Cryptography (Classical Cipher)
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Classical Encryption Techniques
CPE 542: CRYPTOGRAPHY & NETWORK SECURITY Chapter 2: Classical Encryption Techniques Dr. Lo’ai Tawalbeh Computer Engineering Department Jordan University of Science and Technology Jordan Dr. Lo’ai Tawalbeh Fall 2005 Introduction Basic Terminology • plaintext - the original message • ciphertext - the coded message • key - information used in encryption/decryption, and known only to sender/receiver • encipher (encrypt) - converting plaintext to ciphertext using key • decipher (decrypt) - recovering ciphertext from plaintext using key • cryptography - study of encryption principles/methods/designs • cryptanalysis (code breaking) - the study of principles/ methods of deciphering ciphertext Dr. Lo’ai Tawalbeh Fall 2005 1 Cryptographic Systems Cryptographic Systems are categorized according to: 1. The operation used in transferring plaintext to ciphertext: • Substitution: each element in the plaintext is mapped into another element • Transposition: the elements in the plaintext are re-arranged. 2. The number of keys used: • Symmetric (private- key) : both the sender and receiver use the same key • Asymmetric (public-key) : sender and receiver use different key 3. The way the plaintext is processed : • Block cipher : inputs are processed one block at a time, producing a corresponding output block. • Stream cipher: inputs are processed continuously, producing one element at a time (bit, Dr. Lo’ai Tawalbeh Fall 2005 Cryptographic Systems Symmetric Encryption Model Dr. Lo’ai Tawalbeh Fall 2005 2 Cryptographic Systems Requirements • two requirements for secure use of symmetric encryption: 1. a strong encryption algorithm 2. a secret key known only to sender / receiver •Y = Ek(X), where X: the plaintext, Y: the ciphertext •X = Dk(Y) • assume encryption algorithm is known •implies a secure channel to distribute key Dr. -
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International Journal of Integrated Engineering: Special Issue 2018: Data Information Engineering, Vol. 10 No. 6 (2018) p. 183-192. © Penerbit UTHM DOI: https://doi.org/10.30880/ijie.2018.10.06.026 Analysis of Four Historical Ciphers Against Known Plaintext Frequency Statistical Attack Chuah Chai Wen1*, Vivegan A/L Samylingam2, Irfan Darmawan3, P.Siva Shamala A/P Palaniappan4, Cik Feresa Mohd. Foozy5, Sofia Najwa Ramli6, Janaka Alawatugoda7 1,2,4,5,6Information Security Interest Group (ISIG), Faculty Computer Science and Information Technology University Tun Hussein Onn Malaysia, Batu Pahat, Johor, Malaysia E-mail: [email protected], [email protected], {shamala, feresa, sofianajwa}@uthm.edu.my 3School of Industrial Engineering, Telkom University, 40257 Bandung, West Java, Indonesia 7Department of Computer Engineering, University of Peradeniya, Sri Lanka E-mail: [email protected] Received 28 June 2018; accepted 5August 2018, available online 24 August 2018 Abstract: The need of keeping information securely began thousands of years. The practice to keep the information securely is by scrambling the message into unreadable form namely ciphertext. This process is called encryption. Decryption is the reverse process of encryption. For the past, historical ciphers are used to perform encryption and decryption process. For example, the common historical ciphers are Hill cipher, Playfair cipher, Random Substitution cipher and Vigenère cipher. This research is carried out to examine and to analyse the security level of these four historical ciphers by using known plaintext frequency statistical attack. The result had shown that Playfair cipher and Hill cipher have better security compare with Vigenère cipher and Random Substitution cipher. -
COS433/Math 473: Cryptography Mark Zhandry Princeton University Spring 2017 Cryptography Is Everywhere a Long & Rich History
