Quote from: jav on April 30, 2011, 09:38:12 AM

Quote from: doood on April 29, 2011, 03:10:09 PM

This instant deposit feature is great, but you might want to wait until the funds clear before letting people withdraw it back out again.

I thought this wouldn't be an issue, but I'm not so sure anymore. I use the "account" feature of bitcoind and every wallet has its own account. My understanding was, that this will mean that the coins being sent are limited to the account as well. In that case it doesn't matter if the funds end up not confirming, because it will also invalidate the withdraw transaction. But maybe bitcoind uses coins from other accounts as well sometimes? Has someone here more insight into this?

It is definitely an issue-- the account code doesn't keep track of where the coins it is sending out came from, so if you accept 0-confirmation coins you're vulnerable to double-spending attacks (see, for example, the discussion of the "Finney attack" in these forums).

Seeing coins show up right away is a fantastic feature, though, so I'd suggest getting the 0-confirmation balance and a 3+-confirmation balance, allowing only 3+ confirmed coins to be withdrawn, and displaying the difference as 'waiting confirmation'.