[cryptography] New Hand Cipher - The Drunken Bishop

Kevin kevinsisco61784 at gmail.com
Thu Dec 26 14:32:36 EST 2013

On 12/26/2013 2:05 PM, Aaron Toponce wrote:
> I created a new hand cipher over the past few weeks, and announced it on my
> blog yesterday. I'm curious what people on this list think.
>      https://pthree.org/2013/12/25/the-drunken-bishop-cipher/
> The idea comes from taking an 8x8 chessboard, and assigning the values
> 0-63 randomly and uniquely to each square on the board. This gives a total
> keyspace of 64!. The bishop takes a "random walk" around the board, based
> on the square value he's landed on. Details are in the post.
> The idea comes from wanting a hand cipher that wasn't a strenuous as the
> Solitaire Cipher by Bruce Schneier, and takes the idea of the random walk
> from the SSH key ASCII art.
> The algorithm is a base-64 pseudorandom number generator which is applied
> to the plain text, and added modulo 64. It's an output mode stream cipher.
> I haven't done any cryptanalysis on the cipher yet. Lowest hanging fruit
> seems to be frequency analysis with output biases and generating a "heat
> map" of each square the bishop has landed on for a given key and plaintext
> to discover any internal biases.
> I'm not a professional cryptographer, just an amateur hobbyist. I think I
> have a lot of my ducks in a row, but I would be interested in greater
> feedback on how I can improve the cipher, and to discover any weaknesses.
> If this list isn't appropriate for this sort of thing, my apologies. Please
> point me the right direction to discuss this.
> Thanks,
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> cryptography at randombit.net
> http://lists.randombit.net/mailman/listinfo/cryptography
I would be interested to see where this would come in handy.  It's a 
great beginning algorithm for sure.


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