Boats Log

November 24, 2005

Winners for Challenge 6, Honours Board and Timing for Challenge 7

Lots to cover here:

We have emailed the winners for Challenge 6 part A and we will post the details as as soon as the winners get in touch to confirm their details. We have had to delay posting the honours boards for this week. I hope to get them up tonight or tomorrow. I hope you can be patient, though at this stage I can guess it will be hard.

We have decided to keep the timing for Challenge 7 the same as for Challenge 6. Maximum points for a submission before 8pm today, then dropping every four hours by one point with the exception that the period from 8pm to 8am each day counts as four hours for this calculation! (Who says 1 can't equal 2, or even 3?)

Good luck with Challenge 7!

Posted by Harry at November 24, 2005 02:12 PM

Comments

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what cipher is 7b

[It's a Casear shift taking A to B. Just kidding. Why do you think I would tell you all? Harry]

Posted by: freaks at November 25, 2005 03:30 PM

Can you start a new thread please, Harry? It's hard to find things when there are so many comments. Thanks.

[OK Harry]

Posted by: harry de voil at November 25, 2005 10:33 AM

That was posted very quickly. Isn't it a bit early for students to be up?

Posted by: Mike at November 25, 2005 07:53 AM

YES YES YEEEEEEEEEEEEES!!!!!!!!!!!!

IT'S SNOWING AT LAST!!!!

FIRST TIME IN SEVERAL YEARS!!!!!!!!!!

oh and by the way, i've finished 7b.

Posted by: Mike at November 25, 2005 07:49 AM

Blimey!

You know how to make it difficult, don't you?

Is the group length a factor of the length of the cipher text?

And... very clever, Harry. (So clever I haven't done it yet...)

Posted by: Alex at November 24, 2005 11:20 PM

ok so we all know what the cipher is, but none of us can crack it, just so theres a hope of some sleep tonight/a giant snowball fight can u tell us if it uses a keyword and if so has it been mentioned in part a/previous challenges??

if no is there any way of cracking this without knowing a crib and its corresponding cipher text??

come on harry u know u want to help us ...

Posted by: Santa at November 24, 2005 10:57 PM

This cipher makes me feel.... KHAAAAAAAAAAAAAAAAAN!!!!

*Goes on rampage*

Posted by: Jimminy bob-bob at November 24, 2005 10:47 PM

Ugh, tell me about it, I'm crying out for some extra buttons on my calculator :P

**************

[Time to bring the asterisks back out. Harry]

Posted by: Ian at November 24, 2005 10:43 PM

chidders
I know the feeling we think we know what the cipher is and have done for over an hour but cracking it is another matter.

Posted by: little hill at November 24, 2005 10:21 PM

Woo! It's snowing! But what a dilemma... cipher challenge or gigantic snowball fight?

(Apologies to anyone where it is not currently snowing)

Posted by: Danny White at November 24, 2005 10:21 PM

i know what cipher it is, i just cant break it!

and harry, how did you let the comment through from lester hill!!!!

chidders

Posted by: chidders at November 24, 2005 10:01 PM

is this "hint" in 'part a' different from the comment about it not being the rotor machine

because the only other hint i could find was very very very subtle but then i spose im a subtle person (???)

any help would be nice.

[It is very, very, very subtle. There will be hints, but it is too early. Just keep trying things out. If you have found even a subtle hint follow it up. Harry]

Posted by: L Hill at November 24, 2005 09:35 PM

Hugh
If you want to search the leaderboard press ctrl+f and then type in your team name. press find and it will bring you right there.

Posted by: seano at November 24, 2005 09:25 PM

I am really sorri that i am a bit off topic here... I just want to know how you did 6B. Someone, please??.....

[6b was a twisted old European cipher referred to as the Latin Five. The Romans used the letter V for a Latin Five, so together with the European reference we get a Vigenere cipher. To make it interesting we "twisted" it. Here the layout of the text was important. It came in 32 blocks of 32, so it was natural to write it as a square grid. After doing the Vigenere encryption you needed to transpose the grid, i.e., to switch its rows for columns and vice versa. This is like reflecting the grid in its leading diagonal. Another way to think of it is that after deciphering the Vigenere you can read the text by reading down the columns.

It might looks impossible to decrypt. How can you find the Vigenere ekyword when the ciphertext has been transposed? Well it turns out that if you try Babbage Kasiski deciphering on the text it still works even with the twist (because the length of the keyphrase was 11 and the size of the square (32) is one less than a multiple of 11 (the length of the keyword. So you can carry out the first stage and examine the text to find the twist. The crib (all the messages start with Comrades so far) really helps to see the twist. In fact the keyphrase was FialkaMarkI. If you do the Babbage Kasiski trick to the twisted text you find a Vigenere with keyphrase FIKRAMAKLAI.

