The Vigenère cipher was broken by Kasiski in 1863 but I read novels and romans from older time, for example during the French Revolution where a student broke Vigenère cipher.

Is it likely that somebody have broken the code before Kasiski or is it not likely?

  • $\begingroup$ Apparently, Charles Babbage did--en.wikipedia.org/wiki/Vigen%C3%A8re_cipher $\endgroup$ Sep 13, 2016 at 16:49
  • 2
    $\begingroup$ Babbage broke it only a few years before Kasiski (1854), but could not publish it because British Intelligence was too busy using it to eavesdrop on correspondence of European spies and diplomats. The history repeated itself with Cocks and the invention of the RSA cipher. As for the French Revolution, novels are generally not very reliable as historical sources, but please provide specific reference. $\endgroup$
    – Conifold
    Sep 13, 2016 at 19:51


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