Keyless Transposition Ciphers Quiz Answers 1. What is a primary limitation of keyless ciphers when used for longer messages? A. They are easily subjected to pattern recognition. B. They require a complex key to be secure. C. They can only rearrange a limited number of letters. D. They encrypt messages too slowly for practical use. Answer: They are easily subjected to pattern recognition. (A) Keyless ciphers are particularly vulnerable to pattern recognition, especially as message length increases. 2. Which of the following is NOT a common technique used in keyless transposition ciphers? A. Spiral cipher B. Caesar cipher C. Rail fence cipher D. Columnar cipher Answer: Caesar cipher (B) The Caesar cipher is a substitution cipher, not a keyless transposition cipher. 3. Why should keyless ciphers be avoided in important communications? A. They can be secured with complex keys. B. They require a specific transmission medium. C. They are highly susceptible to cryptanalysis. D. They produce very long messages. Answer: They are highly susceptible to cryptanalysis. (C) Keyless ciphers are vulnerable to cryptanalysis, making them unsuitable for securing sensitive communications. 4. What does the security of keyless transposition ciphers primarily depend on? A. The length of the message being encrypted. B. The frequency of letter usage in the language. C. The secrecy of the key used for encryption. D. The complexity and secrecy of the algorithm. Answer: The complexity and secrecy of the algorithm. (D) The security of keyless transposition ciphers is based on the complexity and secrecy of the encryption algorithm. 5. How does the feasibility of cryptanalysis change with keyless ciphers when the message length increases? A. Cryptanalysis becomes impossible. B. Cryptanalysis only affects short messages. C. Cryptanalysis remains constant regardless of length. D. Cryptanalysis becomes significantly easier. Answer: Cryptanalysis becomes significantly easier. (D) As the message length grows, keyless ciphers become more vulnerable to analysis. 6. What is the main characteristic of keyless transposition ciphers? A. They use multiple keys for encrypting messages. B. They substitute letters based on a specific code. C. They rearrange the order of letters based on a fixed algorithm. D. They rely on a secret key for encryption. Answer: They rearrange the order of letters based on a fixed algorithm. (C) Keyless transposition ciphers rearrange letters without the use of a key, relying on a fixed algorithm. 7. Which of the following best describes the columnar transposition technique? A. Writing plaintext in a continuous spiral sequence. B. Writing plaintext in a diagonal pattern and reading vertically. C. Using a grid to randomly place letters before reading them. D. Rearranging columns of plaintext based on a predefined pattern. Answer: Rearranging columns of plaintext based on a predefined pattern. (D) Columnar transposition involves writing plaintext into columns and then reordering them based on a specific pattern. 8. What factor significantly affects the security of keyless transposition ciphers? A. The use of diverse letter frequencies. B. The complexity of the transposition algorithm. C. The length of the message. D. The number of characters used. Answer: The complexity of the transposition algorithm. (B) The complexity of the transposition algorithm is crucial for the strength and security of keyless ciphers. 9. How is the Rail Fence Cipher constructed? A. By arranging letters in a zig-zag pattern across multiple lines. B. By organizing plaintext into a fixed columnar structure. C. By utilizing a matrix to interleave letters. D. By writing letters in a straight horizontal line only. Answer: By arranging letters in a zig-zag pattern across multiple lines. (A) The Rail Fence Cipher arranges letters in a zig-zag manner across multiple lines before reading them. 10. What is the primary method for deciphering a keyless transposition cipher without the given algorithm? A. Applying a brute-force attack with multiple keys. B. Using frequency analysis to identify common letters. C. Employing substitution cipher techniques. D. Trial and error with various transposition techniques. Answer: Trial and error with various transposition techniques. (D) Without the original algorithm, the most viable method is systematically trying possible transposition approaches. 11. What variations can be made to enhance the security of the Rail Fence Cipher? A. Changing the type of alphabet used. B. Applying a different encryption code afterward. C. Including numerical values in the plaintext. D. Altering the number of lines used. Answer: Altering the number of lines used. (D) Changing the number of lines in the Rail Fence Cipher impacts its security and complexity. 12. Which type of cipher writes plaintext in a spiral pattern? A. Spiral Cipher B. Columnar Cipher C. Zig-Zag Cipher D. Reverse Order Cipher Answer: Spiral Cipher (A) The Spiral Cipher organizes plaintext in a spiral layout before extracting the ciphertext. 13. What must both the sender and receiver know to effectively communicate using keyless transposition ciphers? A. The frequency of letters in the message. B. The characters in the original message. C. The length of the plaintext only. D. The algorithm used for transposition. Answer: The algorithm used for transposition. (D) Both parties need to be familiar with the algorithm employed to decipher the message successfully.