COS433/Math 473: Cryptography Mark Zhandry Princeton University Spring 2017 Cryptography Is Everywhere A Long & Rich History Examples: • ~50 B.C. – Caesar Cipher • 1587 – Babington Plot • WWI – Zimmermann Telegram • WWII – Enigma • 1976/77 – Public Key Cryptography • 1990’s – Widespread adoption on the Internet Increasingly Important COS 433 Practice Theory Inherent to the study of crypto • Working knowledge of fundamentals is crucial • Cannot discern security by experimentation • Proofs, reductions, probability are necessary COS 433 What you should expect to learn: • Foundations and principles of modern cryptography • Core building blocks • Applications Bonus: • Debunking some Hollywood crypto • Better understanding of crypto news COS 433 What you will not learn: • Hacking • Crypto implementations • How to design secure systems • Viruses, worms, buffer overflows, etc Administrivia Course Information Instructor: Mark Zhandry (mzhandry@p) TA: Fermi Ma (fermima1@g) Lectures: MW 1:30-2:50pm Webpage: cs.princeton.edu/~mzhandry/2017-Spring-COS433/ Office Hours: please fill out Doodle poll Piazza piaZZa.com/princeton/spring2017/cos433mat473_s2017 Main channel of communication • Course announcements • Discuss homework problems with other students • Find study groups • Ask content questions to instructors, other students Prerequisites • Ability to read and write mathematical proofs • Familiarity with algorithms, analyZing running time, proving correctness, O notation • Basic probability (random variables, expectation) Helpful: • Familiarity with NP-Completeness, reductions • Basic number theory (modular arithmetic, etc) Reading No required text Computer Science/Mathematics Chapman & Hall/CRC If you want a text to follow along with: Second CRYPTOGRAPHY AND NETWORK SECURITY Cryptography is ubiquitous and plays a key role in ensuring data secrecy and Edition integrity as well as in securing computer systems more broadly. -
Amy Bell Abilene, TX December 2005
Compositional Cryptology Thesis Presented to the Honors Committee of McMurry University In partial fulfillment of the requirements for Undergraduate Honors in Math By Amy Bell Abilene, TX December 2005 i ii Acknowledgements I could not have completed this thesis without all the support of my professors, family, and friends. Dr. McCoun especially deserves many thanks for helping me to develop the idea of compositional cryptology and for all the countless hours spent discussing new ideas and ways to expand my thesis. Because of his persistence and dedication, I was able to learn and go deeper into the subject matter than I ever expected. My committee members, Dr. Rittenhouse and Dr. Thornburg were also extremely helpful in giving me great advice for presenting my thesis. I also want to thank my family for always supporting me through everything. Without their love and encouragement I would never have been able to complete my thesis. Thanks also should go to my wonderful roommates who helped to keep me motivated during the final stressful months of my thesis. I especially want to thank my fiancé, Gian Falco, who has always believed in me and given me so much love and support throughout my college career. There are many more professors, coaches, and friends that I want to thank not only for encouraging me with my thesis, but also for helping me through all my pursuits at school. Thank you to all of my McMurry family! iii Preface The goal of this research was to gain a deeper understanding of some existing cryptosystems, to implement these cryptosystems in a computer programming language of my choice, and to discover whether the composition of cryptosystems leads to greater security. -
"Cyber Security" Activity
Cyber Security Keeping your information safe Standards: (Core ideas related to the activity) NGSS: ETS1.B – A solution needs to be tested and them modified on the basis of the test results in order to improve it MS-PS4.C – Digitized signals sent as wave pulses are a more reliable way to encode and transmit information CC Math: 5.OA-3 – Analyze patterns and relationships K12CS: 3-5 CS-Devices – Computing devices may be connected to other devices or components to extend their capabilities. Connections can take many forms such as physical or wireless. 3-5 N&I-Cybersecurity – Information can be protected using various security measures. These measures can be physical or digital 3-5 IoC-Culture – The development and modification of computing technology is driven by people’s needs and wants and can affect different groups differently 6-8 CS-Devices – The interaction between humans and computing devices presents advantages, disadvantages, and unintended consequences. The study of human-computer interaction can improve the design of devices and extend the abilities of humans. 6-8 N&I-Cybersecurity – The information sent and received across networks can be protected from unauthorized access and modification in a variety of ways, such as encryption to maintain its confidentiality and restricted access to maintain its integrity. Security measures to safeguard online information proactively address the threat of breaches to personal and private data 6-8 A&P-Algorithms – Algorithms affect how people interact with computers and the way computers respond. People design algorithms that are generalizable to many situations 6-8 IoC-Culture – Advancements in computing technology change people’s everyday activities. -
