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A Practical Guide
by Elonka Dunin and Klaus Schmeh
July 2023, 488 pp.
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Expert codebreakers Elonka Dunin and Klaus Schmeh introduce you to the world of breaking encrypted texts, whether by hand or using the many free computer tools available today. Each chapter introduces you to a specific cryptographic technique and presents many real-life examples of text encrypted using that scheme, from modern postcards to nineteenth-century newspaper ads, war-time telegrams, notes smuggled into prisons, and even entire encrypted books. 

Learn how to: 

  • Crack simple substitution ciphers, polyalphabetic ciphers, transposition ciphers, dictionary codes, and more
  • Use free online cryptanalysis software, like CrypTool 2, to aid your analysis
  • Identify clues and patterns to figure out what encryption scheme is being used

Codebreaking is the perfect handbook for anyone hoping to break some piece of encrypted text, solve previously undiscovered secrets, or hide their own secret messages.

Author Bio 

Elonka Dunin is an experienced crypto expert and maintains a list of the world's most famous unsolved codes on her 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 LEGO® models.

Table of contents 

Chapter 1: How can I break an encrypted message? And other introductory questions
Chapter 2: The Caesar cipher
Chapter 3: Simple substitution ciphers
Chapter 4: Simple substitution ciphers without spaces between words: Patristocrats
Chapter 5: Simple substitution ciphers in non-English languages
Chapter 6: Homophonic ciphers
Chapter 7: Codes and nomenclators
Chapter 8: Polyalphabetic ciphers
Chapter 9: Complete columnar transposition ciphers
Chapter 10: Incomplete columnar transposition ciphers
Chapter 11: Turning grille transposition ciphers
Chapter 12: Digraph substitution
Chapter 13: Abbreviation ciphers
Chapter 14: Dictionary codes and book ciphers
Chapter 15: Additional encryption methods
Chapter 16: Solving ciphers with hill climbing
Chapter 17: What next?
Appendix A: Kryptos
Appendix B: Useful language statistics
Appendix C: Glossary
Appendix D: Figure sources

The chapters in red are included in this Early Access PDF.