Re: [Christmas Challenge 2024] Crack Doppelkastenschluessel-Hex

On 12/20/2024 1:10 PM, Stefan Claas wrote:

Chris M. Thomasson wrote:

On 12/20/2024 12:51 PM, Stefan Claas wrote:

 

Perhaps we need a larger amount of ciphertext?

>
That would make cryptanalysis easier, right?

>
I think so. Depends on the algorithm. If it's secure than perhaps no so
much... The interesting aspect of SCOS is that it's not secure at all.

 Well, only one key is used and it is a double square cipher, i.e. it is
basically a monoalphabetic bigraphic bipartite substitution, according
to Wikipedia.

Another aspect of SCOS. Richard wanted us to derive an algorithm. If not just outright copy his C impl which he encrypted and posted. I pissed him off a bit in that thread. Sigh. Damn!

 

BTW. For drawing the winners, should they been drawn from
a random pool of entries, or by first come first serve?
>

>
That is up to you! :^)

 O.k. :-) Should there be many entries, I choose random and if
it's only a couple of entrie by first come first serve.
 

Sounds good!
Fwiw:
http://fractallife247.com/test/hmac_cipher/ver_0_0_0_1?ct_hmac_cipher=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
The plaintext is:
It's your contest. So, do with it as you will. Fwiw, I am getting very busy with family and well, it's that time of year. Ho ho ho! ;^)
My test here is too complicated for a fun little contest. It actually might be "secure". Wel, some other people think that it just might be, secure. Strange!
Anyway, merry christmas!
:^)