Protocol Stuff

The single sign-on protocol I gave earlier can be made secure when re-using challenge/response pairs by using HMAC instead of raw sha1 (HMAC is built using sha1). That greatly simplifies implementation on third party web sites and gets rid of a nasty denial of service attack.

Bohemia

I tried playing a few games of Bohemia and was a bit disappointed. There are a few specific things I'm going for with the rules -

• The game should be even on a medium size board, ideally in the ten to twenty on a side range. The rules as I presented them lead to an about even game on a 5 by 5 board, way too small.

• The beginning of the game should be very positional, gradually leading to a very tactical endgame. The rules I gave are a lot more like Renju, with lots of forcing lines.

• There should be a complicated interplay between pieces of either color, with many double-edged moves. With all the forcing moves, the square winds up emphasizing one color and the bohemian mostly plays the other, and the bohemian's color's pieces don't generally make squares.

To try and fix those problems, I've come up with the following rule change - the square's new goal is to form a square whose corners are black on the lower left and upper right, and white on the upper left and lower right. This straightforwardly enforces a complicated interplay between both colored pieces, and since forming a clump of one color is very counterproductive, the square no longer has much benefit in playing lots of forcing moves. Also, the reduction in number of winning arrangements and greater complexity of having to play both colors probably makes the evenly matched board size larger.

Furthur experimentation is once again necessary.

If anyone can figure out a proof that with a sufficiently large board under this new rule the square can force a win, I'd like to hear it. I don't see one immediately.