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25 Sep 18 at 8:55 am #35757AnonymousInactive
Today’s challenge is a bit more back on track, and the answer is a four-letter word:
!!!!!!
Four letter word? I think you better tell me the solution before I publish the challenge, this is a family show! Email it [email protected],
Harry
!!!!!
25 Sep 18 at 8:56 am #35761AnonymousInactiveFrench flag? Eiffel tower?
25 Sep 18 at 4:13 pm #35850AnonymousInactiveOkay so more ideas for the puzzles, the one involving 1478, has it something to do with the Spanish Inquisition? Also the phonetics one, is the first part ‘sunny’? …
26 Sep 18 at 11:50 am #35884AnonymousInactiveThe 1478 one is indeed to do with the spanish inquisition; it’s a monty python quote.
on the wrong track with the phonetics one though, I’m afraid.
26 Sep 18 at 11:51 am #35905AnonymousInactiveWait the ‘nobody_______ 1478’- is a Monty Python quote- ‘nobody expects the Spanish Inquisition’.
The phonetics is ‘sign up to…’ but can’t figure out the last word.
How are those answers?26 Sep 18 at 11:51 am #35923AnonymousInactiveToday’s challenge might be my last:
I am the name of a machine, the first of its kind, built to write out latin.
And if you think of water, you’ve just got the right answer.28 Sep 18 at 3:23 pm #36078AnonymousInactiveThe phonetics one is sinply a pronunciation of the letters of a message backwards if one was to see them written down. It is not sign-up, it is sign-app. The reason for the monty python quote is that 1478 is the date of the start of the spanish inquisiton – so the answer is “expects.”
28 Sep 18 at 3:23 pm #36194AnonymousInactive02 Oct 18 at 8:49 pm #36912AnonymousInactiveHi! Can’t wait for the Cipher Challenge 2018! It’s my first year! I’m really looking forward to the first challenge!
#35265
06 Oct 18 at 12:35 pm #37859AnonymousInactiveHello. If the a word in a sentence doesn’t make sense and it is on the website as that as well, should I just decrypt it as it is or do something else?
[EDIT, Harry: ALWAYS DECRYPT IT AS IT IS. It might just be a mistake, but it might not and in both cases we will mark your answer against a decrypt of what is published!]
08 Oct 18 at 8:55 am #38052AnonymousInactiveHi just how hard will the challenges get in a scale from 1-10? And when will we stop getting hints or tips to help us? I’m quite scared because this is my first time doing the National Cipher Challenge.
[EDIT, Harry: Ooooh, at least 12 on a scale of 1-10! Seriously, they do get pretty hard by the end, and not everyone will crack them all. The real question is, how far can you get this first time! And can you beat that next year? Good luck!!!]
11 Oct 18 at 4:14 pm #38608AnonymousInactiveHi Harry.
It’s not cheating if you use websites to help, is it? Also, if you get the feeling that one of your peers are copying you, what should you do?
Thanks
from CipherGirl1, Jelly Bean Panda and Rick Astley 🙂[EDIT, Harry: It’s not really cheating at this point in the competition. We are still doing practice rounds and people are finding their feet. Later on websites will be less helpful (especially at the devilish end!) and for prizes we ask that submissions are all your own work. As for copying, again, this is still practice and we are all friends here, so I would not take that too seriously. Later on you might want to be a bit more circumspect!]
14 Oct 18 at 1:32 pm #38868AnonymousInactiveI was here last year with shellr but i will say hi anyway.
so………………………………………………………………………………………………………………………………………………………………………………………………………………………..
…HIYA!16 Oct 18 at 3:25 pm #38871AnonymousInactiveHEY!!!
THANKS FOR ALL YOUR HELP HARRY. WE FEEL MORE RELIEVED TO KNOW THE ANSWERS TO OUR QUERIES! 🙂17 Oct 18 at 11:40 am #38939AnonymousInactiveDear Harry, me and my group don’t really understand frequency analysis and we’ve looked at numerous websites. Please can you explain the steps of using frequency analysis to us? Many thanks, the Encryptic Enterprise.
[EDIT, water_biscuit (I hope I’ll do!): Before how to do it, I’ll start with the point of the exercise: it begins with the observation that English uses (for example) the letter ‘e’ far more than the letter ‘z’. It turns out that it does so in a pretty predictable way: in any sufficiently long (and typical) English text, the letter ‘e’ accounts for around 12.5% of the all letters, ‘t’ for about 9% and so on, all the way down to ‘z’ at less than 0.1%. (I got these numbers from here: you can get slightly different numbers depending on how and what you count, but the basic pattern is always the same.)
So the aim of frequency analysis is to exploit this predictable pattern. If I have good reason to believe I’m dealing with a Caesar shift, and I can identify which letter occurs most frequently (particularly if it’s about 12.5%!) then there’s a good chance that if I line it up with ‘e’, I’ll be able to decode it. If I’m dealing with an affine cipher, them two letters and some maths is usually enough to work out what’s going on and how to decode it. So I might also guess which letter is ‘t’.
How you count is up to you: by hand is one (pretty tedious) option; another trick is to use find and replace in Word (find ‘a’, replace with ‘a’, and click “replace all”, which will tell you how many “replacements” it carried out). Or you could think about starting to write some code, or maybe using Excel, to do it for you. But having got the data, you can have a look at it: see if you can see a letter appearing a lot. Try lining it up with ‘e, and see if English comes out when you start to decode. If not, but the letters vary a lot, and in a similar pattern to the list at the link, it is probably still a substitution of some kind.
If I’ve got some substitution cipher, then having good guesses at a few letters will usually give me something to start from as I try and work out the rest. While you can get somewhere just with single letter frequencies, it can also be worth looking at how they appear in relation to one another. One example is ‘the’, which is the most common three letter word in English. Spot that and you’ve got three letters. Or you could ask “which letters can appear twice in a row?”. Or perhaps a long repeated section is an important word in the cipher (maybe ‘the shadow archive’ will appear more than once in some challenges this year, for example). Putting together lots of ideas like that, after maybe a few dead ends, will usually lead you to the right answer!
If I have a more complicated cipher, there is still useful information to be got from frequency analysis. But I think I’ve given you enough (maybe too much) information for the time being – see if you can get the hang of the technique in simple cases, and then maybe have another look at online tutorials!
(If you look at the codebreaking guide, you can see a worked example, as well as another explanation. I hope some of that was helpful!)]
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