Subject: [P2Prg] p2p network assumptions for download auth problem (Re: [p2p-hackers] THEX efficiency for authenticated p2p dload. and alternate approach)

From: Adam Back <[email-masked]>
Date: Thu, 10 Jul 2003 09:33:27 +0100

On Fri, Jul 04, 2003 at 01:26:59PM -0700, Gordon Mohr wrote:
> But the best you can do, in a network where many peers are malicious,
> is to identify them as soon as possible, and then ignore them,
> preferring those who are non-malicious. 

Actually I think this assumption may not be necessarily true in the
general case.  This goes back to what assumptions about what the p2p
network one makes.

The current kazaa jamming is not by peers, but by publishers.  The
publishers try to make their content look otherwise attractive (by
giving rave review self-proclaimed meta data) to encourage others to
download, and then magnify the effect, as people tend to download from
fast sources, which means many sources; and for it to reach many
sources it has to compete with good content which people will tend to
delete less quickly.  Of course they may also be running a number of
peers holding their jammed data to firstly publish, but secondly to
inflate it's apparent popularity.

My interest is in server and user privacy, so I tend to think in terms
of the p2p network features that enable them.

So to get back to the assumptions, if we take the full general case,
which is I think has aspects of gnunet (UDP transport option, small
packets, forwarded so you don't necessarily know which node is
serving, and add swarmcasting to that mix, and server deniability wrt
to what it is serving, then ignoring nodes that serve bad content
might not even be optimal as firstly you don't know which node served
it, and serial tree downloads from a single node may not be available
due to fragmentation and server deniability.

So I'd say in the general case I think you need the parallel
but authenticatable per packet approach I gave.

Freenet also does the chunking and redirection with cacheing for
server privacy, user privacy and dynamic load balancing.

In specific simpler cases where you don't care about tree efficienciy,
server deniability isn't there, forwarding and privacy isn't there
then practically you can do just not bother for simplicity (as perhaps
bittorrent may be doing).

Adam

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From: Adam Back <[email-masked]>
Date: Thu, 10 Jul 2003 09:33:27 +0100

Adam