Ouch!

The eagle eyed among you will have noticed a small difference between the text of Aggie's (graphical) journal page and the text file version yesterday. It's fixed now, but if you have already submitted or are working on the "wrong" version (the version of the Challenge that was showing in the .gif file) don't worry, you will not lose marks as a result. Sorry about the mistake. All the best,

Challenge Four

Harder this week I think, but still not too difficult. Aggie must have figured out that the location crib was a weakness. There's a lot of her Journal missing and I figure she is trying to cover her tracks. Still there must be something important written here. Still looks like frequency analysis is the way to go.

Challenge Three Winners

Congratulations to the following five teams, who each won fifty pounds this week. If you haven't already done so you need to log on and give us a contact address where we should send you the money. For those of you who have won CD's or posters in the first two rounds you will have received, or soon will receive, an email request that you too give us a contact address. The sooner you do so the sooner we can send out the prizes. The top 250 teams on the Hall of Fame for Challenge 3 will get an email telling them how to download the theme tune as an MP3.

Andrew Lee, Oliver Hafner, Anna Baburina, Kehong Jin (Simple) of Millfield School
William Belfield, Alex Weaver, Dan Thomas, Nick Hamish Jehovah (Eta Beta Pi) of Alcester Grammar School
Paul Tinton, Gavin Williams (The Whizz Kidz) from Bishop Rawstorne C Of E Language College
Craig Wyllie from Reading School
Stacey Berridge of Fairham Community College

Challenge Three Solution

Seems like Aunt Aggie tried a little more sophisticated cipher this time, an affine shift cipher x-> 15x+12, but made two big mistakes:

1. she reinstated the word structure weakening the otherwise stronger affine shift .
2. she gave away a very useful crib by encrypting her location (Alexandria August 1911, having revealed it in Challenge 2. If you noticed that then you immediately knew that a was encrypted as M, e as U and I as C and so on.

With this to help you it wasn't even necessary to do frequency analysis this week and that may explain why we had so many correct solutions.

As usual you can examine the solution to Challenge 3 in the Journal. We'll post the names of the five fifty pound winners later on, and Challenge 4 will be posted this afternoon at 4pm. As usual the website will be offline for updating just before then. The new challenge lasts two weeks, crossing half term, but we will continue to mail out feedback as before and I'll give a few hints after a while. Good luck,

Cribs

Figured out the crib yet? Aunt Aggie probably thought she was adding to security by encrypting her location at the begining of her journal entry, but she missed the fact that if anyone had decrypted the previous entry the way we had then they would already know her location and, given that her journal entries all have the same format, would figure out the first word in this one. That will give you three of the vowels to start with!

Good luck with the rest of the decrypt. By the way, we have a theme tune. Figure I'll send the download location of the MP3 to the first 250 teams to crack the current challenge.

All the best,

Challenge Two Winners

By the way, I forgot to say who had won the fifty pound prizes this week, you will find the lucky names below.

If you win something we need an address to send it to. We'll be sending everyone who has won a poster a CD or a cheque an email asking you to fill in a contact address on the web. The sooner the better. Thanks.

CASH PRIZE WINNERS FOR CHALLENGE 2
Jonathan Algar of Benton Park School,
S. Cao of Oxford High School,
Steven Rowley and Simon Pinder of Steve Technologies, Queen Mary's Grammar School,
Michael Bryant of Stanwell,
The L33t H4x0rz, Edmund Craske and Mike Curry of Varndean College

Challenge Three

Looks like Aunt Aggie is getting careless again. Maybe its the stress of her trip across country. Who knows, anyhow, seems like she has gone back to leaving the word structure intact in her Journal. She must have hoped that using a more secure cipher would make that OK. Me, I'm not so sure it's secure enough. Especially given the extra crib she has given us. As usual, one week to get this one. Submit your answers the usual way, on the entry form. There will again be five fifty pound prizes chosen from among the first fifty correct entries we receive. Speed isn't everything, though. You will get marked (for your championship score) on the FIRST submission you make, so make sure to get it right.

Challenge Two Solution

How did you get on? Like I said Aunt Aggie seems keen on Caesar. She did a good job of disguising the shift cipher by breaking the text into blocks, and it didn't help that the text was a little unusual, in that t was more common than e. Still a lot of you got it all or mostly right. The solution is now in Chapter 2 of Aggie's journal.

As you can see, Aunt Aggie seems to be onto something with her suspicions about the guards, but maybe she'll find out more in Alexandria.

We'll put up the Hall of Fame for Challenge two later today, and update the leader board so you can find out how you are getting on.

