Monday, 14 March 2011

Getting On The Naughty List

I quite enjoyed making up codes for the boy's birthday last summer, and decided to have another crack at it for Christmas

I picked out my bit of text to code up - a quote from Alice In Wonderland (spot the theme, anyone?) about how the bonkers people are the best people, because, well... it seemed appropriate at the time, can't think why.
I ummed and arred over various coding methods, but kept getting unstuck by the fact that it has to be breakable without the key - and that it needs to be fairly obvious to Boy at each layer that he's heading down the right lines so he knows to keep going. In the end I decided to keep the actual code itself fairly simple, but to throw in a general knowledge element that might make it a little trickier.

I used the phonetic alphabet to attribute each letter a theme; T is for tango, and the theme is therefore soft drinks, whereas F is for foxtrot and the theme is types of dance. I tried to use a range of high / low brow and fuckin obscure themes: O for Oscar became sesame street characters, whereas R for Romeo is Shakespearean. And Y for Yankee is, obviously, types of submarine.  then it was just a case of using my extensive knowledge of Strictly Ballroom, plus Wikipedia, to provide enough words in each theme to attribute one word per time that theme's letter appears in the quote I was coding.
I tried to make enough of them easily guessable so that Boy would be able to work out what I was doing, but I threw a fair handful of wildcards in there too - stuff that wouldn't be immediately obvious, or where a bit of an insight into how my head works would be useful. E for echo becomes names of nymphs, so most of those will be easy to spot with a  basic knowledge of Greek / Roman mythology. But [Nymphadora] Tonks got thrown into that category too, meaning Boy has to spot the Harry Potter reference before he could work out which category it fits and thereby what letter it represents.
He also need to remember that Ce'nedra, from David Eddings' Belgariad, is a nymph, and that Humbart constantly refers to the object of his affections as one in Lolita... so, no leap of imagination required to draw those parallels at all.
Fortunately for boy, each word is only one letter of the decoded message, so as he cracks parts, others fall into place and provide clues as to what direction I'm thinking in...

I'd generated a page of seemingly disconnected words, but which are still recognisable as English - crucial if Boy is to know that he has successfully broken the initial character substitution layer. For this stage I stole a pre-existing cipher - that which Mary Queen of Scots used to communicate during The Babington Plot, chosen primarily because it's pretty, but also because I knew that Boy actually already had the key to it (it's included in Simon Singh's Code Book). So, if he managed to spot it he wouldn't have to bother with frequency analysis and all that gaff.

As previously, once I'd coded up my message, I write it out on a tea-stained page from Alice In Wonderland. This time I was clever enough to come up with a message that fitted inside the bottle (which fatally meant I had to drink the contents of the bottle. Oh No! Old Hopkin's - chosen for me by Mummy-Noodle - was very scrummy; sweet in a dark way.). I used a bit of ribbon to suspend the rolled up message inside the bottle, and wrapped it up to send to Santa.
Who was very upset that I hadn't saved him any rum
bad bad selfish Noodle

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