On Thu, Dec 26, 2013 at 05:57:11PM -0300, andrew cooke wrote: > here's my suggestion on a possibly harder version. > > first, remove the complicated edge rules. instead, imagine that the > board repeats. so something leaving nort from h4 will arrive at a7. > this might help remove biases from the corners (where you can be stuck > for one move). the drawback is that this almost removes the "drunken" > switching from black to white, but see below. > > second, add a rook that moves in a similar way, but the directions are > horizontal and vertical. this starts at b3, say (see below). > > third, the moves are made alternately (bishop, rook, bishop, rook, > bishop, rook), and if at any time one piece threatens the other, they > change position. > > and maybe the plaintext is only added to one piece? > > and maybe the row number of the rook is a bit rotation applied to the > output?
This is good. I'll take this advice, and see what comes as a result. I have thought of a topological spheroid, where moving off the edges brings the bishop to the other edge, similar to a pacman game. Or going out of corner 'h8' would bring you into corner 'a1', etc. I also thought of two bishops, on their own color, but I couldn't think of a clever way to avoid stream cycles repeating. I need to introduce non-linearity into the system, which seems to be allusive with this type of cipher. I'm afraid adding additional pieces won't be enough, and that the requirement of a mathematical operation, such as "new square = (current square)^2 * mod(64). But reversing it is going to be tricky, and I'm not confident I'll get non-linearity into the algorithm. Thanks very much for your feedback. -- . o . o . o . . o o . . . o . . . o . o o o . o . o o . . o o o o . o . . o o o o . o o o
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