Re: [Taler] Hello

[Joerg Baach]

> This is not correct; refresh does not cause us to loose the
> untraceability of transactions, because the exchange does NOT know that

[...]
> That's interesting, could you elaborate on this? I don't see how you can
> do this _efficiently_, especially as withdrawing EUR 40.52 in advance of
> an EUR 40.52 transaction would obviously seriously reduce my anonymity
> set.  So please elaborate on your solution, I'm really curious.


I guess in the end we both maybe mean the same - reducing anonymity or
leaving traces, a maybe unnecessary piece of the puzzle. In Taler, if I
see an awkward coming in from B, and the matching changing coming in
from A, I can assume that this is a specific transaction. If I can
resolve A to Alice then only depends on TOR.

In opencoin we do it this way: way before any transaction Alice makes
sure that the coins in her wallet allow her to pay any desired
amount.[1] She can then 'directly' pay Bob, without any need for change.
Some time in the future, maybe even after receiving more coin, she can
then rearrange her wallet to again have the coins she needs to be able
to pay any desired amount. This usually will only involve a small subset
of her coins to the "split" again. By this, we think, the issuer doesn't
get even a trace of the transaction, so resolving a A to Alice isn't
even a question (and allows us to require authentication for doing
exchange, if so desired by e.g regulators).

Have a nice new years eve!

  Joerg

[1]
https://github.com/OpenCoin/opencoin-js/blob/master/jsclient/ocapi.js#L148
or

I can't tell much about the efficiency of the code - I wrote it, it's
tested to be working, it seems to be good enough (works for me, cough,
cough), but I am still not ably to explain _why_ it works. It's magic ;-)