Is Chaum's System Traceable or Untraceable?

[jim bell]

At 09:10 AM 5/20/96 -0700, Ian Goldberg wrote:

>>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.

Wouldn't it be interesting if someday, somebody paying for something with 
digital cash asked the shopkeeper "Why can't you give me change for my 
purchase?"  and the answer was, "If we could give you change, you could 
overthrow all the governments in the world."



Jim Bell
jimbell at pacifier.com