[viff-devel] Player thresholds

[Mikkel Krøigård]

Citat af Håvard Vegge <havardv at stud.ntnu.no>:

> Hi!
>
> I'm trying to do some basic benchmarks with different number of  
> players. A few questions:
>
> 1. Why have VIFF defined the threshold t to be the number of corrupt  
> players, while the classical literature defines it as "t  
> participants can reconstruct the message"?
Well, in what I have read, it is most often referred to as the  
threshold for the number of tolerated corruptions, though yes I have  
also seen it described as the number of shares needed to reconstruct.  
I don't think there's anything wrong with the way we do it, as long as  
it is clearly defined.

> 2. Say I create the config files this way:
> python generate-config-files.py -n 5 -t 2 localhost:9001  
> localhost:9002 localhost:9003 localhost:9004 localhost:9005
>
> Would this indicate that the polynomial is quadratic (of degree 2)  
> and that 3 players in theory could reconstruct some secret?
Yes.


> 3. Assume three of these five players provide input, while the last  
> two players do not. Will all players still participate in the actual  
> computation, or are the last two just passive spectators and  
> receives only the output?
-n 5 indicates that 5 servers will participate, regardless of how many  
will provide input. Think of it from the perspective of security. If  
the input was shared to 3 servers, we could not tolerate 2 corruptions.