Thomas P Jakobsen <> writes:

> Hi all,
> As you may or may not know, running the same VIFF program more than
> once using the same set of player configuration files is insecure when
> the runtime relies on pseudo-random secret sharing. This is the case
> for e.g. the PassiveRuntime.
> This is not a bug, but rather a consequence of the way in which we use
> pseudo-random secret sharing. In order to maintain security, a new set
> of player configuration files has to be generated for each run.
> In some practical settings this turns out to be inconvenient. So we
> recently added a changeset (1538:9d4f9551644c) that fixes this. It
> means that one no longer has to use fresh configuration files for each
> run. Instead, there's now a command line option called computation-id,
> e.g.
>     python --computation-id=42 player-1.ini
> When using runtimes based on pseudo-random secret sharing, like
> PassiveRuntime, one can then safely reuse the configuration files as
> long as the computation ids are unique. That is, for each run with a
> given set of configuration files, the players should agree on a
> computation id that has not been used before for that set of
> configuration files.

Would it not be fairly easy to let each of the players secret share a
random integer, add all the shared numbers, open the result, and use
that as the computation ID? That is, automate this so that you don't
have to agree on a certain computation ID in advance.

Martin Geisler

aragost Trifork
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