From: tcmay@localhost.netcom.com (Timothy C. May)
Date: Sat, 20 Aug 94 01:20:28 PDT
To: cypherpunks@toad.com
Subject: coming soon: secure digital time-stamping in practice
Message-ID: <199408200820.BAA21014@netcom14.netcom.com>
MIME-Version: 1.0
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Earlier I said I would forward to the list a posting I did on digital
time-stamping, describing the Haber and Stornetta system.

But I'll instead repost Stu Haber's comments, for more detail.

--Tim


>Date: Sun, 19 Jun 1994 21:52:29 -0700
>From: stuarth@netcom.com (Stuart Haber)
>To: cypherpunks@toad.com
>Cc: stuarth@netcom.com
>Subject: coming soon: secure digital time-stamping in practice
>Sender: owner-cypherpunks@toad.com
>Precedence: bulk
>Status: RO
>
>On Thursday, June 16 Tim May very nicely described a digital
>time-stamping scheme:
>
>>  The canonical reference for digital timestamping is the work of Stu
>>  Haber and Scott Stornetta, of Bellcore. Papers presented at various
>>  Crypto conferences.
>
>See below for pointers to the papers.
>
>>  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.
>>
>>  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.
>
>We do indeed plan to do just that.  Bellcore has spun off a company,
>Surety Technologies, whose charter is to bring digital time-stamping
>into widespread use.  Resisting the charms of the Bay Area, we decided
>to stay in New Jersey.
>
>Instead of closing off our trees once a week and publishing their roots
>in the national edition of the Sunday New York Times, as we've been
>doing for over two years now (including this week: look for the Public
>and Commercial Notices towards the end of the main news section of
>today's paper -- on p. 30 if you get the NY-area edition), we are
>planning to close our trees at sub-minute intervals and make their roots
>widely available.  By the end of the summer, we plan to have a service
>bureau (to build the trees) up and running, and client software
>available to access the service -- both for time-stamping documents and
>for validating (document, time-stamp certificate) pairs.
>
>>  This service has not yet been tested in court, so far as I know.
>
>Nor as far as I know.  But we do plan to push this issue, on several
>legal and regulatory fronts, so as to enhance the legal acceptance of
>appropriately authenticated digital documents.
>
>Here are the references:
>  "How to Time-Stamp a Digital Document,"
>  S. Haber and W.S. Stornetta,
>  Journal of Cryptology, vol. 3, pp. 99-111 (1991).
>  A similar version appeared in the CRYPTO '90 Proceedings
>  (Springer-Verlag LNCS, Vol. 537), pp. 437-455.
>
>  "Improving the Efficiency and Reliability of Digital Time-Stamping,"
>  D. Bayer, S. Haber, and W.S. Stornetta,
>  Sequences II: Methods in Communication, Security, and Computer Science,
>  ed. R.M. Capocelli, A. DeSantis, U. Vaccaro, pp. 329-334,
>  Springer-Verlag (1993).
>
>
>Stuart Haber              | Surety Technologies provides
>Chief Scientist           | Digital Notary(sm) service on the Internet.
>Surety Technologies, Inc. | General info: info@notary.com
>stuart@notary.com         | (201) 993-8178, fax -8748
>
>

..........................................................................
Timothy C. May         | Crypto Anarchy: encryption, digital money,
tcmay@netcom.com       | anonymous networks, digital pseudonyms, zero
408-688-5409           | knowledge, reputations, information markets,
W.A.S.T.E.: Aptos, CA  | black markets, collapse of governments.
Higher Power: 2^859433 | Public Key: PGP and MailSafe available.
"National borders are just speed bumps on the information superhighway."