On Fri, 3 Oct 2003, Benja Fallenstein wrote:bear wrote:Why should this not be applicable to chess? There's nothing to prevent the two contestants from making "nonce" transmissions twice a move when it's not their turn.
I.e., you would need a protocol extension to verify the nonces somehow-- if that's possible at all-- or are you just faster than me, and have thought about a way to do that already?
Not "faster" per se, but I do happen to know the solution to that problem. :-)
Ah, good ;-)
Suppose Alice picks a nonce A(zero). Then for n=one to a thousand (presumably no chess game will last 1000 moves) she calculates A(n) = hash (A(n-1)).
Does it work?
Assume A() is Alice's series, B() is Bob's, MA() is the one Mitch uses with Alice, MB() the one Mitch uses with Bob.
- Mitch sends first half of cyphertext of MA(1000) (to Alice) - Alice sends first half of cyphertext of her move + A(1000) (to Mitch) - Mitch sends second half - Alice sends second half
Mitch can now decrypt Alice's move.
- Bob sends first half of cyphertext of B(1000) (to Mitch) - Mitch sends first half of cyphertext of Alice's move + MB(1000) (to Bob) - Bob sends second half. - Mitch sends second half.
Bob decides on his move.
- Bob sends first half of ciphertext of his move + B(999) (to Mitch) - Mitch sends first half of ciphertext of MB(999) (to Bob) - Bob sends second half. - Mitch sends second half.
Mitch can now decrypt Bob's move...
Am I missing something? - Benja
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