Browsing by Subject "Security of data"
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Item Open Access Architecture framework for software safety(Springer, 2014-09) Gürbüz, Havva Gülay; Pala Er, N.; Tekinerdoğan, BedirCurrently, an increasing number of systems are controlled by soft- ware and rely on the correct operation of software. In this context, a safety- critical system is defined as a system in which malfunctioning software could result in death, injury or damage to environment. To mitigate these serious risks, the architecture of safety-critical systems needs to be carefully designed and analyzed. A common practice for modeling software architecture is the adoption of software architecture viewpoints to model the architecture for par- ticular stakeholders and concerns. Existing architecture viewpoints tend to be general purpose and do not explicitly focus on safety concerns in particular. To provide a complementary and dedicated support for designing safety critical systems, we propose an architecture framework for software safety. The archi- tecture framework is based on a metamodel that has been developed after a tho- rough domain analysis. The framework includes three coherent viewpoints, each of which addressing an important concern. The application of the view- points is illustrated for an industrial case of safety-critical avionics control computer system. © Springer International Publishing Switzerland 2014.Item Open Access Capture resilient ElGamal signature protocols(Springer, 2006-11) Acan, Hüseyin; Kaya, Kamer; Selçuk, Ali AydınOne of the fundamental problems of public key cryptography is protecting the private key. Private keys are too long to be remembered by the user, and storing them in the device which performs the private key operation is insecure as long as the device is subject to capture. In this paper, we propose server-assisted protocols for the ElGamal signature scheme which make the system capture resilient in the sense that the security of the system is not compromised even if the signature device is captured. The protocols also have a key disabling feature which allows a user to disable the device's private key in case both the device and the password of the user are compromised simultaneously. © Springer-Verlag Berlin Heidelberg 2006.Item Open Access A communication scheme by using synchronized chaotic systems(IEEE, 1996) Morgül, Ömer; Feki, MoezA method to synchronize systems with chaotic behavior, in a master-slave configuration adapted to communication systems, is discussed. This work is motivated by the need for secure communication. In this method, the synchronization and message transmission phases are separated, and while the synchronization is achieved in the synchronization phases, the message is only sent in the message transmission phases.Item Open Access Differential entropy analysis of the IDEA block cipher(Elsevier, 2014) Biryukov, A.; Nakahara, Jr. J.; Yıldırım H. M.This paper describes a new cryptanalytic technique that combines differential cryptanalysis with Shannon entropy. We call it differential entropy (DE). The objective is to exploit the non-uniform distribution of output differences from a given mapping as a distinguishing tool in cryptanalysis. Our preferred target is the IDEA block cipher, since we detected significantly low entropy at the output of its multiplication operation. We looked to further extend this entropy analysis to larger components and for a number of rounds. We present key-recovery attacks on up to 2.5-round IDEA in the single-key model and without weak-key assumptions. © 2013 Elsevier B.V. All rights reserved.Item Open Access G-free: Defeating return-oriented programming through gadget-less binaries(ACM, 2010-12) Onarlıoğlu, Kaan; Bilge, L.; Lanzi, A.; Balzarotti, D.; Kirda, E.Despite the numerous prevention and protection mechanisms that have been introduced into modern operating systems, the exploitation of memory corruption vulnerabilities still represents a serious threat to the security of software systems and networks. A recent exploitation technique, called Return-Oriented Programming (ROP), has lately attracted a considerable attention from academia. Past research on the topic has mostly focused on refining the original attack technique, or on proposing partial solutions that target only particular variants of the attack. In this paper, we present G-Free, a compiler-based approach that represents the first practical solution against any possible form of ROP. Our solution is able to eliminate all unaligned free-branch instructions inside a binary executable, and to protect the aligned free-branch instructions to prevent them from being