Free The Philosophical Breakfast Club by Laura J. Snyder

cryptanalyst can begin to make guesses about what the key word is, and use this to solve the rest of the message. Once the whole message is deciphered, the cryptanalyst can very easily determine what each letter of the key is, and then apply the key to any future messages that were encoded using it. 29
    Babbage was the first to develop this method of deciphering the Vigenère cipher, yet the solution is known as the Kasiski examination, or the Kasiski test, because in 1863 Friedrich W. Kasiski, a retired major in the Prussian army, described this method in his pamphlet
Die Geheimschriften und die Dechiffrir-Kunst
. Although Babbage invented the same method nearly ten years earlier, he never publicized his accomplishment, and he lost the chance to gain fame for it. 30
    Why did Babbage keep secret his success in finding a method ofdeciphering
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? In the dispute with Thwaites, he never revealed his identity, hiding forever behind the “C” signature in the pages of the
Journal
. What he published in those pages was only a brief description of how he broke Thwaites’s cipher, not the general solution to the Vigenère. This incomplete explanation was not even published in a scientific journal, but in the journal of the Society of the Arts, hardly the platform for a groundbreaking achievement. And although he had been sending numerous letters about deciphering during this time to both Herschel and Augustus De Morgan, both of whom were also intrigued with ciphers and codes, in none of the letters that remain extant today did Babbage inform his friends that he had deciphered the
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. Not taking credit for something so impressive is out of character for Babbage, to say the least.
    One intriguing—but merely speculative—explanation for this uncharacteristic modesty is that Babbage may have been working for the British government, cracking the code that could give them an edge in the war in Crimea. At the end of March 1854, five months before Thwaites’s letter appeared in the Society of the Arts’s journal, Britain and France had declared war on Russia. The two old enemies had forged an uneasy alliance in order to fight the greater evil, Russia, which had begun a campaign of aggressive annexation in the Middle East, targeting Turkey to gain access to its warm-weather ports, and demanding control of some of the holy sites under Turkish control in Palestine. The Russians were relying on the Vigenère, among other ciphers, to send secret military messages by telegraph. Although the French had used the Vigenère extensively during their wars with Britain, they had not succeeded in discovering how to break the cipher—so the French, like the English, had no way to read messages intercepted from the Russians. Having the means to decipher such messages would give the Royal Navy an enormous advantage, similar to that gained by Britain when it cracked the German “Enigma” cipher during World War II. Indeed, it was shortly after this period that Babbage returned, for the last time, to the plans of his Analytical Engine, raising the possibility that he was tinkering with the idea of creating a code-breaking machine, such as the “Colossus” machine built by the British at Bletchley Park during the Second World War to decipher the German “Enigma.” But any advantage gained by knowing how to crack the code would cease if Babbage publicized his achievement; the Russians would then immediately stop using the Vigenère. IfBabbage had been working for military intelligence, his success would have been a military secret, and publicizing it would have been treason, a capital offense.
    There is no clear evidence in his papers, or at the National Archives of Britain at Kew, that Babbage was working for the military, or that the solution he devised was ever applied to intercepted messages before the end of the war in 1856—though perhaps in this case the lack of evidence is a form of evidence,