Re: [Help-gnunet] INDIRECTION_TABLE_SIZE and download speed

[Christian Grothoff]

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

On Saturday 07 September 2002 04:13 pm, Ingo Ruhnke wrote:
> Christian Grothoff <address@hidden> writes:
> > The only solution is to only "allow" a download after n replicas of the
> > entire file exist in the network and we can guarantee with reasonable
> > probability that not all of them can disappear. But this is still not a
> > good solution since malicious parties could still insert half a file and
> > claim that it's the whole thing. Anonymity constraints prevent us from
> > tracking such malicious parties.
>
> Wouldn't it be possible to automatically send out queries for random
> blocks of a file to ensure that the file is available. If such queries
> stay mostly unanswered, the file could be removed from the search
> results, since its currently not completly available. If all random
> queries on the other site are answered, the probability for the
> availability of the file would be relativly good.

Yes, this idea is feasible (except that in order to download 'random' (leaf) 
blocks, we'd first have to download a couple of inner blocks (those blocks 
are always obtained first and their availability is thus a bad measure for 
overall availability). But note that this will 
a) make searches take longer since availability must first be confirmed
b) will increase bandwidth useage since the availability check woud also
    be performed for files that the user may not be interested in at all (if 
    we do it before displaying results).

If we display all results regardless of availability and then start the 
download when the user selects the file and *then* find out  (using the 
availability check as a part of the download) that the file is not there, we 
can tell the user that it is gone without paying penaltiy a) or b) [with the 
disadvantage that users may get search results for things that they can not 
get, trade-offs, trade-offs...]. 

Christian
P.S.: Please send e-mail to help-gnunet from the address you're subscribed as, 
since I have to confirm your mail manually otherwise (and manual filtering is 
required since we'd die in spam otherwise).
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.0.6 (GNU/Linux)
Comment: For info see http://www.gnupg.org

iD8DBQE9enEe9tNtMeXQLkIRAlKcAJ0VNal+4Tzb8dJnww3p065P0MsPAQCcCRbA
xe2WkjdD9gvC3mVdp4BoLJ4=
=xiBD
-----END PGP SIGNATURE-----