Hi all,

I recently finished my Doppekastenschluessel-Hex project,
which is a simplified version of the original German WWII
cipher, with hex notation.

For more details check my previous thread 'Seriation'

Your task is to crack the provided message, which uses
only one key for encryption, instead of two (default)
or more.

The message:

75 A2 85 D1 84 59 85 2D 25 CB 85 1C 24 70 27 6C
C5 3C 65 2E 87 6C 8E E7 89 E9 C9 3E 8E 7D 8E D6

Please note: The message is written as normal text and
not like plaintext messages from the old days and with
padding applied.

The price for the Winner is a set of EFF lapel pins and
an orginal sticker for the 'age' encryption file program
and for the Runner-Up an 'age' file encryption sticker.

<https://1drv.ms/i/s!AjK3D2S6tPVNgSvTOonKu70ci9aX?e=KMZCdb>

Send your decrypted result to sacenator<at>gmail<dot>com
and do not post your result here.

Merry Christmas
Stefan

On 12/20/2024 12:35 PM, Stefan Claas wrote:
> Hi all,
>
> I recently finished my Doppekastenschluessel-Hex project,
> which is a simplified version of the original German WWII
> cipher, with hex notation.
>
> For more details check my previous thread 'Seriation'
>
> Your task is to crack the provided message, which uses
> only one key for encryption, instead of two (default)
> or more.
>
> The message:
>
> 75 A2 85 D1 84 59 85 2D 25 CB 85 1C 24 70 27 6C
> C5 3C 65 2E 87 6C 8E E7 89 E9 C9 3E 8E 7D 8E D6
>
> Please note: The message is written as normal text and
> not like plaintext messages from the old days and with
> padding applied.

Perhaps we need a larger amount of ciphertext?

Anyway, Merry Christmas!

>
> The price for the Winner is a set of EFF lapel pins and
> an orginal sticker for the 'age' encryption file program
> and for the Runner-Up an 'age' file encryption sticker.
>
> <https://1drv.ms/i/s!AjK3D2S6tPVNgSvTOonKu70ci9aX?e=KMZCdb>
>
> Send your decrypted result to sacenator<at>gmail<dot>com
> and do not post your result here.
>
> Merry Christmas
> Stefan

Chris M. Thomasson wrote:
> On 12/20/2024 12:35 PM, Stefan Claas wrote:
> > Hi all,
> >
> > I recently finished my Doppekastenschluessel-Hex project,
> > which is a simplified version of the original German WWII
> > cipher, with hex notation.
> >
> > For more details check my previous thread 'Seriation'
> >
> > Your task is to crack the provided message, which uses
> > only one key for encryption, instead of two (default)
> > or more.
> >
> > The message:
> >
> > 75 A2 85 D1 84 59 85 2D 25 CB 85 1C 24 70 27 6C
> > C5 3C 65 2E 87 6C 8E E7 89 E9 C9 3E 8E 7D 8E D6
> >
> > Please note: The message is written as normal text and
> > not like plaintext messages from the old days and with
> > padding applied.
>
> Perhaps we need a larger amount of ciphertext?

That would make cryptanalysis easier, right?

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

--
Regards
Stefan

On 12/20/2024 12:51 PM, Stefan Claas wrote:
> Chris M. Thomasson wrote:
>> On 12/20/2024 12:35 PM, Stefan Claas wrote:
>>> Hi all,
>>>
>>> I recently finished my Doppekastenschluessel-Hex project,
>>> which is a simplified version of the original German WWII
>>> cipher, with hex notation.
>>>
>>> For more details check my previous thread 'Seriation'
>>>
>>> Your task is to crack the provided message, which uses
>>> only one key for encryption, instead of two (default)
>>> or more.
>>>
>>> The message:
>>>
>>> 75 A2 85 D1 84 59 85 2D 25 CB 85 1C 24 70 27 6C
>>> C5 3C 65 2E 87 6C 8E E7 89 E9 C9 3E 8E 7D 8E D6
>>>
>>> Please note: The message is written as normal text and
>>> not like plaintext messages from the old days and with
>>> padding applied.
>>
>> 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.

>
> 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! :^)

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.

> > 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.

--
Regards
Stefan

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=fe7ba1c3a324cb23d2f9c6d4b723f882c2ff8e86d1a2fbe3a6bd75f7f703b18fe39e263285743cf854aea3f6e9d84fc985daee13faa338fae791ab7f672979bd24c173e9a75c7f2c6dba6c1335b70b0a209dd5d39ad751c0649b0f5eb795783e7b8c336db178224e098313d9de8972c5a75601aab74f3ebb7c9ccdf8dd99c507b194f230ec87ab5771a6ddd56ddcd793fdc5c61551ee64b977f76390062c0f91832ae4368c3ad6684f29e1ec45c61de3edbf2ee9116e9806292231090ff13e1a753ce12f48617c9c6cf6a934df55807875f44bbac91166c1f9a1afc7e8fbe69b9e94ab168b82f6b96bdb8fd00f8ddfdf722a50656fea6c08d1b4519988faf7594697db153a0b8d07faa6a2bd425a59b0e24eddea917c5e1092b29c5df031db212541d5559a632f925aa94e72eb3c8641634dde3197b28bcde0637c76a15ebc79e7e32746dc2ba45676f99540883b2bdf9693f128a7c9f0c16b8e143e6487c8c390b5c9c15bc505ffdf7062322f6a37d915c2928048101d987ed9c7fac91cb5868d04df8ff5

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!

:^)

Chris M. Thomasson wrote:

> 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!

Well, now he can participate in this challenge... (assuming he is still with us)

--
Regards
Stefan