Codebreaking: A Practical Guide

Brief Contents....10

Contents in Detail....12

Preface....20

Chapter 1: How can I break an encrypted message? And other introductory questions....24

What is this book about?....26

Which technical terms do I need to know?....27

How can I break an encrypted text?....28

How do I know what kind of encryption I am dealing with?....30

I have found an encrypted text in the attic; can you decipher it for me?....33

I have encrypted a text myself; can you break it?....34

I have invented a new encryption method; can you take a look at it?....35

I have solved a famous unsolved cryptogram; what should I do?....35

What tools do I need for codebreaking?....36

How can I encrypt my files and email?....37

I have a comment on this book; what should I do?....37

Who contributed to this book?....37

Chapter 2: The Caesar cipher....40

How the Caesar cipher works....41

How to detect a Caesar cipher....43

How to break a Caesar cipher....45

Success stories....46

A prison inmate’s cipher....46

A spy’s encrypted sheet....48

An encrypted journal from the movie The Prestige....49

Challenges....49

Herbert Yardley’s first challenge....49

A series of newspaper advertisements from 1900....50

Chapter 3: Simple substitution ciphers....52

How simple substitution ciphers work....54

How to detect a simple substitution cipher....57

Example of a cipher that is not a simple substitution cipher....59

Index-of-coincidence technique....60

How to break a simple substitution cipher....61

Performing a frequency analysis....62

Guessing frequent words....62

Guessing words with unusual letter patterns....63

Success stories....64

How Gary Klivans broke a prison inmate’s code....64

How Kent Boklan broke encrypted diary entries from the Civil War....66

Beatrix Potter’s diary....67

Challenges....69

A prison code....69

A postcard....69

Another postcard....70

The Friedmans’ wedding centennial nickel....70

An Aristocrat from the ACA....71

Unsolved cryptograms....71

An encrypted newspaper ad from 1888....71

The Zodiac Celebrity Cypher....72

The Furlong postcard....73

Chapter 4: Simple substitution ciphers without spaces between words: Patristocrats....74

