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106 CHAPTER 6. DECRYPTING MONOALPHABETIC CIPHERS 12. Frequency analysis was probably first invented by the Arabs. Decrypt the following message. The ideas are due to Ibn ad-Duraihim as paraphrased by Qalqashandi in 1412’s Subh al-a sha EJJLF GZPGE BAABO HJPPT OXJHA UOBVT BQAER ZQAGB XBHHD NBDQI PJXCD OBAGZ HFZAG AGBCD AABOQ JUEBA ABOUO BVTBQ PRCOB MZJTH ERXBQ AZJQB IFGBQ RJTHB BAGDA JQBEB AABOJ PPTOH ZQAGB XBHHD NBXJO BJUAB OQAGD QAGBO BHAAG BQDHH TXBAG DAZAZ HDEZU AGBQD HHTXB AGDAA GBQBY AXJHA UOBVT BQAZH EDXAG BDPPT ODPRJ URJTO PJQSB PATOB HGJTE IWBPJ QUZOX BIWRA GBUDP AZQDX DSJOZ ARJUP JQABY AHEDX UJEEJ FHDEZ U A B C D E F G H I J K L M N O P Q R S T U V W X Y Z 40 45 3 20 13 4 19 21 4 24 0 1 1 2 19 15 20 8 2 13 12 3 2 13 2 15 13. The aftermath of the election of 1876 provides us with a number of interesting ciphertexts [Elements and Secret 1876]. Jacksonville, Nov. 16 (1876) Geo. F. Raney, Tallahassee: pp yy em ns ny yy pi ma sh ns yy ss it ep aa en sh ns pe ns sh ns mm pi yy sn pp ye aa pi ei ss ye sh ai ns ss pe ei yy sh ny ns ss ye pi aa ny it ns sh yy sp yy pi ns yy ss it em ei pi mm ei ss ei yy ei ss it ei ep yy pe ei aa ss im aa ye sp ns yy ia ns ss ei ss mm pp ns pi ns sn pi ns im im yy it em yy ss pe yy mm ns yy ss it sp yy pe ep pp ma aa yy pi it L’Engle goes up to-morrow. (signed) Daniel In this cipher pairs of letters were used as substitutes for individual letters. The quote above highlights this by seperating the pairs. (In the original letter this was not the case, and the first progress towards decyphering the letter was realizing the double-letter nature of the cipher.) Given this, and the hint that neither e nor t is the most common letter, can you decrypt it 14. Consider the following telegram [Hassard and Secret 1876]. J. J. DANIEL, Jacsonville, Fla.: TALLAHASSEE, Mov. 19, 1876 84 55 89 31 93 27 66 89 27 20 42 66 34 55 33 93 20 34 84 55 55 39 93 42 55 33 93 48 44 55 52 27 66 33 20 20 55 31 31 66 42 27 82 96 96 93 20 82 66 48 93 52 27 93 44 93 34 82 31 31 27
6.7. EXERCISES 107 93 93 82 48 39 66 82 20 34 42 82 48 93 44 82 96 39 66 42 48 82 84 52 31 66 42 27 66 75 55 52 48 39 66 82 33 93 20 93 39 55 27 82 48 66 52 48 44 55 42 82 48 89 84 55 96 96 52 33 82 84 66 48 93 20 89 93 27 48 93 42 20 66 89 27 31 93 48 48 93 42 96 55 20 82 68 82 93 20 66 27 66 75 55 87 93 82 33 99 52 33 84 48 82 55 33 66 77 66 82 33 27 48 77 55 87 93 42 33 55 42 84 66 33 87 66 27 27 82 33 77 93 31 93 84 48 55 42 66 31 87 55 48 93 66 33 10 96 66 33 20 66 96 52 27 48 55 96 66 25 93 96 84 31 82 33 66 33 20 84 55 34 77 82 33 66 84 48 82 96 96 93 20 82 66 48 93 31 89 34 82 31 31 75 93 27 55 52 77 44 48 48 55 96 55 42 42 55 34 L’ENGLE. At the New York Tribune reported in its expose on the topic It was natural to suppose that this dispatch referred to the chief topic of the day, and if so the word “canvass” must be in it somewhere. The problem was, therefore, to find a combination of seven [pairs of] numbers, of which the second and fifth, standing for A, should be the same, and the sixth and seventh (SS) also the same. The translator began at the beginning and tried every sequence of ciphers until at the end of the twelfth line one was found which fulfilled the desired conditions, namely, ... what Find the set of 7 pairs of numbers that fit the letter pattern of “canvass.” Then, with some frequency work, you should be able to decrypt this cipher. Do so.
