I won’t say I’ve found practical knowledge to use for K4.  It is weird to plan out actually building a model of the Kryptos copperplate and then be left wondering why Sanborn made it the way he did.

My first thought is that it was probably meant to be 28×28 since that would give a perfect square with an alphabet on top and bottom and one on the left hand side of the Vigenere table.  I would imagine that Ed Scheidt always knew the Vignere could be expanded as needed to match the ciphertext side and so it is less a clue and more of a practical consideration that the Vigenere side has the 4 extra letters on the right side.

If you count the letters on each side you get 869 and 867 (869 if you count the spaces).  How?  Well, the ciphertext side has 869 on the left copperplate but we now know that a character was left off which brings the total to 870.  The Vigenere side has a 28×31 grid which gives 866 letters, two spaces and there’s the extra L for a grand total of 869.

So counting extra spaces and L’s and disregarding the missing character he forgot to add to the ciphertext you are left with 869 bits for each side (total of 1,738 bits).  Blah blah blah, why is this strange?  How would you carve it?  I know how I would.  I’d make a 28×31 grid.  For some strange reason, Sanborn has 1 extra letter on the ciphertext side even though you’d have to count it to see it because he didn’t carve the ciphertext in a perfect grid.  He didn’t need to add the extra L to the Vigenere side except to compensate for the ciphertext side.

Especially with the Vigenere tableau so perfectly set up, why is the ciphertext side carved the way it is?  Some letters are wider than others.  If I had to carve something like this by hand with so many letters I would grid that copper out but in sections so if I screwed one up I wouldn’t screw the whole thing up.  I’d plan it out well in advance with even sized gridded cubes to put each letter in to keep them evenly spaced.  The most logical way would be to set them up in the most compact grid (28×31) and I’d rewrite the ciphertext to exclude the extra letter.  For reasons unknown to us, Sanborn kept it and didn’t grid the cipher side evenly.

Maybe that’s significant.  I don’t really know.  I think I’ve figured out a way to draw and cut it by hand.  I’d like to make a transparency and then project it onto a big sheet of paper tacked to the wall.  I could cut it by hand with an Xacto knife.

More to come as it happens, the extra L is probably for balance but the odd arrangement of the letters on the cipher side makes me curious.