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Examining the formation of women’s identity in a Naqshi community:the case of Ismailağa
Get PDFThis thesis aims to examine the formation of women’s identity in Ismailağa community.
This particular community is chosen specially for its unique adherence to traditional
roles and communal upbringing. I employ three different methods of qualitative
research for this study; discourse analysis, semi-structured interviews and participant
observation. Discursive strategies and modes of subjection revealed that female
members of Ismailağa community construct their identity with regards to both Sufi
elements and community experiences. Finally, this study aims to contribute to the
literature of Sufi communities in Turkey with an emphasis on gender and identity.Abstract ............................................................................................................................... iv
Öz ......................................................................................................................................... v
Acknowledgments ............................................................................................................... vi
Table Of Contents .............................................................................................................. vii
CHAPTERS
1. INTRODUCTION ............................................................................................................... 1 1.1.Topic & Rationale of Thesis ...................................................................................... 1 1.2.Research Questions .................................................................................................. 2 1.3.Literature Review ..................................................................................................... 3 1.4.Outline of the Study ............................................................................................... 11 1.5.Theoretical Framework .......................................................................................... 12 1.5.1.Pierre Bourdieu: Field, Capital and Habitus ........................................................ 13 1.5.2.The Theory of Symbolic Interaction .................................................................... 18
2. NAQSHIBANDIYYA AND THE ISMAILAGA COMMUNITY ................................................ 25 2.1 Overview of Sufism ................................................................................................. 25 2.2. The Ismailağa Community ..................................................................................... 28 2.3. Methodological Framework .................................................................................. 30
3. Discursive Construction of Women’s Identity in the Ismailağa Community ................ 40
3.1. Discursive Strategies .............................................................................................. 40
3.1.1. Formation of Identity through “Hocalık” ...................................................... 41 3.1.2. Tasawwuf and Tariqa in Identity Formation ...................................................... 52 3.1.3. Emphasizing Self-Sacrifice .................................................................................. 56 3.1.4. Constituting Identity through Stories ................................................................. 58 3.1.5. Constructing internal hierarchy on the basis of Taqwa ..................................... 62
4. Modes of Subjection: Formation of Ideal Subjects and Community ............................ 66
4.1. Discursive Strategies of Forming Ideal Community and Subjects ......................... 67 4.1.1. The Ideal Sheikh ................................................................................................. 67
4.1.2. Ideal Women ...................................................................................................... 71 4.1.3. Ideal Men ............................................................................................................ 78 4.1.4. The Ideal Community ......................................................................................... 79
5. CONCLUSION ................................................................................................................. 85 5.1. Limitations and Suggestions for Further Research ............................................... 92
REFERENCES ...................................................................................................................... 9
RSA algoritmasının Raspberry Pi üzerinde gerçeklemesine elektromanyetik yayınım analizi
Get PDFIn this paper, security analysis of RSA implementation on a Raspberry Pi against electromagnetic radiation analysis is evaluated. Two different RSA algorithm is implemented on Raspberry Pi. Simple Electromagnetic Analysis and Differential Electromagnetic Analysis attacks are performed. Using Simple Electromagnetic Analysis attack on an unprotected implementation, all key bits are found with one measurement. Also, Differential Electromagnetic Analysis attack is performed against an improved implemantation that has countermeasure against Simple Electromagnetic Analysis attack. One key bit is found using 2500 measurements with a correlation analysis in Differential Electromagnetic Analysis attack
