Sulak, Fatih

Profile URL
https://hdl.handle.net/20.500.14411/7029
Name Variants
Sulak, Fatih F., Sulak S.,Fatih Sulak, F F.,Sulak Fatih, Sulak Sulak,F. S., Fatih
Job Title
Doçent Doktor
Email Address
fatih.sulak@atilim.edu.tr
Main Affiliation
Mathematics
Status
Website
ORCID ID
Scopus Author ID
36624418400
Turkish CoHE Profile ID
Google Scholar ID
WoS Researcher ID
DYX-0428-2022
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Sustainable Development Goals

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Documents

15

Citations

118

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5

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Documents

19

Citations

110

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Scholarly Output

27

Articles

19

Views / Downloads

280/97

Supervised MSc Theses

2

Supervised PhD Theses

0

WoS Citation Count

94

Scopus Citation Count

65

Patents

0

Projects

0

WoS Citations per Publication

3.48

Scopus Citations per Publication

2.41

Open Access Source

16

Supervised Theses

2

JournalCount
Cryptography and Communications3
Communications Faculty of Sciences University of Ankara Series A1: Mathematics and Statistics2
TURKISH JOURNAL OF ELECTRICAL ENGINEERING & COMPUTER SCIENCES2
Turkish Journal of Electrical Engineering and Computer Sciences2
Discrete Applied Mathematics1
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Scholarly Output Search Results

