Reply To: Let’s talk about the Playfair cipher

@Puzzling_Pelican though I have not solved your 10B, I gather that it encrypts three letters at a time, which understandably complicates the playfair rules. My Rubik’s-style cipher is a lot easier to make 3D rules for, because it only encrypts pairs at a time. There are three cases:

1. the letters lie on a line parallel to the x, y, or zed axis: in this case move each letter one place (mod 3) up/forward along the shared line.

2. the letters are two opposing corners of a rectangle in a plane (xy, yz or zx): map each letter to the opposing corner in the rectangle.

3. the letters are opposing corners of a cuboid: map each letter to its opposite at the same zed coordinate.

Another idea I had was to omit the center of the 3x3x3 grid, leaving 26 small cubes which matches a physical Rubik’s cube; the cipher could then be operated by hand by drawing each letter of the alphabet on the 1, 2, or 3 faces of the smaller cubes and physically operating the Rubik’s cube.

Maybe the rules could be refined to be more easily followed by hand.

Might try this out and see how well it works.