Of Ciphers and Neurons Detecting the Type of Ciphers Using Artificial Neural Networks
Of Ciphers and Neurons Detecting the Type of Ciphers Using Artificial Neural Networks Nils Kopal University of Siegen, Germany [email protected] Abstract cuits). ANNs found usages in a broad set of dif- ferent applications and research fields. Their main There are many (historical) unsolved ci- purpose is fast filtering, classifying, and process- phertexts from which we don’t know the ing of (mostly) non-linear data, e.g. image pro- type of cipher which was used to encrypt cessing, speech recognition, and language trans- these. A first step each cryptanalyst does lation. Besides that, scientists were also able to is to try to identify their cipher types us- “teach” ANNs to play games or to create paintings ing different (statistical) methods. This in the style of famous artists. can be difficult, since a multitude of ci- Inspired by the vast growth of ANNs, also cryp- pher types exist. To help cryptanalysts, tologists started to use them for different crypto- we developed a first version of an artifi- graphic and cryptanalytic problems. Examples are cial neural network that is right now able the learning of complex cryptographic algorithms, to differentiate between five classical ci- e.g. the Enigma machine, or the detection of the phers: simple monoalphabetic substitu- type of cipher used for encrypting a specific ci- tion, Vigenere,` Playfair, Hill, and transpo- phertext. sition. The network is based on Google’s In late 2019 Stamp published a challenge on the TensorFlow library as well as Keras. This MysteryTwister C3 (MTC3) website called “Ci- paper presents the current progress in the pher ID”. -
The Mathemathics of Secrets.Pdf
THE MATHEMATICS OF SECRETS THE MATHEMATICS OF SECRETS CRYPTOGRAPHY FROM CAESAR CIPHERS TO DIGITAL ENCRYPTION JOSHUA HOLDEN PRINCETON UNIVERSITY PRESS PRINCETON AND OXFORD Copyright c 2017 by Princeton University Press Published by Princeton University Press, 41 William Street, Princeton, New Jersey 08540 In the United Kingdom: Princeton University Press, 6 Oxford Street, Woodstock, Oxfordshire OX20 1TR press.princeton.edu Jacket image courtesy of Shutterstock; design by Lorraine Betz Doneker All Rights Reserved Library of Congress Cataloging-in-Publication Data Names: Holden, Joshua, 1970– author. Title: The mathematics of secrets : cryptography from Caesar ciphers to digital encryption / Joshua Holden. Description: Princeton : Princeton University Press, [2017] | Includes bibliographical references and index. Identifiers: LCCN 2016014840 | ISBN 9780691141756 (hardcover : alk. paper) Subjects: LCSH: Cryptography—Mathematics. | Ciphers. | Computer security. Classification: LCC Z103 .H664 2017 | DDC 005.8/2—dc23 LC record available at https://lccn.loc.gov/2016014840 British Library Cataloging-in-Publication Data is available This book has been composed in Linux Libertine Printed on acid-free paper. ∞ Printed in the United States of America 13579108642 To Lana and Richard for their love and support CONTENTS Preface xi Acknowledgments xiii Introduction to Ciphers and Substitution 1 1.1 Alice and Bob and Carl and Julius: Terminology and Caesar Cipher 1 1.2 The Key to the Matter: Generalizing the Caesar Cipher 4 1.3 Multiplicative Ciphers 6 -
A Hybrid Cryptosystem Based on Vigenère Cipher and Columnar Transposition Cipher