Anyone who thinks the Latin Five clue was cryptic and unfair should be aware that LATIN FIVE is an anagram of FAINT EVIL! And those who thought that decrypting part B came down to making a lucky guess missed the point that you could get it systematically. Harry]

Posted by: Jenny at November 24, 2005 08:59 PM

Just an idea for next year Harry. In the honours board, i think a search would be a good idea because i always feel sucked into looking to find my position rather than start solving the cipher, i then takes ages for me to find my. To speed it up, i would suggest a search perhaps?
Hope you agree, Hugh

I do agree, but can't you just use the search command in your browser? It would save me time if I didn't have to code this up. Harry]

Posted by: Hugh Bird at November 24, 2005 08:58 PM

Not again, i managed all of cipher 6 eventually but now, i can't even get going on part 7a, i am feeling suicidal already. PLease help, anything, please.
Thanks, hugh

Posted by: Hugh Bird at November 24, 2005 08:53 PM

Nothing to do with fialka!! We just spent the last 4 hours at school trying something completely related to it. Grrrrrrrrrr to you. Clue yet?

[The only clue you will get today is in part A. Harry]

Posted by: Tom at November 24, 2005 08:52 PM

Ok so we know the weather report isnt for &b then what other help have you actually given, from what I can see all we know is about how its not the full fialka, there are still so many things it could be. SO frustrating.

harry have you actually had any correct submissions for 7B yet?

[No solutions last time I looked.To put your minds at rest 7B has nothing to do with the Fialka, which we are saving for 8B. Harry]

Posted by: Tom at November 24, 2005 08:46 PM

notice "19 comment" was posted by a "R.Herring" - red herring perhaps?

[Red faces all round, including mine for not noticing. Harry]

Posted by: hmmm at November 24, 2005 08:38 PM

I take it back I've just reread part A and it does explain the note but it doesn;t help me with part B. Is the 1098 important this time like the 1024 was last time?

[The number is not quite as significant, but will still help. Harry]

Posted by: Tim at November 24, 2005 08:34 PM

Significance of number 19? Clues in part A. Harry I've done part A and that weather report thingy does not "all become clear". Help!

[I'm not sure about the significance of 19 either, but if it works for them .... As for part A, it tells you exactly what the weather report is for. It's a crib for Challenge 8. It was fun watching you all struggling to use it for part 7 though! Harry]

Posted by: Tim at November 24, 2005 08:32 PM

pretty please can we have a little clue for part b! my teamates are going slowly mad!...its worrying...! they have even created some ciphers it might be...

[You already have a clue in part A. Harry]

Posted by: very stuck at November 24, 2005 07:55 PM

yes i am, forgot the paragraph returns

Posted by: jasonwhite at November 24, 2005 07:50 PM

harry, 1098 characters? you have said yes to.
I have 1134. Am i wrong?

Posted by: JasonWhite at November 24, 2005 07:48 PM

Harry,
Is the image supposed to be -35 or 35, as the image says -35, yet the alt text says 35.

Confused,
Mike

[Yes. Harry]

Posted by: Mike at November 24, 2005 07:11 PM

Ah! I finally got it after I realised the significance of the number 19! Nice one Harry!

Posted by: R. Herring at November 24, 2005 07:05 PM

Might Harry also wish to change the picture's alt name, not just the contents of the image itself? And calling the picture 'crib' might also be misleading, who knows? Anyone deciphered it yet?

Posted by: Richard at November 24, 2005 07:02 PM

what does the image below challenge a mean, cos it is driving me mad!

[Once you do Challenge 7A all becomes clear. Harry]

Posted by: lara at November 24, 2005 06:45 PM

The ALT tag for the Crib image shows 35C rather then -35C.

Posted by: Jon Dawson at November 24, 2005 06:35 PM

The image below solution A is the Crib to whatever. How do you know? Look at the image location.

Posted by: Jon Dawson at November 24, 2005 06:16 PM

Harry, is the 64 significant if you catch my drift?....

Posted by: TOMBOLA at November 24, 2005 06:08 PM

don't reckon this is a playfair as you'd have to have either a 25x25 grid (in which case 1 of the letters wouldn't be in the ciphertext) or a 36x36 one which would have numbers as well, and unless i've made a terrible mistake there arent any numbers in the ciphertxt.

anyone cracked it yet? don't intend 2 bribe u or anything, just wanted 2 know :)

Posted by: gg4 at November 24, 2005 06:03 PM

Say, Harry, that's an interesting URL you've put on that image...

Posted by: Ian at November 24, 2005 06:00 PM

Nah, the clues are not obvious! Bad grammar on my part I suppose, but I meant that I was disappointed that the obvious clues didn't exist :P

But yes and no is quite clear... I think.

Posted by: Ian at November 24, 2005 05:50 PM

Are the double slashes a clue?????
I'm really stuck here

Posted by: neel at November 24, 2005 05:36 PM

So if the weather info is a (sort of) clue, does it affect 7a or 7b????

