authentication protocol. The proposed protocol provides authentication for groups of drones and supports recovering a swarm in case of network separation. Likewise, the protocol can handle drone joins and leaves. Moreover, the protocol is not dependent on network infrastructure, secure storage, and secure channels. We tested the protocol using an automated formal security protocol verification tool, called Scyther. The tests resulted in the complete verification of the authentication and secrecy claims for arbitrary network instances and all defined use-cases. The protocol is also shown to have proven performance advantages over the existing schemes.
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    Consensus Approaches of High-Value Crypto Currencies and Application in SHA-3
    (Springer International Publishing Ag, 2020) Emec, Murat; Karatay, Melike; Dalkilic, Gokhan; Alkim, Erdem
    In view of the widespread use of information technologies, the security of data against third parties should be maintained. Blockchain technology is used for this data and especially for transactions in finance. However, although bitcoin is well known as the crypto currency, the use of the blockchain technology is gaining importance in different areas as well. Thus, consensus algorithms have been developed in order to increase the security and especially the integrity of the crypto currencies. These consensus algorithms indirectly influence the market value of crypto currencies. In this study, consensus algorithms of some crypto currencies have been investigated. In addition to the SHA256 algorithm, the advantages and disadvantages of using Shake and Keccak algorithms as a part of the consensus algorithms, have been analyzed. SHA256, Keccak and Shake algorithms are compared regarding to their performance. As a result, we recommend that the cryptographic hash function can be replaced with the Shake algorithm can be an extendable output function for new crypto currencies.
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    Data immutability and event management via blockchain in the Internet of things
    (Tubitak Scientific & Technical Research Council Turkey, 2022) Altas, Hakan; Dalkilic, Gokhan; Cabuk, Umut Can
    The Internet of things (IoT) is the key enabler of the smart systems used in many areas, from agriculture to aviation, industrial automation to autonomous vehicles. Most IoT deployments employ cost-efficient lightweight devices with limited resources (e.g., bandwidth, energy, storage). Although an IoT network must be built in its simplest form, engineers include more sophisticated devices like gateways and servers to provide web-based services and benefit from cloud systems. So, although the nodes can be widely distributed geographically or topologically, the system becomes centralized, which causes bottlenecks and single-points-of-failure. Furthermore, providing data integrity, nonrepudiation, and event management becomes tricky. In most IoT scenarios, data usually flow from sensors to storage and processing units, whereas event-driven commands and triggers flow from these units to actuators, if any. Therefore, an attacker who gained access to parts of the centralized systems may leak, alter, or remove critical data and may exploit event handling features. This is where blockchain technology can be extremely useful. Using a decentralized ledger as the data storage unit provides integrity, immutability, and nonrepudiation for any IoT deployment. And a customized smart contract lets the IoT deployment benefit from decentralized and immutable (i.e. nonmanipulatable) event management features, too. Further, decentralization provides resilience against availability attacks to a large extent. With this motivation, we introduced a novel IoT architecture that incorporates an Ethereum-based private (Quorum) blockchain running a unique ad-hoc smart contract and a message queue telemetry transport (MQTT) based communication scheme between sensor and actuator nodes. The scheme, the ledger, and the smart contract have also been implemented with several nodes, a broker, and a server all on a PC using Docker containers, where the server was running a forest fire risk detection algorithm as the use case scenario. The proof-of-concept successfully validates the abovesaid functionality, scalability, and efficiency for the given IoT scenario (and some others). Moreover, performance tests showed that an instance of the system with 1000 nodes could stably process and record incoming (sensor) data up to 12.5 transactions per second (TPS) and distribute commands up to 4 TPS, whereas higher TPS is achievable depending on the network conditions and tolerance to losses. The scheme was shown to have polynomial message and time complexity.
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    Sidechains: Highlights and Challenges
    (Ieee, 2019) Musungate, Blessing Ngonidzashe; Candan, Busra; Cabuk, Umut Can; Dalkilic, Gokhan
    The revolutionary concept of blockchain and its applications are spectacularly drawing more and more attention in today's world. The crypto-currency platforms have been on the forefront of implementing blockchain technology. However, the capabilities of blockchains are not limited to monetary transactions. Introduction of smart contracts allowed development of various distributed applications. As the need for blockchains continues to grow, there is also a strong demand for larger, more scalable and more flexible "multipurpose" chains. Conventional blockchains (even the ones supporting smart contracts) cannot comprehensively cover these requirements. To address these issues, the concept of sidechains has been introduced. This paper provides a brief overview of sidechains, explains how they work, discusses their benefits and drawbacks; moreover, describes how they can be built using relevant software and tools.