How a Patristocrat, a simple substitution cipher without spaces, works....75

How to detect a Patristocrat....76

How to break a Patristocrat....77

Frequency analysis using digraphs....77

Word guessing....80

Success stories....80

A prison message....80

The Cheltenham Number Stone....82

Challenges....83

Rudyard Kipling’s encrypted message....83

NSA’s second Monday Challenge....84

Unsolved cryptograms....84

The Dorabella cryptogram....84

The Chinese gold bars mystery....85

James Hampton’s notebook....86

Chapter 5: Simple substitution ciphers in non-English languages....88

Detecting the language used....90

How to break a non-English simple substitution cipher....92

Frequency analysis and word guessing....93

Word pattern guessing....93

Success stories....95

A girl’s pigpen cipher (Spanish)....95

The La Buse cryptogram (French)....96

A postcard with a love message (German)....98

A Mafia message (Italian)....100

Challenges....101

An encrypted postcard....101

The third NSA Monday Challenge....101

Christlieb Funk’s challenge cryptogram....102

Unsolved cryptograms....103

The Voynich manuscript....103

The cigarette case cryptogram....104

NSA’s fourth Monday Challenge....105

The Moustier altar inscriptions....106

Chapter 6: Homophonic ciphers....108

How homophonic ciphers work....111

How to detect a homophonic cipher....112

How to break a homophonic cipher....114

Success stories....118

The first Zodiac message (Z408)....118

The Zodiac Killer’s second message (Z340)....119

Ferdinand III’s letters....124

A postcard from Hawaii....127

Challenges....128

A message to the Zodiac Killer....128

Edgar Allan Poe’s second challenge....129

Unsolved cryptograms....130

Beale Papers #1 and #3....130

The Zodiac Killer’s third message (Z13)....132

The Zodiac Killer’s fourth message (Z32)....132

The Scorpion cryptograms....132

Henry Debosnys’s messages....133

Chapter 7: Codes and nomenclators....136

Codes....138

Nomenclators....141

Terminology....143

The history of codes and nomenclators....143

Superencryption of codes and nomenclators....146

How to detect a code or nomenclator....147

How to break a code or nomenclator....149

Finding the nomenclator table or codebook....149

Exploiting weaknesses of codes and nomenclators....152

Solving codes and nomenclators with cribs....156

Success stories....156

A telegram sent to Tel Aviv....156

Encrypted messages by Mary, Queen of Scots....157

Collinson’s search expedition....161

The Japanese JN-25 code....163

Challenges....165

The Mount Everest telegram....165

Unsolved cryptograms....166

The silk dress cryptogram....166

The train station robbery cryptogram....167

A Pollaky newspaper advertisement....168

Lord Manchester’s letter....168

Chapter 8: Polyalphabetic ciphers....170

How a polyalphabetic cipher works....171

Vigenère cipher....172

Other polyalphabetic ciphers....173

One-time pad....174

How to detect a polyalphabetic cipher....175

How to break a polyalphabetic cipher....176

Word guessing....176

Checking for repeating patterns (Kasiski’s method)....178

Using the index of coincidence....180

Dictionary attacks....182

Tobias Schrödel’s method....182

Other Vigenère breaking methods....183

How to break a one-time pad....183

Success stories....184

The Diana Dors message....184

Kryptos 1 and 2....186

The Cyrillic Projector....188

Thouless’s second cryptogram from the crypt....192

The Smithy Code....194

Challenges....196

The Schooling challenge....196

A German radio message from the Second World War....196

Unsolved cryptograms....197

Wood’s cryptogram from the crypt....197

Chapter 9: Complete columnar transposition ciphers....198

How complete columnar transposition ciphers work....199

How to detect a complete columnar transposition cipher....202

How to break a complete columnar transposition cipher....202

The arrange-and-read method....203

Vowel frequencies and multiple anagramming....205

Success stories....211

Donald Hill’s diary....211

The Pablo Waberski spy case....215

Challenges....216

The Lampedusa message....216

The Friedmans’ love messages....217

An encrypted “agony” ad....217

Yardley’s eleventh ciphergram....218

Edgar Allan Poe’s first challenge....218

An IRA message....219

Chapter 10: Incomplete columnar transposition ciphers....220

How an incomplete columnar transposition cipher works....221

How to detect an incomplete columnar transposition cipher....224

How to break an incomplete columnar transposition cipher....224

Success stories....229

Kryptos K3....229

Antonio Marzi’s radio messages....232

Challenges....239

Yet another IRA message....239

The Double Columnar Transposition Reloaded challenge....239

Unsolved cryptograms....239

The Catokwacopa ad series....239

Chapter 11: Turning grille transposition ciphers....242

How turning grille encryption works....244

How to detect a turning grille encryption....246

How to break a turning grille encryption....246

Success stories....250

Paolo Bonavoglia’s turning grille solution....250

André Langie’s turning grille solution....252

Karl de Leeuw’s turning grille solution....255

The Mathias Sandorf cryptogram....257

Challenges....262

The Friedmans’ Christmas card....262

Jew-Lee and Bill’s Cryptocablegram....263

A MysteryTwister challenge....264

A Kerckhoffs cryptogram....264

Chapter 12: Digraph substitution....266

How general digraph substitution works....267

How the Playfair cipher works....268

How to detect a general digraph substitution....271

How to detect a Playfair cipher....273

How to break a digraph substitution....275

Frequency analysis....276

Dictionary attacks....276

Manual attacks....276

Success stories....290

Thouless’s first message....290

Thouless’s third message....291

Challenges....293

The cryptogram in National Treasure: Book of Secrets....293

Unsolved cryptograms....293

The world record digraph challenge....293

The world record Playfair challenge....293

Chapter 13: Abbreviation ciphers....296

How abbreviation ciphers work....297

How to detect an abbreviation cipher....298

How to break an abbreviation cipher....301

Success stories....302

Emil Snyder’s booklet....302

Challenges....304

A birthday card....304

Unsolved cryptograms....305

The Tamám Shud mystery....305

Two unsolved postcards....306

Chapter 14: Dictionary codes and book ciphers....308

How dictionary codes and book ciphers work....309

How to detect a dictionary code or book cipher....312

How to break a dictionary code or book cipher....313

Identifying the book or dictionary....313

Reconstructing the dictionary....313

Treating a book cipher like a simple substitution cipher....316

Success stories....317

The FIDES ads....317

Nicholas Trist’s key book....318

How William Friedman broke a Hindu conspiracy encryption....319

A dictionary code message sent to Robert E. Lee....321

Challenges....322

Dan Brown’s book cipher challenge....322

A dictionary code challenge....323

Unsolved cryptograms....324

Two encrypted newspaper advertisements from 1873....324

Chapter 15: Additional encryption methods....326

Cipher tools....327

Voice encryption....328

Code talking....329

Shorthand (stenography)....330

Hidden messages (steganography)....332

Success story: How Elonka found a hidden message on a tombstone....336

Success story: Deciphering Steganographia....338

Success story: Mysterious Stranger message....343

Challenge: Another steganographic message by the Friedmans....344

Cipher machines....345

Chapter 16: Solving ciphers with hill climbing....352

Solving simple substitution ciphers with hill climbing....354

Simulated annealing....359

Success story: Bart Wenmeckers’s solution to the Baring-Gould cryptogram....360

Success story: The Florida murder case cryptogram....361

Solving a homophonic cipher with simulated annealing....363

Success story: Dhavare, Low, and Stamp’s Zodiac Killer solutions....363

Solving a Vigenère cipher with hill climbing....364

Success story: Jim Gillogly’s solution to IRA Vigenère cryptograms....365

Solving a columnar transposition with hill climbing....366

Success story: Jim Gillogly’s solution to IRA transposition cryptograms....367

Success story: Richard Bean’s solution to the last unsolved IRA cryptogram....369

Success story: George Lasry’s solution of the double columnar transposition challenge....371

Solving a turning grille cipher with hill climbing....372

Success story: Bart Wenmeckers’s solution to a turning grille cryptogram....373

Success story: Armin Krauss’s solution to a turning grille challenge....375

Solving a general digraph substitution with hill climbing....376

Success story: Some digraph challenges....376

Solving a Playfair cipher with hill climbing....377

Success story: Dan Girard’s solution to the Cheltenham Letter Stone....378

Success story: Playfair world records....379

Solving machine ciphers with hill climbing....381

Success story: Breaking original Enigma messages....381

Chapter 17: What next?....384

More unsolved cryptograms....385

The fourth Kryptos message (K4)....385

The Rubin cryptogram....386

Ricky McCormick’s encrypted notes....387

The carrier pigeon message from World War II....387

The encrypted NKRYPT pillars....389

Even more unsolved cryptograms....393

Codebreaking tools....394

Other books about codebreaking....394

Websites about codebreaking....398

Journals and newsletters....400

Events....400

Appendix A: Kryptos....402

Appendix b: Useful language statistics....412

Appendix C: Glossary....418

Appendix D: Morse code....426

Appendix E: Figure sources....428

F....440

Index....470

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.