Re: [Taler] Online wallets

[Jeff Burdges]

On Tue, 2017-06-13 at 15:39 +0530, Noufal Ibrahim wrote:

>    As I understand, the wallet itself is on the phone or computer of
> the user. This is like a physical wallet and if I lose my phone or
> computer, I lose the money I've withdrawn. 

Yes, we envision users managing the risk of losing the value of their
taler wallet similarly to how they manage this risk for their physical
wallet.  

We envision Taler exchanges imposing withdrawal limits similar to ATMs
as well, so users cannot easily run around will massive balances
anyways.  Also, there is an anonymity loss when making large purchases
since Taler does not conceal the value of a transaction.   Finally,
there is a small fee for refresh operation that Taler exchanges impose
to help prevent denial of service attacks.  You must occasionally
refresh coins left in the wallet for an extended time however, so these
fees create a small negative interest rate on the balance of the
wallet. 

> I want to make something a little more resilient. DOes it make sense
> to have a copy of the wallet on a server that it synced to a local
> device when I connect? 

I'm unsure about the current situation, but we plan to work on
user-friendly backup options for wallets.  

> If I spend something but then try to get the old copy from the server
> and respend it, the exchange will tell the merchant that it's already
> spent so there won't be any problems there as far as I can tell. 

Yes, the exchange keeps you from double spending.  Also, your wallet can
run the refresh protocol to anonymize any unspent coins that you
attempted to spend along with spent ones.  

There are privacy concerns however since you've created a link between
two attempted purchases, one of which may contain personal details.  I'm
unsure if we currently support a "refresh my whole wallet" option for
users who wish to avoid this. 

Jeff

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