From: Ian Goldberg <iang@cs.berkeley.edu>
Date: Tue, 21 May 1996 09:28:32 +0800
To: cypherpunks@toad.com
Subject: Re: Is Chaum's System Traceable or Untraceable?
In-Reply-To: <199605182017.WAA07561@digicash.com>
Message-ID: <199605201610.JAA03504@abraham.cs.berkeley.edu>
MIME-Version: 1.0
Content-Type: text/plain


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In article <199605190626.BAA62897@rs5.tcs.tulane.edu>,
Matthew Carpenter  <mcarpent@mailhost.tcs.tulane.edu> wrote:
>My PDA receives
>back any coins as change if needed, and logs info about the transaction
>for my financial records.
>
>When I get back home I 'deposit' my change using the same ATM interface.
>This also removes from my home computer the copies of the coins I spent,
>and automatically updates the transaction records on my PC.
>
>So are there any flaws with above procedure?

Yup; with the current protocols, there's no way to do change.  For the shop
to pay you change, besides suddenly losing your anonymity as a payee, you
would have to go online immediately to clear the coins, which assumedly
is infeasable.

However, if you use the "fully anonymous" protocol, change becomes trivial.
You don't have to go online; the payer (the shop) does, which it assumedly
already is.  Another benefit is that coins received in this way as change
are immediately spendable by you, without having to go online in between.

The "fully anonymous" protocol turns out to be _exactly_ what is needed
for situations like this.

   - Ian "this is one of those 'pay attention' posts Sameer mentioned..."

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