Sulak, Fatih
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Sulak, Fatih
F., Sulak
S.,Fatih
Sulak, F
F.,Sulak
Fatih, Sulak
Sulak,F.
S., 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
Turkish CoHE Profile ID
Google Scholar ID
WoS Researcher ID
Scholarly Output
22
Articles
16
Citation Count
67
Supervised Theses
2
21 results
Scholarly Output Search Results
Now showing 1 - 10 of 21
Article Modifications of Knuth Randomness Tests for Integer and Binary Sequences(2018) Koçak, Onur; Sulak, Fatih; Doğanaksoy, Ali; Uğuz, Muhiddin; MathematicsGenerating 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.Article Citation - WoS: 14New Statistical Randomness Tests Based on Length of Runs(Hindawi Ltd, 2015) Doganaksoy, Ali; Sulak, Fatih; Uguz, Muhiddin; Seker, Okan; Akcengiz, Ziya; MathematicsRandom sequences and random numbers constitute a necessary part of cryptography. Many cryptographic protocols depend on random values. Randomness is measured by statistical tests and hence security evaluation of a cryptographic algorithm deeply depends on statistical randomness tests. In this work we focus on statistical distributions of runs of lengths one, two, and three. Using these distributions we state three new statistical randomness tests. New tests use chi(2) distribution and, therefore, exact values of probabilities are needed. Probabilities associated runs of lengths one, two, and three are stated. Corresponding probabilities are divided into five subintervals of equal probabilities. Accordingly, three new statistical tests are defined and pseudocodes for these new statistical tests are given. New statistical tests are designed to detect the deviations in the number of runs of various lengths from a random sequence. Together with some other statistical tests, we analyse our tests' results on outputs of well-known encryption algorithms and on binary expansions of e, pi, and root 2. Experimental results show the performance and sensitivity of our tests.Conference Object Citation - WoS: 0Statistical Randomness Tests of Long Sequences by Dynamic Partitioning(Ieee, 2020) Akcengiz, Ziya; Asian, Melis; Karabayir, Ozgur; Doganaksoy, Ali; Uguz, Muhiddin; Sulak, Fatih; MathematicsRandom 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.Conference Object Citation - Scopus: 2Statistical Randomness Tests of Long Sequences by Dynamic Partitioning(Institute of Electrical and Electronics Engineers Inc., 2020) Akcengiz,Z.; Aslan,M.; Karabayir,O.; Doganaksoy,A.; Uguz,M.; Sulak,F.; MathematicsRandom 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 Citation - WoS: 25Citation - Scopus: 25On 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; MathematicsRandom 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.Article On the Success Probabilities of Differential Attacks On Present(2016) Sulak, Fatih; Şeker, Okan; MathematicsAdvanced 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 attacksArticle Citation - WoS: 1A SECOND PRE-IMAGE ATTACK AND A COLLISION ATTACK TO CRYPTOGRAPHIC HASH FUNCTION LUX(Ankara Univ, Fac Sci, 2017) Sulak, Fatih; Kocak, Onur; Saygi, Elif; Ogunc, Merve; Bozdemir, Beyza; MathematicsCryptography is a science that provides the security of information in communication. One of the most important sub-branches of cryptography is the hash functions. Hash functions are known as the digital fingerprints. Following the recent attacks on the widely used hash functions MD5 and SHA-1 and the increase in computational power, the need for a new hash function standard has arisen. For this purpose, US National Institute of Standards and Technology (NIST) had announced a competition to select a standard hash function algorithm which would eventually become the Third Secure Hash Algorithm, SHA-3. Initially 64 algorithms were submitted to NIST and 51 of them were announced as the First Round Candidates. After an analysis period, 14 of these algorithms were announced as the Second Round Candidates, and 5 algorithms were announced as Finalists. The winner of the competition, Keccak, was announced in 2012. LUX is one of the 64 algorithms submitted to the SHA-3 competition by Nikolic et al. It is designed as a byte oriented stream cipher based hash function. For LUX-256, Schmidt-Nielsen gave a distinguisher and later Wu et al. presented collision attacks, both of which for reduced rounds of LUX. As a result of these attacks, LUX is eliminated in the first round. In this work, we first give a procedure for the second preimage attack. Then we extend this to the collision and second preimage attacks for the reduced rounds of LUX hash family. Moreover, we implement the attacks and give the specific examples by taking the padding into consideration.Article A Second Pre-Image Attack and A Collision Attack To Cryptographic Hash Function Lux(2017) Sulak, Fatih; Koçak, Onur; Saygı, Elif; Öğünç, Merve Ö.; Bozdemır, Beyza; MathematicsCryptography is a science that provides the security of informationin communication. One of the most important sub-branches of cryptographyis the hash functions. Hash functions are known as the digital ...ngerprints.Following the recent attacks on the widely used hash functions MD5 and SHA1 and the increase in computational power, the need for a new hash functionstandard has arisen. For this purpose, US National Institute of Standards andTechnology (NIST) had announced a competition to select a standard hashfunction algorithm which would eventually become the Third Secure HashAlgorithm, SHA-3. Initially 64 algorithms were submitted to NIST and 51 ofthem were announced as the First Round Candidates. After an analysis period,14 of these algorithms were announced as the Second Round Candidates, and5 algorithms were announced as Finalists. The winner of the competition,Keccak, was announced in 2012.LUX is one of the 64 algorithms submitted to the SHA-3 competition byNikolic et al.function. For LUX-256, Schmidt-Nielsen gave a distinguisher and later Wu etal. presented collision attacks, both of which for reduced rounds of LUX. As aresult of these attacks, LUX is eliminated in the ...rst round. In this work, we...rst give a procedure for the second preimage attack. Then we extend this tothe collision and second preimage attacks for the reduced rounds of LUX hashfamily. Moreover, we implement the attacks and give the speci...c examples bytaking the padding into consideration.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, FatihAvrupa’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: 11Citation - Scopus: 12Mutual 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; MathematicsRandom 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.
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