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Explore the fascinating and rich world of Secret Key cryptography! This book provides practical methods for encrypting messages, an interesting and entertaining historical perspective, and an incredible collection of ciphers and codes—including 30 unbreakable methods.In Secret Key Cryptography: Ciphers, from simple to unbreakable you will: Measure the strength of your ciphers and learn how to guarantee their security Construct and incorporate data-compression codes Generate true random numbers in bulk Construct huge primes and safe primes Add an undetectable backdoor to a cipher Defeat hypothetical ultracomputers that could be developed decades from now Construct 30 unbreakable ciphers Secret Key Cryptography gives you a toolbox of cryptographic techniques and Secret Key methods. The book's simple, non-technical language is easy to understand and accessible for any reader, even without the advanced mathematics normally required for cryptography. You'll learn how to create and solve ciphers, as well as how to measure their strength. As you go, you'll explore both historic ciphers and groundbreaking new approaches—including a never-before-seen way to implement the uncrackable One-Time Pad algorithm. Whoever you are, this book is for you! History buffs will love seeing the evolution of sophisticated cryptographic methods, hobbyists will get a gentle introduction to cryptography, and engineers and computer scientists will learn the principles of constructing secure ciphers. Even professional cryptographers will find a range of new methods and concepts never published before. About the technology From the Roman empire's Caesar cipher to the WWII Enigma machine, secret messages have influenced the course of history. Today, Secret Key cryptography is the backbone of all modern computing infrastructure. Properly designed, these algorithms are efficient and practical. Some are actually unbreakable, even using supercomputers or quantum technology! About the book Secret Key Cryptography teaches you how to create Secret Key ciphers, ranging from simple pen-and-paper methods to advanced techniques used in modern computer-based cryptography. It reveals both historic examples and current innovations. You'll learn how to efficiently encrypt large files with fast stream ciphers, discover alternatives to AES encryption, and avoid strong-looking but weak ciphers. Simple language and fun-to-solve mini-ciphers make learning serious concepts easy and engaging. What's inside Construct 30 unbreakable ciphers Measure the strength of your ciphers and guarantee their security Add an undetectable backdoor to a cipher Defeat hypothetical ultracomputers of the future About the reader For professional engineers, computer scientists, and cryptography hobbyists. No advanced math knowledge is required. About the author Frank Rubin has been doing cryptography for over 50 years. He holds an MS in Mathematics, and a PhD in Computer Science. Table of Contents 1 Introduction 2 What is cryptography? 3 Preliminary concepts 4 Cryptographer's toolbox 5 Substitution ciphers 6 Countermeasures 7 Transposition 8 Jefferson Wheel Cypher 9 Fractionation 10 Variable-length fractionation 11 Block ciphers 12 Principles for secure encryption 13 Stream ciphers 14 One-time pad 15 Matrix methods 16 Three pass protocol 17 Codes 18 Quantum computers

If you liked Dan Brown's Da Vinci Code—or want to solve similarly baffling cyphers yourself—this is the book for you! A thrilling exploration of history's most vexing codes and ciphers that uses hands-on exercises to teach you the most popular historical encryption schemes and techniques for breaking them.Solve history's most hidden secrets alongside expert codebreakers Elonka Dunin and Klaus Schmeh, as they guide you through the world of encrypted texts. With a focus on cracking real-world document encryptions—including some crime-based coded mysteries that remain unsolved—you'll be introduced to the free computer software that professional cryptographers use, helping you build your skills with state-of-the art tools. You'll also be inspired by thrilling success stories, like how the first three parts of Kryptos were broken. Each chapter introduces you to a specific cryptanalysis technique, and presents factual examples of text encrypted using that scheme—from modern postcards to 19-century newspaper ads, war-time telegrams, notes smuggled into prisons, and even entire books written in code. Along the way, you'll work on NSA-developed challenges, detect and break a Caesar cipher, crack an encrypted journal from the movie The Prestige, and much more.You'll learn: How to crack simple substitution, polyalphabetic, and transposition ciphers How to use free online cryptanalysis software, like CrypTool 2, to aid your analysisHow to identify clues and patterns to figure out what encryption scheme is being usedHow to encrypt your own emails and secret messagesCodebreaking is the most up-to-date resource on cryptanalysis published since World War II—essential for modern forensic codebreakers, and designed to help amateurs unlock some of history's greatest mysteries.