misused by an attacker. We developed a prototype based on our approach, and evaluated it by compiling GNU libc and a number of real-world applications. The results of the experiments show that our solution is able to prevent any form of return-oriented programming. © 2010 ACM.Item Open Access Imaging capability of pseudomorphic high electron mobility transistors, AlGaN/GaN, and Si micro-Hall probes for scanning Hall probe microscopy between 25 and 125 °c(American Vacuum Society, 2009) Akram, R.; Dede, M.; Oral, A.The authors present a comparative study on imaging capabilities of three different micro-Hall probe sensors fabricated from narrow and wide band gap semiconductors for scanning hall probe microscopy at variable temperatures. A novel method of quartz tuning fork atomic force microscopy feedback has been used which provides extremely simple operation in atmospheric pressures, high-vacuum, and variable-temperature environments and enables very high magnetic and reasonable topographic resolution to be achieved simultaneously. Micro-Hall probes were produced using optical lithography and reactive ion etching process. The active area of all different types of Hall probes were 1×1 μ m2. Electrical and magnetic characteristics show Hall coefficient, carrier concentration, and series resistance of the hall sensors to be 10 mG, 6.3× 1012 cm-2, and 12 k at 25 °C and 7 mG, 8.9× 1012 cm-2 and 24 k at 125 °C for AlGaNGaN two-dimensional electron gas (2DEG), 0.281 mG, 2.2× 1014 cm-2, and 139 k at 25 °C and 0.418 mG, 1.5× 1014 cm-2 and 155 k at 100 °C for Si and 5-10 mG, 6.25× 1012 cm-2, and 12 k at 25 °C for pseudomorphic high electron mobility transistors (PHEMT) 2DEG Hall probe. Scan of magnetic field and topography of hard disc sample at variable temperatures using all three kinds of probes are presented. The best low noise image was achieved at temperatures of 25, 100, and 125 °C for PHEMT, Si, and AlGaNGaN Hall probes, respectively. This upper limit on the working temperature can be associated with their band gaps and noise associated with thermal activation of carriers at high temperatures.Item Open Access Improved DST cryptanalysis of IDEA(Springer, 2006-08) Ayaz, Eyüp Serdar; Selçuk, Ali AydınIn this paper, we show how the Demirci-Selcuk-Ture attack, which is currently the deepest penetrating attack on the IDEA block cipher, can be improved significantly in performance. The improvements presented reduce the attack's plaintext, memory, precomputation time, and key search time complexities. These improvements also make a practical implementation of the attack on reduced versions of IDEA possible, enabling the first experimental verifications of the DST attack. © Springer-Verlag Berlin Heidelberg 2007.Item Open Access Modeling urbanization using building patterns(2007) Doǧrusöz, E.; Aksoy, S.Automatic extraction of buildings and modeling of their spatial arrangements provide essential information for urban applications. This paper describes our work on modeling urbanization using spatial building patterns. Building detection is done using Bayesian classification of multi-spectral information. The individual buildings are used as textural primitives, and co-occurrence based spatial domain features and Fourier spectrum-based frequency domain features are used to model their repetitiveness and periodicity at particular orientations. These features are used to classify image neighborhoods as organized (regular) and unorganized (irregular). Experiments with high-resolution Ikonos imagery show that the proposed technique can be used for automatic segmentation of urban scenes and extraction of valuable information about urban growth.Item Open Access Online balancing two independent criteria(Springer, 2008-10) Tse, Savio S.H.We study the online bicriteria load balancing problem in this paper. We choose a system of distributed homogeneous file servers located in a cluster as the scenario and propose two online approximate algorithms for balancing their loads and required storage spaces. We first revisit the best existing solution for document placement, and rewrite it in our first algorithm by imposing some flexibilities. The second algorithm bounds the load and storage space of each server by less than three times of their trivial lower bounds, respectively; and more importantly, for each server, the value of at least one parameter is far from its worst case. The time complexities for both algorithm are O(logM). © 2008 Springer Berlin Heidelberg.Item Open Access Online bicriteria load balancing using object reallocation(Institute of Electrical and Electronics Engineers, 2009-03) Tse, S. S. H.We study the bicriteria load balancing problem