From: pmetzger@snark.shearson.com (Perry E. Metzger)
Subject: Re: A Copper Balloon
Organization: /usr/local/lib/news/organization
Date: Mon, 9 Nov 1992 17:21:32 GMT

denning@guvax.acc.georgetown.edu writes:
>I'd like to suggest another possibility, which for want of a
>better name I'll call the "copper balloon".
[...]
>The basic idea is very simple.  Use a 3-way Diffie-Hellman public-key
>exchange protocol to set up a session key for use with say DES 
>encryption.  The third party would be the service provider (actually
>equipment owned by the service provider), which would make the key
>available to law enforcement if a court order has been received and
>an intercept activated.

I don't see much of an improvement here, Professor Denning. From what
I can tell, all that has happened is that "trusted third party" has
turned into "telephone company", and "private key" has turned into
"session key".

As a political dissident, I'm pretty certain that the government will
listen in on my phone conversations and use the information to
sabotage my activities with or without a court order, given the
opportunity. They've shown the inclination and capacity to do this
with others in the past. To you, this is all academic. To me, this is
a question of whether 10 years from now I end up in an unmarked grave
somewhere. Please don't tell me that it can't happen here -- thats
what they always say.

Even ignoring this particular subissue, all the problems we have dealt
with before, or even worse versions, such as third parties still being
able to tap the line (after all, people can just spoof the phone
company part of the transaction), all continue to arise. I can't think
of a single thing that this scenario improves.

>Assuming that the 3rd party devices were reliably constructed, this 
>would at least superficially provide more protection since no keys 
>would be kept unless a court order were issued.

No, Professor -- no keys will be kept unless someone chooses to record
them, regardless of a court order. A court order is just a piece of
paper. The government has shown an inclination to ignore such scraps
of paper in the past. As has been noted, "confidential informant" is
often just a euphamism for "illegal wiretap".

Secret communication is supposed to be just that -- secret. If I
wanted someone else to be able to read it, I'd hand them the key, too.
It is not the function of a free society to constrain all human
behavior to make it easy to surveil. The police managed without phone
taps for the first century and a half of our republic's existance and
we didn't collapse without them. The next step after compelling people
to make sure that everything they say on the phone can be tapped is a
law requiring installation of bugging devices in all homes. After all,
the police would have so much easier a time if they were there all the
time, and no one would listen to them without a court order.

As I've noted before, all that is necessary for a police state to
succeed in our society is that we build an infrastructure for one and
that someone unscrupulous takes it over. Your scheme is, as with all
other such schemes, a wonderful tool for a police state to use to
consolidate its power. For the moment we might have a government that
shows some scruples about using that power, but when we produce an
unbeatable system for universal surveilance all that will be necessary
for a shift to fascism would be a little tiny change in attitude. No
proposal that requires the disclosure of keys to a third party,
regardless of how well intentioned the purpose, is acceptable to me.

--
Perry Metzger		pmetzger@shearson.com
--
"They can have my RSA key when they pry it from my cold dead fingers."
Libertarian Party info: Phone 1-800-682-1776, E-Mail 345-5647@mcimail.com
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