[Who said it was a clue for Challenge 7? Harry]

Posted by: Margaret at November 24, 2005 05:22 PM

is the fialka anything to do with it this time?

Posted by: lara at November 24, 2005 05:21 PM

in what timescale is "eventually"?

Posted by: help at November 24, 2005 05:20 PM

Can you give us a hint?

[Eventually, yes. harry]

Posted by: Clue Please at November 24, 2005 05:15 PM

Harry, is the subtle changing of the temperature from 35 degrees C to -35 degrees C significant?

[Yes, it proves I am an idiot with Photoshop. I missed out the minus and had to put it in. Harry]

Posted by: Jonathan at November 24, 2005 05:13 PM

none of this involves a playfair cipher does it?

[I think you are supposed to tell me (but not anyone else). Harry]

Posted by: lara at November 24, 2005 05:12 PM

For next year, I think a forum should be implemented into the site. I personally would find it a lot easier browsing a forum than to look through all the archives, and the newest posts would be displayed quite easily meaning no one would really miss any important information.

Sorry if this has been suggested before.

[This is something I would like to do, but the problems is implementing it so that it ties in with the content manager we use. Harry]

Posted by: Ned at November 24, 2005 05:11 PM

Does part B contain 1098 characters?

[Yes, Harry]

Posted by: Luke at November 24, 2005 05:06 PM

What do you MEAN, yes and no? How can something be a hint and yet not be a hint?! (rhetorical)

[Isn't it obvious? Harry]

Posted by: harry de voil at November 24, 2005 05:05 PM

It's only been out an hour Katriel! Try looking more closely and
reading up on the different sorts of ciphers they might have used
(there aren't that many). Then take a break, do some homework :) and
try again. Good luck everyone!

Everybody's getting paranoid over whether any of the messages posted
are hints now...(this isn't a hint) Let's just assume that nothing is
a hint unless specifically said to be a hint, yes?

Posted by: harry de voil at November 24, 2005 05:02 PM

I use a scripting language (JavaScript) which is like a baby programming language. If you want to learn how to do this have a look around www.w3schools.com

Posted by: Tiddy at November 24, 2005 05:00 PM

is the weather conditions in the cipher room by challenge 7a a clue?

[Yes and no. Harry]

Posted by: x at November 24, 2005 05:00 PM

True...I didn't think I'd get one ;). Oh well, no harm asking.

"The part A challenges will be aimed at beginning cryptographers and should be accessible to everyone throughout the competition."

Very smart beginning cryptographers these are ;)!

Anyway, will keep trying and thanks Harry.

Kati

[By this stage you are ALL very smart (if not all beginning) cryptographers. I didn't say they would be accessible to beginners without hints, and we have got two weeks again. Harry

Posted by: Katriel Cohn-Gordon at November 24, 2005 04:57 PM

Ugh, finally did 7A, don't know what took me so long... stupid freq graph really. Got it now though, and disappointing as to really obvious clues to B :P

[You mean the clues are too obvious? Harry]

Posted by: Ian at November 24, 2005 04:56 PM

Is it too early for a very very subtle hint for 7A? I've tried everything - the index of coincidence is all wrong for monalphabetic cipher. Does the number 5 have anything to do with it?

(That wasn't a hint by the way - I'm asking for one :)).

[It is way too early for a hint of any kind! Keep at it. Harry]

Posted by: Katriel Cohn-Gordon at November 24, 2005 04:51 PM

hey, does everyone else know how to do computer programming or sumthing? cos i've been working it out with MS word's find and replace and pencil and paper. where's everyone learn programming from?

[We had a long discussion of this a few weeks back. Actually even part B can be done with pencil and paper if you are patient. Harry]

Posted by: lara at November 24, 2005 04:48 PM

Damn ciphers and all who invented them. Especially 7b.

Posted by: Tiddy at November 24, 2005 04:45 PM

u mean u got part a ages ago? how? the frequency is way weird!

Posted by: lara at November 24, 2005 04:43 PM

HELLO HARRY!!!!!!!!!!!!!!!!!!!!

Posted by: HELLO!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! at November 24, 2005 04:37 PM

HERE WE DON'T GO, HERE WE DON'T GO, HERE WE DON'T GO!

Posted by: Here we don't go! at November 24, 2005 04:30 PM

we got it ages ago come on ppl

[Got what? Not part B that's for sure. Harry]

Posted by: Alex at November 24, 2005 04:26 PM

WOW THIS IS HARD!!!!!!!!!!!!!!! i can't even get into part a

Posted by: lara at November 24, 2005 04:20 PM

HERE WE GO, HERE WE GO, HERE WE GO!!!!

Posted by: martyn compton at November 24, 2005 04:04 PM