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164 CHAPTER 8. POLYALPHABETIC CIPHERS (a) On November 8, 1913 The Adjutant General’s Office in the War Department, Washington sent the following to the Chief of Staff, U.S. Army. HBYID EEKRA VVOIU RROGI FUIIJ ONADJ XKRBO SKPYU VFZGF JRZBV ZYKFS WYOMV MCIVP CYIUO IOPVV RSFSW PWKLQ SQVFG VKQTF VGKZI ZHSMR FIQQO XRYRZ TMSXD RBOWM DOEBK GIPHI KYWN. AAPH. What did it say (b) The HQ of Coast Defenses of Chesapeake Bay, Fort Monroe VA, struggled with this new cipher, as they reported in a letter of Nov 9, 1913. To attempt a decipherment of a Larrabee message they first crossed “out the inadmissible code letters”, and then used (probably) the Red code book to treat the remaining letters as code groups. This gave “Appropriations for the 4th quarter British Minister J. F. Reynolds Landis Henry J. Nichols Facts do not justify having party arrested” as the message. Trying a slightly different technique gave “Congress did not appropriate merited unknown unknown permanent arrangement.” They eventually realized their mistake: “It was evident that the meaning was not that which was intended. [And, after further consideration] It is thought that this message might be translated by the Larrabee Cipher Code Card which was sent to the Depot Quartermaster, Newport News, Va., on March 10, 1913, but which has apparently been misplacedby [sic] that officer as he is unable to furnish it.” Then on November 12 the same HQ sent ESAID FRTRQ DTTFV CRHOI DOSCN FNENF ITBRZ GMSHI RQSMH FHYNJ ZQMEI LFSJJ AOIZA DJWEF WJVCI SRLIG BHLYM SXVLA VWFFV ERKKS DURVJ GQEDF ULRGO PMSVR OSZGU QLVLQ JHQCI WHFIM EIIU Have they figured it out What does the message say (c) How is the Larrabee cipher related to the Vignere 24. (a) Two very long message have been enciphered with a Vigenère cipher using the same five letter keyword. How do the ciphertexts’ frequency charts compare (“Very long” here indicates that the plaintext’s frequencies are close to that of typical English.) (b) Continuing, how the two ciphertext’s Φ values compare (c) Two very long message have been enciphered with Vigenère ciphers using five letter keywords. If the two ciphertexts’ frequency charts are very similar, can we conclude that the keywords were the same If yes, why If no, why not, and what may we conclude 25. Explain in your own words why an endless, senseless key is needed for perfect secrecy.
8.9. EXERCISES 165 26. Decipher SVQYU EFNKW BHNRQ VIUZI CVSNR TVEZF WYXFA UNJYW MOADU KSVRS LUSJI JWVKC WCKYX PBVZK CDNOQ BZVGQ BMYMX QARTU G if the one-time pad key was FHEUC MFHGO JPNMM NVSRT VRBTE IRMHM PUNBC FGSYE IGIBG YDVAS KJOBV YSIEJ PGCFQ WURNG KLNIM TGDCF WXYVN MJKLB N. 27. Decipher LYLWZ FDHIG AWYOE GRKTZ TJGWC OQDQK CAEOO VBXLQ ITHJL REZOI POMZT QOMQS GTABM MJRMS BVFQC CNLQD RCAJA AYZM if the one-time pad key was PRNDS BQZQN TOGUT NJYTG PHYHV KZQCR UNKBG AXGTQ XZPFK NCZUQ LAHGM MWTWD CGXNS UTXMF INMIY KZGGZ TLWTG SHVJ.
