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 my_viff_program.py --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. A consequence of this is that the length of all program counters are increased by one. This means that the data that needs to be sent across the network increases a bit, but we expect it to have only negligible impact on performance. Regards, Thomas _______________________________________________ viff-devel mailing list (http://viff.dk/) firstname.lastname@example.org http://lists.viff.dk/listinfo.cgi/viff-devel-viff.dk