From: pcw@access.digex.net (Peter Wayner)
Date: Fri, 17 Jun 94 06:59:02 PDT
To: tcmay@netcom.com (Timothy C. May)
Subject: Re: Digital Timestamping
Message-ID: <199406171356.AA03172@access3.digex.net>
MIME-Version: 1.0
Content-Type: text/plain



>The canonical reference for digital timestamping is the work of Stu
>Haber and Scott Stornetta, of Bellcore. Papers presented at various
>Crypto conferences. 

More importantly, they have patented the plan. I've requested information
on licensing and received no response. Who knows what they are up
to.


>
>Their work involves having the user compute a hash of the document he
>wishes to be stamped and sending the hash to them, where they merge
>this hash with other hashes (and all previous hashes, via a tree
>system) and then they *publish* the resultant hash in a very public
>and hard-to-alter forum, such as in an ad in the Sunday New York
>Times.

Does anyone know of any definitive prior art that reads against these
patents? Hash functions are old news. Does anyone know of a published
descriptions of a system that would report hash functions of large blocks
of centralized data? 

>
>In their parlance, such an ad is a "widely witnessed event," and
>attempts to alter all or even many copies of the newspaper would be
>very difficult. (In a sense, this WWE is similar to the "beacon" term
>Eric Hughes used recently in connection with timed-release crypto.)


>
>Haber and Stornetta plan some sort of commercial operation to do this,
>and, last I heard, Stornetta was moving to the Bay Area (where else?)
>to get it started.
>
>This service has not yet been tested in court, so far as I know.
>
>The MIT server is an experiment, and is probably useful for
>experimenting. But it is undoubtedly even less legally significant, of
>course.
>
>--Tim May
>
>
>-- 
>..........................................................................
>Timothy C. May         | Crypto Anarchy: encryption, digital money,  
>tcmay@netcom.com       | anonymous networks, digital pseudonyms, zero
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>W.A.S.T.E.: Aptos, CA  | black markets, collapse of governments.
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