From: Tim May <tcmay@got.net>
Date: Thu, 21 Aug 1997 10:55:20 +0800
To: Adam Back <cypherpunks@cyberpass.net
Subject: Re: coercion proof timestamping services
In-Reply-To: <199708202137.WAA00738@server.test.net>
Message-ID: <v03102803b0215d30e528@[207.167.93.63]>
MIME-Version: 1.0
Content-Type: text/plain



At 2:37 PM -0700 8/20/97, Adam Back wrote:
>Just some thoughts about creating more robust time-stamping services.
>
>Current time stamping services just generate a PGP key, and sign any
>messages you send them.  PGP signatures already include a time stamp.
>
>Problem: if we find some interesting uses for time-stamps where it
>becomes important that no one can coerce the timestamping service into
>back-signing timestamps in the past, the current timestampers will be
>able to comply, or as they are automated services, simply confiscating
>the machine will likely give the attacker all information required to
>back date any number of time-stamps.

The Surety folks do (or did, as I don't know their current market status) a
lot more than this, and the published hash makes "back-signing"
problematic! Their URL is www.surety.com, and my own Cyphernomicon has a
description.

--Tim May


There's something wrong when I'm a felon under an increasing number of laws.
Only one response to the key grabbers is warranted: "Death to Tyrants!"
---------:---------:---------:---------:---------:---------:---------:----
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."