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Kardas S.,Tubitak Bilgem Uekae | Kardas S.,Sabanci University | Celik S.,Tubitak Bilgem Uekae | Celik S.,Sabanci University | And 3 more authors.
Journal of Network and Computer Applications | Year: 2012

RFID (Radio Frequency IDentification) based communication solutions have been widely used nowadays for mobile environments such as access control for secure system, ticketing systems for transportation, and sport events. These systems usually depend on readers that are not continuously connected to a secure backend system. Thus, the readers should be able to perform their duties even in offline mode, which generally requires the management by the readers of the susceptible data. The use of RFID may cause several security and privacy issues such as traceability of tag owner, malicious eavesdropping and cloning of tags. Besides, when a reader is compromised by an adversary, the solution to resolve these issues getting worse. In order to handle these issues, several RFID authentication protocols have been recently proposed; but almost none of them provide strong privacy for the tag owner. On the other hand, several frameworks have been proposed to analyze the security and privacy but none of them consider offline RFID system. Motivated by this need, in this paper, we first revisit Vaudenays model, extend it by considering offline RFID system and introduce the notion of compromise reader attacks. Then, we propose an efficient RFID mutual authentication protocol. Our protocol is based on the use of physically unclonable functions (PUFs) which provide cost-efficient means to the fingerprint chips based on their physical properties. We prove that our protocol provides destructive privacy for tag owner even against reader attacks. © 2012 Elsevier Ltd. All rights reserved.

Dal G.M.,Bilkent University | Erguner B.,TuBITAK BILGEM UEKAE | Sagiroglu M.S.,TuBITAK BILGEM UEKAE | Yuksel B.,TuBITAK MAM GEBI | And 3 more authors.
Journal of Medical Genetics | Year: 2014

Background: Human de novo single-nucleotide variation (SNV) rate is estimated to range between 0.82-1.70×10-8 mutations per base per generation. However, contribution of early postzygotic mutations to the overall human de novo SNV rate is unknown. Methods: We performed deep whole-genome sequencing (more than 30-fold coverage per individual) of the whole-blood-derived DNA samples of a healthy monozygotic twin pair and their parents. We examined the genotypes of each individual simultaneously for each of the SNVs and discovered de novo SNVs regarding the timing of mutagenesis. Putative de novo SNVs were validated using Sanger-based capillary sequencing. Results: We conservatively characterised 23 de novo SNVs shared by the twin pair, 8 de novo SNVs specific to twin I and 1 de novo SNV specific to twin II. Based on the number of de novo SNVs validated by Sanger sequencing and the number of callable bases of each twin, we calculated the overall de novo SNV rate of 1.31×10-8 and 1.01×10-8 for twin I and twin II, respectively. Of these, rates of the early postzygotic de novo SNVs were estimated to be 0.34×10-8 for twin I and 0.04×10-8 for twin II. Conclusions: Early postzygotic mutations constitute a substantial proportion of de novo mutations in humans. Therefore, genome mosaicism resulting from early mitotic events during embryogenesis is common and could substantially contribute to the development of diseases.

Boztas O.,Tubitak BILGEM UEKAE | Boztas O.,Middle East Technical University | Karakoc F.,Tubitak BILGEM UEKAE | Karakoc F.,Technical University of Istanbul | And 2 more authors.
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2013

TWINE is a lightweight block cipher designed for multiple platforms and was proposed at Selected Areas in Cryptography, 2012. The number of rounds of TWINE is 36 and the most powerful attack given by the designers is the impossible differential attack against 24 rounds of TWINE-128 whose time complexity is 2115.10 encryptions and data complexity is 252.21 blocks. The best attack known so far is the biclique attack on the full round cipher with a time complexity of 2126.82 and data complexity of 2 60. However the time complexity of biclique attack is near exhaustive search and data needed for the attack is near the whole codebook. In this paper we propose some meet-in-the-middle type attacks on reduced round TWINE-128. We show that meet-in-the-middle type attacks can be applied on more rounds than the best attack done by the designers while they claim that the first 5 rounds contain all the key bits for TWINE-128. Our attacks are due to the slow diffusion of both the cipher and the key schedule algorithm. One of our attacks just use 212 chosen plaintext-ciphertext pair with time complexity of 2124 to break 21 rounds of the algorithm. Also we propose another attack on 25 rounds of the cipher by using 248 chosen plaintext-ciphertext pairs with the time complexity of 2122 and memory complexity of 2125 while the best attack proposed by the designers is for 24 rounds. © 2013 Springer-Verlag.

Karakoc F.,Tubitak BILGEM UEKAE | Karakoc F.,Technical University of Istanbul | Demirci H.,Tubitak BILGEM UEKAE | Harmanci A.E.,Technical University of Istanbul
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2012

In this paper, we improve the impossible differential attack on 20-round LBlock given in the design paper of the LBlock cipher. Using relations between the round keys we attack on 21-round and 22-round LBlock with a complexity of 269.5 and 279.28 encryptions respectively. We use the same 14-round impossible differential characteristic observed by the designers to attack on 21 rounds and another 14-round impossible differential characteristic to attack on 22 rounds of LBlock. © 2012 IFIP International Federation for Information Processing.

