Telea ve Naiver Stokes Algoritmaları Kullanılarak Görüntülerdeki Bozulmaları Düzeltme

Görseller üzerindeki bozulmaları düzeltmek veya görsel üzerindeki istenilmeyen bazı kısımları, görselin orijinal halini bilmeyen kişilerin algılayamayacağı şekilde kaldırmak veya değiştirmek insanların çok uzun zamandır talep ettiği işlemlerdir. Bilgisayarların bu işlemler için kullanılması hem işlemin kalitesini arttırmış hem de işlemi kolaylaştırmıştır, fakat bilgisayar ortamında yapılıyor olsa da görsel üzerindeki işlemler halen manuel olarak yapılmaktadır. Görüntü boyama (Image Inpainting) yöntemi ile bu işlem hem daha hızlı yapılmaya başlanmış hem de işlem otomatikleştirilmiştir. Open CV kütüphanesi için geliştirilen inpaint_telea ve inpaint_ns sınıfları ile görsel üzerinde görüntü boyama işlemi yapılabilmektedir

A New Short Signature Scheme with Random Oracle from Bilinear Pairings, Journal of Telecommunications and Information Technology, 2011, nr 1

In this paper, we propose a new and efficient short signature scheme from the bilinear pairings. Our scheme isconstructed by bilinear inverse-square Diffie-Hellman problem (BISDHP) and does not require any special hash function. The exact security proofs are also explained in the random Oracle model. We give the implementation and comparison results of our proposed signature scheme with the signature scheme proposed by Boneh, Lynn, Shacham (BLS) and Zhang, Safavi, Susilo (ZSS). Furthermore, we use this signature scheme to construct a ring signature scheme

misty1, kasumi and kasumi-r'nin çığ özellikleri üzerine.

The Global System for Mobile (GSM) Communication is the most widely used cellular technology. The privacy has been protected using some version of stream ciphers until the 3rd Generation of GSM. KASUMI, a block cipher, has been chosen as a standard algorithm in order to be used in 3rd Generation. In this thesis, s-boxes of KASUMI, MISTY1 (former version of KASUMI) and RIJNDAEL (the Advanced Encryption Standard) are evaluated according to their linear approximation tables, XOR table distributions and satisfaction of the strict avalanche criterion (SAC). Then, the nonlinear part, FI function, of KASUMI and MISTY1 are investigated for SAC. A new FI function is defined by replacing both s-boxes of KASUMI by RIJNDAEL’s s-box. Calling this new version KASUMI-R, it is found to have an FI function significantly better than others. Finally, the randomness characteristics of the overall KASUMI-R for different rounds are compared to those of MISTY1 and KASUMI, in terms of avalanche weight distribution (AWD) and some statistical tests. The overall performance of the three ciphers is found to be same, although there is a significant difference in their FI functions.M.S. - Master of Scienc

Sonlu cisimlerin gösterimi üzerine.

The representation of field elements has a great impact on the performance of the finite field arithmetic. In this thesis, we give modified version of redundant representation which works for any finite fields of arbitrary characteristics to design arithmetic circuits with small complexity. Using our modified redundant representation, we improve many of the complexity values. We then propose new representations as an alternative way to represent finite fields of characteristic two by using Charlier and Hermite polynomials. We show that multiplication in these representations can be achieved with subquadratic space complexity. Charlier and Hermite representations enable us to find binomial, trinomial or quadranomial irreducible polynomials which allows us faster modular reduction over binary fields when there is no desirable such low weight irreducible polynomial in other representations. These representations are very interesting for the NIST and SEC recommended binary fields GF(2^{283}) and GF(2^{571}) since there is no optimal normal basis (ONB) for the corresponding extensions. It is also shown that in some cases the proposed representations have better space complexity even if there exists an ONB for the corresponding extension.Ph.D. - Doctoral Progra

Indistinguishability under adaptive chosen-ciphertext attack secure double-NTRU-based key encapsulation mechanism

In this article, we propose a double-NTRU (D-NTRU)-based key encapsulation mechanism (KEM) for the key agreement requirement of the post-quantum world. The proposed KEM is obtained by combining one-way D-NTRU encryption and Dent’s KEM design method. The main contribution of this article is to construct a D-NTRU-based KEM that provides indistinguishability under adaptive chosen-ciphertext attack (IND-CCA2) security. The IND-CCA2 analysis and primal/dual attack resistance of the proposed D-NTRU KEM are examined in detail. A comparison with similar protocols is provided regarding parameters, public/secret keys, and ciphertext sizes. The proposed scheme presents arithmetic simplicity and IND-CCA2 security that does not require any padding mechanism