Now showing 1 - 10 of 27
  • Book
    100. Yılında Türkiye Cumhuriyeti
    (Atılım Üniversitesi, 2024) Garibova, Jala; Sığırcı, İlhami; Aysal, Necdet; Sümer, Nebi; Çelik, S. Dilek Yalçın; Birlik, Gültekin Kamil; Elbir, Nüket Belgin; Sulak, Fatih
    Avrupa’nın geçirdiği Rönesans, Reform, Aydınlanma Çağı ve Sanayi Devrimi sürecini yaşayamayan Osmanlı Devleti başta ekonomi olmak üzere, eğitim, kültür, sanat gibi alanlarda çağın gerisinde kalmıştır. Bunun yanı sıra 20. yüzyılda yaşadığı Trablusgarp ve Balkan Savaşı, özellikle de Birinci Dünya Savaşı Osmanlı Devleti’nin sonunu getirmiş, Anadolu dâhil pek çok toprağı işgal edilmiştir. Neredeyse bütün varlığını yitirmiş olan Türk toplumu Mustafa Kemal Paşa’nın liderliğinde ve yol göstericiliğinde işgalcilere karşı Milli Mücadeleyi başlatmış ve Misak-ı Milliyi büyük oranda gerçekleştirerek Türkiye Cumhuriyetini kurmuştur. Cephede elde edilen bu başarı sonrasında, Türkiye Cumhuriyeti başta eğitim olmak üzere hayatın her alanında büyük devrimler gerçekleştirerek, Avrupa ile arasındaki mesafeyi kapatmayı, medeni devletler arasında yer almayı hedeflemiştir. Bu hedef doğrultusunda kısa sürede olumlu gelişmeler elde edilmiş, eğitim seviyesi hızla yükseltilmiş, ekonomide üretken olan, bilim ve sanatta önemli başarılar elde eden bir toplum yaratılmıştır. Cumhuriyetin 100. yılına gelindiğinde ise, bu hedef doğrultusunda çok önemli ilerlemeler başarılmış, Avrupa ile aradaki yüzlerce yıllık açık önemli ölçüde ortadan kaldırılmıştır. Cumhuriyetin 100. yılında, Atılım Üniversitesinde gerçekleştirilen “100. Yılında Türkiye Cumhuriyeti Sempozyumu”nda bu ilerlemeler sunulan bildirilerle ortaya konulmuştur. Sempozyumda sunulan bildirilerdeki tespitler daha geniş bir kitleye hitap edebilmesi amacıyla, yeniden düzenlenerek kitap haline getirilmiştir. Böylece Atılım Üniversitesi olarak, topluma hizmet etme noktasında yürütülen çalışmalara yeni bir halka daha eklenmiştir.
  • Article
    Citation - WoS: 12
    Citation - Scopus: 13
    Mutual Correlation of Nist Statistical Randomness Tests and Comparison of Their Sensitivities on Transformed Sequences
    (Tubitak Scientific & Technological Research Council Turkey, 2017) Doganaksoy, Ali; Sulak, Fatih; Uguz, Muhiddin; Seker, Okan; Akcengiz, Ziya
    Random sequences are widely used in many cryptographic applications and hence their generation is one of the main research areas in cryptography. Statistical randomness tests are introduced to detect the weaknesses or nonrandom characteristics that a sequence under consideration may have. In the literature, there exist various statistical randomness tests and test suites, defined as a collection of tests. An efficient test suite should consist of a number of uncorrelated statistical tests each of which measures randomness from another point of view. `Being uncorrelated' is not a well-defined or well-understood concept in the literature. In this work, we apply Pearson's correlation test to measure the correlation between the tests. In addition, we define five new methods for transforming a sequence. Our motivation is to detect those tests whose results are invariant under a certain transformation. To observe the correlation, we use two methods. One is the direct correlation between the tests and the other is the correlation between the results of a test on the sequence and its transformed form. In light of the observations, we conclude that some of the tests are correlated with each other. Furthermore, we conclude that in designing a reliable and efficient suite we can avoid overpopulating the list of test functions by employing transformations together with a reasonable number of statistical test functions.
  • Conference Object
    Citation - Scopus: 2
    Statistical Randomness Tests of Long Sequences by Dynamic Partitioning
    (Institute of Electrical and Electronics Engineers Inc., 2020-12-03) Akcengiz,Z.; Aslan,M.; Karabayir,O.; Doganaksoy,A.; Uguz,M.; Sulak,F.
    Random numbers have a wide usage in the area of cryptography. In practice, pseudo random number generators are used in place of true random number generators, as regeneration of them may be required. Therefore because of generation methods of pseudo random number sequences, statistical randomness tests have a vital importance. In this paper, a randomness test suite is specified for long binary sequences. In literature, there are many randomness tests and test suites. However, in most of them, to apply randomness test, long sequences are partitioned into a certain fixed length and the collection of short sequences obtained is evaluated instead. In this paper, instead of partitioning a long sequence into fixed length subsequences, a concept of dynamic partitioning is introduced in accordance with the random variable in consideration. Then statistical methods are applied. The suggested suite, containing four statistical tests: Collision Tests, Weight Test, Linear Complexity Test and Index Coincidence Test, all of them work with the idea of dynamic partitioning. Besides the adaptation of this approach to randomness tests, the index coincidence test is another contribution of this work. The distribution function and the application of all tests are given in the paper. © 2020 IEEE.
  • Article
    Modifications of Knuth Randomness Tests for Integer and Binary Sequences
    (2018) Koçak, Onur; Sulak, Fatih; Doğanaksoy, Ali; Uğuz, Muhiddin
