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Frequency analysis - Quiz
Frequency analysis
  • 1. Who provided the first known recorded explanation of frequency analysis?
A) Leone Alberti
B) Al-Kindi
C) Cicco Simonetta
D) Charles Wheatstone
  • 2. In which century was the first explanation of frequency analysis written?
A) 20th century
B) 19th century
C) 14th century
D) 9th century
  • 3. What is suggested to have helped discover the characteristic letter frequency of Arabic?
A) Diplomatic letters
B) Study of Latin poetry
C) Merchant logs
D) Study of the Qur'an
  • 4. Who wrote a manual in 1474 regarding the deciphering of Latin and Italian text?
A) Al-Kindi
B) Leone Alberti
C) Cicco Simonetta
D) Edgar Allan Poe
  • 5. What technique uses several alternatives for the most common letters to defeat frequency analysis?
A) Polygraphic substitution
B) Rotor encryption
C) Homophonic substitution
D) Polyalphabetic substitution
  • 6. Who was the first person to propose the use of polyalphabetic substitution?
A) Cicco Simonetta
B) Charles Wheatstone
C) Al-Kindi
D) Leone Alberti
  • 7. What type of substitution treats pairs or triplets of letters as units?
A) Homophonic substitution
B) Rotor substitution
C) Monoalphabetic substitution
D) Polygraphic substitution
  • 8. Who invented the Playfair cipher?
A) Charles Wheatstone
B) Al-Kindi
C) Cicco Simonetta
D) Leone Alberti
  • 9. What is cited as a major disadvantage of schemes designed to defeat frequency counting?
A) Incompatibility with telegrams
B) Increased complication leading to mistakes
C) High cost of paper and ink
D) Lack of security for short messages
  • 10. Why did a British Foreign Secretary supposedly reject the Playfair cipher?
A) It was already broken by the enemy
B) It required bulky machinery
C) It was too expensive to implement
D) He believed attachés could not learn it
  • 11. Which machines were considered essentially immune to straightforward frequency analysis?
A) Simple substitution machines
B) Polygraphic cipher boards
C) Rotor machines
D) Manual telegraph keys
  • 12. What method did the British and Americans use to recruit codebreakers during World War II?
A) University math exams
B) Chess tournaments
C) Linguistic aptitude interviews
D) Crossword puzzle contests
  • 13. Which Axis power had consular ciphers that were breakable by frequency analysis?
A) Germany
B) Italy
C) Austria
D) Japan
  • 14. What equipment was first used by the US Army's SIS for statistical analysis during WWII?
A) IBM card type machinery
B) Enigma rotor machines
C) Mechanical sliding rulers
D) Early vacuum tube computers
  • 15. Which literary work by Edgar Allan Poe describes the use of frequency analysis?
A) The Tell-Tale Heart
B) The Gold-Bug
C) The Fall of the House of Usher
D) The Murders in the Rue Morgue
  • 16. Which Sherlock Holmes story mentions frequency analysis?
A) The Adventure of the Dancing Men
B) The Sign of Four
C) The Hound of the Baskervilles
D) A Study in Scarlet
  • 17. What is another term for frequency analysis?
A) Counting letters
B) Pattern matching
C) Data decryption
D) Cipher breaking
  • 18. What is the primary purpose of frequency analysis?
A) Breaking classical ciphers
B) Writing secure messages
C) Speeding up encryption
D) Creating new alphabets
  • 19. Which of the following letters are considered rare in English text?
A) T, H, E, and R
B) E, T, A, and O
C) S, S, E, and E
D) Z, Q, X, and J
  • 20. What does the nonsense phrase 'etaoin shrdlu' represent?
A) The 12 rarest letters
B) The 12 most frequent letters
C) The 12 most common bigrams
D) The 12 most common trigrams
  • 21. In a simple substitution cipher, how are plaintext letters transformed?
A) Letters are rearranged based on position
B) Each letter is replaced by another consistent letter
C) Each letter is replaced by a random symbol
D) Letters are removed entirely
  • 22. In the example provided, what were the most common ciphertext findings?
A) I (letter), XL (bigram), XLI (trigram)
B) E (letter), TH (bigram), THE (trigram)
C) X (letter), LI (bigram), LIX (trigram)
D) L (letter), IV (bigram), LIV (trigram)
  • 23. What is a lipogram?
A) A type of frequency distribution graph
B) A cipher that uses only vowels
C) A text that omits a specific letter
D) A method of encrypting numbers
  • 24. What is a likely cause for initial guesses in frequency analysis to be incorrect?
A) The language is not English
B) The cryptanalyst is not using a computer
C) The cipher is too long
D) Variation in statistics for individual plaintexts
  • 25. What effect do shorter messages have on frequency analysis?
A) They have no statistical properties
B) They are easier to solve
C) They show less variation
D) They show more variation
  • 26. Which letters are the most common in English according to the text?
A) Z, Q, X, and J
B) E, T, A, and O
C) T, H, E, and R
D) S, S, E, and E
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