Master Degree / Yüksek Lisans Tezleri
Permanent URI for this collectionhttps://hdl.handle.net/11147/3008
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Master Thesis The Web-Based Application of Key Exchange Protocols for Digital and Mobile Signatures(Izmir Institute of Technology, 2008) Akalp, Evren; Koltuksuz, Ahmet HasanMany people want to communicate and send their data securely, for this reason they use encryption methods. Symmetric cryptosystems are commonly used for securing data.They are fast and reliable. But there is a problem of exchanging keys in symmetric cryptosystems. Sender and receiver must share keys to get the plain text. In this thesis, different scenarios for key exchange protocols are developed. Solutions for securing communication to block man in the middle attack are also defined in this thesis.Master Thesis A Firewall Design for Academic Environments(Izmir Institute of Technology, 2001) Tok, Metin; Koltuksuz, Ahmet HasanComputer networks in academic environments could have many secUlity problems if there weren't enough precaution. The source of these problems is generally vulnerabilities of TCP/IP protocol and Internet. Vulnerabilities can cause threats. These threats will be analyzed in this thesis. There are many kind of countelmeasures to prevent the assets of the academic networks. Firewalls are a kind of countermeasure against these attacks. In this thesis, these countelmeasures will be also analyzed and a firewall will be designed and proposed for academic environments against these threats.Master Thesis A Genetic Algorithmic Approach To the Differential and Linear Cryptanalysis(Izmir Institute of Technology, 1999) Eminağaoğlu, Mete; Koltuksuz, Ahmet HasanThe two most well known and recently developed methods in cryptanalysis of DES and DES-like symmetric block ciphers are difTerential and linear cryptanalysis. But these cryptanalytic attacks need to be improved due to the computational performance and storage capacity problems On the other hand, genetic algorithms can be a good solution in cases where the optimum value or near-optimum solutions are sought in complex systems or for non-linear problems. This is a valid situation for the cryptanalysis case where DES and DES-like ciphers are non-linear in structure making dilTerential and linear cryptanalysis a complex system with a very large search landscape and extreme amount of conditional and probabilistic candidates for the key being sought. In this study, a new and promising method wit h bet ter performance is to be developed for differential/linear cryptanalysis of DES and similar symmetric cryptosystems exploiting genetic algorithms' broadened search and optimum finding capacity.Master Thesis Quality Life Cycle of Object Oriented Software Development in Extreme Programming(Izmir Institute of Technology, 2008) Mutlu, Gökçe; Koltuksuz, Ahmet HasanAlthough there are many teams using Extreme Programming, many people still think that applying its values, principles and practices will cause catastrophic results.However extreme programming is not only compatible with today.s software standards, technologies and most importantly with the changes at every phase of software development but also improves the quality of software. In my thesis I analyze its values, principles, and practices and how they increase the quality comparing to old software development methodologies.Master Thesis A Mathematical Modelling for Manpower Planning(Izmir Institute of Technology, 2001) Uludağ, Mehmet; Koltuksuz, Ahmet HasanInformation systems are one of the most important tools for organizations to conduct business today. The dependency of organizational functions to information systems makes them critical for the people using them. So becomes the impact of failure or success of information systems more significant in organizations. The initial task for information systems designers is to appreciate this real life situation and understand various aspects of information systems and their evolution over the past decades.Information system design is a detailed process which has to be planned and implemented with great care not only for, but also with the business experts and users. Designers and users should be aware of the problems, requirements within the organizational context. In this thesis, we will describe and discuss various information systems in organizations. Different information system types will be given.Database management systems (or databases in organizations) are the essential parts of information systems. A "good" information system is surely backed up with a "good" database behind it. Designing a "good" database systems is the critical part of the process. Following structural and well defined methods on database design is something we need in today in organizations. We will present, further in this thesis, various database management systems and database types. Relational model is the most widely used database management system today. We will study various relational database model concepts which will be a base for our management information system database design. We will follow various design and refinement methodologies to end-up with a well documented and refined relational database model. During our design we will utilize a sophisticated database design tool. We will use the database design tool Sybase PowerDesigner. Our design will be modeling a man-power planning database ..Master Thesis A Turkish Password Cracker for Unix Based Operating Systems(Izmir Institute of Technology, 2001) Tahaoğlu, Osman Okyar; Koltuksuz, Ahmet; Koltuksuz, Ahmet HasanUNIX and UNIX-based operating systems have been widely utilized in local area and wide area network systems that supply application and development chain of users through remote access as well as online connections. Although UNIX operating system has got powerful tools which have secure methods for user authentication, user management and for password storage, weak password choices of the users affect the entire system security negatively. This study aims to crack the password hashes which are encrypted by DES using the method of dictionary attack. The developed application is introduced and compared with the previous utilities. Password encryption, password storage, and the structure which was developed against a possible dictionary attack of UNIX are examined. The good password choosing method for the users and the system administrator are given.Master Thesis Modelling of Turkey Turkish Words by Discrete Markov Processes(Izmir Institute of Technology, 1998) Güventürk, Jale; Koltuksuz, Ahmet HasanThis study based on the previous works of Assistant Prof. Dr. Ahmet Hasan KOLTUKSUZ, is about obtaining cryptanalytical measures of Turkey Turkish words based on Markov processes approach.Master Thesis An Approch To the Security Problems in the Tcp/Ip Protocol Suite for a Network Security Monitor Design(Izmir Institute of Technology, 1999) Mutaf, Pars; Koltuksuz, Ahmet HasanThere are a number of security problems in the TCP/IP protocol suite. In this thesis these problems will be analyzed in detail. The problems in several existing prevention methods will be analyzed as well in order to show that security policies based merely on preventive measures are not completely secure and convenient. Therefore, "network security moniJoring" will be proposed as an alternative and supplementary approach against Internet attacks.Master Thesis Basic Key Exchange Protocols for Secret Key Cryptosystems Under Crympix Library(Izmir Institute of Technology, 2007) Uslu, Sevgi; Koltuksuz, Ahmet HasanKey exchange protocols are developed in order to overcome the key distribution problem of symmetrical cryptosystems. These protocols which are based on various algebraic domains are different implementations of public-key cryptography. In this thesis, the basic key exchange protocols are reviewed and CRYMPIX implementations of them are provided. CRYMPIX has a portable structure that provides platform independence for generated code. Hence, the implemented key exchange mechanisms are suitable to be used on different hardware and software platforms.Master Thesis The Comparative Performance Analysis of Lattice Based Ntru Cryptosystem With Other Asymmetrical Cryptosystems(Izmir Institute of Technology, 2007) Mersin, Ali; Koltuksuz, Ahmet HasanCurrent popular asymmetrical cryptosystems are based on hardness of number theoretic problems. In the future, these problems may become practically solvable with the improvements of processing power, the development of quantum computation and distributed computation. So the need for new cryptosystems which are not based on these problems has risen. Researches on hardness of lattice problems have brought a new candidate for asymmetrical cryptography: Lattice Based Cryptography. NTRU is one of these cryptosystems. For practical use, the actual performance results of NTRU with respect to current asymmetrical cryptosystems should be known. This thesis is developed based on this purpose.