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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
Page 55 and 56: Chapter 4 The Euclidean Algorithm I
Page 57 and 58: 4.2. GCD’S AND THE EUCLIDEAN ALGO
Page 59 and 60: 4.3. MULTIPLICATIVE INVERSES 59 (2)
Page 61 and 62: 4.3. MULTIPLICATIVE INVERSES 61 (2)
Page 63 and 64: 4.4. DECIPHERING DECIMATION AND LIN
Page 65 and 66: 4.5. BREAKING DECIMATION AND LINEAR
Page 67 and 68: 4.6. SUMMARY 67 To put it more blun
Page 69 and 70: 4.8. EXERCISES 69 5. Here we work w
Page 71 and 72: Chapter 5 Monoalphabetic Ciphers He
Page 73 and 74: 5.2. KEYWORD MIXED CIPHERS 73 Examp
Page 75 and 76: 5.4. INTERRUPTED KEYWORD CIPHERS 75
Page 77 and 78: 5.6. BASIC LETTER CHARACTERISTICS 7
Page 79 and 80: 5.7. ARISTOCRATS 79 the 69971 or 42
Page 81 and 82: 5.9. TOPICS AND TECHNIQUES 81 5.9 T
Page 83 and 84: 5.10. EXERCISES 83 (h) DYVTP KKIQ.
Page 85 and 86: 5.10. EXERCISES 85 13. Ciphers in w
Page 87 and 88: 5.10. EXERCISES 87 17. General Pier
Page 89 and 90: Chapter 6 Decrypting Monoalphabetic
Page 91 and 92: 6.2. DECRYPTING MONOALPHABETIC CIPH
Page 97 and 98: 6.3. SUKHOTIN’S METHOD FOR FINDIN
Page 99 and 100: 6.4. FINAL MONOALPHABETIC TRICKS 99
Page 101 and 102: 6.5. SUMMARY 101 our ciphertext muc
Page 103 and 104: 6.7. EXERCISES 103 Frequency count:
Page 105: 6.7. EXERCISES 105 53++!305))6*;482
Page 109 and 110: Chapter 7 Vigenère Ciphers It was
Page 111 and 112: 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
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8.9. EXERCISES 157 6. As is this on
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8.9. EXERCISES 159 13. It has been
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8.9. EXERCISES 161 This is Equation
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8.9. EXERCISES 163 A: AB CDE FGH I
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8.9. EXERCISES 165 26. Decipher SVQ
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Chapter 9 Digraphic Ciphers Althoug
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9.1. POLYGRAPHIC CIPHERS 169 f a g
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9.2. HILL CIPHERS 171 th 2.96 es 1.
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9.2. HILL CIPHERS 173 We will be us
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9.3. RECOGNIZING AND BREAKING POLYG
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9.4. PLAYFAIR 177 Playfair Ciphers:
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9.5. SUMMARY 179 9.5 Summary Polygr
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9.7. EXERCISES 181 (b) The use of
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9.7. EXERCISES 183 10. Just as we c
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9.7. EXERCISES 185 (d) (For those(
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9.7. EXERCISES 187 The rules that W
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Chapter 10 Transposition Ciphers In
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10.3. TURNING GRILLES 191 1 2 3 7 4
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10.4. COLUMNAR TRANSPOSITION 193 co
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10.5. TRANSPOSITION VS. SUBSTITUTIO
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10.6. LETTER CONNECTIONS 197 F 2 G
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10.7. BREAKING THE COLUMNAR TRANSPO
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10.8. DOUBLE TRANSPOSITION 201 Sinc
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10.9. TRANSPOSITION DURING THE CIVI
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10.9. TRANSPOSITION DURING THE CIVI
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10.10. THE BATTLE OF THE CIVIL WAR
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10.13. EXERCISES 209 14. What is a
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10.13. EXERCISES 211 and the second
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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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