The first edition of this award-winning book attracted a wide audience. This second edition is both a joy to read and a useful classroom tool. Unlike traditional textbooks, it requires no mathematical prerequisites and can be read around the mathematics presented. If used as a textbook, the mathematics can be prioritized, with a book both students and instructors will enjoy reading.Secret History: The Story of Cryptology, Second Edition incorporates new material concerning various eras in the long history of cryptology. Much has happened concerning the political aspects of cryptology since the first edition appeared. The still unfolding story is updated here.The first edition of this book contained chapters devoted to the cracking of German and Japanese systems during World War II. Now the other side of this cipher war is also told, that is, how the United States was able to come up with systems that were never broken.The text is in two parts. Part I presents classic cryptology from ancient times through World War II. Part II examines modern computer cryptology. With numerous real-world examples and extensive references, the author skillfully balances the history with mathematical details, providing readers with a sound foundation in this dynamic field.FEATURES Presents a chronological development of key concepts Includes the Vigenère cipher, the one-time pad, transposition ciphers, Jefferson's wheel cipher, Playfair cipher, ADFGX, matrix encryption, Enigma, Purple, and other classic methods Looks at the work of Claude Shannon, the origin of the National Security Agency, elliptic curve cryptography, the Data Encryption Standard, the Advanced Encryption Standard, public-key cryptography, and many other topics New chapters detail SIGABA and SIGSALY, successful systems used during World War II for text and speech, respectively Includes quantum cryptography and the impact of quantum computers

Cryptology: Classical and Modern, Second Edition proficiently introduces readers to the fascinating field of cryptology. The book covers classical methods including substitution, transposition, Alberti, Vigenère, and Hill ciphers. It also includes coverage of the Enigma machine, Turing bombe, and Navajo code. Additionally, the book presents modern methods like RSA, ElGamal, and stream ciphers, as well as the Diffie-Hellman key exchange and Advanced Encryption Standard. When possible, the book details methods for breaking both classical and modern methods. The new edition expands upon the material from the first edition which was oriented for students in non-technical fields. At the same time, the second edition supplements this material with new content that serves students in more technical fields as well. Thus, the second edition can be fully utilized by both technical and non-technical students at all levels of study. The authors include a wealth of material for a one-semester cryptology course, and research exercises that can be used for supplemental projects. Hints and answers to selected exercises are found at the end of the book. Features: Requires no prior programming knowledge or background in college-level mathematics Illustrates the importance of cryptology in cultural and historical contexts, including the Enigma machine, Turing bombe, and Navajo code Gives straightforward explanations of the Advanced Encryption Standard, public-key ciphers, and message authentication Describes the implementation and cryptanalysis of classical ciphers, such as substitution, transposition, shift, affine, Alberti, Vigenère, and Hill

••'Title of Most Fiendish Book goes to Conundrum: Crack the Ultimate Cipher Challenge by the ever-excellent science writer Brian Clegg.'Daily Mail, Books of the Year•• The ultimate trial of knowledge and cunning, Conundrum features 200 cryptic puzzles and ciphers. The solutions link throughout the book – so you need to solve them all to get to the final round. With a focus on ciphers and codebreaking, Conundrum contains twenty sections, each built around a specific subject from music to literature, physics to politics. To take on Conundrum you need good general knowledge and the ability to think laterally. But if you need help, there are plenty of hints to point you in the right direction. Whether you attempt to crack it alone or work in a team, Conundrum will challenge you to the extreme. Can you take on Conundrum and win? There's only one way to find out…

This book provides the first extensive survey of block ciphers following the Lai-Massey design paradigm. After the introduction, with historical remarks, the author structures the book into a chapter on the description of the PES, IDEA and other related ciphers, followed by a chapter on cryptanalysis of these ciphers, and another chapter on new cipher designs. The appendices include surveys of cryptographic substitution boxes and of MDS codes. This comprehensive treatment can serve as a reference source for researchers, students and practitioners.

