It contains different codes where very applicable to all of you who loves mysteries. I also includes all of my learnings and studies that talks about unfamiliar ideas or codes stuffs. I make it for my own book and I want to share it to all of my co...
>An autokey cipher is a cipher that incorporates the message into the key. The key is generated from the message in some automated fashion, sometimes by selecting certain letters from the text or, more commonly, by adding a short primer key to the front of the message.
+ There are two forms of autokey cipher: key-autokey and text-autokey ciphers. A key-autokey cipher uses previous members of the keystream to determine the next element in the keystream. A text-autokey uses the previous message text to determine the next element in the keystream.
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Example:
As an example we shall encode the plaintext "meet me at the corner" using the keyword king. First we must generate the keystream, which starts with the keyword, and then continues with the plaintext itself, getting kingmeetme....
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The keystream in the Autokey CIpher starts with the keyword, and is then followed by the plaintext itself.
With the keystream generated, we use the Tabula Recta, just like for the Vigenère Cipher. We find K across the top, and M down the left side. The ciphertext letter is "W".
For the second letter, "e", we go to I across the top, and E down the left to get the ciphertext letter "M".
Continuing in this way we get the ciphertext "WMRZYIEMFLEVHYRGF".
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The Tabula Recta is used in the same way as we used it for encrypting the Vigenère Cipher.
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The plaintext, keystream and ciphertext generated using the Autokey Cipher.
