Frequency Analysis Attack

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Frequency analysis is an attack particularly efficient when the attacker tries to disclose ciphertexts corresponding to texts in natural language.

• in natural languages, certain letters appear more than others
  • by examining those frequencies, you can derive some information about the key
• exploits the:
  • frequency of letters in texts
  • frequency of the first letter in words
  • repetition of words and spaces in texts
• differs from one language to another
• basic tool for breaking most classical ciphers