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Keys

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  • #87140
    Mattyrat2027
    Participant

    Wasn’t sure where to post this so I’ll do it here:

    With regards to alphabets (particularly ones used in the challenges so far), 1. Were keys used to form the alphabets, and 2. If it is permitted to say, how does one extract said keys?

    #87152
    madness
    Participant

    Tell me what you think the alphabet was for 3B and I might be able to show you.

    #87168
    madness
    Participant

    It’s gonna take the elves forever to moderate, so I might as well explain now.

    You probably kept track of the key that decrypts from ciphertext to plaintext. For 3B, that would be

    BOPQRSTUVWXYZFEGHIDCJKALMN

    But the key of a substitution cipher is the mixed alphabet that takes you in the other direction: from plaintext to ciphertext.
    So you have to invert the key that you found. And here is how to do it.

    Put the unmixed ciphertext alphabet in capital letters under the mixed plaintext alphabet in lower-case (the key you found):

    bopqrstuvwxyzfeghidcjkalmn
    ABCDEFGHIJKLMNOPQRSTUVWXYZ
    

    Then, move the columns around until the upper row is straightened out. The first column to move is the aW column:

    a bopqrstuvwxyzfeghidcjklmn
    W ABCDEFGHIJKLMNOPQRSTUVXYZ
    

    The bA column is already where it belongs. Next is cT:

    abc opqrstuvwxyzfeghidjklmn
    WAT BCDEFGHIJKLMNOPQRSUVXYZ
    

    When you are done you will have

    abcdefghijklmnopqrstuvwxyz
    WATSONPQRUVXYZBCDEFGHIJKLM
    

    and you can just see the keyword.

    #87287
    Mattyrat2027
    Participant

    Wowzers, that is like REALLY cool.
    Thanks @madness

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