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The official Challenge 9B hints thread

The Body in My Library Forums Harry’s Meeting Place The official Challenge 9B hints thread

  • This topic has 78 replies, 43 voices, and was last updated 2 months ago by Cribbage.
Viewing 15 posts - 61 through 75 (of 79 total)
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  • #92599
    The_Code_Less_Traveled
    Participant

    Is [please delete from here on, leaving the answer (if allowed) of course] the over-encrypted keyword {55, 14, 23, 45, 51, 55, 44}?

    #92661
    Harry
    Keymaster

    If you are still stuck on Challenge 9B, then you might want to read the brand new BOSS Technical Note 008 on Nihilist ciphers and how to break them. You will find it in the BOSS Library. It is by Madness and is an expanded version of Unit 80 in his fantastic codebreaking book, which you will also find there (BOSS Technical Note 004). Happy reading! Harry

    #92664
    Blarthox_
    Participant

    The Nihilist cipher is neat, but that’s not how I solved this week’s puzzle. There’s more than one way to relieve a mammal of its pelt.

    #92701
    The_Pi-thon_Person
    Participant

    Please, ive been working on it solidly all week. Can you at least say whether ive got the right key length: is the key length 7?

    [Yes I can, and yes it is. At least, one of them is. There is a keyword for the repeating pattern on the ciphertext and another one to fill the grid. Hope that helps. Harry]

    #92702
    madness
    Participant

    Keep in mind that there is an error in Tech Note 008: if there is a carry digit in the addition, then there can be SIX different digits in the ten’s place for each column.

    [Thanks madness, let me know if you edit it. Apologies for delaying the publication. Harry]

    #92703
    The_Pi-thon_Person
    Participant

    I finally did it! @Madness you are a genius. Seriously! Your book helped me tremendously last year, and this year its helped incrediblly. Its amazing. Thank you so so much.

    #92704
    madness
    Participant

    @Pi-thon
    You are welcome.
    Thanks for the kind words.


    @Harry
    , check your email.

    [Have done, thank you. I have replaced BOSS Technical Note 008 with the updated version, for which we are all truly thankful. All the best, Harry]

    #92710
    momo
    Participant

    now that the deadline has passed, what were the keys?

    #92714
    kford_academy
    Participant

    @momo, #92710

    The keywords (in my experience) were NOTHING (keystream) and ZERO (square). This was done in the following way. ZERO was arranged in a square as shown:

    _12345
    1ZEROP
    2QSTUV
    3WXYAB
    4CDFGH
    5IKLMN

    And each letter was substituted for a two-digit number in the form (row,column). (So Z=11,E=12,etc. I=J=51.)

    Now NOTHING can be encrypted as:
    55-14-23-45-51-55-44

    This string of seven numbers was repeated to match the length of the ciphertext and then added to the relevant numbers in the encrypted plaintext. So the start of the message is encrypted:

    Plaintext_ – _D _E _A _R __M _R …
    Polybius__ – 42 12 34 13 _54 13 …
    Keystream_ – 55 14 23 45 _51 55 …
    Ciphertext – 97 26 57 58 105 68 …

    #92715
    f6exb_the_frenchy
    Participant

    ZERO and NOTHING

    #92716
    id-hkj
    Participant

    The polybius square used to encrypt it was as below:
    1 2 3 4 5
    1 Z E R O P
    2 Q S T U V
    3 W X Y A B
    4 C D F G H
    5 I K L M N
    The keyword for that was ‘ZERO’

    The thing that you had to subtract at the start was 55 14 23 45 51 55 44 – if you put that into the square, it gives you:
    NOTHING

    #92726
    The_Letter_Wriggler
    Participant

    TYPE : Nihilist Cipher
    GRID : 5 x 5
    KEY1 : ZERO
    KEY2 : NOTHING
    MIXED: ZEROPQSTUVWXYABCDFGHIKLMN

    \ 12345
    1 ZEROP
    2 QSTUV
    3 WXYAB
    4 CDFGH
    5 IKLMN
    ———————————
    Notes: mixed alpha variant used
    ZEROPQSTUVWXYABCDFGHIKLMN instead of
    ZEROABCDFGHIKLMNPQSTUVWXY

    As if the cipher was not hard enough Harry used a variant mixed alphabet.
    Well done Harry for the agony that caused!!!

    #92731
    oliviacat3
    Participant

    Now that the deadline has passed, did anyone manage to solve this one in excel? I tried initially but vlookup often gives errors when working with numbers and mid didn’t work to split the text as not all the numbers had the same number of digits.

    #92733
    f6exb_the_frenchy
    Participant

    Try with modulo 100 of numbers

    #92743
    Jeffery_Bezos_the_second
    Participant

    hello

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