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208 CHAPTER 10. TRANSPOSITION CIPHERS To find the ciphertext pull out the columns of this array in the alphabetical order of the letters of the keyword. Deciphering is the reverse process, with the bit of complication that the length of the ciphertext and length of the keyword must first be used to determine how many letters each column contains. Recognizing transposition ciphers is easy – the frequency chart of a ciphertext appears to be that of normal English. Breaking transposition ciphers is, obviously, a matter of putting the letters back into their proper positions. For columnar transposition one first decides upon a guess of the size of the ciphertext rectangle and then creates the proposed columns of the plaintext. By knowing which letters are more likely to contact which one then proceeds by putting the columns next to their proper neighbors. The North used columnar transposition of words to great success during the Civil War. Keeping the words largely prevented Morse Code-based garbles, and the extensive use of code words, for proper names and locations, prevented the South from having any easy entry into the messages. 10.12 Topics and Techniques 1. From what do transposition cipher receive their security 2. What is the main difference between transposition ciphers and substitution ciphers 3. What is a route cipher What does its name mean 4. What is a geometrical cipher 5. What is a turning grille Explain how to construct one. 6. Explain how to use a keyword to set up a columnar transposition. 7. In a columnar transposition, how is the plaintext entered 8. In a columnar transposition, how is the ciphertext removed 9. Given the number of letters in the ciphertext and the length of the keyword, how are the lengths of the columns used that transposition determined 10. How does one decipher a columnar transposition cipher 11. How does one recognize that a cipher is a transposition 12. How does one decide whether a ciphertext is from a substitution cipher or from a transposition cipher 13. Explain how to break a columnar transposition ciphertext.
10.13. EXERCISES 209 14. What is a double transposition Is it a better or a worse cipher than single transposition Why 15. Explain the basics of the North’s system of transposition ciphers during the Civil War. 16. Was Stager’s system more like route ciphers or more like columnar transposition ciphers Explain. 10.13 Exercises 1. Decipher the following geometric ciphers. (a) SIYEE OLYMS MLYTS ESOOE SQUAR. (b) ASNRE NDPUT SELZT RESPA UTCLP. (c) ARBHUN OSOQM IEUSA ASRE. 2. Decipher the following rail fence ciphers. (a) RIRAS ALOD. (b) ABDIB BREWRE. (c) FET ECPSS NO. 3. These ciphers are based on the 12, 3, 6 and 9 o’clock positions on a clock. Decipher them. (a) HORPCK TEMSERUHEOC EUATL. (b) OHHLL FRWOTELTLS WNBO. (c) HSUS URINESCO OMTED. 4. Encipher the following short messages using a columnar transposition based on the given keyword. (a) let us hear from you at once concerning the jewels. Keyword jewels. (b) rft diamonds must be received by thursday morning ee. Keyword wealth. (c) rubies hidden in oatmeal containers in pantry floor. Keyword cereal. (d) sapphires were fake so was painting weve been setup flee. Keyword manetmonet.
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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
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7.3. BELASO, THE UNKNOWN AND PORTA,
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7.4. VIGENÈRE CIPHERS 115 to encip
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7.6. HOW TO BREAK VIGENÈRE CIPHERS
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7.6. HOW TO BREAK VIGENÈRE CIPHERS
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7.7. THE KASISKI TEST 121 Kasiski
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7.8. SUMMARY 123 Repetition Start P
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7.10. EXERCISES 125 2. Little Miss
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7.10. EXERCISES 127 to Gen. E. K. S
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7.10. EXERCISES 129 MEJMY JKXCD LCN
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7.10. EXERCISES 131 22. (a) Use Kas
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7.10. EXERCISES 133 (a) Construct a
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Chapter 8 Polyalphabetic Ciphers Th
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8.1. COINCIDENCES 137 (being born o
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8.2. THE MEASURE OF ROUGHNESS 139 I
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8.2. THE MEASURE OF ROUGHNESS 141 P
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8.3. THE FRIEDMAN TEST 143 The Frie
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8.4. MULTIPLE ENCIPHERINGS 145 Bein
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8.4. MULTIPLE ENCIPHERINGS 147 Just
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8.5. VIGENÈRE’S AUTO KEY CIPHER
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8.5. VIGENÈRE’S AUTO KEY CIPHER
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8.6. PERFECT SECRECY 153 invent now
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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 and 164: 8.9. EXERCISES 163 A: AB CDE FGH I
Page 165 and 166: 8.9. EXERCISES 165 26. Decipher SVQ
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
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Page 211 and 212: 10.13. EXERCISES 211 and the second
Page 213 and 214: 10.13. EXERCISES 213 evening Adam h
Page 215 and 216: 10.13. EXERCISES 215 Several codewo
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Page 219 and 220: Chapter 11 Knapsack Ciphers Merkle
Page 221 and 222: 11.3. AN EASY KNAPSACK PROBLEM 221
Page 223 and 224: 11.4. THE KNAPSACK CIPHER SYSTEM 22
Page 225 and 226: 11.4. THE KNAPSACK CIPHER SYSTEM 22
Page 227 and 228: 11.5. PUBLIC KEY CIPHER 227 Even wi
Page 229 and 230: 11.8. EXERCISES 229 2. Given the we
Page 231 and 232: Chapter 12 RSA Take two large prime
Page 233 and 234: 12.1. FERMAT’S THEOREM 233 Exampl
Page 235 and 236: 12.3. COMPLICATION II: A SUBSTANTIA
Page 237 and 238: 12.3. COMPLICATION II: A SUBSTANTIA
Page 239 and 240: 12.5. COMPLICATION IV: THE LAST ONE
Page 241 and 242: 12.6. PUTTING IT ALL TOGETHER 241 1
Page 243 and 244: 12.8. RSA 243 The RSA Algorithm Set
Page 245 and 246: 12.9. RSA AND PUBLIC KEYS 245 There
Page 247 and 248: 12.10. HOW TO BREAK RSA 247 had to
Page 249 and 250: 12.12. SUMMARY 249 cannot read the
Page 251 and 252: 12.14. EXERCISES 251 6. What is a
Page 253 and 254: 12.14. EXERCISES 253 Bob is going t
Page 255 and 256: Bibliography [Antonucci] Michael An
Page 257: BIBLIOGRAPHY 257 [Shamir] [SRA] A.
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