Unraveling the Voynich Codex reviews the historical, botanical, zoological, and iconographic evidence related to the Voynich Codex, one of the most enigmatic historic texts of all time. The bizarre Voynich Codex has often been referred to as the most mysterious book in the world. Discovered in an Italian Catholic college in 1912 by a Polish book dealer Wilfrid Voynich, it was eventually bequeathed to the Beinecke Rare Book and Manuscript Library of Yale University. It contains symbolic language that has defied translation by eminent cryptologists. The codex is encyclopedic in scope and contains sections known as herbal, pharmaceutical, balenological (nude nymphs bathing in pools), astrological, cosmological and a final section of text that may be prescriptions but could be poetry or incantations. Because the vellum has been carbon dated to the early 15th century and the manuscript was known to be in the collection of Emperor Rudolf II of the Holy Roman Empire sometime between 1607 and 1622, current dogma had assumed it a European manuscript of the 15th century. However, based on identification of New World plants, animals, a mineral, as well as cities and volcanos of Central Mexico, the authors of this book reveal that the codex is clearly a document of colonial New Spain. Furthermore, the illustrator and author are identified as native to Mesoamerica based on a name and ligated initials in the first botanical illustration. This breakthrough in Voynich studies indicates that the failure to decipher the manuscript has been the result of a basic misinterpretation of its origin in time and place. Tentative assignment of the Voynichese symbols also provides a key to decipherment based on Mesoamerican languages. A document from this time, free from filter or censor from either Spanish or Inquisitorial authorities has major importance in our understanding of life in 16th century Mexico. Publisher's Note: For the eBook editions, Voynichese symbols are only rendered properly in the PDF format.

This is the unique book on cross-fertilisations between stream ciphers and number theory. It systematically and comprehensively covers known connections between the two areas that are available only in research papers. Some parts of this book consist of new research results that are not available elsewhere. In addition to exercises, over thirty research problems are presented in this book. In this revised edition almost every chapter was updated, and some chapters were completely rewritten. It is useful as a textbook for a graduate course on the subject, as well as a reference book for researchers in related fields.·Unique book on interactions of stream ciphers and number theory. ·Research monograph with many results not available elsewhere. ·A revised edition with the most recent advances in this subject. ·Over thirty research problems for stimulating interactions between the two areas. ·Written by leading researchers in stream ciphers and number theory.

This book provides a survey on different kinds of Feistel ciphers, with their definitions and mathematical/computational properties. Feistel ciphers are widely used in cryptography in order to obtain pseudorandom permutations and secret-key block ciphers. In Part 1, we describe Feistel ciphers and their variants. We also give a brief story of these ciphers and basic security results. In Part 2, we describe generic attacks on Feistel ciphers. In Part 3, we give results on DES and specific Feistel ciphers. Part 4 is devoted to improved security results. We also give results on indifferentiability and indistinguishability.

Explaining the mathematics of cryptographyThe Mathematics of Secrets takes readers on a fascinating tour of the mathematics behind cryptography—the science of sending secret messages. Using a wide range of historical anecdotes and real-world examples, Joshua Holden shows how mathematical principles underpin the ways that different codes and ciphers work. He focuses on both code making and code breaking and discusses most of the ancient and modern ciphers that are currently known. He begins by looking at substitution ciphers, and then discusses how to introduce flexibility and additional notation. Holden goes on to explore polyalphabetic substitution ciphers, transposition ciphers, connections between ciphers and computer encryption, stream ciphers, public-key ciphers, and ciphers involving exponentiation. He concludes by looking at the future of ciphers and where cryptography might be headed. The Mathematics of Secrets reveals the mathematics working stealthily in the science of coded messages.A blog describing new developments and historical discoveries in cryptography related to the material in this book is accessible at http://press.princeton.edu/titles/10826.html.

