This isn't a problem as I see it, he'll only know what bits he flipped, not the actual state.

Wouldn't even know that if you permuted it. You _could_ use a fixed permutation, or you could use input information from another source to select the permutation. Even something as simple as taking 5 bits from one source and using another source mod(random seed length) to decide where to xor it into the random seed. (Rotating back to the front if needed, or you could let the bits fall off the end.) And if all you ever give out to randomness partners is the result of a good hash there's no way they could ever determine anything from it, or determine what effect their contribution had. Shoot, they wouldn't know if their contribution went into the seed, or merely affected how someone elses contribution went into the seed. Patrick _______________________________________________________________________ / These opinions are mine, and not Verity's (except by coincidence;). \ | (\ | | Patrick J. Horgan Verity Inc. \\ Have | | patrick@verity.com 1550 Plymouth Street \\ _ Sword | | Phone : (415)960-7600 Mountain View \\/ Will | | FAX : (415)960-7750 California 94303 _/\\ Travel | \___________________________________________________________\)__________/