From: tcmay@got.net (Timothy C. May)
Date: Mon, 22 Jan 1996 09:02:58 +0800
To: cypherpunks@toad.com
Subject: Re: "Trustworthy" PGP Timestamping Service ??
Message-ID: <ad27fbf00302100409e3@[205.199.118.202]>
MIME-Version: 1.0
Content-Type: text/plain


At 6:51 PM 1/21/96, Matthew Richardson wrote:
>-----BEGIN PGP SIGNED MESSAGE-----
>
>I have recently setup a free PGP timestamping service which operates
>by email.
>
>The objective of the service is to be able to produce "trustworthy"
>timestamps which cannot be backdated without detection.  It achieves
>this by:-
>
>(a)  giving every signature a unique sequential serial number;
>
>(b)  every day making a ZIP file of that day's detached signatures
>and feeding the ZIP file back for signing (and hence the assignment
>of another serial number);
...

It sounds like a variant of the Haber and Stornetta work on digital
timestamping, about which much has been written on our list (check the
archives, and/or sections of my Cyphernomicon).

They have a company, Surety, which is doing this (or was, last time I heard).

www.surety.com will get you there.

My hunch is that your scheme implements a version of a hash (the idea of
hashing the doc and then publishing the hash as a "widely witnessed event,"
in Haber and Stornetta terms) that could infringe on their patents
(assuming they applied, as I recall hearing they did).

Before you go much further on this, it would behoove you to check on what
they are doing and on what patents, if any, you might need to license.

--Tim May

Boycott espionage-enabled software!
We got computers, we're tapping phone lines, we 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: 2^756839 - 1  | black markets, collapse of governments.
"National borders aren't even speed bumps on the information superhighway."