From: Hal <hfinney@shell.portal.com>
Date: Tue, 20 Dec 94 13:36:00 PST
To: cypherpunks@toad.com
Subject: HTTP redirectors
Message-ID: <199412202135.NAA21822@jobe.shell.portal.com>
MIME-Version: 1.0
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I posted some experiments on this a few weeks ago.  Some existing web
proxies, at least the one at CERN, will accept connections from anyone.
Set your proxy server to one of those and you have a bit of anonymity
already.

There is a problem with trying to get much more anonymity than this -
most connections are for a very short period.  So there is not as much
possibility for batching and mixing as with remailers.  Only those
connections which are actually active at the same moment could have their
in/out mapping confused from the perspective of someone watching the
redirector site.  So generally our goals have to be somewhat more limited
than with remailers.

The way proxies work, as I understand it, is that normally when you
connect to, say, http://site.org/dir/file.html, it connects to the
special port number for http at site.org, then sends it the remainder of
the URL, dir/file.html.  When you use a proxy, it always connects to the
proxy machine, then sends the whole URL (possibly not including the
http:, I forget), e.g. site.org/dir/file.html.  This way the proxy knows
where you want to connect and does that for you.

The nice thing about this is that it is already built in to most clients.
The bad thing is that it does not lend itself to chaining.  Ideally, the
purpose of chaining is so that no single link in the chain knows both
ends.  That way no one person can betray your trust.  But with the
current client software the very first proxy server sees both your
address and your destination, so even if it went on to set up a chain you
would have to trust it.

One idea that was suggested here would be to have a local proxy process,
a very simple one which your fancy client connected to for all your net
accesses.  This would be where you would implement encryption, or new
protocols for chaining, etc.  This way we don't have to try to persuade
client writers to incorporate our improvements; the existing proxy
support provides the loophole we need.  One nice feature, for example,
would be a full 128 bit IDEA or RC4 encryption engine so that overseas
Netscape users (or domestic ones who are stuck with crippled versions)
can get good security.

However, running this kind of local proxy or a general chaining proxy
does require root access.  Most systems will not let you create a
low-numbered socket unless you are root.  So this is not something which
people will be able to do from their user accounts.

Hal

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