The official Challenge 10 tips and hints thread

[Harry]

We will publish occasional, official hints for Challenge 10 here, so bookmark it and check regularly. Hope they help, but not too much! We might also publish your own hints, especially if we think are suitably devious and don’t give too much away, but we will try to keep pretty much to the pace below, so if you submit a hint that is significantly stronger than the ones we have already published then we are likely to hold it back and it might not appear. Still worth sending them in, as we like to read them!

This year, for the first time ever, there is an actual schedule for the planned hints and tips. Best not to rely on it if you can avoid it, but if you get stuck you will at least know when the help will arrive:

Challenge 10A	Publication at 9am on	Challenge 10B
A hint for 10A	16/12/2022
Another hint for Challenge 10A	17/12/2022	A first hint for Challenge 10B
A third hint for Challenge 10A	18/12/2022	A second hint for Challenge 10B
A fourth hint for Challenge 10A	19/12/2022	A third hint for Challenge 10B
A fifth hint for Challenge 10A	20/12/2022
A sixth hint for Challenge 10A	21/12/2022
A seventh hint for Challenge 10A	22/12/2022	A fourth hint for Challenge 10B
An eighth and final hint for Challenge 10A	23/12/2022	A fifth hint for Challenge 10B
	26/12/2022	A Boxing Day hint for Challenge 10B
	29/12/2022	The seventh official hint for Challenge 10B
	02/01/2023	The first official hint of 2023, Happy New Year!
	03/01/2023	The ninth and final official hint for Challenge 10B

Good luck,

Harry

[Harry]

I know you already know this, but step 1 for both parts of the Challenge is frequency analysis. It won’t help much, but you should still do it!

Harry

[abc123abc]

Will the hints be straight forward or will the meaning behind them be unclear?

[Yes. As in, yes they will either be straightforward or their meaning will be unclear. And sometimes you won’t know which. And sometimes you will. I have to have some fun! Harry]

[QuantumError1036]

10B is not a Caesar cipher! [Edited by Harry]

[Roxy_Pi-thonsRcool]

I have Part A, but B is sticking me almost as much as 8b did for a while! Are there multiple layers of encryption or is it just one particularly hard cipher? Im thinking that it may be double (if not triple!) encoded. Is this the challenge to beat Harry, or are you just messing with our strategies?

[Yep! Messing with your strategies AND your minds. You’ll thank me one day. Harry]

[Cyvann]

when you say frequency analysis, should we be focused more on the 2-grams or the 1-grams?

[I think I will leave that up to you! Harry]

[The-Letter-Wriggler]

@Harry The hint timetable is not too easy to read, maybe put this up as well? [Thanks will do. Will get the Elves to fix the table layout above too. Harry]

THE HINTS DATE TIMETABLE IN A MORE COMPACT FORM.

Publication at 9am on the date shown.
=====================================
Hint 1 for Challenge 10A 16/12/2022

Hint 2 for Challenge 10A 17/12/2022
Hint 1 for Challenge 10B

Hint 3 for Challenge 10A 18/12/2022
Hint 2 for Challenge 10B

Hint 4 for Challenge 10A 19/12/2022
Hint 3 for Challenge 10B

Hint 5 for Challenge 10A 20/12/2022

Hint 6 for Challenge 10A 21/12/2022

Hint 7 for Challenge 10A 22/12/2022
Hint 4 for Challenge 10B

Hint 8 for Challenge 10A 23/12/2022
Hint 5 for Challenge 10B

Hint 6 for Challenge 10B 26/12/2022 Boxing Day

Hint 7 for Challenge 10B 29/12/2022

Hint 8 for Challenge 10B 02/01/2023 the first official hint of 2023, Happy New Year!

Hint 9 for Challenge 10B 03/01/2022 the final official hint for Challenge 10B

[Shinglington]

I’m completely stumped, and I’m doing it individually so don’t have anyone to discuss it with. Do you think I should keep trying random things, or just take a break? I feel like I’ve wasted my time, since I’ve done so much programming and research in the past few months about cryptography, completing all the other challenges really quickly, or always knowing what steps to take to get closer to solving it, but for this, I’m just completely stuck. This probably isn’t a good place to post this, but I don’t really have anyone to share my feelings about this to

[Perfectly natural to feel like this. It is no accident that we allow three weeks to crack this cipher. Up to now things have been deliberately straightforward while you all develop your skills, but now you are faced with something a bit left field. It could take a while to figure out what is going on and you will need to take time away from it to let things turn over in the back of your mind. I would say, take a break, but don’t give up! Harry]

[Mattyrat2027]

@Harry anyone solved it yet? I remember the first cipher clock (2020) solve was within a few hours…

[We don’t announce anything until the challenge has ended. Keeps everyone on their toes! Harry]

[Harry]

A hint for 10A

This is a Hill cipher, though a not particularly complicated one. They are usually set up using matrices and modular arithmetic, but in fact this one can be solved without any of that.

[url_alone]

i THINK WE ARE ALL HERE WAITING, I’M TRYING TO SEE IF I AM MOVING IN THE RIGHT DIRECTION

[Flappyasdf]

Hi, When will you release the leaderboard for 9A and 9B? Also at what point will we get feedback for 10A and 10B or is the answer to this never?

[The Leaderboards are up now. Apologies from the Elves, they were busy packing Santa’s sleigh and didn’t have time to post yesterday. I am sure we all agree that they had their priorities right, even if it was hard to wait. Feedback will be off for a little while longer, and will be on “delayed” mode, so you will only get feedback on a submission after the next points boundary. That means it pays to do your own checking, even after submitting. If you find your own mistakes and correct them before the time band ends, you will get more points than if you wait for the feedback. Hope that is clear, Harry]

[bedales22]

I thought I had it by using the matrix written in Chinese left in the vault… but no luck!

[floatingyunsan]

Harry is 10 A suppose to help with B in anyway?
I know you technically can’t give hints but feel that if something is in A I will find help to read the English.
I have broken A but me being Dyslexic I struggle to read the decrypt, haha oops if it’s supposed to help …

[Not a lot! You are not missing much. The hints and tips will appear separately on the forum as the days go by … Harry]

[Harry]

Another hint for Challenge 10A

Technically, this is a 2×2 Hill cipher, so while frequency analysis helps a bit, you really need to do bigram analysis for it. That just means counting the frequency of pairs of letters. Challenge 10A starts

RVSUU CNTAN NNFWO ATAEL ILESU NOBCG DDRZS DANDZ

which can be reformatted to

RV SU UC NT AN NN FW OA TA EL IL ES UN OB CG DD RZ SD AN DZ

and in this fragment the most frequent bigram is AN. If you compute them all, across the whole message you will see which ones are the most popular. What do you think they might represent?

[Author]

Posts