You are a retailer. You wish to trust a customer and give them an immediate sale, regardless of confirmations. You have a Bitcoin wallet running on your local machine. Now you have two options:
- Your method: Ask customer for their sending Bitcoin address. Customer has to have a client running that will allow them to select which address to send from. If they can't cover the bill from a single address, they have to send from multiple addresses, which further complicates your creation of green addresses. Once you input the customer's addresses, the customer sends to your Bitcoin address. A few seconds later, you see one or more sending addresses pop up as "green" addresses, and you know it is ok to give the customer the goods without waiting for confirmations.
- My method: The customer sends to your Bitcoin address. You watch the wallet until you see the transaction pop up with 0 confirms. You make sure the total is correct with the receipt amount, then call it good.
Not sure who you in "your method" is referring too, but I think you are missing a piece. I believe that the green address thread had the idea that a transaction that has any of its inputs coming from a green adress should be considered green.
This is the workflow I was imagining for a POS that can use green transaction.
1) Create an address for the customer's payment and show it to them (maybe via a QR code or something)
2) The customer pays the given address and tells their client to send the payment through a green address (on instawallet, it's a checkbox)
3) Your POS sees the new 0 confirmation transaction contains an input from a green address and accepts it immediately.
OR
1) Create an address for the customer's payment and show it to them (maybe via a QR code or something)
2) The customer pays the given address with a wallet service that does not support green addresses
3) Your POS sees the new 0 confirmation transaction and you either give them the item now or you make them wait for 6 confirmations
The second option 3 seems pretty stupid to me though. I'm convinced now that green addresses solve a non-existant problem since waiting the 6 confirmations seems unnecessary. So I guess my new feature request is to be able to spend inputs from transactions that have a customizable number of confirmations. I think this would be simple to implement and would allow for people to setup their clients for their own needs.
https://en.bitcoin.it/wiki/Myths#Point_of_sale_with_bitcoins_isn.27t_possible_because_of_the_10_minute_wait_for_confirmationOption 3 seems like it could work with Green addresses, but I no longer see the need for such heavy protection against double spends.