[p2p-hackers] Nash equilibrium on p2p networks

[Michael Rogers]

On 07/03/12 20:05, James A. Donald wrote:
> If I understand the proposed system
> http://www.ee.ucl.ac.uk/~mrio/papers/infocom09.pdf correctly:
> 
> Every entity has a public key.
> 
> Leechers issue IOUs to seeders.  This creates a network of IOUs.  The
> pledgeroute software looks for ways to cancel out IOUs, thus honoring
> them - for example Ann seeds Bob, Bob seeds Carol, and Carol seeds Ann.
> 
> If your IOUs get cancelled out, your key gains reputation, causing your
> IOUs to be valued.
> 
> It is not clear to me how the sybil attack is avoided:  Is it that you
> only gain reputation with those benefiting from the cancellation?

If you consider a cluster of Sybils, the creator of the Sybils is free
to create any structure of IOUs within the cluster, and any structure of
IOUs from Sybils to non-Sybils. But IOUs from non-Sybils to Sybils can
only be created by non-Sybils, and that only happens when the Sybils
provide a service.

No matter how many Sybils a person creates, the total debt owed to them
by non-Sybils is limited by the total amount of service they provide. So
there's no advantage in creating Sybils. It's not impossible - it's just
pointless.

I think that's how it works, anyway - it's been a while since I read the
paper and I could be confusing it with the Sybilproof reputation
mechanisms paper Matteo mentioned.

Cheers,
Michael
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