When the United States declared war on Germany in April 1917, it was woefully unprepared to wage a modern war. Whereas their European counterparts already had three years of experience in using code and cipher systems in the war, American cryptologists had to help in the building of a military intelligence unit from scratch. This book relates the personal experiences of one such character, providing a uniquely American perspective on the Great War. It is a story of spies, coded letters, plots to blow up ships and munitions plants, secret inks, arms smuggling, treason, and desperate battlefield messages. Yet it all begins with a college English professor and Chaucer scholar named John Mathews Manly.In 1927, John Manly wrote a series of articles on his service in the Code and Cipher Section (MI-8) of the U.S. Army's Military Intelligence Division (MID) during World War I. Published here for the first time, enhanced with references and annotations for additional context, these articles form the basis of an exciting exploration of American military intelligence and counter-espionage in 1917-1918. Illustrating the thoughts of prisoners of war, draftees, German spies, and ordinary Americans with secrets to hide, the messages deciphered by Manly provide a fascinating insight into the state of mind of a nation at war.

A thrilling new novella from the bestselling author of the Bob Lee Swagger series. A captain in the British Army, Basil St. Florian has been tasked with a dangerous mission in the midst of World War II. He has been sent across the English Channel to find and photograph a manuscript that does not officially exist, one that may hold the key to a code that, if cracked, could prevent the deaths of millions. St. Florian's mission presents him with one challenge after another, and it doesn't help that the SS and the Abwehr are following his every move in a cat-and-mouse chase across occupied France. But St. Florian is willing to risk his life to get to the manuscript—even if the genius professor Alan Turing can't guarantee he'll be able to break the code.The Bibliomysteries are a series of short tales about deadly books, by top mystery authors.

A comprehensive evaluation of information security analysis spanning the intersection of cryptanalysis and side-channel analysis Written by authors known within the academic cryptography community, this book presents the latest developments in current research Unique in its combination of both algorithmic-level design and hardware-level implementation; this all-round approach - algorithm to implementation – covers security from start to completion Deals with AES (Advanced Encryption standard), one of the most used symmetric-key ciphers, which helps the reader to learn the fundamental theory of cryptanalysis and practical applications of side-channel analysis

Basil St. Florian is a captain in the British Army, an agent tasked with a dangerous mission in the midst of World War II. He has been sent across the channel into occupied France to find and photograph a manuscript that does not officially exist, one that may hold the key to a code that, if cracked, could prevent the death of millions and possibly even end the war two years earlier than anticipated. Basil's mission challenges him with one problem after another, and it doesn't help matters that the S.S. and the Abwehr are following his every move in a cat-and-mouse chase across France. But Basil is willing to risk his life to get to the manuscript, even if the genius professor Alan Turing can't guarantee he'll be able to extract the code if Basil is successful.

Gaines's Cryptanalysis (formerly published as Elementary Cryptanalysis) is a standard elementary and intermediate text for persons seriously interested in modern science methods for enciphering and deciphering cryptograms. It does not simply repeat older material, but contains much about modern cryptanalysis that is not generally known except to experts. It is especially strong in modern forms of cipher solution.This clear and thorough text also provides the reader with 166 specimen codes to solve. This edition for the first time also includes solutions. A special appendix includes final letters, sequence charts, digram, trigram tables, most common words in English and frequencies in English, German, French, Italian, Spanish, and Portuguese.

