Practice Challenge 1

[Harry]

Please don’t publish hints or tips here without checking with the Elves first! Feel free to discuss the story though, at least in the Practice Rounds)

[Anonymous]

I really liked how the first challenge was possible to do just online. I actually was just playing around with the cipher thingy, looked back at the text and it was deciphered. Second challenge was quite easy as well (Thanks to my programming skills). I’m wondering how the story will unfold, see you next week.

[Anonymous]

Hi, I like the sound of the story so far, ‘The Shadow Archive’ and ‘The Secret Secretary’. Sounds nice and mysterious, as usual

[Anonymous]

And Here we go again, good luck to everyone competing this year. stories of to a good start no?

[Anonymous]

Does anyone have any theories for the storyline of practice challenge one?

[Anonymous]

hey, I have a question. Does punctuation and capital letters matter in the competition? I dont want to miss out on points for not having capitals!

[Edit, Harry: No, spacing, punctuation and capitalisation don’t matter]

• This reply was modified 5 years, 7 months ago by Harry.
• This reply was modified 5 years, 7 months ago by Harry.

[Anonymous]

I think it’s a little early to start predicting…. so that’s exactly what I’m gonna do!

Don’t wanna spoil too much for those who haven’t solved it, but judging from the introduction text and 1B alone, I reckon that this secret secretary is gonna be up to some shady business that Jodie will be discovering! We know Russia is somehow involved in all of this, but there are references to issues in the mainland and conflicts that are having effects in Britain, so likely something along that route!

Loving 1A, really nice way to introduce the (cipher-type here) concept to beginners – I’ve got a few of my friends doing the challenge on a different team for their first time, and they’ve been able to pick it up, so that’s always a good sign!

[Anonymous]

Has anyone else got a typo in the first line of part b? We have ‘you’ where it reads like it should be ‘your’?

[Anonymous]

As said in many places on the website, if you spot a mistake, keep it as it is deciphered, as it might have been done just to throw people off (Or at least that’s what they say)

[Anonymous]

Interesting thought for those who would like to start writing programs to break ciphers: A little Inspect Element on the Challenge A cipher wheel can give you a pretty good idea how you can go about creating a simple caesar decryptor… If only there was some way of knowing the shift so you could input that into your program…

[Anonymous]

“… If only there was some way of knowing the shift so you could input that into your program…”

That is at the heart of all decryption, whether manual or automated. There are many techniques to compare your decryption attempts with the target language (English in this case). For example the relative frequency of each letter can be considered (observed vs expected) and when you get the best fit – Bingo! (a Chisquare test is one such comparison method).

For more complex ciphers, other techniques would be more appropriate, but maybe more of those later…

Good luck with the programming.

[Anonymous]

how do you use your programming skills for coding and decrypting? Do you use Python? If so, please tell me how–> Much Thanks

[EDIT, water_biscuit: Python is one good option, particularly for a first programming language. You could take a look at the programming guide written by a former competitor to get started. (Although you should now go for Python 3. It is seven years later, and there are lots of tutorials available!) I’m afraid the first time you try coding it is something of a hard uphill slog, but it is (a) very useful for cryptography and (b) a generally very useful skill to gain. And even if you need to learn a different language, having any experience in any language is already a good start.]

• This reply was modified 5 years, 6 months ago by .
• This reply was modified 5 years, 6 months ago by .

[Harry]

Just to confirm as our team joined late, the points for section B don’t hold value?

[EDIT, water_biscuit: For this challenge, and the next two which are also “Practice Challenges”, they have no impact on the final results. For the Competition Challenges (ie, 4-10) they will hold value, but the latest possible 100% solution is still better than a super quick 99.9% solution.]

• This reply was modified 5 years, 6 months ago by .
• This reply was modified 5 years, 6 months ago by .

[Anonymous]

As someone who used python for a long time, I can tell you that decrypting using python will be way longer than using some other languages such as C++. So if you just want to play around, do use python, but if you want to do really important and big programs I’d tell you to use C++, which is in my opinion the best programming language. Whichever one you choose, to learn it I recommend the website france-ioi.org, which is in french but google translate is your friend.

[Anonymous]

@Philanche, I’d disagree. I don’t want to sound like a Python fanboy or anything, but if you’re doing simple stuff like cipher things, and/or if you’re not particularly good at programming, then Python is definitely your friend. C++ really isn’t ideal for newbies. (Also, your statement that “decrypting using python will be way longer” basically isn’t true – Python’s a lot more expressive than C++, in my opinion anyway).

But remember that this [i]is[/i] just my personal opinion – use whatever you want, if it works for you! 🙂

[Author]

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