Don't forget the next challenge goes up at four pm today, and the website will be down for fourty five minutes or so before then for maintenance.

The next deadline approaches

Just nine and a half hours to go before the deadline for Challenge 2 expires. How are you getting on? I'm not giving too much away to say that Aunt Aggie seems to have a thing about Caesar. Must be her obsession with the ancient world. Let's hope it doesn't get her into too much trouble.

I'll post the solution, and some comments on Aggie's diary, here tomorrow, then at 4pm I'll post the next page for you to crack.

Aggie's niece is pretty pleased with our progress. Who knows maybe there will be a bonus in it for us.

Solutions

Got it yet? Some of you have written in to ask about punctuation. Before I compare your answer to mine I strip out all the punctuation and spaces then convert all the letter to uppercase. So the answer is I don't mind whether you put the punctuation in or not. Hope that helps. All the best,

Challenge Two

Seems like Aunt Aggie has ambition. I like that in a dame. What she didn't have back then was sophistication. Any damn fool knows that leaving word structure weakens a cipher and makes the Caesar shift pretty straightforward to crack. You can see from this next page in her journal that she got sophisticated pretty fast, and I figure maybe she had something more important to hide in this part of her diary. Who knows what? Maybe she's rude about her brother, but I figure that with her ambition she's figured something out about the Babylon Stone and she doesn't want to share. See what you make of it. You have one week, more or less. Actually, make that less. The deadline is midnight next Wednesday, but I don't want your mothers writing to complain that you stayed up to do it!

Just like before I have five cash prizes. I'll choose five of the first fifty correct answers and dole out fifty pound cheques next week. Got a little extra for the rest of you too. Since it's a little harder, this week we are giving away 500 copies of Simon Singh's CD - The Code Book on CD ROM - courtesy of IBM.

Don't forget though. Speed isn't everything. Your score for the overall Championship prize is based on your first submission for each challenge, so take time to get it right.

We'll try and get some feedback to you early next week, so you can try again if you make a mistake.

Good Luck,

Challenge One Winners

OK, so here's how it worked out:

We had 728 submissions to the first challenge from 577 different teams. Most of you got pretty close to the right answer with 339 teams getting it exactly right. Congratulations to all of you. We'll be sending out posters to the first 213 teams. The following were drawn at random from the first fifty correct entries received and will be getting a fifty pound cheque. I know I said we would draw from the first twenty five, but the rules said the first fifty so we had better stick with that:

Julian Granger-Bevan of Varndean College,

Karim M Ladhu of North London Tutorial College,

The Guilford Colossus Ben King of Ellis Guilford School And Sports College,

Simon Pinder, Steven Rowley ( Steve & SJP) of Queen Mary's Grammar School

and the Iron Raven, Edward Huggett of Kings' School.

For the record Yan Mei of St. Annes was the first to submit a correct entry last week. Well done Yan Mei!.

By the way there are over 2,200 of you registered from around 1100 teams.

You can view the solution to last weeks challenge in Chapter 1 of the Journal. The next challenge (Chapter 2) will go up at or soon after 4pm today (Thursday 9th October), here and at Education.Guardian.co.uk, but but the server will be down for a short while before then for maintenance. If you want to read some more about the tale of the Suevic, then read the extended entry for this note.

The White Star liner Suevic has a remarkable story. On 17th March 1907 she ran aground on rocks off the Lizard. Her bow was wrecked by the collision whcih was so severe that the owners were unable to float her, but amazingly the stern section remained dry. Engineers cut the ship in two using dynamite (which had been invented by Alfred Nobel in 1866 (yes, the Nobel whose fortune sponsors, among other things, the Nobel peace prize). We assume that this apparently extreme method was the only practical technique available to separate the two halves safely. According to one website "although this sounds quite dangerous, a skilled operator could use just the right amount of charge to remove a rivet head ". Another web site claims that gas cutting equipment had not yet been invented, but the oxyacetylene torch was invented in 1900 by Edmund Fouche (or was it Charles Picard? or the Canadian Thomas Wilson? the history of Science and technology is not as straightforward as you might think) and can reach temperatures of 300C, more than enough to cut steel. It works by combining oxygen with the gas acetylene, which was discovered by Sir Humphrey Davy's cousin Edmund Davy in 1836.
Once the stern was free it was sailed to Southampton for refitting. The most remarkable feature of this voyage is that the Suevic, mnus her bow sailed under own steam with tugs used only for steering purposes, remaining watertight throughout the voyage. Normally refitting would refer to a general refurbishment, but in this case of course the ship needed to have an entirely new bow fitted. This remarkable operation was carried out in two stages by the shipwrights Harland and Wolff in Belfast, who constructed the new bow, and then by J. I. Thorneycraft & Co who attached the new bow in dock at Southampton.

