From: shields@tembel.org (Michael Shields)
Date: Sat, 11 Nov 95 18:15:21 PST
To: cypherpunks@toad.com
Subject: Re: Who needs time vaults anyway?
In-Reply-To: <199511110843.AAA18344@infinity.c2.org>
Message-ID: <483l88$1f0@yage.tembel.org>
MIME-Version: 1.0
Content-Type: text/plain


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In article <199511111953.MAA26503@nagina.cs.colorado.edu>,
Bryce <wilcoxb@nagina.cs.colorado.edu> wrote:
> A single station could serve up multiple pieces.  It would only
> reveal the k piece if the querying agent can prove that he has the 
> k-1 piece.  Of course if the total number of stations is small then 
> the "physically move the pieces" trick might work.

But you're back to trusting an agent or device not to reveal a secret.
What have you gained?

The point about moving the elements of the message physically apart has
merit, though.  So the one-time pad of timerel, the ideally secure but
unworkable model, is to encrypt your message with an OTP, then securely
transport the pad and location to points that are $ct$ metres apart,
where $t$ is the length of time you want to keep your message secret.
You could do this with a reflector $ct/2$ metres away, assuming your
opponent and you are in the same location.

I suppose this could be useful for very short-term applications (for
reference, the diameter of the solar system is about 5.4 light-hours),
but like the OTP, its application is limited.

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-- 
Shields.