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Thread: Re: Applying Recreational Mathematics to Secure Multiparty Computation




Re: Applying Recreational Mathematics to Secure Multiparty Computation
country flaguser name
United States
2007-09-26 15:13:31
Saqib Ali writes:
> This is interesting:
> http://tinyurl.com/2zko7n
>
> Abstract
> The problem of a mice traveling through a maze is well
known....
>
> The problem finds its origin in the problem of secure
multiparty computation....

This was presented at Crypto this year. It was interesting
that they were
able to reduce this secure MPC problem to a very concrete
graph coloring
question. However they did not include the motivating
example about the
doctor visit, and just presented it in terms of MPC over
non-abelian
groups. I had the impression at the time that it was a
pretty abstract
problem. It's not clear to me how the doctor problem can be
expressed
as a non-abelian group operation.

The one thing I understood from the talk is that the abelian
group case
(commutative and associative) is trivial. You want to do Z =
X op Y, so
you break X up into shares such that X = X1 op X2 op ... Xn
and the same
for Y1..Yn. Then the first guy does Z1 = X1 op Y1, and so
on, and they
all combine their results: Z = Z1 op Z2 op ... Zn. This
trivially gets
the right answer, but it doesn't work with non-abelian
groups because
you can't rearrange the terms. So they build a graph that
shows how
shares get joined, and that eventually leads to their
coloring problem.

Hal Finney

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