About the mission

[Ernie]

Hello Harry,
Thanks we will keep trying.

[Madness]

Here’s another clue for you all: The Walrus is Paul.

For a transposition cipher of this type, the block size divides the length of the ciphertext (not including spaces and punctuation).

[The-letter-wriggler]

@Madness
4B keyword
I got SCOUR because they are scouring the country, but PHOTO seem good too as ‘photographic hobby’ was mentioned in 3B.

[Cribbage]

5B HIDDEN MESSAGE SPOLIER
Is it … ? [Yes it is, well done. Now, what to do with that knowledge?]

[Madness]

Now that 4 is over, can you reveal the intended keyword? For a permutation that short, there are too many
possibilities for my cats to sort through.

[Feefen]

I solved 5B and tried looking for the hidden message but to no avail. Would you be willing to give a hint or two, Harry (or anyone else who’s found it)?

[Jbrintcrypt]

To everyone,
I’d like to ask if it’s worth finding the secret message in 5B. I solved the main part relatively quickly, but I haven’t got round to looking for the secret text as I’ve had more important work to do. For this reason, I’d like to ask someone who has found it if it has relevance to part 6 or is worth finding even if I don’t have much free time. Thanks in advance.

[Ernie]

Hello Harry,

We’ve struggled with 5B, we are using the same cipher as we for 5A, is that right please. Any tips or clues? Thanks.

[Alright, since you asked so nicely. The Mission Briefing tells you that the spyclist telegram is encrypted with a substitution cipher, so you need to use frequency analysis to try to work out what the most likely letters standing for E and T are, then use the fact that THE is the most common word in a text to try to figure out where that appears. Then you might also need to look for some common words that you expect to see knowing the sort of things the spyclists often talk about, or look for words or phrases they often use. Those are called cribs. I hope this helps. Good luck, Harry]

[Ernie]

Thanks. Ernie

[17cmere]

Part 6B was really hard but with many different resources, YouTube, Wikipedia, and some programming, I finally managed to solve it! Thanks Harry for this great challenge, however I am a bit scared of what is to come next week.

Yesterdays Challenge B gave us ninjas a bit of a run for our money! Had to break out vim and python to get it done, wish I had been more prepared. Thank you so much for all the challenges, both looking forward to and terrified of the final.

[Well done, sounds like you had fun breaking it. And, Muhaha! Harry]

[Madness]

You should be scared. Very scared.

[67105112104101114]

I forgot about this yesterday so was very glad to see the deadline for this one was 2 days not one. This cipher was good fun to crack and I found that it is possible to completely automate the cracking even when you don’t know the transposition key because if it is not the correct transposition the resulting ADFGVX will generally have 34-36 different pairs when the ciphertext is this long so you just have to check for any which are shorter than or equal to 26 different pairs. Unfortunately this is quite slow because it has to test every permutation although it can be sped up by only checking a section and then where that section is fine checking the whole thing and potentially may be able to be sped up for larger keys by removing some sections of permutations early on although I don’t know if that would be worth the time it would take to do that as it may not give much gain.

[Nice thinking. I will postpone publishing this for a bit to allow people to find their own way, but hopefully this will be a useful tip for others in a day or so. Thanks, Harry\

[The-letter-wriggler]

=======================================
On 24th November 2020 at 4:47 pm #52282
Feefen Posted…
Harry, will we ever know the answer to the puzzle at the end of 3B?
I tried but couldn’t figure it out!(yet?)
=======================================
Here is my take on it…

At the end of challenge 3B’s plaintext it says:

Let me finish with a little puzzle for you.
Can you find an eight letter English word which you can change
by altering the order of its letters to produce four other
different English words? Yours sincerely, Otto

I have a problem with the word ‘other’ here, it seems to imply a 5 words
anagram, but if it really means just 4 words then here is my answers.

======== SET 1
outgrins
outrings
rousting
tourings
======== SET 2
evilness
liveness
veinless
vileness
======== SET 3
epistler
peltries
perlites
reptiles
——–

[Leo_yates]

Just been looking back at previous challenges and decrypts and in challenge 1b the letter is signed by a Nikolaus R. I was wondering if that had any significance, if so could it by any chance be Nikolaus Riehl
link:https://en.wikipedia.org/wiki/Nikolaus_Riehl
or I am I reading too deep into this stuff.
Thanks

[That would be telling … Harry]

[Author]

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