Cracking Codes
Posted by tpc at November 17th, 2007
Was happily reading the Saturday morning papers when I came across the following advertisement by a local defence agency.
It looked easy enough and got me off my butt and to my computer to try and break it. The first guess is of course plain old substitution cipher and in this passage of 36 numbers, you can already make good guesses with frequency analysis.
But I’m a recreational code-breaker and so it took me quite some time to set everything up using a spreadsheet. Halfway through I had a great idea about the most frequent number in the code: 32. But I did not pursue it. After an hour or so of fiddling, I found out that idea was right and how to do this. It’s very easy if you see how.