This well-illustrated book provides strong qualitative and comparative support for the main arguments developed by Nerida Ellerton and Ken Clements in their groundbreaking Rewriting this History of School Mathematics in North America 1607–1861: The Central Role of Cyphering Books. Eleven extraordinary handwritten school mathematics manuscripts are carefully analyzed—six were prepared entirely in Great Britain, four entirely in North America, and 1 partly in Great Britain and partly in North America. The earliest of the 11 cyphering books was prepared around 1630, and the latest in 1835. Seven of the manuscripts were arithmetic cyphering books; three were navigation cyphering books, and one was a mensuration/surveying manuscript.One of the cyphering books examined in this book was prepared, over the period 1819–1826, by a young Abraham Lincoln, when he was attending small one-teacher schools in remote Spencer County, Indiana. Chapter 6 in this book provides the first detailed analysis of young Abraham's cyphering book—which is easily the oldest surviving Lincoln manuscript. Another cyphering book, this one prepared by William Beattie in 1835, could have been prepared as a special gift for the King of England. The analyses make clear the extent of the control which the cyphering tradition had over school mathematics in North America and Great Britain between 1630 and 1840.In their final chapter Ellerton and Clements identify six lessons from their research into the cyphering tradition which relate to present-day circumstances surrounding school mathematics. These lessons are concerned with sharp differences between intended, implemented and attained curricula, the remarkable value that many students placed upon their cyphering books, the ethnomathematical circumstances which surrounded the preparations of the extraordinary cyphering books, and qualitative differences betweenBritish and North American school mathematics.

Winner of an Outstanding Academic Title Award from CHOICE MagazineMost available cryptology books primarily focus on either mathematics or history. Breaking this mold, Secret History: The Story of Cryptology gives a thorough yet accessible treatment of both the mathematics and history of cryptology. Requiring minimal mathematical prerequisites, the

Easily Accessible to Students with Nontechnical Backgrounds In a clear, nontechnical manner, Cryptology: Classical and Modern with Maplets explains how fundamental mathematical concepts are the bases of cryptographic algorithms. Designed for students with no background in college-level mathematics, the book assumes minimal mathematical prerequisite

Chapter 1 - Cryptography Chapter 2 - History of Cryptography Chapter 3 - Transposition Cipher and Substitution Cipher Chapter 4 - Public-Key Cryptography and Cryptanalysis Chapter 5 - Cipher Chapter 6 - Commitment Scheme Chapter 7 - Digital Signature and Data Encryption Standard

The origins of linear cryptanalysis can be traced back to a number of seminal works of the early 1990s. Since its invention, several theoretical and practical aspects of the technique have been studied, understood and generalized, resulting in more elaborated attacks against certain ciphers, but also in some negative results regarding the potential of various attempts at generalization. This book gives an overview of the current state of the discipline, as well as taking a look at potential future developments, and is divided into five parts. The first part deals with basic assumptions in linear cryptanalysis and their consequences for the design of modern block ciphers; part two explores a theory of multi-dimensional linear attacks on block ciphers; the third part covers how linear attacks can be applied to stream ciphers, and gives an overview of the development of linear attacks as well as a theoretical explanation of their current use. Part four details interesting and useful links between linear cryptanalysis and coding theory, and the fifth and final part discusses how correlation analysis can be conducted at the level of elements of GF (2n) without the need to deal with field representation issues. This book will be of interest to anybody who wishes to explore this fascinating yet complex part of symmetrical cryptanalysis.

This book is about language that is designed to mean what it does not seem to mean. Ciphers and codes conceal messages and protect secrets. Symbol and magic hide meanings to delight or imperil. Languages made to baffle and confuse let insiders talk openly without being understood by those beyond the circle. Barry Blake looks at these and many more. He explores the history and uses of the slangs and argots of schools and trades. He traces the centuries-old cants used by sailors and criminals in Britain, among them Polari, the mix of Italian, Yiddish, and slang once spoken among strolling players and circus folk and taken up by gays in the twentieth century. He examines the sacred languages of ancient cults and religions, uncovers the workings of onomancy, spells, and gematria, looks into the obliqueness of allusion and parody, and celebrates the absurdities of euphemism and jargon. Secret Language takes the reader on fascinating excursions down obscure byways of language, ranging across time and culture. With revelations on every page it will entertain anyone with an urge to know more about the most arcane and curious uses of language.

