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History of frequency analysis

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  • History of frequency analysis

    According to Wikipedia, the first known use of frequency analysis was by the Arab polymath al-Kindi in the ninth century. Considering how old substitution ciphers are (Atbash cipher in the Bible, Caesar cipher), isn't it strange how late that was in the course of human history? Today, using frequency analysis to break a cipher seems obvious and intuitive. Sure, most people were illiterate, but it's surprising that there wasn't a single one of Caesar's enemies, for example, who could read Latin and thought of trying the most common Latin letters in place of the most common ciphertext letters.

  • #2
    I'm sure there were attempts of using frequency analysis prior to that. Additionally in order to be actually useful, frequency analysis requires you to generally know the relative frequencies of letters which was likely not known back then. Even people who were literate probably didn't read very much for the most part. If you gave a person who can barely read and has never seen a substitution cipher before a caesar cipher, I doubt they'll solve it. But you never know, maybe someone did figure out caesar's code, but it was never recorded in history.


    • #3
      Spelling wasn't standardized in English until the last couple of hundred years, and there are still regional variations. (British vs American spellings, for example) Is there such a thing as an ancient Latin dictionary? It's hard to code when spelling isn't standardized, or is open to poetic interpretation (looking at you, A. Pope).