Tord Ingolf Reistad <[EMAIL PROTECTED]> writes:
> I agree only sharing and opening will be asymmetric, and there are
> many cases in which an opening will be asymmetric. To make it really
> confusing there might be cases in which the opening might be
> dependent upon some secret shared variable.
>
> E.g. lets say you are in a hospital and that the nurses (doctors and
> administrators also) would have Pda's with location information. Now
> the nurses do not want their location to be tracked, so there is no
> central location server.
>
> [... cool scenario ...]
>
> In this example who the receiver of the message is, is not known
> until we have determined who is the closest.
Wouldn't you have to implement this by
1. Compute a secret sharing of the message m where each player holds
a share.
2. Compute secret shared indicator variables b_i, one for each
player. The variable b_i would be 1 iff player i should receive
the message.
3. Compute m * b_1, m * b_2, ..., m * b_n.
3. For all i, open m * b_i asymmetrically so that only player i
learns the value.
I don't know if there is an easier way to do this, but I think the
above would work. And it would only require that VIFF can open shares
to a subset of the players. Or maybe I am missing something... this
was just my initial though :-)
--
Martin Geisler
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