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Solving the AusSHIRT 2013 Sophos Puzzle

Written on:June 5, 2013
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Intro

This was a fun little puzzle that served as a quick brain-teaser/diversion a short while back. I didn’t see this puzzle when it was first announced but eventually noticed it on Twitter so I got a bit of a late start. Several people had already solved it when I began, one of them using Notepad. I didn’t feel like writing yet another script so I figured why not try Microsoft Word.

The Puzzle

sophos_puzzle1

The instructions for the puzzle were located here: http://nakedsecurity.sophos.com/2013/05/21/ausshirt-2013-the-sophospuzzle-instructions-in-full/

It’s a pretty straightforward substitution and transposition puzzle

  • Letters appearing more than once are all shifted by the same fixed amount (from 1 to 25).
  • Each letter that appears just once in the puzzle is shifted by a different amount, with one letter shifted by 9, another by 8, and so on down to a shift of 1.
  • The three blocks of text are not necessarily in the correct order

First I identified all of the repeating letters (highlighted). I had a hunch that the word “Sophos” would be somewhere in the puzzle and there was only one place in the current arrangement that would allow for S….S which gave me this:

sophos_puzzle2

Since all repeating letters had to be shifted by the same fixed amount I could fill in some more blanks:

sophos_puzzle3

The remaining letters are each shifted by a different amount (1 to 9) and you can’t repeat any of the letters already identified. I created a grid and marked all of those letters in red.

sophos_puzzle4

Then I simply used some deduction/educated guessing to fill in the blanks and eliminate more letters(the R was most likely an L to spell SIMPLE, the Q’s didn’t make sense in most places, etc).

sophos_puzzle5

As I did this, it quickly became apparent what order the letter blocks should be in:

That’s it!

sophos_puzzle6

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