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I understand that "anagramming" is often used after frequency analysis of a traditional substitution cipher, but anagramming requires prior frequency analysis to provide a starting point. Is there any technique other than frequency analysis for a cipher-text only attack on a traditional substitution cipher?

Roddus
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1 Answers1

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Yes, there are many. Here are the few that I know:

  1. Brute-Force: Simply trying all possible keys.
  2. Kasiski examination: Exploiting the repeated words in the ciphertext to figure out the key length in Vigenere Cipher.
  3. Friedman test aka Kappa Test: Measures the unevenness of the cipher letter frequencies to break the Vigenere cipher.
  4. Key elimination: Eleminate the key by XORing two plaintexts with the same key.