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I found a "drawing" in a 60 year old notebook of my grandfather and I am trying to solve it. First I thought it was the "Drunken bishop algorithm" but then I found out that this algorithm isn't this old (presumably). My grandfather was an avid chess player in Austria, so I assume it has something to do witch chess or a chessboard and the solution is gonna be in German.

Can you tell me what kind of cipher this is?

Drawing

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  • $\begingroup$ rot13(Tevq pbagnvaf rnpu qvtvg 0-9 rknpgyl bapr, rnpu yrggre n-m rknpgyl gjvpr, cyhf gur qbgf. V qbhog gurer vf n zrffntr uvqqra va guvf, dhrfgvba vf jung ybtvp jnf hfrq gb cynpr gurz.) $\endgroup$ Commented Nov 5, 2022 at 18:14
  • $\begingroup$ sry I don't understand? Is this your proposed solution? $\endgroup$ Commented Nov 5, 2022 at 19:38
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    $\begingroup$ It looks like the key you would use to encode or decode, not the actual cipher text $\endgroup$
    – JLee
    Commented Nov 5, 2022 at 20:17

2 Answers 2

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This isn't an encoded cipher message, but is the cipher itself. It is the key that would allow one to record messages as chess games.

Each square on a chess board encodes a letter or a point (in two different ways) or a digit. Neatly: $$(26+1)\times2+10=64=8\times8$$

This would allow what looks like a record of a chess game to actually be an encoded message.

Have you found any recorded games that might actually be cypher texts?

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I don't think this is a cipher. At any rate, if it is it's sufficiently constrained that I don't think it can be conveying very much actual information. Observe:

enter image description here

It's almost a knight's tour. More precisely, it's two chains of knight's moves A-X and Z-A-Y; outside the chains we have digits 0-9, a Y, a Z, and two dots.

It's not clear to me exactly what's going on here -- perhaps it was meant to produce a knight's tour but didn't quite work out, or perhaps the idea was going to be that something is somehow encoded by the choice of squares that aren't part of a chain, or something.

At any rate, I reckon your grandfather was experimenting with knights' tours; maybe something more subtle than that is happening in this diagram (e.g., maybe some information is encoded in the choice of omitted squares), but it's not obvious to me whether that's so.

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    $\begingroup$ Wow, thanks for the time you took and showing me all of this. There are two things I want to correct/add: 1. The square with the number 54 is a Y and not a 7. The 7 is in square 84 2. Every letter exist two times and the numbers 0 to 9 are there one time and there are two dots. It*s not clear to me which of the 3 O's are the two O's and which is the zero / 0. I will look further into the "knight's tour"-thing. $\endgroup$ Commented Nov 5, 2022 at 22:11
  • $\begingroup$ Last thing I want to add is that my grandfather was a war prisoner during the second world war around 1945 for several month or even years in russia. Maybe this could be relevant in anyway, But thanks again for the time and effort you took to show me your solution. Much appreciated!! $\endgroup$ Commented Nov 5, 2022 at 22:11
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    $\begingroup$ @TryonGravity Yup, sorry, the Y/7 thing was an oversight; having fixed that I am more convinced than ever that none of the digits is meant to be part of a knights'-move chain. I've made some adjustments to reflect that. $\endgroup$
    – Gareth McCaughan
    Commented Nov 5, 2022 at 22:58

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