The fast and easy way to crack codes and cryptograms Did you love Dan Brown's The Lost Symbol? Are you fascinated by secret codes and deciphering lost history? Cracking Codes and Cryptograms For Dummies shows you how to think like a symbologist to uncover mysteries and history by solving cryptograms and cracking codes that relate to Freemasonry, the Knights Templar, the Illuminati, and other secret societies and conspiracy theories. You'll get easy-to-follow instructions for solving everything from the simplest puzzles to fiendishly difficult ciphers using secret codes and lost symbols. Over 350 handcrafted cryptograms and ciphers of varying types Tips and tricks for cracking even the toughest code Sutherland is a syndicated puzzle author; Koltko-Rivera is an expert on the major symbols and ceremonies of Freemasonry With the helpful information in this friendly guide, you'll be unveiling mysteries and shedding light on history in no time!

The Most Progressive and Complete Guide to DDO-Based Ciphers Developers have long recognized that ciphers based on Permutation Networks (PNs) and Controlled Substitution-Permutation Networks (CSPNs) allow for the implementation of a variety of Data Driven Operations (DDOs). These DDOs can provide fast encryption without incurring excessive

A cipher is a scheme for creating coded messages for the secure exchange of information. Throughout history, many different coding schemes have been devised. One of the oldest and simplest mathematical systems was used by Julius Caesar. This is where Mathematical Ciphers begins. Building on that simple system, Young moves on to more complicated schemes, ultimately ending with the RSA cipher, which is used to provide security for the Internet. This book is structured differently from most mathematics texts. It does not begin with a mathematical topic, but rather with a cipher. The mathematics is developed as it is needed; the applications motivate the mathematics. As is typical in mathematics textbooks, most chapters end with exercises. Many of these problems are similar to solved examples and are designed to assist the reader in mastering the basic material. A few of the exercises are one-of-a-kind, intended to challenge the interested reader. Implementing encryption schemes is considerably easier with the use of the computer. For all the ciphers introduced in this book, JavaScript programs are available from the Web. In addition to developing various encryption schemes, this book also introduces the reader to number theory. Here, the study of integers and their properties is placed in the exciting and modern context of cryptology. Mathematical Ciphers can be used as a textbook for an introductory course in mathematics for all majors. The only prerequisite is high school mathematics.

A compulsively readable account of the most mysterious manuscript in the world, one that has stumped the world's greatest scholars and codebreakers.The Voynich Manuscript, a mysterious tome discovered in 1912 by the English book dealer Wilfrid Michael Voynich, has puzzled scholars for a century. A small six inches by nine inches, but over two hundred pages long, with odd illustrations of plants, astrological diagrams, and naked women, it is written in so indecipherable a language and contains so complicated a code that mathematicians, book collectors, linguists, and historians alike have yet to solve the mysteries contained within. However, in The Friar and the Cipher, the acclaimed bibliophiles and historians Lawrence and Nancy Goldstone describe, in fascinating detail, the theory that Roger Bacon, the noted thirteenth-century, pre-Copernican astronomer, was its author and that the perplexing alphabet was written in his hand. Along the way, they explain the many proposed solutions that scholars have put forth and the myriad attempts at labeling the manuscript's content, from Latin or Greek shorthand to Arabic numerals to ancient Ukrainian to a recipe for the elixir of life to good old-fashioned gibberish. As we journey across centuries, languages, and countries, we meet a cast of impassioned characters and case-crackers, including, of course, Bacon, whose own personal scientific contributions, Voynich author or not, were literally and figuratively astronomical.The Friar and the Cipher is a wonderfully entertaining and historically wide-ranging book that is one part The Code Book, one part Possession, and one part The Da Vinci Code and will appeal to bibliophiles and laypeople alike.