on two independent parameters under the allowance of object reallocation. The scenario is a system of $M$ distributed file servers located in a cluster, and we propose three online approximate algorithms for balancing their loads and required storage spaces during document placement. The first algorithm is for heterogeneous servers. Each server has its individual tradeoff of load and storage space under the same rule of selection. The other two algorithms are for homogeneous servers. The second algorithm combines the idea of the first one and the best existing solution for homogeneous servers. Using document reallocation, we obtain a smooth tradeoff curve of the upper bounds of load and storage space. The last one bounds the load and storage space of each server by less than three times of their trivial lower bounds, respectively; and more importantly, for each server, the value of at least one parameter is far from its worst case. The time complexities of these three algorithms are O(\log M) plus the cost of document reallocation. © 2009 IEEE.Item Open Access A scratch-pad memory aware dynamic loop scheduling algorithm(IEEE, 2008-03) Öztürk, Özcan; Kandemir, M.; Narayanan, S. H. K.Executing array based applications on a chip multiprocessor requires effective loop parallelization techniques. One of the critical issues that need to be tackled by an optimizing compiler in this context is loop scheduling, which distributes the iterations of a loop to be executed in parallel across the available processors. Most of the existing work in this area targets cache based execution platforms. In comparison, this paper proposes the first dynamic loop scheduler, to our knowledge, that targets scratch-pad memory (SPM) based chip multiprocessors, and presents an experimental evaluation of it. The main idea behind our approach is to identify the set of loop iterations that access the SPM and those that do not. This information is exploited at runtime to balance the loads of the processors involved in executing the loop nest at hand. Therefore, the proposed dynamic scheduler takes advantage of the SPM in performing the loop iteration-to-processor mapping. Our experimental evaluation with eight array/loop intensive applications reveals that the proposed scheduler is very effective in practice and brings between 13.7% and 41.7% performance savings over a static loop scheduling scheme, which is also tested in our experiments. © 2008 IEEE.Item Open Access A strong user authentication protocol for GSM(IEEE, 2005-06) Aydemir, Özer; Selçuk, Ali AydınTraditionally, the authentication protocols for cellular phone networks have been designed for device authentication rather than user authentication, which brings certain limitations and restrictions on the functionality of the system. In this paper we propose a user authentication protocol for the Global Standards for Mobile (GSM) which permits the use of weak secrets (e.g. passwords or PINs) for authentication, providing new flexibilities for the GSM users. © 2005 IEEE.Item Open Access A survey on information security threats and solutions for Machine to Machine (M2M) communications(Academic Press Inc., 2017) Tuna, G.; Kogias, D. G.; Gungor, V. C.; Gezer, C.; Taşkın, E.; Ayday, E.Although Machine to Machine (M2M) networks allow the development of new promising applications, the restricted resources of machines and devices in the M2M networks bring several constraints including energy, bandwidth, storage, and computation. Such constraints pose several challenges in the design of M2M networks. Furthermore, some elements that contributed to the rise of M2M applications have caused several new security threats and risks, typically due to the advancements in technology, increasing computing power, declining hardware costs, and freely available software tools. Due to the restricted capabilities of M2M devices, most of the recent research efforts on M2M have focused on computing, resource management, sensing, congestion control and controlling technologies. However, there are few studies on security aspects and there is a need to introduce the threats existing in M2M systems and corresponding solutions. Accordingly, in this paper, after presenting an overview of potential M2M applications, we present a survey of security threats against M2M networks and solutions to prevent or reduce their impact. Then, we investigate security-related challenges and open research issues in M2M networks to provide an insight for future research opportunities. Moreover, we discuss the oneM2M standard, one of the prominent standard initiatives for more secure and smoother M2M networks and the Internet of Things. © 2017 Elsevier Inc.