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Cryptology: An Historical Introduct
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Contents List of Figures 8 1 Caesar
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CONTENTS 5 9 Digraphic Ciphers 167
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List of Figures 1.1 Saint Cyr Slide
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Chapter 1 Caesar Ciphers There are
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11 Examples: Encipher or decipher t
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1.1. SAINT CYR SLIDE 13 paper turne
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1.3. FREQUENCY ANALYSIS 15 PX PBEE
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1.3. FREQUENCY ANALYSIS 17 A bit mo
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1.3. FREQUENCY ANALYSIS 19 Examples
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1.4. LINQUIST’S METHOD 21 the cip
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1.7. EXERCISES 23 12. What is the m
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1.7. EXERCISES 25 (d) VTXLTKBTG LXV
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1.7. EXERCISES 27 (d) IKSUT JKIOT K
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Chapter 2 Cryptologic Terms Cryptog
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Chapter 3 The Introduction of Numbe
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3.1. THE REMAINDER OPERATOR 33 Exam
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3.1. THE REMAINDER OPERATOR 35 Perf
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3.1. THE REMAINDER OPERATOR 37 As a
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3.2. MODULAR ARITHMETIC 39 While %
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3.3. DECIMATION CIPHERS 41 previous
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3.4. DECIPHERING DECIMATION CIPHERS
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3.6. KOBLITZ’S KID-RSA AND PUBLIC
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3.6. KOBLITZ’S KID-RSA AND PUBLIC
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3.9. EXERCISES 49 8. How do we enci
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3.9. EXERCISES 51 (c) Encipher 54 4
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3.9. EXERCISES 53 (b) Encipher secr
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Chapter 4 The Euclidean Algorithm I
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4.2. GCD’S AND THE EUCLIDEAN ALGO
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4.3. MULTIPLICATIVE INVERSES 59 (2)
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4.3. MULTIPLICATIVE INVERSES 61 (2)
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4.4. DECIPHERING DECIMATION AND LIN
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4.5. BREAKING DECIMATION AND LINEAR
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4.6. SUMMARY 67 To put it more blun
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4.8. EXERCISES 69 5. Here we work w
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Chapter 5 Monoalphabetic Ciphers He
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5.2. KEYWORD MIXED CIPHERS 73 Examp
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5.4. INTERRUPTED KEYWORD CIPHERS 75
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5.6. BASIC LETTER CHARACTERISTICS 7
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5.7. ARISTOCRATS 79 the 69971 or 42
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5.9. TOPICS AND TECHNIQUES 81 5.9 T
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5.10. EXERCISES 83 (h) DYVTP KKIQ.
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5.10. EXERCISES 85 13. Ciphers in w
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5.10. EXERCISES 87 17. General Pier
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Chapter 6 Decrypting Monoalphabetic
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6.2. DECRYPTING MONOALPHABETIC CIPH
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6.3. SUKHOTIN’S METHOD FOR FINDIN
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6.4. FINAL MONOALPHABETIC TRICKS 99
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6.5. SUMMARY 101 our ciphertext muc
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6.7. EXERCISES 103 Frequency count:
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6.7. EXERCISES 105 53++!305))6*;482
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6.7. EXERCISES 107 93 93 82 48 39 6
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Chapter 7 Vigenère Ciphers It was
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7.2. TRITHEMIUS, THE FATHER OF BIBL
Page 113 and 114: 7.3. BELASO, THE UNKNOWN AND PORTA,
Page 115 and 116: 7.4. VIGENÈRE CIPHERS 115 to encip
Page 117 and 118: 7.6. HOW TO BREAK VIGENÈRE CIPHERS
Page 119 and 120: 7.6. HOW TO BREAK VIGENÈRE CIPHERS
Page 121 and 122: 7.7. THE KASISKI TEST 121 Kasiski
Page 123 and 124: 7.8. SUMMARY 123 Repetition Start P
Page 125 and 126: 7.10. EXERCISES 125 2. Little Miss
Page 127 and 128: 7.10. EXERCISES 127 to Gen. E. K. S
Page 129 and 130: 7.10. EXERCISES 129 MEJMY JKXCD LCN
Page 131 and 132: 7.10. EXERCISES 131 22. (a) Use Kas
Page 133 and 134: 7.10. EXERCISES 133 (a) Construct a
Page 135 and 136: Chapter 8 Polyalphabetic Ciphers Th
Page 137 and 138: 8.1. COINCIDENCES 137 (being born o
Page 139 and 140: 8.2. THE MEASURE OF ROUGHNESS 139 I
Page 141 and 142: 8.2. THE MEASURE OF ROUGHNESS 141 P
Page 143 and 144: 8.3. THE FRIEDMAN TEST 143 The Frie
Page 145 and 146: 8.4. MULTIPLE ENCIPHERINGS 145 Bein
Page 147 and 148: 8.4. MULTIPLE ENCIPHERINGS 147 Just
Page 149 and 150: 8.5. VIGENÈRE’S AUTO KEY CIPHER
Page 151 and 152: 8.5. VIGENÈRE’S AUTO KEY CIPHER
Page 153 and 154: 8.6. PERFECT SECRECY 153 invent now
Page 155 and 156: 8.8. TERMS AND TOPICS 155 multiple
Page 157 and 158: 8.9. EXERCISES 157 6. As is this on
Page 159 and 160: 8.9. EXERCISES 159 13. It has been
Page 161 and 162: 8.9. EXERCISES 161 This is Equation
Page 163: 8.9. EXERCISES 163 A: AB CDE FGH I
Page 167 and 168: Chapter 9 Digraphic Ciphers Althoug
Page 169 and 170: 9.1. POLYGRAPHIC CIPHERS 169 f a g
Page 171 and 172: 9.2. HILL CIPHERS 171 th 2.96 es 1.
