Classical Ciphers (Caesar, Vigenere, Playfair, ADFGVX) ECES Practice Questions (Page 3)

Questions 11–15

1. 11application · medium

   A historian is explaining the ADFGVX cipher to a class. She states that the cipher's security relied on two stages. Which two stages does the ADFGVX cipher combine?

   • AA Caesar shift followed by a Vigenere encryption
   • BA Polybius square substitution followed by a columnar transposition
   • CA monoalphabetic substitution followed by a running-key cipher
   • DA Playfair digraph substitution followed by a route transposition
   Reveal Solution Discussion Select an answer first
2. 12application · medium

   A cybersecurity instructor is explaining why the Vigenere cipher was considered unbreakable for centuries. She encrypts the message 'MEET AT NOON' with the keyword 'KEY' and obtains 'RIJVSUYVJN'. She then asks students which feature of the Vigenere cipher makes it resistant to simple frequency analysis that breaks the Caesar cipher.

   • AIt uses a 6x6 grid to represent letters and numbers
   • BIt encrypts letters in pairs, hiding single-letter frequencies
   • CIt adds a random number to each letter, making the key unguessable
   • DIt uses a keyword to shift each letter by a different amount, creating multiple substitution alphabets
   Reveal Solution Discussion Select an answer first
4. 13application · medium

   A developer is implementing a Vigenere cipher for a legacy system. The plaintext is 'SECRET' and the keyword is 'KEY'. What is the correct ciphertext?

   • AXUZPZX
   • BSJCNGR
   • CCIABIR
   • DCIBBIR
   Reveal Solution Discussion Select an answer first
5. 14application · medium

   A cryptography instructor is explaining why the ADFGVX cipher was more secure than earlier ciphers like Playfair. Which statement best captures the reason?

   • AIt combines substitution and transposition, making cryptanalysis significantly harder
   • BIt uses a 6x6 Polybius square, allowing digits to be encrypted
   • CIt is a polyalphabetic cipher, using multiple substitution alphabets
   • DIt uses a longer keyword, making brute force impossible
   Reveal Solution Discussion Select an answer first
6. 15foundation · easy

   Which two cryptographic techniques are combined in the ADFGVX cipher?

   • ACaesar shift substitution and Vigenere keying
   • BPlayfair digraph substitution and rail fence transposition
   • CMonoalphabetic substitution and route transposition
   • DPolybius square substitution and columnar transposition
   Reveal Solution Discussion Select an answer first