9B

[Robb27]

Well I eventually got 9B.

I thought I had it quickly, about 90% of the text was plain, but noticed something wasn’t quite right. I ended-up checking it by hand (actually with Excel help) and working out your deviousness @Harry. A nice subtle twist!

I held this back for a while so as not to distract anyone, hope you don’t mind. Harry

[Pneumonoultramicroscopicsilicovolcanoconiosis]

@Robb27 Any hints on what the “subtle twist” could be? Thank you

[NoESC]

The worst part about 9B is that i know exactly what’s going on but I’m stuck at 97% accuracy. I’m going insane just deciphering it over and over again trying to find the errors

[T]

If you look at the result you get using the grid posted in the Case Files the next step is to look at the garbled part of the plain text you have produced and work out what you would expect some of those letters to be and where those letters are located on the grid compared to the cypher text. If you do this for several pairs of letters hopefully you will start to see a pattern.

[Robb27]

@Pneumonoultramicroscopicsilicovolcanoconiosis –
Given the full Playfair Grid is now in case file 9.5 … the first incorrect part of my plaintext involved the RH IS pairs not giving the ‘correct’ decrypt for a ‘normal’ playfair. I looked into that, and whether there were similar mis-decryptions. That led me to realise something was different and to make a simple change in my playfair program.

@NoESC – Regarding accuracy, like 8B, take the text ‘as-is’ with X’s inserted where necessary for double letters. As a tip, having been enjoying the NCC for a few years now, I submit plaintext without any spaces or punctuation straight from my decryption program output (although I will have read it to check it looks correct). I understand the NCC site checking program removes punctuation anyway. I only add spaces, remove extra X’s etc afterwards once confirmed.

@Harry, as usual, I leave to your moderation discretion to assess if this is too much.

[BuzzBoy]

Does anyone have any hints about 9B? I am 11 years old and my teachers are not helping me this year. I have come so far and do not want to go out now. Any hints would help. Thank you.

Have you tried the hints on the Case Files? Jodie has published the Playfair grid you need in Casefile 9.5, but it turns out that Babbage and Wheatstone had changed the rules a bit, so you will need to do a bit of work to sort out what the new rules are. I would suggest using the grid with the usual rules to see if that gives something useful, then changing the rules to see if it improves things! Good luck, Harry

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