16 August 1998

Date: Sun, 16 Aug 1998 09:56:27 -0500
To: cypherpunks@toad.com
From: Bruce Schneier <schneier@counterpane.com>
Subject: Microsoft Electronic Commerce patent: Prior Art?

I just received this in email.


------------begin forwarded message--------

Dear Bruce,

the Microsoft Patent 5,768,385 filed Aug. 29, 1995, issued Jun. 16, 1998
on "Untraceable Electronic Cash" is nothing more than a well written remake
of the "Anonymously Transferable Standard Values" presented at IFIP Sec
1986 under the name "Anonymous Standard Value Accounts", published both in
the Pre- and Post-Proceedings there, more detailed in a research report of
1987 and even published in a refereed journal, Computers & Security in
1989, see below.

I do not know the legal system of the US well enough to know whether
challenging the patent is worthwhile and I do neither have the time nor
money to do it for myself, but I think it is at least worthwhile for the
security community to know.

So please feel free to distribute this information, e.g. within CRYPTO-GRAM.

Yours Andreas


Most of the references below can be downloaded at


Holger Bürk, Andreas Pfitzmann: Value transfer systems enabling security
and unobservability; Security and Protection in Information Systems
(IFIP/Sec. '86), A. Grissonnanche (ed.), North-Holland, 1989, 225-237.
(Superseded by the following BüPf-papers.)

Holger Bürk, Andreas Pfitzmann: Value Transfer Systems Enabling Security
and Unobservability; Interner Bericht 2/87, Fakultät für Informatik,
Universität Karlsruhe 1987.
(37 pages; Abstract and paper available online. See also BüPf_89, BüPf_90.)

BüPf_89 Holger Bürk, Andreas Pfitzmann: Digital Payment Systems Enabling
Security and Unobservability; Computers & Security 8/5 (1989) 399-416.
(Abstract and paper available online.)

BüPf_90 Holger Bürk, Andreas Pfitzmann: Value Exchange Systems Enabling
Security and Unobservability; Computers & Security 9/8 (1990) 715-721.
(Abstract and paper available online.)


Andreas Pfitzmann

Technische Universitaet Dresden      Phone     (home) +49 351 3161973
Fakultaet Informatik                         (office) +49 351 4638277
Institut Theoretische Informatik          (secretary) +49 351 4638247
D 01062  Dresden                     Fax              +49 351 4638255
Germany                              e-mail  pfitza@inf.tu-dresden.de

------------end forwarded message-------- 
Bruce Schneier, President, Counterpane Systems     Phone: 612-823-1098
101 E Minnehaha Parkway, Minneapolis, MN  55419      Fax: 612-823-1590
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