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