A Comparison between Memetic algorithm and Genetic algorithm for the cryptanalysis of Simplified Data Encryption Standard algorithm

Genetic algorithms are a population-based Meta heuristics. They have been successfully applied to many optimization problems. However, premature convergence is an inherent characteristic of such classical genetic algorithms that makes them incapable of searching numerous solutions of the problem domain. A memetic algorithm is an extension of the traditional genetic algorithm. It uses a local search technique to reduce the likelihood of the premature convergence. The cryptanalysis of simplified data encryption standard can be formulated as NP-Hard combinatorial problem. In this paper, a comparison between memetic algorithm and genetic algorithm were made in order to investigate the performance for the cryptanalysis on simplified data encryption standard problems(SDES). The methods were tested and various experimental results show that memetic algorithm performs better than the genetic algorithms for such type of NP-Hard combinatorial problem. This paper represents our first effort toward efficient memetic algorithm for the cryptanalysis of SDES.Comment: 9Page

Attack on the Simple Substitution Ciphers Using Particle Swarm Optimization

This paper considers a new approach to cryptanalysis based onsimulation of behavior of flocks of birds and schools of fish called ParticleSwarm Optimization (PSO). It is shown that such algorithm could be usedto break the key for a simple substitution cipher. This paper presents aproposed 2-opt PSO algorithm to enhance the efficiency of PSO algorithmon attacking simple substitution ciphers

Kriptoanaliz problemlerinin çözümünde evrim stratejisi uygulaması

06.03.2018 tarihli ve 30352 sayılı Resmi Gazetede yayımlanan “Yükseköğretim Kanunu İle Bazı Kanun Ve Kanun Hükmünde Kararnamelerde Değişiklik Yapılması Hakkında Kanun” ile 18.06.2018 tarihli “Lisansüstü Tezlerin Elektronik Ortamda Toplanması, Düzenlenmesi ve Erişime Açılmasına İlişkin Yönerge” gereğince tam metin erişime açılmıştır.Bu çalışmada, Kriptografi ve Kriptanaliz üzerinde duruldu ve çeşitli algoritmalar uygulandı. Optimizasyon, geometri ve diferansiyel hesabın iyileştirilmesini uygulayan en yaşlı matematiksel tiplerden biridir, fakat şimdi problemleri çözmek için bilimsel ve mühendislik tarafından uygulanan en iyi algoritmalardan biridir. Günümüzde, optimum özümü bulmak için optimizasyon problemi uygun şekilde tanımlanmalıdır, daha sonra optimum özüm ilgili Matematiksel yaklaşım kullanılarak bulunabilir. Stokastik algoritmalar için, Sezgisel ve Meta-heuristik olmak üzere iki tanıtıcı optimizasyon tekniği türü vardır. En yaygın kullanılan Meta-heuristics, Sürü zekası (swarm intelligence) ve evrimsel algoritmalar'dır (evolutionary algorithms). Bu araştırma, üç farklı algoritma uyguladı: Evrim Stratejisi, uygunluk Fonksiyonu ve Sütun Transferi Şifreleri. Aynı şekilde, araştırmanın temel amacı, Evrim Stratejisini uygulayarak Sütun Transferi Şifrelemelerini deşifre etmektir. Ayrıca, çalışma, Kriptografi (Sütun Transferi Şifreleri) ve Kriptanaliz (uygunluk fonksiyonu ile Evrim stratejisi) içeren bir uygulama uyguladı uygulama şifreleme (Kriptografi) düz metni ve son olarak şifre metnini deşifre ederek (Kriptanaliz) kullandı. Sütunlu Taşıma Şifreleri, düz metinleri 13 anahtar uzunluğuyla şifrelemektedir. Evrim Stratejisi Algoritması anahtarı ve düz metni bulmaya ve en sonunda şifre metnini hızlı bir şekilde deşifre etmeye çalışır böylece ES, şifreli metnin bigramlarını (iki harfli) ve trigramları (üç harfli) toplamak için geliştirilmiş fitness fonksiyonunu kullanır. Bulgulara göre, çalışma, tüm şifre metinlerini, projede açıklandığı üzere, daha önce uygulanan diğer algoritmalara kıyasla daha etkili ve daha kısa bir sürede deşifre etti.In this study, the Cryptography and Cryptanalysis are focused on them and applied various algorithms. Optimization is one of the most aged mathematical types which applied the improvement of the geometry and differential calculus, but now it's one of the best algorithms applied by scientific and engineering to solve problems. At present, to find the optimum solution the optimization problem has to be defined suitably, then the optimum solution can be found using relevant Mathematical approach. For stochastic algorithms, there are two familiar types of optimization techniques, Heuristic and Meta-heuristic. the most widely used Meta-heuristics are Swarm Intelligence and Evolutionary Algorithms. This research applied three different algorithms, Evolution Strategy combined with Fitness Function and Columnar Transposition Ciphers. Likewise, the main objective of the study is to decipher the Columnar Transposition Ciphers by applying Evolution Strategy. Moreover, the study applied an application which contain Cryptography (Columnar Transposition Ciphers) and Cryptanalysis (Evolution Stratgey with fitness function), the application is encrypting (Cryptography) the plain text and finally deciphering (Cryptanalysis) the cipher text. The Columnar Transposition Ciphers is encrypting the plain text using with 13 key length. The Evolution Strategy Algorithm attempts to find the key and the plain text and finally deciphering the cipher text quickly, so ES uses improved fitned fitness function to gather the bigrams (two letters) and trigrams (three letters) of cipher text. According to the findings the study deciphered all the cipher texts effectively and less time than all the other algorithms previously applied, as explained insdie the project

On the Construction and Cryptanalysis of Multi-Ciphers

In this compilational work, we combine various techniques from classical cryptography and steganography to construct ciphers that conceal multiple plaintexts in a single ciphertext. We name these multi-ciphers . Most notably, we construct and cryptanalyze a Four-In-One-Cipher: the first cipher which conceals four separate plaintexts in a single ciphertext. Following a brief overview of classical cryptography and steganography, we consider strategies that can be used to creatively combine these two fields to construct multi-ciphers. Finally, we cryptanalyze three multi-ciphers which were constructed using the techniques described in this paper. This cryptanalysis relies on both traditional algorithms that are used to decode classical ciphers and new algorithms which we use to extract the additional plaintexts concealed by the multi-ciphers. We implement these algorithms in Python, and provide code snippets. The primary goal of this work is to inform others who might be otherwise unfamiliar with the fields of classical cryptography and steganography from a new perspective which lies at the intersection of these two fields. The ideas presented in this paper could prove useful in teaching cryptography, statistics, mathematics, and computer science to future generations in a unique, interdisciplinary fashion. This work might also serve as a source of creative inspiration for other cipher-making, code-breaking enthusiasts