Is there any way a practical Bitcoin ATM could be done? I.e. a machine where you...

elliottcarlson · on July 16, 2012

One was previously announced - seems to now have been made open source as well: http://bitcoinatm.com/

highpixels · on July 16, 2012

Something like that, but it could be done ahead of time - receive a bitcoin address & redemption code online, send your coins then ~30mins later go to the machine, enter your redemption code and receive your BTC.

Redemption code could also be a QR code. Put it on your phone & hold it up to the machine.

HostFat · on July 16, 2012

You can instant accept any bitcoin value that is lower to the investment to do the 51% attack or similar. Example: no one is going to make a 51% attack to steal only 10 bitcoin from a vending machine.

Simply put a limit, or just say to the user that any amount of bitcoin over X will need Y time to get verified. Anything lower that X amount will be instantly processed.

fryguy · on July 16, 2012

Doesn't it require ~10 minutes to solidify into the record to prevent double-spending without having the 51% attack?

elliottcarlson · on July 16, 2012

Correct - there are various attack vectors besides the 51% attack. Ideally, a transaction shouldn't be closed until there have been 2 confirmations.

hammock · on July 16, 2012

It would be interesting for a retailer/restaurant to have a Bitcoin ATM on-premise and offer a discount for people who paid that way.