SSCP · Question #634
Which of the following is best at defeating frequency analysis?
The correct answer is B. Polyalphabetic cipher. Frequency analysis exploits the fact that certain letters appear more predictably in a language (e.g., 'E' is the most common letter in English). Monoalphabetic ciphers - including simple substitution ciphers and the Caesar cipher - map each plaintext letter to one fixed…
Question
Options
- ASubstitution cipher
- BPolyalphabetic cipher
- CTransposition cipher
- DCeasar Cipher
How the community answered
(24 responses)- A4% (1)
- B92% (22)
- C4% (1)
Explanation
Frequency analysis exploits the fact that certain letters appear more predictably in a language (e.g., 'E' is the most common letter in English). Monoalphabetic ciphers - including simple substitution ciphers and the Caesar cipher - map each plaintext letter to one fixed ciphertext letter, preserving frequency patterns. A polyalphabetic cipher (like the Vigenère cipher) uses multiple substitution alphabets, so the same plaintext letter maps to different ciphertext letters depending on its position and a repeating key. This flattens frequency distributions and makes frequency analysis significantly harder. Transposition ciphers rearrange letters but don't change them, so they also remain vulnerable.
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