Modified graph-based algorithm to analyze security threats in IoT

In recent years, the growing and widespread usage of Internet of Things (IoT) systems has led to the emergence of customized structures dependent on these systems. Industrial IoT (IIoT) is a subset of IoT in terms of applications and usage areas. IIoT presents many participants in various domains, such as healthcare, transportation, agriculture, and manufacturing. Besides the daily life benefits, IIoT technology provides major contributions via the Industrial Control System (ICS) and intelligent systems. The convergence of IoT and IIoT systems brings some integration and interoperability problems. In IIoT systems, devices interact with each other using information technologies (IT) and network space. However, these common usages and interoperability led to some security risks. To avoid security risks and vulnerabilities, different systems and protocols have been designed and published. Various public databases and programs identify and provide some of the security threats to make it easier for system administrators' missions. However, effective and long-term security detection mechanisms are needed. In the literature, there are numerous approaches to detecting security threats in IoT-based systems. This article presents two major contributions: First, a graph-based threat detection approach for IoT-based network systems is proposed. Threat path detection is one of the most critical steps in the security of IoT-based systems. To represent vulnerabilities, a directed acyclic graph (DAG) structure is constructed using threat weights. General threats are identified using Common Vulnerabilities and Exposures (CVE). The proposed threat pathfinding algorithm uses the depth first search (DFS) idea and discovers threat paths from the root to all leaf nodes. Therefore, all possible threat paths are detected in the threat graph. Second, threat path-reducing algorithms are proposed considering the total threat weight, hop length, and hot spot thresholds. In terms of available threat pathfinding and hot spot detecting procedures, the proposed reducing algorithms provide better running times. Therefore, all possible threat paths are founded and reduced by the constructed IoT-based DAG structure. Finally, simulation results are compared, and remarkable complexity performances are obtained

Efficient arithmetic for lattice-based cryptography on GPU using the CUDA platform

The demand to lattice-based cryptographic schemes has been inreasing. Due to processing unit having multiple processors, there is a need to implements such protocols on these platforms. Graphical processing units (GPU) have attracted so much attention. In this paper, polynomial multiplication algorithms, having a very important role in lattice-based cryptographic schemes, are implemented on a GPU (NVIDIA Quadro 600) using the CUDA platform. FFT-based and schoolbook multiplication methods are implemented in serial and parallel way and a timing comparison for these techniques is given. It's concluded that for the polynomials whose degrees are up to 2000 the fastest polynomial multiplication method is iterative NTT

Multiplication in a Galois Ring

In this paper, we focus on the efficient multiplication in a Galois ring of the size 4(n), where n is a positive integer. We consider to adapt the finite field multiplication methods to the Galois ring multiplication. We give the polynomial multiplication in the Galois ring as a Toeplitz matrix-vector multiplication design with a modification used in finite fields of characteristic two. By this method, we reduce the multiplication complexity. Note that the proposed approach can be easily generalized to Galois rings of arbitrary characteristic. To the best of our knowledge, this is the first study to have a subquadratic space complexity to multiply two elements in the Galois rings

Efficient interleaved Montgomery modular multiplication for lattice-based cryptography

In this paper, we give modified version of interleaved Montgomery modular multiplication method for lattice-based cryptography. With the proposed algorithms, we improve the multiplication complexity and embed the conversion operation into the algorithm with almost free cost. We implement the proposed methods for the quotient ring (Z/qZ)[x]/(x(n) - 1) and (Z/pZ)[x]/(x(n) + 1) on the GPU (NVIDIA Quadro 600) using the CUDA platform. NTRUEncrypt is accelerated approximately 35% on the GPU by using the proposed method. We receive at least 19% improvement with the proposed method for the polynomial multiplication in (Z/pZ)[x]/(x(n) + 1), where n is an element of{1024, 2048, 4096}

Polynomial Multiplication over Binary Fields Using Charlier Polynomial Representation with Low Space Complexity

In this paper, we give a new way to represent certain finite fields GF(2(n)). This representation is based on Charlier polynomials. We show that multiplication in Charlier polynomial representation can be performed with subquadratic space complexity. One can obtain binomial or trinomial irreducible polynomials in Charlier polynomial representation which allows us faster modular reduction over binary fields when there is no desirable such low weight irreducible polynomial in other representations. This representation is very interesting for NIST recommended binary field GF(2(283)) since there is no ONB for the corresponding extension. We also note that recommended NisT and SEC binary fields can be constructed with low weight Charlier polynomials