    Generating random numbers and random sequences that are in-distinguishable from truly random sequences is an important task for cryptog-raphy. To measure the randomness, statistical randomness tests are applied tothe generated numbers and sequences. Knuth test suite is the one of the .rststatistical randomness suites. This suite, however, is mostly for real numbersequences and the parameters of the tests are not given explicitly.In this work, we review the tests in Knuth Test Suite. We give test para-meters in order for the tests to be applicable to integer and binary sequencesand make suggestions on the choice of these parameters. We clarify how theprobabilities used in the tests are calculated according to the parameters andprovide formulas to calculate the probabilities. Also, some tests, like Per-mutation Test and Max-of-t-test, are modi.ed so that the test can be usedto test integer sequences. Finally, we apply the suite on some widely usedcryptographic random number sources and present the results.
  • Conference Object
    Citation - Scopus: 1
    Threshold Structure-Preserving Signatures With Randomizable Key
    (Science and Technology Publications, Lda, 2025) Ağırtaş, A.R.; Çelik, E.; Kocaman, S.; Sulak, F.; Yayla, Oğuz; Çelik, Emircan; Ağırtas, Ahmet Ramazan
    Digital signatures confirm message integrity and signer identity, but linking public keys to identities can cause privacy concerns in anonymized settings. Signatures with randomizable keys can break this link, preserving verifiability without revealing the signer. While effective for privacy, complex cryptographic systems need to be modular structured for efficient implementation. Threshold structure-preserving signatures enable modular, privacy-friendly protocols. This work combines randomizable keys with threshold structure-preserving signatures to create a valid, modular, and unlinkable foundation for privacy-preserving applications. © 2025 by Paper published under CC license (CC BY-NC-ND 4.0).
  • Conference Object
    Differential and Linear Analyses of DIZY Through MILP Modeling
    (Springer Science and Business Media Deutschland GmbH, 2026) İlter, M.B.; Koçak, O.; Kara, O.; Sulak, F.
    In this work, we present the first independent security analysis of DIZY, a recently proposed ultra-lightweight stream cipher with two variants: DIZY-80 and DIZY-128. Our analysis focuses on DIZY’s resistance to linear and differential cryptanalysis. We employ a formal technique known as Mixed Integer Linear Programming (MILP), which enables us to model the internal structure of DIZY and search for characteristics that describe how XOR differences or linear masks propagate through the cipher. Specifically, we construct such characteristics to evaluate how many S-boxes become “active” during keystream generation, as this number directly affects the cipher’s resistance to these attacks. Contrary to the designers’ claim that any linear or differential characteristic over 8 rounds must involve at least 20 active S-boxes in DIZY-80 and 22 in DIZY-128, we identify characteristics with only 18 differentially or linearly active S-boxes and 20 linearly active S-boxes, respectively. We mount two distinguishing attacks on each cipher. Our 3-round linear distinguishing attack requires 223 bits of keystream, while the 4-round version requires 235 bits for DIZY-128 and DIZY-80, respectively. Our 2-round differential resynchronization attacks succeed using only the first four bytes of keystream data from approximately 230 and 226 different initializations with chosen initialization vectors (IVs) for DIZY-128 and DIZY-80, respectively. While these attacks do not compromise the full 15-round version of the cipher, they provide valuable insights into the design of DIZY and contribute to a deeper understanding of the security requirements of its diffusion layer. © The Author(s), under exclusive license to Springer Nature Switzerland AG 2026.
  • Article
    On the Success Probabilities of Differential Attacks On Present
    (2016) Sulak, Fatih; Şeker, Okan
    Advanced growth in ubiquitous devices leads to increasing popularity of lightweight cryptography and as a result, various block ciphers are designed. The analysis of these algorithms has become popular and as a result, underlying theory of analysis tools including success probabilities has widely been studied recently. In this work, we focus on Present, a lightweight block cipher introduced by Bogdanov et al. and the analysis of this algorithm. We give a detailed information of differential cryptanalysis and multiple differential cryptanalysis on Present. Also, the underlying theory of statistical cryptanalysis are presented. As an important part of cryptanalysis, success probability is examined and expressed by the formulas given by Selçuk and Blondeau et al. The main aim of this work is to contribute to the theory of statistical cryptanalysis. Therefore, we give a general framework of statistical cryptanalysis and success probabilities. The details of success probabilities are given with experimental results. Also, we apply the sieving phase to decrease the cost of the attacks
  • Article
    Citation - WoS: 33
    Citation - Scopus: 34
    On the Independence of Statistical Randomness Tests Included in the Nist Test Suite
    (Tubitak Scientific & Technological Research Council Turkey, 2017) Sulak, Fatih; Uguz, Muhiddin; Kocak, Onur; Doganaksoy, Ali
