From: "Timothy C. May" <tcmay@got.net>
Date: Thu, 5 Dec 1996 14:25:47 -0800 (PST)
To: cypherpunks@toad.com
Subject: Re: [crypto] Avatar Protection?
In-Reply-To: <9612050108.AA07734@notesgw2.sybase.com>
Message-ID: <v03007802aeccfc52bf4e@[207.167.93.63]>
MIME-Version: 1.0
Content-Type: text/plain


At 3:32 PM -0500 12/5/96, Nelson Minar wrote:

>Ah, the age-old question. This is the same question as "is there a way
>for me to show a web page to someone and not let them copy it?", "is
>there a way I can loan someone my CD and not let them copy it?", etc.
>If you have control of the viewer, the answer is trivially yes. If you
>don't, then it's not.
>
>Digital watermarks / fingerprints are one alternative - if someone
>steals it, you can at least prove whom it was stolen from. Or you
                             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>might be able to exploit some of the structure of VRML to show people
>an avatar but not ever reveal the *whole* thing for copying. But in
>general, this sort of problem seems to demand a social solution
>(intellectual property law), not technical.

Yes, you can perhaps show whom it was stolen _from_, i.e., the creator, but
not _who_ stole it.

Even in the case where each end recipient receives a uniquely watermarked
or marked image, e.g., where N different instances of the work are
instantiated, there are ways to obscure the source of the theft (or leak,
when one is using such techniques to detect leaks of confidential
information, a la the famous "canary traps"). To whit, M recipients of the
work can compare their copies and remove or modify the bits which don't
match up. This then yields only a "collusion set" the original creator can
narrow things down to. Enough to cast doubt on the M recipients, but
probably not enough to "probabalistically convict" them of a crime, unless
the crime is "conspiracy."

An interesting question. As Nelson notes, not something with easy technical
solutions.

--Tim May


Just say "No" to "Big Brother Inside"
We got computers, we're tapping phone lines, I know that that ain't allowed.
---------:---------:---------:---------:---------:---------:---------:----
Timothy C. May              | Crypto Anarchy: encryption, digital money,
tcmay@got.net  408-728-0152 | anonymous networks, digital pseudonyms, zero
W.A.S.T.E.: Corralitos, CA  | knowledge, reputations, information markets,
Higher Power: 2^1398269     | black markets, collapse of governments.
"National borders aren't even speed bumps on the information superhighway."