Codebreaking: A Practical Guide

Front Cover
No Starch Press, Sep 19, 2023 - Computers - 488 pages
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 analysis
  • How to identify clues and patterns to figure out what encryption scheme is being used
  • How to encrypt your own emails and secret messages

Codebreaking 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.
 

Contents

What is this book about?
3
have found an encrypted text in the attic can you decipher it for me?
10
The Caesar cipher
17
How the Caesar cipher works
18
Simple substitution ciphers
29
How simple substitution ciphers work
31
How to break a simple substitution cipher
38
Success stories
41
Turning grille transposition ciphers
219
How to detect a turning grille encryption
223
Challenges
239
Digraph substitution
243
How the Playfair cipher works
245
How to break a digraph substitution
252
Success stories
267
Abbreviation ciphers
273

Simple substitution ciphers without spaces between words Patristocrats
51
Challenges
60
Simple substitution ciphers in nonEnglish languages
65
Detecting the language used
67
Challenges
78
Unsolved cryptograms
80
Homophonic ciphers
85
How homophonic ciphers work
88
Success stories
95
Challenges
105
Codes and nomenclators
113
Codes
115
Superencryption of codes and nomenclators
123
Challenges
142
Polyalphabetic ciphers
147
How a polyalphabetic cipher works
148
Success stories
161
Challenges
173
Complete columnar transposition ciphers
175
How to detect a complete columnar transposition cipher
179
Success stories
188
Incomplete columnar transposition ciphers
197
Success stories
206
Challenges
216
How abbreviation ciphers work
274
Challenges
281
Dictionary codes and book ciphers
285
How to detect a dictionary code or book cipher
289
Challenges
299
Additional encryption methods
303
Voice encryption
305
Cipher machines
322
16
328
Solving ciphers with hill climbing
329
Solving a homophonic cipher with simulated annealing
340
Solving a turning grille cipher with hill climbing
349
Solving machine ciphers with hill climbing
358
What next?
361
Codebreaking tools
371
Journals and newsletters
377
Kryptos
379
Useful language statistics
389
Glossary
395
MORSE CODE
403
References
417
Index
447
Copyright

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About the author (2023)

Elonka Dunin is an experienced crypto expert and maintains a list of the world's most famous unsolved codes on her elonka.com website. Bestselling author Dan Brown even named one of the characters in his Da Vinci Code sequel, The Lost Symbol, after her: “Nola Kaye” is a scrambled form of “Elonka." She is co-founder and co-leader of a group of cryptographers who are working hard to crack the final cipher on the famous Kryptos sculpture at CIA Headquarters, and in 2021 she was invited to give the TEDx talk "2,000 Years of Ordinary Secrets."

Klaus Schmeh is the most-published cryptology author in the world. He has written 15 books (in German) about the subject, as well as over 200 articles, 25 scientific papers, and 1,500 blog posts. He is a member of the editorial board of the scientific magazine, Cryptologia. Schmeh's main fields of interest are codebreaking and the history of encryption. His blog Cipherbrain is read by crypto enthusiasts all over the world. Schmeh is a popular speaker, known for his entertaining presentation style involving self-drawn cartoons and LEGOŽ models.

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