    Random numbers and random sequences are used to produce vital parts of cryptographic algorithms such as encryption keys and therefore the generation and evaluation of random sequences in terms of randomness are vital. Test suites consisting of a number of statistical randomness tests are used to detect the nonrandom characteristics of the sequences. Construction of a test suite is not an easy task. On one hand, the coverage of a suite should be wide; that is, it should compare the sequence under consideration from many different points of view with true random sequences. On the other hand, an overpopulated suite is expensive in terms of running time and computing power. Unfortunately, this trade-off is not addressed in detail in most of the suites in use. An efficient suite should avoid use of similar tests, while still containing sufficiently many. A single statistical test gives a measure for the randomness of the data. A collection of tests in a suite give a collection of measures. Obtaining a single value from this collection of measures is a difficult task and so far there is no conventional or strongly recommended method for this purpose. This work focuses on the evaluation of the randomness of data to give a unified result that considers all statistical information obtained from different tests in the suite. A natural starting point of research in this direction is to investigate correlations between test results and to study the independences of each from others. It is started with the concept of independence. As it is complicated enough to work even with one test function, theoretical investigation of dependence between many of them in terms of conditional probabilities is a much more difficult task. With this motivation, in this work it is tried to get some experimental results that may lead to theoretical results in future works. As experimental results may reflect properties of the data set under consideration, work is done on various types of large data sets hoping to get results that give clues about the theoretical results. For a collection of statistical randomness tests, the tests in the NIST test suite are considered. Tests in the NIST suite that can be applied to sequences shorter than 38,912 bits are analyzed. Based on the correlation of the tests at extreme values, the dependencies of the tests are found. Depending on the coverage of a test suite, a new concept, the coverage efficiency of a test suite, is defined, and using this concept, the most efficient, the least efficient, and the optimal subsuites of the NIST suite are determined. Moreover, the marginal benefit of each test, which also helps one to understand the contribution of each individual test to the coverage efficiency of the NIST suite, is found. Furthermore, an efficient subsuite that contains five statistical randomness tests is proposed.
  • Conference Object
    Statistical Randomness Tests of Long Sequences by Dynamic Partitioning
    (Ieee, 2020-12-03) Akcengiz, Ziya; Asian, Melis; Karabayir, Ozgur; Doganaksoy, Ali; Uguz, Muhiddin; Sulak, Fatih
    Random numbers have a wide usage in the area of cryptography. In practice, pseudo random number generators are used in place of true random number generators, as regeneration of them may be required. Therefore because of generation methods of pseudo random number sequences, statistical randomness tests have a vital importance. In this paper, a randomness test suite is specified for long binary sequences. In literature, there are many randomness tests and test suites. However, in most of them, to apply randomness test, long sequences are partitioned into a certain fixed length and the collection of short sequences obtained is evaluated instead. In this paper, instead of partitioning a long sequence into lixed length subsequences, a concept of dynamic partitioning is introduced in accordance with the random variable in consideration. Then statistical methods are applied. The suggested suite, containing four statistical tests: Collision Tests, Weight Test, Linear Complexity Test and Index Coincidence Test, all of them work with the idea of dynamic partitioning. Besides the adaptation of this approach to randomness tests, the index coincidence test is another contribution of this work. The distribution function and the application of all tests are given in the paper.
  • Article
    Cryptographic Randomness Testing of Block Ciphers: SAC Tests
    (IEEE-Inst Electrical Electronics Engineers Inc, 2026) Aslan, Melis; Doganaksoy, Ali; Kocaman, Sermin; Saygi, Zulfukar; Sulak, Fatih
    Block ciphers are designed to function as random mappings, making it essential for them to successfully pass statistical randomness tests. These tests evaluate whether the distribution of a test statistic, derived empirically through various data manipulations over states of the algorithm, aligns with the theoretical distribution for cryptographic randomness. Beyond this, evaluating the cryptographic properties of the algorithm is also important to ensure its security and reliability. One of the important cryptographic randomness properties is the Strict Avalanche Criterion (SAC), which assesses the impact of a one-bit alteration in the input over the output. In this work, we introduce new SAC-based tests to offer more reliable evaluation for the cryptographic randomness of block cipher algorithms. The tests are utilized for the application of AES, PRESENT, and CLEFIA block ciphers. The results are compared with Soto's evaluation methods, which are known for their comprehensive approach to block ciphers. According to this, it is apparent that our novel SAC tests improve upon Soto's results, thus providing a more comprehensive understanding of randomness.