Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7148
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Conference Object Citation - Scopus: 5Nfa Based Regular Expression Matching on Fpga(IEEE, 2021) Sert, Kamil; Bazlamaçcı, CüneytString matching is about finding all occurrences of a string within a given text. String matching algorithms have important roles in various real world areas such as web and security applications. In this work, we are interested in solving regular expression matching hence a more general form of string matching problem targeting especially the field of network intrusion detection systems (NIDS). In our work, we enhance a non-deterministic finite automata (NFA) based method on FPGA considerably. We propose to use a matching structure that processes two consecutive characters instead of one in order to yield better memory utilization and provide a novel mapping of this new architecture onto FPGA. The amount of digital circuitry needed to represent the NFA is reduced due to having less number of states and less number of LUTs in the devised 2-character regex matching process. An evaluation study is performed using the well-known Snort rule set and a sizable performance improvement is demonstrated.Article Comparison of Group Key Establishment Protocols(Türkiye Klinikleri Journal of Medical Sciences, 2017) Şahin, Serap; Aslanoğlu, RabiaRecently group-oriented applications over unsecure open networks such as Internet or wireless networks have become very popular. Thus, group communication security over unsecure open networks has become a vital concern. Group key establishment (GKE) protocols are used to satisfy the confidentiality requirement of a newly started communication session by the generation or sharing of an ephemeral common key between the group members. In this study, we analyze the computation and communication efficiency of GKE protocols. Besides confidentiality, the security characteristics of identification and integrity control are also required for all steps of the protocol implementations. Thus, the main contribution of this work is to provide the computation and communication efficiency analysis of the same GKE protocols along with the identification of the group entities and integrity control of messages during the protocol steps. The specific implementation and analysis of GKE protocols are performed by group key agreement (GKA) with pairing- based cryptography and group key distribution (GKD) with verifiable secret sharing, respectively. Finally, a comparison of GKA and GKD protocols on the basis of their strong points and cost characteristics are also provided to inform potential users.Conference Object Citation - WoS: 9Towards Denial-Of Key Agreement Protocols(Springer Verlag, 2009) Stebila, Douglas; Ustaoğlu, BerkantDenial of service resilience is an important practical consideration for key agreement protocols in any hostile environment such as the Internet. There are well-known models that consider the security of key agreement protocols, but denial of service resilience is not considered as part of these models. Many protocols have been argued to be denial-of-service-resilient, only to be subsequently broken or shown ineffective. In this work we propose a formal definition of denial of service resilience, a model for secure authenticated key agreement, and show how security and denial of service resilience can be considered in a common framework, with a particular focus on client puzzles. The model accommodates a variety of techniques for achieving denial of service resilience, and we describe one such technique by exhibiting a denial-of-service-resilient secure authenticated key agreement protocol. Our approach addresses the correct integration of denial of service countermeasures with the key agreement protocol to prevent hijacking attacks that would otherwise render the countermeasures irrelevant. © 2009 Springer Berlin Heidelberg.Conference Object Citation - WoS: 19Comparing the Pre- and Post-Specified Peer Models for Key Agreement(Springer Verlag, 2008) Menezes, Alfred; Ustaoğlu, BerkantIn the pre-specified peer model for key agreement, it is assumed that a party knows the identifier of its intended communicating peer when it commences a protocol run. On the other hand, a party in the post-specified peer model for key agreement does not know the identifier of its communicating peer at the outset, but learns the identifier during the protocol run. In this paper we compare the security assurances provided by the Canetti-Krawczyk security definitions for key agreement in the pre- and post-specified peer models. We give examples of protocols that are secure in one model but insecure in the other. We also enhance the Canetti-Krawczyk security models and definitions to encompass a class of protocols that are executable and secure in both the pre- and post-specified peer models. © 2008 Springer-Verlag Berlin Heidelberg.Conference Object Citation - WoS: 5Citation - Scopus: 6The 1st Workshop on Model-Based Verification & Validation: Directed Acyclic Graph Modeling of Security Policies for Firewall Testing(Institute of Electrical and Electronics Engineers Inc., 2009) Tuğlular, Tuğkan; Kaya, Özgür; Müftüoğlu, Can Arda; Belli, FevziCurrently network security of institutions highly depend on firewalls, which are used to separate untrusted network from trusted one by enforcing security policies. Security policies used in firewalls are ordered set of rules where each rule is represented as a predicate and an action. This paper proposes modeling of firewall rules via directed acyclic graphs (DAG), from which test cases can be automatically generated for firewall testing. The approach proposed follows test case generation algorithm developed for event sequence graphs. Under a local area network setup with the aid of a specifically developed software for this purpose, generated test cases are converted to network test packets, test packets are sent to the firewall under test (FUT), and sent packets are compared with passed packets to determine test result.