[p2p-hackers] Re: Memory and reputation calculation

Paul Campbell paul at ref.nmedia.net
Fri Dec 10 17:29:27 UTC 2004


With regards to the history function, I recall seeing a paper (no idea where
or what the title was) that looked at it a different way.

The concern is that in a P2P environment, there's no central assumed
tamper-proof central server. One must rely on the peers themselves for
history.

It would be relatively easy for a peer to simply erase and ignore bad
history, or for peers to be able to collude to report false history, unless
one of two things happens:

1. The vector/group concept of Advogato among others prevents collusion simply
because there are no multple paths...the false history shows up as a
self-referential structure and not as a web of trust links. The group/vector
concept searches for multiple disjoint paths of trust, which lessens or
destroys collusion.

2. That the history passed on by a peer should be serialized in such a way
that it is tamper-proof. That is, the client can't selectively delete events
from the history. For instance, a one-way accumulator-type function intertwined
into the data performs the protection. It doesn't circumvent the possibility
of a client simply deleting the last few events in the history (and nothing
is going to stop a client from doing a snapshot to achieve this), but it at
least makes such selective editting an all-or-nothing function.




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