Re: digital cash and identity disclosure

Scott Brickner writes:
>Andreas Bogk writes:
>>But as far as I got Chaums idea, Alice would not reveal Bobs identity,
>>but rather her own. Am I missing a point here?
>
>You're right.  Tim's wrong.  Bob can't spend the money Alice gave him
>without depositing it in the bank and getting new money issued.  Each
>coin has "This money was issued to Alice" as an invisible imprint which
>only shows up when two coins with the same serial number are together.

I don't understand how this could happen? The two coins are identical
(as I understood it from the tech backgound of ecash). what has a double-
spended coin what a copied single-spended coin not has?

Forgive if I missed relevant postings to this subject since I only read
parts from the list offline.


read you later  -  Holger Reif
http://remus.prakinf.tu-ilmenau.de/Reif/

i would like to propose the following radical idea:  Chaumian digicash is 
a nice curiosity.  The future in the mdeium term (10+ years) for better 
or worse belongs to Mondex.

Comments?

A. Michael Froomkin        | +1 (305) 284-4285; +1 (305) 284-6506 (fax)
Associate Professor of Law | 
U. Miami School of Law     | froomkin@law.miami.edu
P.O. Box 248087            | http://www.law.miami.edu/~froomkin
Coral Gables, FL 33124 USA | It's hot here.  And humid.

Michael Froomkin wrote:

| i would like to propose the following radical idea:  Chaumian digicash is 
| a nice curiosity.  The future in the mdeium term (10+ years) for better 
| or worse belongs to Mondex.

	Deploying hardware is VERY expensive.  30m internet users at
$100 (half hardware, half tech support) is 3 billion dollars to deploy
today.  Secure commerce on the internet would drive that 30m figure
(which will probably double this year anyway) way up.

	Digicash doesn't need observer cards, which gives them a huge
advantage.  If they ever sign with a real bank.

	"Tired of mondex's spending limits and slow servers?  Convert
your Mondex to Digicash today, and we'll give you a FREE copy of
Cypherpunk Lab's Lottery Screensaver!!!"

	On the other hand, Digicash might never deploy.  But it does
have features other than privacy that make it attractive.  (So does
FV, possibly other schemes)

Adam

-- 
"It is seldom that liberty of any kind is lost all at once."
					               -Hume

>>>>> "Holger" Reif <Holger.Reif@PrakInf.TU-Ilmenau.DE> writes:

Holger> I don't understand how this could happen? The two coins are
Holger> identical (as I understood it from the tech backgound of
Holger> ecash). what has a double- spended coin what a copied
Holger> single-spended coin not has?

In Chaum's system spending a coin is a cut-and-choose protocol: with
overwhelming probability you reveal informations about your ID, when
you present your e-coin a second time.


Bye!

Michael Deindl

>>>>> "Michael" == Michael Froomkin <froomkin@law.miami.edu> writes:

Michael> i would like to propose the following radical idea: Chaumian
Michael> digicash is a nice curiosity.  The future in the mdeium term
Michael> (10+ years) for better or worse belongs to Mondex.

Michael> Comments?

Mondex keeps their protocols confidential.  Not so good to establish
trust in the system.

I also heart _rumours_, that several things went wrong in their
current field-test.  Reminds me that I should go after these rumors.

Additionally several banks begin to establish their own e-cash
systems.  E.g. in Germany from 1st January 1997 on nearly every
bank-customer will have an electronic-purse.


The main problem with e-cash proposed by Chaum et al. is that current
SmartCards are not powerful enough to handle the needed computation in
a timely fashion.

The purse proposed by the german banks you have a simple counter on
your SmartCard.  With this system you _must_ have identification of
payer and payee to clear malfunctions or frauds by either party.


Bye!

Michael Deindl