Posted By BigMacKrell
Posted on: August 27, 2014

Posted in: Code Cracking 101

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Code Cracking 101: The Vigenere Cipher

Royal Code Crack 101 VIGENERE copy

Welcome to this lesson of Code Cracking 101!

In this episode I discuss how to use a Vigenère Cipher!


ROotHM Vigenere Cipher Northwest Square copy

In this episode of Code Cracking 101, we take a look at our first Polyalphabetic Cipher, the Vigenere Cipher. This cipher is used moderly in the second season of the hit Disney TV show Gravity Falls, and was first used in the episode, Scary-oke!

The Vigenere Cipher is cryptologic method that is shrouded in misattributed credit and cover-up. The cipher got it’s start in 1508 when Johannes Trithemius produced the very first Tabula Recta – a square tool of shifting alphabets. The cipher he invented based off his Tablua Recta proved to be easily deciphered though, when news of it’s predictable shift pattern was discovered.

But in 1553, Giovan Battista Bellaso created a new method of using the Tabula Recta in conjunction with a password or passphrase separate from the encoded message. At the time it proved to be nearly uncrackable through cryptanalysis, so he published the method to share it with the world.

Unfortunately, Bellaso’s book wasn’t that popular – until just a little over thirty years later, when well regarded rich guy Blaise de Vigenère presented Bellaso’s same method to the court of King Henry the III of France as the Autokey Cipher. Due to it’s relative unbreakableness the code became an overnight success, and the cipher was quickly named after Vigenère. In some circles the Tabula Recta is still known as the Vigenère Square!

If you have any issues with deciphering messages encoded with the Vigenère Cipher, please sound off in the comments below, and I’ll try to lend a hand!

Royal Code Crack 101 VIGENERE copy

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