International Journal of Advanced Technology & Engineering Research (IJATER) www.ijater.com A HYBRID CRYPTOSYSTEM BASED ON VIGENÈRE CIPHER AND COLUMNAR TRANSPOSITION CIPHER Quist-Aphetsi Kester, MIEEE, Lecturer Faculty of Informatics, Ghana Technology University College, PMB 100 Accra North, Ghana Phone Contact +233 209822141 Email: [email protected] / [email protected] graphy that use the same cryptographic keys for both en- Abstract cryption of plaintext and decryption of cipher text. The keys may be identical or there may be a simple transformation to Privacy is one of the key issues addressed by information go between the two keys. The keys, in practice, represent a Security. Through cryptographic encryption methods, one shared secret between two or more parties that can be used can prevent a third party from understanding transmitted raw to maintain a private information link [5]. This requirement data over unsecured channel during signal transmission. The that both parties have access to the secret key is one of the cryptographic methods for enhancing the security of digital main drawbacks of symmetric key encryption, in compari- contents have gained high significance in the current era. son to public-key encryption. Typical examples symmetric Breach of security and misuse of confidential information algorithms are Advanced Encryption Standard (AES), Blow- that has been intercepted by unauthorized parties are key fish, Tripple Data Encryption Standard (3DES) and Serpent problems that information security tries to solve. [6]. This paper sets out to contribute to the general body of Asymmetric or Public key encryption on the other hand is an knowledge in the area of classical cryptography by develop- encryption method where a message encrypted with a reci- ing a new hybrid way of encryption of plaintext. -
The Solving of a Fleissner Grille During an Exercise by the Royal Netherlands Army in 1913
The Solving of a Fleissner Grille during an Exercise by the Royal Netherlands Army in 1913 Karl de Leeuw University of Amsterdam / Informatics Institute Science Park 904, 1098 XH Amsterdam [email protected] Abstract Initially the grille was intended for hiding that a secret message was being sent at all, rather than In 1885 the General Staff of the Royal as a means of encryption. This all changed dur- Netherlands Army had adopted a variant ing the course of the 18th century, when the grille of the turning grille devised by Edouard was increasingly used for jumbling the characters Fleissner von Wostrowitz as a means for in a message by rotating them, according to the encrypting messages, exchanged by tele- holes in the mask. The first description of such graph between the General Headquarters use we find by the German mathematician Carl and commanders in the field. Some staff Friedrich von Hindenburg (1796) who was aware members harbored serious doubts about that such use could only be made at the expense the security of this device, however, and of a loss in entropy and, therefore, cryptographic during a military exercise in 1913 it was strength. The perforation pattern in one quadrant solved with surprising ease by an army of the mask would automatically limit the possi- captain. The matter was investigated by bilities for perforation in all others, because two a committee of staff officers, concluding punch holes could not be allowed to cover the that the army lacked the expertise to judge same position after a rotation. -
EVOLUTIONARY COMPUTATION in CRYPTANALYSIS of CLASSICAL CIPHERS 1. Introduction
Ø Ñ ÅØÑØÐ ÈÙ ÐØÓÒ× DOI: 10.1515/tmmp-2017-0026 Tatra Mt. Math. Publ. 70 (2017), 179–197 EVOLUTIONARY COMPUTATION IN CRYPTANALYSIS OF CLASSICAL CIPHERS Eugen Antal — Martin Elia´ˇs ABSTRACT. Evolutionary computation has represented a very popular way of problem solving in the recent years. This approach is also capable of effectively solving historical cipher in a fully automated way. This paper deals with empirical cryptanalysis of a monoalphabetic substitution using a genetic algorithm (GA) and a parallel genetic algorithm (PGA). The key ingredient of our contribution is the parameter analysis of GA and PGA. We focus on how these parameters affect the success rate of solving the monoalphabetic substitution. 1. Introduction Historical (also called classical) ciphers belong to historical part of cryptology. They had been used until the expansion of computers and modern cryptosys- tems. Under a classical cipher we can consider a standard cryptosystem based on commonly used definition [6]. Comparing the main properties of classical ciphers to modern cryptosystems (used nowadays) leads to major differences in their properties. Some selected differences [5] are: • The encryption algorithm of classical ciphers can be performed using paper and pencil (or some mechanical device) easily. • Classical ciphers are mostly used to encrypt text written in some natural language. • Classical ciphers are vulnerable to statistical analysis. c 2017 Mathematical Institute, Slovak Academy of Sciences. 2010 M a t h e m a t i c s Subject Classification: 94A60,68P25. K e y w o r d s: historical ciphers, grid, MPI, genetic algorithm, parallel genetic algorithm. This work was partially supported by grants VEGA 1/0159/17. -