Democratic uprisings in the new middle east: youth, technology, human rights and foreign policy
No full textMasquerade in fingersmit
No full textIn the last decades, intertextuality has been used to question issues of gender identity and desire, and, in a lively dialogue with theoretical debates
within feminist thought, has come to define women’s writing. An early example of such intertextuality is the rewriting of the female subject in Angela Carter’s spectacular novel Nights at the Circus (1984). Fevvers, the
self-proclaimed bird woman found at the door of a brothel, hatched from
an egg, raised by prostitutes, and trained by the witch-like anarchist
Lizzie, wanders around the world, traversing alternative communities, ideologies, and the world of fiction, while exploring the feminine experience
in relation to her indeterminate female body symbolized by her alleged
wings and searching for a place and language for the new woman. The figure of the woman writer in confrontation with the literary heritage is ubiquitous in contemporary women’s writing; a recent example is Kate Atkinson’s Emotionally Weird (2000), a postmodern novel that produces its new
woman by rewriting and questioning the realist novel. Unlike most of their
fictive predecessors in the realist novel, who begin as single women and
end up in socially appropriate, acceptable heterosexual marriages, the female protagonists of postmodern fiction strive to break free of both their
biological roots and the marriage institution and stage female experience
in the discursive field. While exposing the inadequacy of traditional literary forms and their implicit gender norms, this figure of the woman writer
in search of a language offers a viable, desirable form of female existence
instead
Estimating the selectivity of LIKE queries using pattern-based histograms
No full textAccurate cost and time estimation of a query is one of the major success indicators for database management systems. SQL allows the expression of flexible queries on text-formatted data. The LIKE operator is used to search for a specified pattern (e.g., LIKE "luck%") in a string database. It is vital to estimate the selectivity of such flexible predicates for the query optimizer to choose an efficient execution plan. In this paper, we study the problem of estimating the selectivity of a LIKE query predicate over a bag of strings. We propose a new type of pattern-based histogram structure to summarize the data distribution in a particular column. More specifically, we first mine sequential patterns over a given string database and then construct a special histogram out of the mined patterns. During query optimization time, pattern-based histograms are exploited to estimate the selectivity of a LIKE predicate. The experimental results on a real dataset from DBLP show that the proposed technique outperforms the state of the art for generic LIKE queries like %s(1)%s(2)%...%s(n) % where s(i) represents one or more characters. What is more, the proposed histogram structure requires more than two orders of magnitude smaller memory space, and the estimation time is almost an order of magnitude less in comparison to the state of the art
Sensor based cyber attack detections in critical infrastructures using deep learning algorithms
Get PDFThe technology that has evolved with innovations in the digital world has also caused an increase in many security problems. Day by day the methods and forms of the cyber attacks began to become complicated, and therefore their detection became more difficult.
In this work we will use datasets prepared in collaboration with Raymond Borges and OakRidgeNationalLaboratories. ThesedatasetsincludemeasurementsoftheIndustrial Control Systems related to chewing attack behavior. These measurements include synchronized measurements and data records from Snort and relays with simulated control panel.
In our work, we developed two models using this dataset. The first is the model we call the Deep Neural Network (DNN) Model and build using the latest Deep Learning algorithms. Second is the model which we created by adding the AutoEncoder (AE) structure to the DNN Model. All of the variables used when developing our models were set parametrically. A number of variables such as Activation Method, number of hidden layers in the model, number of nodes in the layers, number of iterations were analyzed to create the optimum model design.
When we run our model with optimum settings, we obtained better results than related publications. The learning speed of the model we have obtained 100% accuracy rate is also quite satisfactory. While the training speed of the dataset containing about 4 thousand different operations lasts about 90 seconds, the model which completes the learning process is at the level of milliseconds to detect new attacks. This increases the applicability of the study. Detailed information about the results of the model is interpretedinChapter5andtheproposalsforthedevelopmentofthemodelarediscussed in Chapter 6.
