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 - WoS: 37Graph Theoretic Clustering Algorithms in Mobile Ad Hoc Networks and Wireless Sensor Networks (survey)(Azerbaijan National Academy of Sciences, 2007) Erciyeş, Kayhan; Dağdeviren, Orhan; Çokuslu, Deniz; Özsoyeller, DenizClustering in mobile ad hoc networks (MANETs) and wireless sensor networks (WSNs) is an important method to ease topology management and routing in such networks. Once the clusters are formed, the leaders (coordinators) of the clusters may be used to form a backbone for efficient routing and communication purposes. A set of clusters may also provide the underlying physical structure for multicast communication for a higher level group communication module which may effectively be used for fault tolerance and key management for security purposes. We survey graph theoretic approaches for clustering in MANETs and WSNS and show that although there is a wide range of such algorithms, each may be suitable for a different cross-layer design objective.Conference Object Duyarga Ağları için Bir Γ Eşuyumcusu Tasarım ve Uygulaması(IEEE, 2008) Özsoyeller, Deniz; Erciyeş, Kayhan; Dağdeviren, OrhanImplementation of synchronous algorithms in distributed systems in general is less troublesome than the implementation of asynchronous algorithms. Synchronizers provide synchronous execution of an asynchronous algorithm in distributed systems. In this study, we propose a gamma synchronizer for Wireless Sensor Networks (WSNs). This synchronizer consists of a and beta synchronizers. In our work, the WSN is first divided into clusters and then these clusters are connected using a ring protocol. Synchronization is provided using the beta synchronizer in the cluster and a synchronizer among the clusters. We describe the clustering algorithm and the ring formation algorithm for the WSNs and give the results obtained so far.Conference Object Citation - Scopus: 15Gezgin Tasarsız Ağlar için Taşırma Tabanlı Yönlendirme Yordamı(IEEE, 2008) Çokuslu, Deniz; Erciyeş, KayhanMobile Ad Hoc Networks (MANETs) are videly in use in rescue, military operations, scientific and business areas. Many studies are addressed in MANETs because of their need to long lasting liveness, fault tolerance, dynamic addressing, collusion prevention, mobility management and security. Especially, self clustering, backbone construction and routing are the most interesting academic and industrial research areas in MANETs. A wide range of studies addressed the routing problem in MANETs. Many previous studies address the clustering and routing problems as seperate subjects. However, rowing approaches which are specific to the clustering methodologies may have many advantages in terms of efficiency and availability. In this study, a flooding based routing algorithm is proposed. First, a detailed description of the algorithm is explained, then the analysis and test results using the ns2 simulator are given which show that the designed algorithm is scalable and has favorable performance.Conference Object Citation - WoS: 1Automatic Enforcement of Location Aware User Based Network Access Control Policies(World Scientific and Engineering Academy and Society, 2008) Tuğlular, TuğkanMultiple interconnected network segments distributed across various locations, such as corporate networks, where users or employees constantly travel among segments and require to access servers, need to have network access control mechanisms that are able to adapt to these location changes. The idea of a firewall changing or adapting its rules depending on the location of users is presented by an architecture in this paper. This architecture proposes deployment of a policy server at the management level and policy agents at the firewall level, so that policy-driven network security management is enabled by specifying location aware user based network access control policies at the network security management and enforcing them at the managed firewalls. The architecture presented in this paper utilizes user VPN connection event triggers for dynamic policy configuration and automated policy deployment to firewalls. Location aware user based network access control policies, which are management level policies, are implemented using XACML. A network level policy is usually a configuration, or policy, file local to the firewall. The policy agent incorporated into the firewall performs the mapping from management level policy to firewall policy.Conference Object Citation - Scopus: 4Test Case Generation for Firewall Implementation Testing Using Software Testing Techniques(Tafford Publishing, 2008) Tuğlular, TuğkanThe firewall implementation testing approach checks actions performed by the firewall with respect to corresponding firewall rules. This type of firewall testing can be implemented by developing test cases from firewall rule sequence, generating test packets using those test cases and injecting those test packets into the firewall. Although this method has been already defined in the academic world, an approach to generate test cases does not exist in the literature. In this work, a test case generation approach is developed using software testing techniques. © 2008 Atilla Elçi.Conference Object The Performance Results of Ecdsa Implementation on Different Coordinate Systems(Tafford Publishing, 2008) Atay, SerapElliptic Curve Cryptography has a high computational cost due to arithmetic operations of point addition and point doubling. But the cost can be reduced if different coordinate systems utilized. This paper shows that the performance of an elliptic curve digital signature algorithm (ECDSA) can be significantly increased by using different coordinate systems.Conference Object On Ntru and Its Performance(Tafford Publishing, 2008) Mersin, Ali; Beyazıt, MutluHardness of lattice problems has introduced a new candidate for public key cryptosystems. NTRU is one of such cryptosystems. The fact that it works with small integers and that the complexities of key generation, encryption and decryption are relatively small leads to good overall performance when compared to the other public key cryptosystems. The aim of this study is to make a theoretical to practical introduction to NTRU and investigate how it performs against popular public key cryptosystems such as RSA and, especially, ECC. © 2008 Atilla Elçi.Conference Object A Memory Management Model for Cryptographic Software Libraries(Tafford Publishing, 2008) Mersin, Ali; Beyazıt, MutluCryptographic protocols are implemented on the abstraction of multiple precision number libraries in which the dominant design criterion mostly turns out to be the maximization of the system performance. In contrast, each protocol may have its own memory usage pattern. In general case, the memory allocation and release routines are frequently called during the runtime. For this reason, an improper memory management strategy may yield an inefficient implementation. In this paper, we propose a memory management technique which is constructed under the consideration of the context of high level cryptographic software running on multi-programmed environments. Also, we show the implementation results of our approach and discuss with respect to the common static and dynamic memory allocation strategies. © 2008 Atilla Elçi.Conference Object Monitoring of Policy Operations in a Distributed Firewall Environment(2008) Çakı, Oğuzhan; Tuğlular, Tuğkan; Çetin, FüsunDistributed firewalls concept has been introduced to overcome some drawbacks of traditional firewalls. Distributed firewall approach is based on the idea of enforcing policy rules at the intermediate and end points rather than a single entry point to the network. Management of policy rules in a distributed firewall environment requires surveillance of policy operations performed on each firewall. With this paper, we propose a monitoring architecture and its application prototype for distributed firewalls to keep track of actions, such as create, read, update, and delete, carried out on policy rule sets. We performed some emulation and laboratory experiments to obtain operational values of the proposed architecture. ©2008 by Bo?aziçi University.