[BitTorrent] Re: Clearing up things for John Hoffman

fahlmanc_ca fahlmanc_ca at yahoo.co.uk
Mon Aug 23 20:04:01 EDT 2004

--- In BitTorrent at yahoogroups.com, John Hoffman <theshadow at s...> wrote:
> >>The assumption that the same files can not be finded in the
> >>network is false.
> >>Actually, when a torrent die and Shareaza users have incomplete 
> >>torrents, thay are able to (Manually - sic.) search for the single
> >>over the networks Shareaza connect.
> >>But they need to search using keywords and looking for the right 
> >>filesize, hoping to find the right copy of the files.
> >>    
> >>
> >
> >_I_'m assuming something? Seems like you're almost agreeing that it
is a
> >non-trivial exercise to find the same file on Shareaza...
> >  
> >
> Let me settle this very quickly.  BitTorrent has a VERY specific 
> purpose:  The mass distribution of LEGITIMATE data.  The assumption is 
> made that the owner of the content will create a DEDICATED SEED for
> content, and that the torrent will not die until the content owner 
> DECIDES it should.  Modifying BitTorrent for the sake of supporting 
> torrents like the ones used for w4r3z, where torrent spawners stop 
> seeding after a while and then leave the torrent hanging, is not 
> desirable and will NOT happen.  If you're looking for pirated content, 
> you should use some other system, perhaps Shareaza or whatever.  Maybe 
> something built on principles similar to BitTorrent would be nice, but 
> it will not BE BitTorrent.

Hi -- just some points about Shareaza. I am a moderator on the
Shareaza forums. 

Shareaza has the ability to find fellow torrenters (using shareaza) by
querying for the torrent's inforhash using the G2 hub network. This is
fairly benign to bit-torrent. It might be useful to fellow torrenters
using Shareaza if the tracker goes offline, and it shows that ideas
for trackerless torrenting can work (although I guess the protocol is
slightly different around the peerid areas). It has a risk that
someone might maliciously reply to a Shareaza's user's btih query and
start serving bad data to the user (that's equally a risk on the bt
network now -- a rarer one than one the G2 network I would think
though). This could affect other torrenters because this Shareaza
client would likely be throwing away many pieces, and other bt clients
would have to re-serve those pieces to him. There is no risk of
Shareaza serving bad data. I emphasize this is a potential risk --
I've never seen it myself, or heard of an instance of it occurring.
Furthermore, I think (I am not certain) that Shareaza tries to
identify people giving data that doesn't hash-out and forgets them.
This would minimize the bad behaviour of needing to re-ask other
legitimate bit-torrenters for pieces. Also, Shareaza users are
encouraged to use security block lists, which can prevent this
potentially roguish behaviour from being widespread.

If the original bit-torrent metainfofile's creator included properly
formatted SHA-1 or ed2k hashes in the info section of the .torrent
file, Shareaza will accept these hashes as valid for the files being
torrented, and will also try to download from sources of those files
on the G2/Gnutella/ed2k networks. The two common make torrent programs
that include these hashes in the info Dictionary, Azureus's
maketorrent and TorrentAid don't make known mistakes. I think this
method is secure. You could devise a malicious program to include fake
info here, but not in the rest of the info dictionary, and so hope to
screw-up Shareaza clients which might use the information in this
dictionary, while leaving regular torrents unaffected.

For batch torrents which include SHA-1 or ed2k hashes for the
constituent files in the info dictionary, Shareaza doesn't currently
doesn't use that information for any purpose (it potentially could

For torrents in progress Shareaza has the ability to add a G2 or ed2k
hash not included in the .torrent file, or actually change a hash in
the torrent file. Potentially users could corrupt their own
bit-torrent that way by associating it with an incorrect hash. However
Shareaza only shares content (pieces) that have been verified by the
bt piece hashes in .torrent file. There was the problem that Shareaza
would download content via bt that wouldn't hash-out properly
according to the incorrectly manually added ed2k or SHA-1 hash. This
is obviously harmful to bit-torrent, since they are in good faith
distributing good data, which Shareaza rejects and re-requests, which
is bad behaviour. This particular bad behaviour would be rare; it can
only occur in the circumstances I outlined, or if one used a
deliberately maliciously corrupted .torrent file all other torrenters
are using. In later versions of Shareaza, it disconnects from BT when
you manually add an ed2k or sha-1 hash to a torrent in progress. This
negates the probem to rest of the bt community with users manually
adding incorrect hashes. 

There is one situation where Shareaza ability to add hashes to
torrents can be beneficial. If a file being torrented is without
seeds, a shareaza client can stop torrenting, add a hash from ed2k or
G2/G1 to the download, and continue the download to completion. If the
hash the Shareaza user added was indeed the correct one for the file
being torrented, the Shareaza user may re-seed the torrent if he is
inclined, and so potentially help out any remaining torrenters. I have
done this myself (although it was awhile ago).


The fact that Shareaza is in the bit-torrent community doesn't present
undue risks in my opinion. It presents, as I outlined, a few minimal
risks to other torrenters, mostly mitigated by the client, in having
to potentially re-serve data more often. I can't put a size to this
problem, but I think it is tiny. The tangible benefits of having
Shareaza outweigh these risks in my mind -- make of that what you will.


The bit-torrent protocol makes no mention of its Ultimate Purpose.
John Hoffman shouldn't try to create a religion out of bit-torrent.
When debates begin to border the metaphysical everyone wins and
everyone loses. I don't appreciate this style he writes with. He
should be intelligent enough to fairly state his personal opinions,
rather than wrap them up in his otherwise legitimate cloak of
authority. Otherwise that authority won't continue be seen as fair or
legitimate, something no one wants.


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