In our work, we intend to minimize the cost of recognizing and learning new attacks by using deep learning methods to more effectively protect industrial systems such as critical infrastructures.CONTENTS:
Declaration of Authorship ii
Abstract iii
Öz iv
Acknowledgments v
List of Figures viii
List of Tables xi
Abbreviations xiii
1 Introduction 1 1.1 Contribution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2 Related Work 5 2.1 Developing a Hybrid Intrusion Detection System Using Data Mining for Power Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 2.2 Classification of Disturbances and Cyber-attacks in Power Systems Using Heterogeneous Time-synchronized Data . . . . . . . . . . . . . . . . . . . 6 2.3 A Specification-based Intrusion Detection Framework for Cyber-physical Environment in Electric Power System . . . . . . . . . . . . . . . . . . . . 6 2.4 Machine Learning for Power System Disturbance and Cyber-attack Discrimination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
3 Preliminaries 8 3.1 Datasets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 3.2 Autoencoder . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 3.3 Deep Learning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
4 Methodology 14 4.1 System Model without Autoencoder . . . . . . . . . . . . . . . . . . . . . 14 4.2 System Model with Autoencoder . . . . . . . . . . . . . . . . . . . . . . . 16
5 Experiments 19 5.1 Experimental Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 5.2 Experiments Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 5.2.1 DNN Model Results . . . . . . . . . . . . . . . . . . . . . . . . . . 20
5.2.1.1 Binary Data Class Results . . . . . . . . . . . . . . . . . 22 5.2.1.2 Triple Data Class Results . . . . . . . . . . . . . . . . . . 30 5.2.1.3 Multi Data Class Results . . . . . . . . . . . . . . . . . . 36 5.2.2 AutoEncoder Results . . . . . . . . . . . . . . . . . . . . . . . . . . 42 5.2.2.1 Binary Data Class Results with AutoEncoder Model . . . 44 5.2.2.2 Triple Data Class Results with AutoEncoder Model . . . 53 5.2.2.3 Multi Data Class Results with AutoEncoder Model . . . 60 5.2.3 Classification Models Results . . . . . . . . . . . . . . . . . . . . . 66 5.2.3.1 Binary Data Class Results with Classification Models . . 66 5.2.3.2 Triple Data Class Results with Classification Models . . . 67 5.2.3.3 Multi Data Class Results with Classification Models . . . 68
6 Conclusuion and Future Work 69
Bibliography 7
Web güvenliğinde SSL/TLS kriptografik protokolü:açıklıklar, saldırılar ve güvenlik önlemleri
Get PDFHaberleşme teknolojilerinin gelişmesi ile birlikte bilgi güvenliği bilimi önemini artırmaktadır. Internet üzerinden güvenli iletişim için SSL/TLS protokolleri ve açık anahtar altyapısı (PKI) kullanılır. Bu yöntemlerin kullanıcıları için pek çok kolaylık ve fayda sağlamasının yanı sıra tehlikeleri de bulunmaktadır. Haberleşme protokolleri ve güvenli haberleşme için geliştirilen SSL/TLS protokollerinde son 20-25 yıla bakıldığında gerçek anlamda güvenlikten ve gizlilikten bahsetmek pek mümkün değildir. SSL/TLS protokolleri ve açık anahtar altyapısı, zaman içerisinde tehlikeli açıklıklar barındırmış ve hatalarından ders çıkararak daha korunaklı hale gelmişlerdir. Bu tezde, Internet güvenliğinin zaman içerisindeki açıklıklarından bahsedilmiş, güncel tüm kritik saldırılar detaylı olarak anlatılmıştır. Bununla birlikte ataklar incelenirken hem kripto ve açık anahtar altyapısı hem de siber güvenlik yaklaşımları göz önünde bulundurulmuştur. İncelenen saldırıların kapalı ve açık ağlardaki sunucular üzerinde güvenlik analizleri ve tavsiyeleri için bir altyapı geliştirilmiştir.İÇİNDEKİLER:
Yazarlık Beyanı ii
Öz iv
Abstract v
Teşekkür vi
Şekil Listesi xii
Tablo Listesi xiv
Kısaltmalar xv
1 Giriş 1 1.1 Internet Güvenliği ve Taşıma Katmanı Güvenliği Protokolü . . . . . . . . 1 1.2 Tezin Hedefi ve Motivasyonu . . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.2.1 Hedef . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 1.2.2 Motivasyon . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 1.2.3 Tezin İçeriği ve Başlıkları . . . . . . . . . . . . . . . . . . . . . . . 4