Page 173 and 174: 9.2. HILL CIPHERS 173 We will be us
Page 175 and 176: 9.3. RECOGNIZING AND BREAKING POLYG
Page 177 and 178: 9.4. PLAYFAIR 177 Playfair Ciphers:
Page 179 and 180: 9.5. SUMMARY 179 9.5 Summary Polygr
Page 181 and 182: 9.7. EXERCISES 181 (b) The use of
Page 183 and 184: 9.7. EXERCISES 183 10. Just as we c
Page 185 and 186: 9.7. EXERCISES 185 (d) (For those(
Page 187 and 188: 9.7. EXERCISES 187 The rules that W
Page 189 and 190: Chapter 10 Transposition Ciphers In
Page 191 and 192: 10.3. TURNING GRILLES 191 1 2 3 7 4
Page 193 and 194: 10.4. COLUMNAR TRANSPOSITION 193 co
Page 195 and 196: 10.5. TRANSPOSITION VS. SUBSTITUTIO
Page 197 and 198: 10.6. LETTER CONNECTIONS 197 F 2 G
Page 199 and 200: 10.7. BREAKING THE COLUMNAR TRANSPO
Page 201 and 202: 10.8. DOUBLE TRANSPOSITION 201 Sinc
Page 203 and 204: 10.9. TRANSPOSITION DURING THE CIVI
Page 205 and 206: 10.9. TRANSPOSITION DURING THE CIVI
Page 207 and 208: 10.10. THE BATTLE OF THE CIVIL WAR
Page 209 and 210: 10.13. EXERCISES 209 14. What is a
Page 211 and 212: 10.13. EXERCISES 211 and the second
Page 213 and 214: 10.13. EXERCISES 213 evening Adam h
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10.13. EXERCISES 215 Several codewo
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10.13. EXERCISES 217 4. (which is t
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Chapter 11 Knapsack Ciphers Merkle
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11.3. AN EASY KNAPSACK PROBLEM 221
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11.4. THE KNAPSACK CIPHER SYSTEM 22
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11.4. THE KNAPSACK CIPHER SYSTEM 22
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11.5. PUBLIC KEY CIPHER 227 Even wi
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11.8. EXERCISES 229 2. Given the we
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Chapter 12 RSA Take two large prime
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12.1. FERMAT’S THEOREM 233 Exampl
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12.3. COMPLICATION II: A SUBSTANTIA
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12.3. COMPLICATION II: A SUBSTANTIA
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12.5. COMPLICATION IV: THE LAST ONE
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12.6. PUTTING IT ALL TOGETHER 241 1
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12.8. RSA 243 The RSA Algorithm Set
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12.9. RSA AND PUBLIC KEYS 245 There
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12.10. HOW TO BREAK RSA 247 had to
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12.12. SUMMARY 249 cannot read the
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12.14. EXERCISES 251 6. What is a
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12.14. EXERCISES 253 Bob is going t
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Bibliography [Antonucci] Michael An
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BIBLIOGRAPHY 257 [Shamir] [SRA] A.
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