Computer Engineering / Bilgisayar Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/10
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Conference Object Citation - WoS: 1On Defining Security Metrics for Information Systems(Brill Academic Publishers, 2005) Koltuksuz, Ahmet[No abstract available]Conference Object Citation - Scopus: 4A Model of Distributed Key Generation for Industrial Control Systems(Elsevier Ltd., 2012) Kılınç, Görkem; Fovino, Igor Nai; Ferigato, Carlo; Koltuksuz, AhmetThe cyber-security of industrial control systems (ICS) is gaining high relevance due to the impact of industrial system failures on the citizen life. There is an urgent need for the consideration of security in their design, and for the analysis of the related vulnerabilities and potential threats. The high exposure of industrial critical infrastructure to cyber-threats is mainly due to the intrinsic weakness of the communication protocols used to control the process network. The peculiarities of the industrial protocols (low computational power, large geographical distribution, near to real-time constraints) make hard the effective use of traditional cryptographic schemes and in particular the implementation of an effective key management infrastructure supporting a cryptographic layer. In this paper, we describe a "model of distributed key generation for industrial control systems" we have recently implemented. The model is based on a known Distributed Key Generator protocol we have adapted to an industrial control system environment and to the related communication protocol (Modbus). To validate in a formal way selected security properties of the model, we introduced a Petri Nets representation. This representation allows for modeling attacks against the protocol and understanding some potential weaknesses of its implementation in the industrial control system environment.Conference Object Modeling Efficient Multi-Chained Stream Signature Protocol Using Communicating Sequential Processeses(Institute of Electrical and Electronics Engineers Inc., 2010) Koltuksuz, Ahmet; Özkan, Murat; Külahçıoğlu, BurcuCommunicating Sequential Processes (CSP) is a process algebra, designed for modeling and analyzing the behavior of concurrent systems. Several security protocols are modeled with CSP and verified using model-checking or theorem proving techniques successfully. Unlike other authentication protocols modeled using CSP, each of the Efficient Multi-chained Stream Signature (EMSS) protocol messages are linked to the previous messages, forming hash chains, which introduces difficulties for modeling and verification. In this paper; we model the EMSS stream authentication protocol using CSP and verify its authentication properties with model checking, by building an infinite state model of the protocol which is reduced into a finite state model. © 2010 IEEE.Conference Object Citation - Scopus: 7Utilization of Timed Automata as a Verification Tool for Security Protocols(Institute of Electrical and Electronics Engineers Inc., 2010) Koltuksuz, Ahmet; Külahçıoğlu, Burcu; Özkan, MuratTimed Automata is an extension to the automata-theoretic approach for the modeling of real time systems that introduces time into the classical automata. It has become an important research area in both the context of formal languages and modeling and verification of real time systems since it was proposed by Alur and Dill in the early nineties. Timed automata proposes an efficient model checking method for verification real time systems having mature and efficient automatic verification tools. One of the application areas of timed automata is the verification of security protocols which are known to be time sensitive. This study aims to make use of timed automata as a verification tool for security protocols and gives a case study on the initial part of the Neuman- Stubblebine Repeated Authentication Protocol. © 2010 IEEE.Conference Object Citation - WoS: 2Citation - Scopus: 4Computational Cost Analysis of Elliptic Curve Arithmetic(Institute of Electrical and Electronics Engineers Inc., 2006) Atay, Serap; Koltuksuz, Ahmet; Hışıl, Hüseyin; Eren, ŞabanElliptic curves are proposed for the asymmetrical cryptography by Neal Koblitz and Victor Miller in 1986 separately. Elliptic curve cryptography (ECC) is utilized by hardware embedded solutions on mobile equipments and smart cards after 2000. Currently, software implementation of ECC faces the computational speed problem. One of the proposed solutions is to do the arithmetic operations on different Euclidean coordinate systems. This paper concentrates on the research of this technique and delineates the performance results of the implementation of the aforementioned technique on the different cryptographic libraries such as CRYMPIX, GMP and MIRACL.Conference Object Citation - WoS: 1Citation - Scopus: 7Intelligence analysis modeling(Institute of Electrical and Electronics Engineers Inc., 2006) Koltuksuz, Ahmet; Tekir, SelmaIntelligence is the process of supporting the policymakers in making their decisions by providing them with the specific information they need. Intelligence analysis is the effort of extracting the nature of intelligence issue with the policy goal in mind. It is performed by intelligence analysts who form judgments that add value to the collected material. With the increased open source collection capabilities, there has emerged a need for a model of intelligence analysis that covers the basic elements of valuable information: relevancy, accuracy, and timeliness. There exist models such as vector space model of information retrieval which only addresses the relevancy aspect of information and cannot cope with nonlinear document spaces. In this paper, we discuss the requirements of an integrated model of intelligence analysis along with its peculiar characteristics.Conference Object Citation - WoS: 1Citation - Scopus: 1Satellite Networks for Key Management(Institute of Electrical and Electronics Engineers Inc., 2007) Koltuksuz, AhmetThe cryptographic key management center is the place where all the cryptographical protocols and related keys are in action. Traditionally the key management centers operate on the ground. However; with the satellites, it is possible to conceive a space based key management center. This paper underlines the pros and cons of having a satellite networks key management center.Conference Object Citation - Scopus: 2Crympix: Cryptographic Multiprecision Library(Springer Verlag, 2005) Koltuksuz, Ahmet; Hışıl, HüseyinThis paper delineates the results gained throughout the development of a cryptographic multiprecision1 integer library, CRYMPIX. To obtain the know-how for cryptographic computation and thus being able to create the high level cryptographic protocols in an in-housefashion are the main reasons of this development. CRYMPIX is mainly designed to supply code readability and portability plus an increased performance over other similar libraries. The whole work is achieved by detailed investigation of current algorithms and multi-precision libraries. The selected algorithms are discussed by means of efficiency and various implementation techniques. The comparative performance measurements of CRYMPIX against other multiprecision libraries show that the overall performance of CRYMPIX is not behind its predecessors if not superior.