distributed document popularity metrics using amortizable hashcash (Re: [p2p-hackers] BitTorrent measurements / fully decentralizedsystems)

Adam Back adam at cypherspace.org
Fri Dec 17 13:40:35 UTC 2004

On Thu, Dec 16, 2004 at 10:42:33PM -0800, "Hal Finney" wrote:
> Adam Back writes:
> > [...]
> > C) voting on content:
> >
> > during playback (implicit) or after explicit voting action the peer
> > votes on the content.  We might have positive as well as negative
> > votes, tracked separately, just add up their +ve and -ve normalized
> > value to reach the overall value.
> Would this require an extra communications step, to reconnect back into
> the network and provide feedback to the server(s) that you downloaded
> the song from?

Not necessarily, just associate it with the file locally and when the
downloader acts as a server that information will get propagated.

(This delays slightly but in a busy p2p net it'll get distributed fast
enough anyway).  Leechers would need an explicit connect (if someone
disables sharing you would want to enable explicit connects).

So one could have another optional step D):

D) vote upload: optionally send the vote to one or more servers
downloaded from.  If user is operating in leech mode this connection
is non-optional.

> > I tend to think it would be more effective to note vote directly on
> > content but vote on the reputation of pseudonymous content raters.
> If we stick to the idea of voting on the content, are there some naming
> issues?  I think the hashcash stamp would have to identify the content
> in some way.  It's not clear to me if this should be by filename, by
> an internal title (e.g. from an MP3 tag), or by a crypto hash of the
> file itself.  Maybe some combination of these?

Yes I was thinking the hash of the content and the document human
readable name.  (Well in fact the hash of the content should be a root
hash from a Merkle Hash Tree based hash of the content to facilitate
integrity verification during download so jammers can't send you bogus
data that you only notice after downloading 1GB file and then don't
know which chunks were bogus.)

The voters should bind the name to their vote as well as the document
hash otherwise you get the other kind of jamming: renaming good
content so you get something high integrity but the wrong thing.


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