RE: Anonymous cash via blinded authentication

James A. Donald (jamesd@echeque.com)
Thu, 11 Mar 1999 23:40:34 -0500

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    --
At 10:40 PM 3/10/99 +0100, Anonymous wrote:
> David's method does require that the bank choose a
> generator g and publish g^k, so we are back to having a
> public key in the system.

True: However we are not back to
     "7 The method according to claim 3"

nor are we back to
    "9 The method as in claim 1, "

Because we are not back to having a public key that outsiders
can use to verify that a document has been signed.

So it would appear that patent
http://www.patents.ibm.com/details?pn10=US04947430 does not
cover David Wagner's protocol described in
http://x9.dejanews.com/getdoc.xp?AN=145097228 even though the
signing and blinding steps in David Wagner's protocol are
identical to those proposed in claims 7 and 9 of Chaum's
undeniable blinded signatures patent.

What patent, then, does cover David Wagner's method?

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         James A. Donald
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http://www.jim.com/jamesd/      James A. Donald

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