The Difficulty of Source Level Blocking

[Theodore Ts'o]

   From: tcmay at netcom.com (Timothy C. May)
   Date: Tue, 15 Feb 1994 13:25:11 -0800 (PST)

   And part of the problem lies in Usenet itself, as we have been
   discussing. The "broadcast" model, without any form of postage along
   the way, means that any message can in principle be sent to thousands
   of sites (though dial-in users are of couse not obligated to read
   these posts, and hence don't have to incur expenses). 

   Long range, Usenet will likely be restructured in some way so that
   users choose what they wish to receive.

OK, well, at least I understand how digital postage would work,
technically.  But it sounds like we all agree that it's not enough.

If we assume that Usenet is "broken", how do we fix it?  Considering how
many users there are (which must be at least one or two orders of
magnitude more than there are of the thousands of news sites), how do
you efficiently get articles only to the users who want them, and no
others.  And heck, how do you even have the users *describe* which
postings they want?  In some ways, rec.pets.birds is a rough description
of what they want, by common consensus.  The problem is that there's no
enforcement on it, so anyone can become Detweilered.

And if you do have to send your filter out across the network, there are
obvious privacy implications as well --- it's one of the reasons why
Usenet's flooding algorithm is somewhat useful.  Users at MIT can read
alt.sex.bondage without needing to send their identity out on the global
network (and we *DON'T* keep logs on our news server!).

For this reason, ``your long range solution'' has a lot of very tough
technical challenges hiding behind it!!!

Instead of just hearing people say that "Usenet is broken", I'd love to
hear about some suggestions about how to re-architect it, at a real
technical level.  "Cypherpunks write code" --- well, it sounds like
there's a really big and interesting problem here.

						- Ted