Language, Probability, and Cryptography
Language, Probability, and Cryptography Adriana Salerno [email protected] Bates College MathFest 2019 I Plain: ABCDEFGHIJKLMNO... I Cipher: XYZABCDEFGHIJKL... Substitution ciphers Julius Caesar 100 - 40 BCE Example: Shift the letters in the alphabet a fixed amount. I Cipher: XYZABCDEFGHIJKL... Substitution ciphers Julius Caesar 100 - 40 BCE Example: Shift the letters in the alphabet a fixed amount. I Plain: ABCDEFGHIJKLMNO... Substitution ciphers Julius Caesar 100 - 40 BCE Example: Shift the letters in the alphabet a fixed amount. I Plain: ABCDEFGHIJKLMNO... I Cipher: XYZABCDEFGHIJKL... Definition A simple substitution cipher is any function from one alphabet to another of the same size. For example, permutations of the English alphabet. Substitution ciphers In general: Substitution ciphers are maps from one alphabet to another. For example, permutations of the English alphabet. Substitution ciphers In general: Substitution ciphers are maps from one alphabet to another. Definition A simple substitution cipher is any function from one alphabet to another of the same size. Substitution ciphers In general: Substitution ciphers are maps from one alphabet to another. Definition A simple substitution cipher is any function from one alphabet to another of the same size. For example, permutations of the English alphabet. Example 1: Random permutation of beginning of Pride and Prejudice HR HD V RBXRN XSHMKBDVYYJ VCUSOIYKPQKP RNVR V DHSQYK ZVS HS AODDKDDHOS OG V QOOP GOBRXSK ZXDR FK HS IVSR OG V IHGK NOIKMKB YHRRYK USOIS RNK GKKYHSQD OB MHKID OG DXCN V ZVS ZVJ FK OS NHD GHBDR KSRKBHSQ V SKHQNFOXBNOOP RNHD RBXRN HD DO IKYY GHTKP HS RNK ZHSPD OG RNK DXBBOXSPHSQ GVZHYHKD RNVR NK HD COSDHPKBKP RNK BHQNRGXY ABOAKBRJ OG DOZK OSK OB ORNKB OG RNKHB PVXQNRKBD ZJ PKVB ZB FKSSKR DVHP NHD YVPJ RO NHZ OSK PVJ NVMK JOX NKVBP RNVR SKRNKBGHKYP AVBU HD YKR VR YVDR ZB FKSSKR .. -
Substitution Ciphers
Foundations of Computer Security Lecture 40: Substitution Ciphers Dr. Bill Young Department of Computer Sciences University of Texas at Austin Lecture 40: 1 Substitution Ciphers Substitution Ciphers A substitution cipher is one in which each symbol of the plaintext is exchanged for another symbol. If this is done uniformly this is called a monoalphabetic cipher or simple substitution cipher. If different substitutions are made depending on where in the plaintext the symbol occurs, this is called a polyalphabetic substitution. Lecture 40: 2 Substitution Ciphers Simple Substitution A simple substitution cipher is an injection (1-1 mapping) of the alphabet into itself or another alphabet. What is the key? A simple substitution is breakable; we could try all k! mappings from the plaintext to ciphertext alphabets. That’s usually not necessary. Redundancies in the plaintext (letter frequencies, digrams, etc.) are reflected in the ciphertext. Not all substitution ciphers are simple substitution ciphers. Lecture 40: 3 Substitution Ciphers Caesar Cipher The Caesar Cipher is a monoalphabetic cipher in which each letter is replaced in the encryption by another letter a fixed “distance” away in the alphabet. For example, A is replaced by C, B by D, ..., Y by A, Z by B, etc. What is the key? What is the size of the keyspace? Is the algorithm strong? Lecture 40: 4 Substitution Ciphers Vigen`ere Cipher The Vigen`ere Cipher is an example of a polyalphabetic cipher, sometimes called a running key cipher because the key is another text. Start with a key string: “monitors to go to the bathroom” and a plaintext to encrypt: “four score and seven years ago.” Align the two texts, possibly removing spaces: plaintext: fours corea ndsev enyea rsago key: monit orsto gotot hebat hroom ciphertext: rcizl qfkxo trlso lrzet yjoua Then use the letter pairs to look up an encryption in a table (called a Vigen`ere Tableau or tabula recta).