The story of Suevic can be found at Great Ships and Titanic-Titanic

You can read more about the inventors Alfred Nobel, The Davys and Thomas Wilson around the web, and look up Acetylene on the wikipedia.

The deadline approaches

You have until midnight tonight to get your first solution in if you want it to count towards your challenge score. We'll publish the solution tomorrow, and the hall of fame sometime in the next few days.

The website will be offline from 3.30 to 4pm in order to allow us to upload the next challenge. By the way, some of you didn't realise that clicking on the image of Agatha's diary page takes you to a text version of the challenge which you can copy and edit when you are deciphering it. If you want to go straight to the text version you can use the link after 4pm:

/journal/Challenge_2.txt

Entry form

We know that some of you have had a little difficulty with the entry form, and we hope the changes we have made help those of you who were affected (without messing it up for the several hundred who have been able to enter already!) Let us know of any problems but please note the following:

If your password has o,O or 0 in it (or i, I or 1) please be careful when entering it.

Your username for the competition is the email address you registered with us so please use that when entering each challenge

You only need to resubmit if you have made an error in your submission

If our form acknowledging you r entry has backslash characters in it that you didn't type, don't worry. Our solution checker removes all the punctuation from our solution and yours (including spaces) before comparing them so it won't affect your mark.

We will be sending you feedback on your entries sometime tomorrow/wednesday so you can one last go if you didn't quite get it right.

All the best,

Security geeks

Heard a rumour that some of your security guys are making it difficult to access our entry forms - something about cyber patrol, whatever that might mean. In any case here are the links you need to register and use the entry form in case it helps:

/entry/
/registration/
/entry/entryform
/entry/forgotpassword

How are you getting on with Aggie's Journal?

The clock is running

At 4pm this afternoon I'll be posting the first Challenge for you. Doesn't look like Aunt Aggie knew or cared too much about security at this point in her adventure, so I reckon you can crack it. In particular she's left the punctuation in her text - makes deciphering it a whole lot easier. See what you make of it. Just take a look over in the Journal round about 4.

Best of luck

Introduction

January 1937

Harry Schultz Vandiver is the name, and number theory is the game. Or
at least it was until the dame dropped by with her journal...

I was working out of an office in the basement of the Alamo Hotel. It wasnt much, but it was home, and Fermat was paying the bills, courtesy of a case other investigators had worked on for two hundred years. I figured it should be good for another fifty at least and had been counting on it to see me into a comfortable retirement.
Journals I was used to, and I figure thats why this dame brought me hers, but this one was different. Full of weird symbols that didnt make a lot of sense. She laughed when I mentioned it, and made some comment about pots and kettles that I didnt get, but something about her and her damn book wouldnt let me go and thats why, fifteen days later I found myself on a boat out of New York, heading for Egypt.
I spent most of the journey working on Fermat, but by the time we docked in Southampton I knew I needed to start work on the Journal. The money wasnt that good, but the lady was paying for the ticket, and if I was going along for the ride I figured I had to give something back. Hell the first page didnt look too hard anyway.
She told me her Aunt, Agatha Highfield, had written it. There was a story about her and some slab, the Babylon Stone she called it, and she reckoned it was cursed. Thing is Aunt Aggie and the stone disappeared back in 12 and they havent been seen since. Either she knew she was in trouble or she had a weird sense of humour, but before she went missing she sent this journal to her sister and now it is sitting on my desk courtesy of her sisters kid a broad with a mission to get rich. Seems like the Babylon Stone might be worth hard currency and she is pretty keen to get it. Problem is the journal is in code, or, to be more accurate, lots of different ciphers, and she needs a mathematician to help out.
The first bit doesnt look too hard, and I reckon by next week we might have it cracked. Ill post the ciphertext here on Thursday at 4pm. Maybe you can crack it before I do.
Just to make it interesting lets say that the first 400 of you to get it right get a copy of the Cipher Challenge poster. And how about I randomly pick five teams out of the first twenty five to submit correct answers and give them 50 each? If you get the message wrong I'll let you know on Tuesday and you can try again but dont hurry too much. Remember we will be scoring the accuracy of your FIRST answer to each challenge. These scores get added up to give you your Cipher Challenge Score for the Hall of Fame and a chance at the overall winners prize.