From: jamesd@netcom.com (James A. Donald)
Date: Thu, 1 Sep 94 14:15:13 PDT
To: cypherpunks@toad.com
Subject: Is the following digicash protocol possible?
Message-ID: <199409012115.OAA16764@netcom8.netcom.com>
MIME-Version: 1.0
Content-Type: text/plain


A question about offline digicash:

Is it possible to arrange digicash as follows:

If A, the original issuer, issues a unit of digicash to 
to B, and B gives it to C, and C gives it to D, and D,
gives it to E, and E cashes it with A,  --  and
everyone colludes except C and D, it is impossible
to prove that C got this unit from D.

If A, the original issuer, issus a unit of digicash to 
to B, and B gives it to C, and C gives it to D, and D,
gives it to E, and E cashes it with A,  --  and
C double spends it to D', who then gives it to E'
who then attempts to cash it with A, -- then A
will detect the double spending and rebuff the attempt,
E' will complain to D', and D', with information
supplied by E' and A, can then prove that C dishonorably 
double spent the money, without discovering that C gave 
the money to D, and hence without discovering that D 
gave the money to E.



-- 
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We have the right to defend ourselves and our
property, because of the kind of animals that we              James A. Donald
are.  True law derives from this right, not from
the arbitrary power of the omnipotent state.                jamesd@netcom.com