[bittorrent] The size of XML (was: DTD for hashed files)

larytet.8708132 at bloglines.com larytet.8708132 at bloglines.com
Tue Apr 12 19:12:12 EDT 2005

--- Justin Cormack <justin at street-vision.com wrote:
On Tue, 2005-04-12 at
20:21 +0000, larytet.8708132 at bloglines.com wrote:
> > --- Olaf van der Spek
<olafvdspek at gmail.com wrote:
> > > "two torrents with the
> > same contents
are supposed to result in the
> > > > same info hash"
> > > > 
> > >
> > i do not see what i need hash of the torrent file for ? i
> > > > do
not need
> > to distinguish torrent files by their hashes, do i ? it's enough

> > > > to parse
> > the torrent file and find out what the hash of the
data is.
> > > 
> > > The hash
> > is used to identify the torrent to the
> > > 
> > 
> > I think that i succesfully
> > got rid of trackers
- i  do not need key to look in the database. 
> > 
> > this
> > is how
my "torrent" file looks like for 500K archive
> > 
> > <rodiHash>
> > 
> > name="rodi">
> >    <file name="C:\temp\rodi\rodi_0.3.04.zip"
> > PM 4/9/2005" size="566944" blockSize="4194304" blocksNumber="1"
> > 
> >       <blocks type="md5">

> >         <block index="0">56675f2303d5087e80f3aea757a37d45</block>
> >       </blocks>
> >    </file>
> >  </folder>
> > </rodiHash>
> > 
> > What is really nice
> > about it, that you can send this thing
using email or chat or any message
> > board or mailing list, you can event
write it down on paper and send by regular
> > mail.
> Yes, "really
nice" is fine. How do you know that it hasnt been modified
> maliciously
or accidentally by someone on the chat or email or message
> board? Thats
what the issue is.
i do not know and i do not care. i can
create torrent file and even compile it in a way that it will have the hash
of some othe torrent file. and then i will send you this torrent file to you
using your email. how do you know that the torrent  is not "maliciously" modified
? you probably trust me or you probably trust Ubuntu web site or whatever
any other web site you visit and find torrent file there.

In Rodi i solve
the problem in the most natural way possible. you (justin) ask me (arkady)
to send you hash of the file. arkady forms a packet containing file hash and
blocks hash, signs the packet with private key and sends the packet to justin
(and probably spoof IP source, just to make things more interesting). justin
gets the signed packet and checks the signature. 
Signature contains two
- nickname arkady
- encrypted with arkady's private key hash of the
justin tells to himself - "fine, what i am going to do about this
?" and decides to accept the nickname. now justin needs to find out what is
the public key of arkady. justin goes to http://larytet.sourceforge.net/ipRange/ipRanges.php

justin makes sure that packet is signed with arkady's private. just has
no idea who arkady is and justin does not care about it and justin is not
interested to find out about personality(s) behind arkady. justin wants data.
justin pulls the data out of the network using hashes arkady sent. justin
gets the data, let's say porn clip and this is exactly the clip justin was
looking for. justin tells to himslef - "this guy, arkady or whatever, he has
good collection of porn clips". justin adds arkady's public key and nickname
to the list of trusted hosts.

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