Karakoc F.,Tubitak BILGEM UEKAE | Karakoc F.,Technical University of Istanbul | Demirci H.,Tubitak BILGEM UEKAE | HarmancI A.E.,Technical University of Istanbul
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2012

In this paper we analyze the security of PRINTcipher using a technique that combines differential and linear cryptanalysis. This technique is different from differential-linear cryptanalysis. We use linear approximations to increase the probability of differential characteristics. We show that specific choices of some of the key bits give rise to a certain differential characteristic probability, which is far higher than the best characteristic probability claimed by the designers. We give the underlying mechanism of this probability increase. We have developed attacks on 29 and 31 rounds of PRINTcipher-48 for 4.54% and 0.036% of the keys, respectively. Moreover, we have implemented the proposed attack algorithm on 20 rounds of the cipher. © 2012 Springer-Verlag.

Dikici A.,Tubitak Bilgem UEKAE | Turetken O.,TU Eindhoven | Demirors O.,Middle East Technical University
Proceedings - 38th EUROMICRO Conference on Software Engineering and Advanced Applications, SEAA 2012 | Year: 2012

Requiring solid engineering disciplines and best practices rather than human talents for developing complex software systems results an increasing interest in software processes. The quality of software processes has considerable influence over the success of an organization. Process quality measurement addresses an essential and largely overlooked aspect of processes. We performed a case study on the application of a process quality measurement method with the main objective of examining the extent of the support it offers for software process improvement in practice. We discuss the challenges and lessons learned as well as the limitations of the measurement method applied. © 2012 IEEE.

IET Signal Processing | Year: 2011

The author analyses the target range estimation errors in pulse compression high-resolution radars (HRRs). Conventional radar signal processors assume a point target model in matched filtering-based detection and tracking. The author demonstrates through simulations that the performance degradation, under the point target assumption, can be significant for HRRs, where targets extend across several detection cells. Also, the author models events of backscatters from illuminated target and clutter as a non-homogenous Poisson process (NHPP). The corresponding maximum likelihood, maximum a posteriori, minimum mean square error and minimum mean absolute error estimators are derived for range estimation. Typical target detection process has been simulated and the performance of NHPP-based estimators has been compared to that of the most commonly used peak estimators, namely, the maximum point and interpolation peak estimators. Simulation results show that the proposed estimators significantly reduce target range estimation errors in HRRs. © 2011 The Institution of Engineering and Technology.

Karakoc F.,Tubitak BILGEM UEKAE | Karakoc F.,Technical University of Istanbul | Demirci H.,Tubitak BILGEM UEKAE | Harmanci A.E.,Technical University of Istanbul
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2013

In this paper, we propose a software oriented lightweight block cipher, ITUbee. The cipher is especially suitable for resource constrained devices including an 8-bit microcontroller such as sensor nodes in wireless sensor networks. For a sensor node one of the most important constraints is the low energy consumption because of the limited battery power. Also, the memory on sensor nodes are restricted. We have simulated the performance of ITUbee in the AVR ATtiny45 microcontroller using the integrated development platform Atmel Studio 6. We have evaluated the memory usage and clock cycles needed for an encryption. The number of clock cycles gives a metric for energy consumption. The simulation results show that ITUbee is a competitive block cipher on 8-bit software platforms in terms of energy consumption. Also, less memory requirement of the cipher is remarkable. In addition, we have shown that the attacks which are effective on software oriented lightweight block ciphers can not reduce the 80-bit security level of ITUbee. © 2013 Springer-Verlag.

Ustuner F.,Tubitak Bilgem Uekae
Progress in Electromagnetics Research Symposium | Year: 2011

The safety distance concept is widely used in the installation of cellular base stations to define a radiation hazard zone around the periphery of the base station. In this paper, three dimensional safety distance analysis around a specific cellular base station is carried out using ray optic techniques with the diffraction theory included. The calculated electric field equivalent to health limit is plotted in a contour line form to illustrate the safety distance around the base station. The resulting plots illustrate the radiation hazard areas.

PubMed | Howard Hughes Medical Institute, Wah Medical College, Tubitak Bilgem Uekae, Hacettepe University and 14 more.
Type: Journal Article | Journal: Nature genetics | Year: 2015

Pediatric-onset ataxias often present clinically as developmental delay and intellectual disability, with prominent cerebellar atrophy as a key neuroradiographic finding. Here we describe a new clinically distinguishable recessive syndrome in 12 families with cerebellar atrophy together with ataxia, coarsened facial features and intellectual disability, due to truncating mutations in the sorting nexin gene SNX14, encoding a ubiquitously expressed modular PX domain-containing sorting factor. We found SNX14 localized to lysosomes and associated with phosphatidylinositol (3,5)-bisphosphate, a key component of late endosomes/lysosomes. Patient-derived cells showed engorged lysosomes and a slower autophagosome clearance rate upon autophagy induction by starvation. Zebrafish morphants for snx14 showed dramatic loss of cerebellar parenchyma, accumulation of autophagosomes and activation of apoptosis. Our results characterize a unique ataxia syndrome due to biallelic SNX14 mutations leading to lysosome-autophagosome dysfunction.

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