Cryptology nowadays is one of the most important areas of applied mathematics, building on deep results and methods from various areas of mathematics. This text is devoted to the study of stochastic aspects of cryptology. Besides classical topics from cryptology, the author presents chapters on probabilistic prime number tests, factorization with quantum computers, random-number generators, pseudo-random-number generators, information theory, and the birthday paradox and meet-in-the-middle attack. In the light of the vast literature on stochastic results relevant for cryptology, this book is intended as an invitation and introduction for students, researchers, and practitioners to probabilistic and statistical issues in cryptology.

The design of code and cipher systems has undergone major changes in modern times. Powerful personal computers have resulted in an explosion of e-banking, e-commerce and e-mail, and as a consequence the encryption of communications to ensure security has become a matter of public interest and importance. This book describes and analyses many cipher systems ranging from the earliest and elementary to the more recent and sophisticated, such as RSA and DES, as well as wartime machines such as the ENIGMA and Hagelin, and ciphers used by spies. Security issues and possible methods of attack are discussed and illustrated by examples. The design of many systems involves advanced mathematical concepts and this is explained in detail in a major appendix. This book will appeal to anyone interested in codes and ciphers as used by private individuals, spies, governments and industry throughout history.

'A fascinating, challenging book.'― A.L.A. BooklistLearn to use the most important codes and methods of secret communication in use since ancient times. Cipher and decipher codes used by spies. Explore the famous codes that changed the fate of nations and political leaders. And enjoy hours of fun experimenting with cryptography ― the science of secret writing. Beginning with simple letter substitutions and transposition ciphers, world-famous science writer Martin Gardner explains how to break complicated polyalphabetical ciphers and codes worked with grids, squares, triangles, and charts. You'll learn codes that are keyed to typewriters and telephone dials... even codes that use playing cards, knots, and swizzle sticks. Experiment with invisible writing ― inks that glow in black light and turn red under heat ― and explore the possibilities of sending messages through outer space to unknown worlds. Using this book, you can solve the historically famous Playfair Cipher used by Australia in World War II, the Pigpen Cipher used by Confederate soldiers during the Civil War, Thomas Jefferson's Wheel Cipher, the Beaufort system used by the British Royal Navy, codes devised by authors for heroes in literature ― Sherlock Holmes, Captain Kidd, and the Shadow. And you will enjoy experimenting with bizarre methods of message sending ― the Dot Code, Knot Code, Swizzle Code, and more. Young cryptanalysts, cipher fans, and puzzlists of all ages will find hours of intrigue and challenge in Codes, Ciphers and Secret Writing.'A stimulating must for the intermediate cryptographer.'― The Kirkus Reviews

For over eighty years this delightful classic has provided entertainment through mathematical problems commonly known as recreations. Although they often involve fundamental mathematical methods and notions, their chief appeal is as games or puzzles rather than the usefulness of their conclusions. This new edition upholds the original, but the terminology and treatment of problems have been updated and much new material has been added. There are new selections on polyominoes and the notion of dragon designs, and a new chapter, ‘Introduction to Combinatorics.'Other topics dealt with in the fourteen chapters include arithmetical and geometrical recreations and problems, polyhedra, chess-board recreations, unicursal problems, cryptography and cryptanalysis, and calculating prodigies. Since no knowledge of calculus or analytic geometry is necessary to enjoy the recreations, this book will appeal widely to teachers of mathematics and students and to anyone who is mathematically inclined.

This book is almost entirely concerned with stream ciphers, concentrating on a particular mathematical model for such ciphers which are called additive natural stream ciphers. These ciphers use a natural sequence generator to produce a periodic keystream. Full definitions of these concepts are given in Chapter 2.This book focuses on keystream sequences which can be analysed using number theory. It turns out that a great deal of information can be deducted about the cryptographic properties of many classes of sequences by applying the terminology and theorems of number theory. These connections can be explicitly made by describing three kinds of bridges between stream ciphering problems and number theory problems. A detailed summary of these ideas is given in the introductory Chapter 1.Many results in the book are new, and over seventy percent of these results described in this book are based on recent research results.