From: jim@bilbo.suite.com (Jim Miller)
Date: Thu, 18 Nov 93 18:51:42 PST
To: cypherpunks@toad.com
Subject: Re: All our eggs in one basket?
Message-ID: <9311190248.AA24338@bilbo.suite.com>
MIME-Version: 1.0
Content-Type: text/plain


Perry Metzger writes

> What needed is a) the bank has to be able to show a third party a
> signed request for every transaction they've performed, and b) you
> have to be able to show a third party a signed (by the bank) receipt
> for every transaction you've performed. In other words, you are
> protected because the bank can't simply claim to the arbitrator "oh,
> he withdrew all his money yesterday" because they can't show an order.
> The bank is protected because you can't claim "oh, I deposited ten
> million dollars yesterday" if you can't show a receipt.
> 


I'm still confused, only in a different way.  Let's let I want to withdraw  
$10,000...


1) I send the bank a signed request to withdraw 10,000 dollars

2) The bank withdraws the money but doesn't sends it to me.

I go to the arbitrator and say: "The bank cheated me!!"

The bank says: "We sent you the money.  Here is your withdraw request, signed  
by you.  You are lying."

------

How can I prove that the bank did not send me the money?  


The withdraw protocol must somehow produce a receipt, signed by *me*, saying I  
receiving the money.  If the bank cannot present such a receipt, then the  
arbitrator shouldn't believe that the bank really sent the money.

Yet why would I sign a receipt before verifying that the bits the bank sent me  
was a valid chunk of digital money?  Does this mean the bank sends me valid  
digital money first and I reply with a signed receipt?

If so, what if I claim that the transmition failed and I didn't receive the  
money, but I really *did* get the money?  I could then tell the bank that I  
changed my mind and I want them to rollback the withdraw transaction?  I would  
walk off with a valid chuck of digital money, yet my account was not  
decremented.

Obviously I'm still missing something.


Jim_Miller@suite.com