2 Ön Bilgi ve Gerekli Matematiksel Altyapılar 6 2.1 Açık Anahtar Altyapısı . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 2.1.1 Sertifika . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 2.1.1.1 Sertifika İçeriği . . . . . . . . . . . . . . . . . . . . . . . . 7 2.1.1.2 Sertifika Eklentileri . . . . . . . . . . . . . . . . . . . . . 8 2.1.2 Sertifika Zincirleri . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 2.1.3 Sertifika Otoriteleri . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 2.1.4 Sertifika Yaşam Döngüsü . . . . . . . . . . . . . . . . . . . . . . . 9 2.1.5 Sertifika İptali . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 2.1.5.1 Sertifika İptal Listesi (SİL) . . . . . . . . . . . . . . . . . 10 2.1.5.2 Çevrimiçi Sertifika Durumu Protokolü (ÇSDP) . . . . . . 10 2.2 Matematiksel Temeller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 2.2.1 Ayrık Logaritma Problemi (ALP) . . . . . . . . . . . . . . . . . . . 11 2.2.2 Hesapsal & Kararsal Diffie-Hellman Problemleri (HDH & KDH) . . 11 2.2.3 Çarpanlarına Ayırma Problemi . . . . . . . . . . . . . . . . . . . . 13 2.2.4 Eliptik Eğri Ayrık Logaritma Problemi . . . . . . . . . . . . . . . . 13
2.2.5 Tek Yönlü Fonksiyonlar . . . . . . . . . . . . . . . . . . . . . . . . 13 2.2.5.1 Özet Fonksiyonları . . . . . . . . . . . . . . . . . . . . . . 14 2.2.6 Açık Anahtarlı Algoritmalar . . . . . . . . . . . . . . . . . . . . . . 15 2.2.6.1 ElGamal Açık Anahtar Şifreleme Algoritması . . . . . . . 15 2.2.6.2 Dijital İmza Algoritması . . . . . . . . . . . . . . . . . . . 16 2.3 Anahtar Anlaşma Protokolleri . . . . . . . . . . . . . . . . . . . . . . . . . 17 2.3.1 Anahtar Anlaşma Protokolünde Güvenlik Gereksinimleri . . . . . . 18 2.3.1.1 Kimlik Doğrulama . . . . . . . . . . . . . . . . . . . . . . 18 2.3.2 Anahtar Anlaşma Protokolüne Yapılan Saldırılar . . . . . . . . . . 20 2.3.2.1 Saldırı Karakteristiği . . . . . . . . . . . . . . . . . . . . 20 2.3.2.2 Aktif ve Pasif Saldırılar . . . . . . . . . . . . . . . . . . . 20 2.3.2.3 Farklı Saldırı Türleri . . . . . . . . . . . . . . . . . . . . . 20
3 Mevcut Anahtar Anlaşma Protokolleri ve Güvenlik Analizleri 22 3.1 Temel Diffie-Hellman Anahtar Anlaşma Protokolü . . . . . . . . . . . . . 22 3.2 Sertifikalı Diffie-Hellman Anahtar Anlaşma Protokolü . . . . . . . . . . . . 25 3.2.1 Anahtar İfşası ile Yerine Geçme (KCI) Saldırısı . . . . . . . . . . . 26 3.3 Kısa Ömürlü (Ephemeral) Diffie-Hellman Anahtar Anlaşma Protokolü . . 27 3.4 MQV Anahtar Anlaşma Protokolü . . . . . . . . . . . . . . . . . . . . . . 28 3.4.1 MQV Protokolünün Eksiklikleri . . . . . . . . . . . . . . . . . . . . 30 3.4.2 Bilinmeyen Anahtar Paylaşımı (UKS) Saldırısı . . . . . . . . . . . 30 3.5 HMQV Anahtar Anlaşma Protokolü . . . . . . . . . . . . . . . . . . . . . 31 3.6 FHMQV Anahtar Anlaşma Protokolü . . . . . . . . . . . . . . . . . . . . 32 3.7 RSA Tabanlı Anahtar Anlaşma Protokolü . . . . . . . . . . . . . . . . . . 32 3.8 Rastsallaştırma-Tuzlama . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
4 SSL/TLS Protokolü 35 4.1 Kayıt Protokolü . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 4.2 Uyarı Protokolü . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 4.3 El Sıkışma Protokolü . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37 4.3.1 Hello Mesajları . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 4.3.1.1 Hello Request. . . . . . . . . . . . . . . . . . . . . . . . . 38 4.3.1.2 Client Hello . . . . . . . . . . . . . . . . . . . . . . . . . . 39 4.3.1.3 Server Hello . . . . . . . . . . . . . . . . . . . . . . . . . 40 4.3.2 Server Certificate . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 4.3.3 Server Key Exchange . . . . . . . . . . . . . . . . . . . . . . . . . . 41 4.3.4 Server Hello Done . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 4.3.5 Client Certificate . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 4.3.6 Client Key Exchange . . . . . . . . . . . . . . . . . . . . . . . . . . 42 4.3.6.1 RSA İle Şifreli Ön Ana Giz . . . . . . . . . . . . . . . . . 43 4.3.6.2 Diffie-Hellman ile Açık Değer Gönderme . . . . . . . . . . 43 4.3.7 Change Cipher Spec . . . . . . . . . . . . . . . . . . . . . . . . . . 43 4.3.8 Finished . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43 4.4 Oturum Yenileme . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44 4.5 Anahtar Paylaşımı . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44 4.6 Uyarı Protokolü . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 4.7 Haberleşme Güvenliği Protokolü - SSL/TLS . . . . . . . . . . . . . . . . . 45
4.7.1 SSL Versiyonları- v1,v2,v3 . . . . . . . . . . . . . . . . . . . . . . . 46 4.7.2 TLSv1.0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46 4.7.3 TLSv1.1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46 4.7.4 TLSv1.2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47 4.7.5 TLSv1.3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47 4.8 Ağ Güvenliği Zaman Süreci . . . . . . . . . . . . . . . . . . . . . . . . . . 48
5 SSL/TLS Protokolündeki Elektronik Sertifika Altyapısına Yapılan Saldırılar 53 5.1 Sertifika Otoritelerinin Güvenliği . . . . . . . . . . . . . . . . . . . . . . . 53 5.1.1 Sertifikaların Zaman İçerisindeki Sorunları . . . . . . . . . . . . . . 54 5.1.2 Sertifika Otoriteleri’nin Güven Mekanizmasının Dağıtımı . . . . . . 54 5.1.2.1 Yetkili Anahtar Yöntemi . . . . . . . . . . . . . . . . . . 54 5.1.2.2 Sertifika Şeffaflığı . . . . . . . . . . . . . . . . . . . . . . . 55 5.1.2.3 Sorumlu Anahtar Altyapısı . . . . . . . . . . . . . . . . . 55 5.1.2.4 Saldırıya Dirençli Açık Anahtar Altyapısı . . . . . . . . . 56 5.1.3 Bilinen Saldırılar ve Yanlış Kullanımlar . . . . . . . . . . . . . . . 56 5.2 Pratik Saldırılar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57 5.2.1 Microsoft’un Sertifika Hatası . . . . . . . . . . . . . . . . . . . . . 57 5.2.2 OCSP Saldırısı . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58 5.2.3 Let’s Encrypt Sertifika Otoritesi ve Oltalama Saldırısı . . . . . . . 58 5.3 Sertifika Özetlerinin Çakışması . . . . . . . . . . . . . . . . . . . . . . . . 59 5.3.1 MD5 Özet Çakışması . . . . . . . . . . . . . . . . . . . . . . . . . . 59 5.3.2 SHA1 Özet Çakışması . . . . . . . . . . . . . . . . . . . . . . . . . 59 5.4 Internet Explorer SSL Sertifika Açıklığı . . . . . . . . . . . . . . . . . . . . 59 5.5 Sahte Sertifika Otoritesi Sertifikası (RapidSSL) . . . . . . . . . . . . . . . 60 5.6 Unicode Alan Adları ile Oltalama Saldırısı . . . . . . . . . . . . . . . . . . 61
6 SSL/TLS Haberleşme Protokolüne Yönelik Saldırılar 63 6.1 Şifre Paketi Düşürme Saldırısı . . . . . . . . . . . . . . . . . . . . . . . . . 63 6.2 Şifreli İletişime Geçme Mesajını Düşürme . . . . . . . . . . . . . . . . . . 64 6.3 MAC’in tuzlama uzunluğunu kapsamaması açıklığı . . . . . . . . . . . . . 65 6.4 Bleichenbacher Saldırısı . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65 6.4.1 Saldırının Ön Koşulları . . . . . . . . . . . . . . . . . . . . . . . . . 65 6.4.2 Saldırı Senaryosu . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65 6.4.2.1 Seçili Şifreli Metin Saldırısı Senaryosu . . . . . . . . . . . 66 6.4.2.2 Bleichenbacher Saldırısının Senaryosu . . . . . . . . . . . 67 6.4.3 Saldırıya Karşı Alınan Önlemler . . . . . . . . . . . . . . . . . . . 68 6.5 Geliştirilmiş Bleichenbacher Saldırısı . . . . . . . . . . . . . . . . . . . . . 69 6.6 BEAST . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69 6.6.1 Saldırının Ön Koşulları . . . . . . . . . . . . . . . . . . . . . . . . . 70 6.6.2 Saldırının Senaryosu . . . . . . . . . . . . . . . . . . . . . . . . . . 70 6.6.2.1 ECB Güvenliği . . . . . . . . . . . . . . . . . . . . . . . . 70 6.6.2.2 Tahmin Edilebilir IV ile CBC modu . . . . . . . . . . . . 71 6.6.2.3 Saldırının Adımları . . . . . . . . . . . . . . . . . . . . . . 72 6.6.3 Saldırıya Karşı Alınan Önlemler . . . . . . . . . . . . . . . . . . . 75 6.7 CRIME . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
