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Re: [Taler] Hello

From: Joerg Baach
Subject: Re: [Taler] Hello
Date: Wed, 7 Dec 2016 23:55:49 +0100
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.5.1

> You're missing that linking the refresh to the spending is not an issue,
> running the refresh operation is just part of the overall spending
> transaction, that does by itself not deanonymize you, as long as refresh
> does not require you to disclose your identity. Hence exposing your IP
> during refresh is the only issue, and for that Tor fixes it nicely.

My point is not about really about anonymity of the customer or the
merchant, it is about the untraceability of the transaction itself. Or
you could say: it is about prevent leaking metadata about the
transaction, which connects Alice to Bob. In my understanding the whole
point of blind signatures is to prevent the central issuer / exchange /
bank gaining knowledge about transactions. The central instance can't
learn about the transaction by protocol design - you would need an
'network observer' to learn about the transactions (which is given, you
could argue, bit I think that the central instance and the three letter
agencies play on different levels).

In taler, if Alice asks for a specific amount to be refreshed that
matches Bobs deposit, the transaction itself becomes visible to the
central entity (the exchange).  Taler then relies on tor etc. to
'disconnect' the entities from the transaction, by tor providing anonymity.

In my point of view (if I understand it correctly) the ability to
refresh parts of a coin is a trade-off. You loose the untraceability of
transactions, but win the comfort of not needing to have proper change
before doing a transaction.

In opencoin we have a mechanism to always equip the wallets with the
right change to be able to do a transaction of any value (<= the sum of
coins in the wallet). One can then delay preparation of the wallet and
the transaction itself, leaving no traces of the transaction to the
central issuer. If this is a desired property of the system is another
question :-)

> Well, the customer already trusts exactly this infrastructure to
> identify the merchant in the first place, and to confidentially

Good point!

> More reliable? I'm right now in India. Watch the news. Cash is hardly
> reliable, and once you only have INR 2000 and INR 100 bills, counting

Good example...

> the change also takes quite some time (and having it in the first place
> is a nightmare as well!!!).
> So no, cash is not always the answer ;-)

But no cash isn't always the answer either ;-)

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