The view of a parent coaching their 12 year old son…
I might be missing the point here, but I feel this challenge has gravitated toward the likes of The Times’ cryptic crossword, which requires a particular type of cerebral “wiring”, possibly at the expense of enthusing those with a desire to learn more about mathematics, cryptanalysis and algorithm design.
Please don’t get me wrong, my son has *loved* working on the challenges thus far and is keen to understand how the mechanics of the various ciphers work. I also take my hat off to those that have devised the challenges, the ciphers and the back-story.
However, taking 8B as an example, without the extensive clues in the forum, I can’t see how anyone could make the assertion that a Hill cipher is at play. Even now, it’s not 100% clear, as there’s a reasonable amount of misdirection in the unofficial posts. Assuming for one moment that a Hill cipher is being used for 8B, where does Joan’s clue of “12 is a number you may be interested in” possibly fit in? There’s also a suggestion of two ciphers being used, but the relatively flat frequency analysis of the cipher text makes it impossible to know where to start.
Back to the Hill cipher… today, I took my son through how a Hill cipher works. We then looked at matrix multiplication, GCD calculations, adjugate matrices and multiplicative inverses. Finally, we wrote some code to brute-force the cipher text using a 2×2 matrix (hey, we need to start somewhere).
The result … nothing. 456,976 possible keys (26^4), of which 157,248 have an inverse matrix and 144,144 of these can work with a Hill Cipher with a 26 character alphabet. But, non of the resultant “plain” text contains any discernible words. Back to the drawing board then.
I guess what I’m trying to say is that trying to “guess” the ciphers being used detracts from the opportunities of learning the ciphers and their underlying mathematics/algorithms themselves.
Having said all that, please keep up the awesome work of running the challenge!
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