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Challenge "Double-Column Transposition/Granit — Part 1"

Challenge "Double-Column Transposition/Granit — Part 1"  

  By: admin on July 1, 2015, 6:20 p.m.

This challenge series is about the GRANIT cipher, a method that can be done manually. It has been used for instance by the former GDR spy Günter Guillaume till about 1960.

Part 1, 2 and 3 of this series use the same keyword for generating the key matrix, but different permutation keys. In this part a codebook is used additionally, and the given ciphertext has 70 characters.
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 Last edited by: admin on Oct. 31, 2021, 2:55 a.m., edited 1 time in total.

Re: Challenge  

  By: Scatha on July 6, 2015, 5 p.m.

Hello,

the MTC3 team likes to ask people working at the GRANIT challenges to share with us (Python or C or Java, preferable Python) code they developed and which implements the whole process, gets a code book and the other parameters as input, and does ciphering and deciphering.
We also would like to share the code with everyone within MTC3.

Best regards,
Scatha

————————————————

Hallo,

falls Sie im Zuge Ihrer Arbeit an GRANIT einen Code entwickeln, der das Verfahren implementiert und als Eingabe ein Codebuch und die anderen Parameter enthält (in Python oder C oder Java, vorzugsweise Python), würde sich das MTC3-Team sehr freuen, wenn Sie uns den Quellcode zukommen lassen würden.
Wir würden den Quellcode dann gerne auch im MTC3 allen zur Verfügung stellen.

Beste Grüße,
Scatha

Re: Challenge  

  By: george4096 on Sept. 4, 2015, 8:01 p.m.

Granit is a safer cipher than the regular double-transposition cipher, which requires at least 500-600 for having any chance of being solved ciphertext-only (I happened to be the one to have solved the original Level X DT cipher :-).

Is it expected that a Granit challenge with 60 characters should be solved as a ciphertext-only challenges? If yes, this is not really practical, even theoretically, and this challenge (and the others) are not really relevant. Or there is another assumption to make (or a hint provided), for example regarding the book from which the transposition keys are taken?

While I enjoy very much the description of this very interesting cipher, I do not really see the purpose of the challenges in their current form.

Please advise,

Thank you,
George

Re: Challenge  

  By: Integral on Oct. 12, 2015, 5:17 p.m.

First of all, I agree with George and I'm a bit disappointed that he did not get any reply from the author since 04 September…

Nevertheless, I'll ask a question:
In the PDF describing Granit-Part1, page 5, it is stated as a hint that:
"All parts of this series use the very same keyword for the generation of the key matrix"

Does this mean that the two row markers (for example 8 & 9) are also the same, or just the keyword ?

Thank you,

Integral

Re: Challenge  

  By: Integral on Oct. 12, 2015, 7:26 p.m.

Hi,

Two more questions, if I may:

  1. The mentionned site (in the pdf), http://scz.bplaced.net/m.html#dwa , states that a J should be replaced by a double i. The pdf itself states that a J must be replaced by a single i. What shoukd we take for this challenge ?

  2. The first entry of the code-book on page 6 is "000", for a replacement of "abgesandt" and so is surrounded by two "zs" (Zahlensignal): zs 000 zs
    However, the digit 0, if alone between two words is also represented by zs 000 zs
    How can this be handled ?

Thank you,
Integral

Re: Challenge  

  By: Scatha on Oct. 12, 2015, 11:50 p.m.

Hello Integral, hello George,

I'll try to answer your questions to your satisfaction.

Does this mean that the two row markers (for example 8 & 9) are also the same, or just the keyword ?

Yes, it does mean that the two row markers are also the same. Additionally, after contacting the author I got to know the keyword was meant to be published, so I will change the templates accordingly. This will take a little while since I will change some other things according to Integral's second post.
For the meantime I'll tell you the keyword here: 'MEINHAUS'.

Regarding 1.)
It seems I overlooked that and read a single 'i' instead of 'ii'. I'll contact the author and tell you what to use, but it seems to me you should go with ii.

Regarding 2.)
I cannot answer that right away, so I will ask the author. Please be patient until I can tell you how to handle that. But I can tell you that you won't have to deal with this problem in the challenges since the replacement '000 = abgesandt' has not been used.

@Integral:
Regarding your question for Weakened GRANIT I also will ask the author and tell you what he answered.

Best regards,
Scatha

Re: Challenge  

  By: Scatha on Oct. 13, 2015, 9:26 p.m.

Hello,

Regarding 1.)
Substituting j with ii is correct, I read it wrong when I created the challenge. I'll change the example and update the templates.

Regarding 2.)
You have to decide how to decrypt that 'zs 000 zs' out of context. Normally it shouldn't be too difficult to get it right that way.

I hope I answered your questions to your satisfaction. If not, feel free to contact us again :)

Best regards,
Scatha

Re: Challenge  

  By: Scatha on Oct. 28, 2015, 8:52 p.m.

Hello,

the challenges are now updated, and the description of the GRANIT-Cipher has been corrected and revised.

Best regards,
Scatha


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