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December 09, 2005
Winners for Challenge 7A
And the lucky winners are:
Thomas Cappleman and Robert Harman, the The Joker Of No Trumps from Reading School, Reading,
Timothy Palmer from King Edward VI College Stourbridge,
Francesca Golding from North London Collegiate School,
Mark Dessain, the Shadow from St John Fisher Catholic High School, Harrogate,
Becci Rushton from Endon High School, Stoke-on-Trent,
Charmaine Law, Jenny, Zoe, Roberta and Rosi, the Dark Knights from Clarendon House Grammar School, Ramsgate,
Jun Kawakami, Max Ankers, Charles Barry, George Kiff and Tsubasa Sato from The King's School, Cheshire,
Emma Forth from The Grange School, Cheshire, Northwich, Cheshire,
Graham Smith, Brett Hornby, Sasha Brookesbank, Mark Freeman, Huw Foden, Matthew Powell, Neil Hayes and Alex Dawson, the Mathemagicians from Harry Carlton Comprehensive School, Loughborough.
You should have got an email from us. Get in touch to confirm your details. All the best,
Posted by Harry at December 9, 2005 04:33 PM
Comments
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Hi -
One question: when the reflector returns a character through the rotors, does it go through the rotors the 'normal' way or backwards? That is, the rotors work in two directions. Does the character go through the rotor forwards -> reflector -> backwards, or forwards -> reflector -> forwards.
That is as clear as mud ;).
Kati
Posted by: Katriel Cohn-Gordon at December 12, 2005 03:07 PM
On a similar theme to Kati, it would help a bit if you could tell us some more about the rotation mechanism. Is the fast-moving rotor the one nearest to the reflector, or the one furthest away from it? Does the fast-moving reflector move in the positive direction, and the slow-moving one in the negative direction, or vice-versa? (By 'positive direction' I mean from the A position to the B position and so on.) I think that you cannot simulate the effect of changing the direction of motion or the identity of the fast-moving rotor by swapping the rotors or the location of the wiring mazes or the starting positions of the rotors.
[I'll try to get some of this info out with the rotor diagram this afternoon. Harry]
Posted by: Sean at December 12, 2005 11:03 AM
I've got a program that at the moment can brute force 50 settings per second when run within the Visual Basic 2005 IDE and about the 330 per second when run outside of it.
I really recommend sticking a progress bar on your form - it will tell you if your computer is actually doing anything, rather than you have to wait until it's done all several million combinations.
Posted by: Simon at December 12, 2005 08:41 AM
i didnt go to bed saturday night cracking it. i got quite a bit of the plaintext, by working out my own way of solving it. im really annoyed because i cant work out how to get the rest of the text from my idea :S
chidders
Posted by: chidders at December 12, 2005 08:39 AM
I made one assumption - can you clear it up for me? Thanks ;) I guessed that the rotors rotate AFTER the electrical signal has been transmitted (i.e. if they're in pos1 to start the first letter will be encrypted in pos1 not pos2).
Kati
[That is a reasonable assumption, but if you think about it, if the opposite was the case that would just correspond to a different starting position for the rotors so wouldn't make much difference. Harry]
Posted by: Katriel Cohn-Gordon at December 12, 2005 08:12 AM
Well, I thought I had a good cracking method, but I can't get it to work, I guess I'll have to leave it to Monday evening. If no-one else has done it I'm not too disappointed though :P The extra rotor wirings will definitely help.
Posted by: Ian at December 11, 2005 10:16 PM
What type of clue are we getting tomorrow, will it be more wirings?
[With luck the image of the second rotor will have been cleaned up by the lab guys so that would give you more wirings. Harry]
Posted by: Sean at December 11, 2005 09:38 PM
Anybody cracked it YET, Harry?
[None yet. Harry]
Posted by: alm00st at December 11, 2005 08:20 PM
Anyone done it yet?
[Not yet. Harry]
Posted by: ключ at December 11, 2005 08:19 PM
Do the rotors rotate again on the way back - after the electric signal has been reflected by the reflector?
[No, just the once per character. Harry]
Posted by: Jane at December 10, 2005 12:45 PM
would love to come to southhampton for a meeting/party, whatever you wanna call it, would be great, do you think it would be possible to do harry?
[I think it might! Harry]
Posted by: martyn compton at December 10, 2005 11:56 AM
We won! All our efforts are piad off!
Posted by: charmaine at December 9, 2005 11:52 PM
Why does the morsecode in the xml feed give a completely different ciphertext, yet the same length, to the morsecode in the text file?
xml file gives cipher text that starts with "FTHIQ" not "MDY5H".
[Seems like the careless operator has sent the same message using different rotor settings for the machine. There weren't any other components available so I reckon it must have just been the initial positions of the rotors that changed. Harry]
Posted by: tom at December 9, 2005 10:58 PM
so is the next hint on monday? i want to spend the weekend trying a few ideas out, so im hoping there wont be any more hints for a while.
chidders
[The next main hint will be on Monday. I will be away until Sunday night so even small hints are unlikely before then. Harry]
Posted by: chidders at December 9, 2005 09:39 PM
advice from one of the greatest code-breakers of all time - alan turing (not me :P)
"no cipher is cracked by simply staring at it"
otherwords, dont just sit there until u have eyestrain, try every possible idea that occurs to you.
tats what im doing at any rate :P went to bed at 1am, and got up 4am to have another go :S been working hard :P
keep going, one of us is sure to break it eventually, but not with brute force
chidders
Posted by: chidders at December 9, 2005 09:11 PM
Harry, you know you said that about 90 tickets would be issued...
1. does that mean that the top 90 or so competitors get to go?
[It means that 90 people (including teachers/paretns etc) can go. We usually give tickets to the overall winners and then issue them by lottery to some of the people who want them.]
2. is cracking challenge 8b essensial to be issued with a ticket?
[No]
3. what does 'prizegiving' involve apart from, well, prizegiving? who do competitors get to meet?
[A tour round the museum]
4. do i have any chance at all of going? i'm 71st on the overall leader board at the moment.
[The same chance as everyone else, Harry]
Posted by: lara at December 9, 2005 08:39 PM
yeah, to meet at southampton some time would be great, even though i live in truro, cornwall - long drive :P
a few questions, harry:
1) have we got enough information now to crack it (in theory)
[Not in reasonable time I don't think, Harry]
2) when do u expect the first person to crack it, if some1 hasnt cracked it already
[I'm not at all sure!]
3) has any1 cracked it yet
[No, Harry]
chidders
Posted by: chidders at December 9, 2005 08:13 PM
harry, is there going to be some big celebration/meetin or something like that at the end of the challenge?
[There is a prizegiving at Bletchley Park on March 31st. Tickets will be very limited (we can issue about 90 altogether). Would people be interested in coming to Southampton some time for a less official celebration? Harry]
Posted by: martyn compton at December 9, 2005 06:54 PM
A quote from Edgar Allan Poe:
"Few people can be made to believe that it is impossible to create a method of secret writing which can baffle investigation. Yet it is roundly asserted that human ingenuity cannot concuct a cipher that human ingenuity cannot solve."
Posted by: Stephen Harris at December 9, 2005 05:55 PM
Heheh, well done Tom ;)
Posted by: Ian at December 9, 2005 05:16 PM