6.7.1 Saldırının Ön Koşulları . . . . . . . . . . . . . . . . . . . . . . . . . 76 6.7.2 Saldırı Senaryosu . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76 6.7.3 Saldırıya Karşı Alınan Önlemler . . . . . . . . . . . . . . . . . . . 78 6.8 TIME . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79 6.8.1 Saldırının Ön Koşulları . . . . . . . . . . . . . . . . . . . . . . . . . 79 6.8.2 Saldırı Senaryosu . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79 6.8.3 Saldırıya Karşı Alınan Önlemler . . . . . . . . . . . . . . . . . . . 80 6.8.4 BREACH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80 6.9 Lucky 13 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81 6.9.1 Saldırının Ön Koşulları . . . . . . . . . . . . . . . . . . . . . . . . . 81 6.9.2 Saldırı Senaryosu . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81 6.9.3 Saldırıya Karşı Alınan Önlemler . . . . . . . . . . . . . . . . . . . 83 6.10 POODLE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84 6.10.1 Saldırının Ön Koşulları . . . . . . . . . . . . . . . . . . . . . . . . . 85 6.10.2 Saldırı Senaryosu . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85 6.10.3 Saldırıya Karşı Alınan Önlemler . . . . . . . . . . . . . . . . . . . 89 6.11 Heartbleed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89 6.11.1 Saldırının Ön Koşulları . . . . . . . . . . . . . . . . . . . . . . . . . 90 6.11.2 Saldırı Senaryosu . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90 6.11.3 Saldırıya Karşı Alınan Önlemler . . . . . . . . . . . . . . . . . . . 91 6.12 FREAK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91 6.12.1 Saldırının Ön Koşulları . . . . . . . . . . . . . . . . . . . . . . . . . 91 6.12.2 Saldırı Senaryosu . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91 6.12.3 Saldırıya Karşı Alınan Önlemler . . . . . . . . . . . . . . . . . . . 93 6.13 Logjam . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93 6.13.1 Saldırının Ön Koşulları . . . . . . . . . . . . . . . . . . . . . . . . . 93 6.13.2 Saldırı Senaryosu . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94 6.13.2.1 Number Field Sieve Algoritması . . . . . . . . . . . . . . 95 6.13.3 Saldırıya Karşı Alınan Önlemler . . . . . . . . . . . . . . . . . . . 96 6.14 DROWN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96 6.14.1 Saldırının Ön Koşulları . . . . . . . . . . . . . . . . . . . . . . . . . 97 6.14.2 Saldırı Senaryosu . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97 6.14.3 Saldırıya Karşı Alınan Önlemler . . . . . . . . . . . . . . . . . . . 97 6.15 SSL/TLS’e Yönelik Protokol Saldırılarının Özeti . . . . . . . . . . . . . . 98
7 Diğer Saldırılar 100 7.1 Rastgele Sayı Tahmini . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100 7.2 Debian OpenSSL Uygulaması Açıklığı . . . . . . . . . . . . . . . . . . . . 100 7.3 Uyarı Mesajları ile DOS Saldırısı . . . . . . . . . . . . . . . . . . . . . . . 101 7.4 SSL/TLS’in Üst Katmanda Engellenmesi . . . . . . . . . . . . . . . . . . 101
8 SSL/TLS Analiz Aracı (Webtester) 103 8.1 Giriş . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103 8.2 Analiz Araçlarının Özellikleri . . . . . . . . . . . . . . . . . . . . . . . . . 104 8.3 Webtester Uygulaması ve Gerekliliği . . . . . . . . . . . . . . . . . . . . . 105 8.4 Analiz Araçlarında Performans Arttırma Önerileri . . . . . . . . . . . . . 106 8.4.1 Webtester Uygulamasında Uygulanan Pratik Yaklaşımlar . . . . . 109
8.4.2 Webtester Uygulamasında Yer Almayan Özellikler . . . . . . . . . 111 8.5 Webtester Uygulamasında Kontrol Edilen Maddeler . . . . . . . . . . . . . 113 8.6 Webtester Uygulamasının Performansı . . . . . . . . . . . . . . . . . . . . 115 8.6.1 Açık ve Kapalı Ağlarda Performans Testleri . . . . . . . . . . . . . 115 8.6.2 Başarı Oranları . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117
9 Sonuç 119 9.1 Sonuç . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Impact of channel length scaling on electrical transport properties of slicon carbide nanowire based field effect transistors (SiCNW-FETs)
Get PDFThe rapid evolution of technology forces the existing electronic devices to be much more smaller as well as to able to operate at higher frequency with low power consumption. However, current devices (ex. CMOS (Complementary Metal Oxide Semiconductor)) mostly based on Silicon (Si) and Si based transistor technology is almost saturated in terms of device size and operating frequency. In order to overcome these issues and realize much faster and smaller transistor with new geometry, 1-D nanostructures (such as nanowires(NWs)andnanotubes(NTs))andtheirelectricaltransportpropertieshavebecome focus of tremendous research in recent years. Silicon carbide (SiC) nanostructures, a wide band gap semiconductor with excellent properties such as as high break-down voltage, high thermal conductivity, high drift velocity physical and chemical properties as well as compatibility with existing Si devices, have been intensly studied in terms of material properties, fabrication, characterization as well as their various applications. SiCNWs are one of the most promising candidate to be used as channel material or substrate.
In this study, we synthesize 3C-SiCNWs via Metal-Organic Chemical Vapor Deposition (MOCVD) method and fabricate SiCNW-FETs in order to examine the channel length dependent electrical transport characteristic of SiCNW with varying channel lengths ranging from 120 nm to 1.5 µm. Further we report the important performance parameters of SiCNW-FET devices and compare them with recently reported studies. The device with the 120 nm channel length has led a very high on/off current ratio (Ion/Ioff = 1.34⇥104) and very strong gating effect. Furthermore, the transconductance and the hole mobility have been determined as 6.9 nS and 1.696 cm2/V.s, respectively, at Vds of 0.05 V. This study shows good promise of the SiCNW-FET devices to be used in advanced solid-state nanoelectronic devices capable of operating at high frequency and high temperature.CONTENS:
Declaration of Authorship ii
Abstract iv
Öz v
Acknowledgments vii
List of Figures x
List of Tables xii
Abbreviations xiii
Physical Constants xv
Symbols xvi
1 Introduction 1 1.1 Research Background .............................. 1 1.2 Literature Review ................................ 2 1.3 Motivation Behind the Work ......................... 4 1.4 Thesis Organization .............................. 5
2 SiC Nanowire Synthesis and FET Device Fabrication 6 2.1 NW Fabrication Methods ........................... 6 2.1.1 Top Down Methods .......................... 7 2.1.2 Bottom Up Methods .......................... 8 2.2 SiCNWs Growth ................................ 8 2.3 SiCNW Characterization ............................ 13 2.3.0.1 Scanning Electron Microscope (SEM) ........... 13 2.3.0.2 X-Ray Diffraction (XRD) .................. 16 2.4 SiCNW-FET Device Design and Fabrication ................. 18 2.4.0.1 NW-FET ........................... 18 2.4.0.2 Design Specifications..................... 19 2.4.0.3 Device Fabrication ...................... 20
3 Electrical Characterization of 3C-SiCNW 25 3.1 The Experimental Setup and Equipment ................... 25
3.2 Contact Issues and Annealing ......................... 28 3.3 Electrical Characterization of SiCNW-FETs ................. 29 3.3.1 Electrical Properties of SiCNWs.................... 29 3.3.1.1 Transconductance ...................... 29 3.3.1.2 Carrier Mobility ....................... 29 3.3.1.3 Carrier Concentration .................... 30 3.3.1.4 On-Off Current Ration ................... 30 3.3.2 Current-Voltage (I V) Characteristics of 3C-SiCNW-FETs ... 30 3.4 Results and Comparison with Other Studies ................ 36 3.5 Effect of Channel Scaling on Performance of SiCNW-FETs ........ 37
4 Conclusion and Future Work 39 4.1 Conclusions ................................... 39 4.2 Future Work .................................. 40
Bibliography 4
