Bitcoin Forum

For a standard BTC transaction the fastest confirmation time is likely to be > 3 minutes, average 10 minutes.  I can't see how this can compete with a credit card payment that confirms in seconds.

How do people envisage the payment use case scenario working?  I can only imagine sitting in a shop for 30 minutes while the merchant waits for 3 confirmations before letting me walk out the door.  Am I missing something?

To me the confirmation time seems suitable for remittances, but not for shopping payments.

credit cards do not confirm in second, they have a charge back up to 180 days for visa and 120 for mastercards, american express is 90, still none compare with bitcoin , where is zero

for small payments merchants should accept zero confirmations without problem, and usually none buy expensive stuff on phisical shop anymore, if you want to buy a vehicle, i'm sure you can wait one hour for six confirmations...

there are shops, bars and restaurants who accept your bitcoin payment without a single confirmation. but that's probably up to €50. not sure if they also accept it without confirmations above that amount.

I do it all the time. The transaction takes seconds.

If the buyer is right next to you sending you coins for a product, then shouldn't be a problem as you cna find out if its a double spend there itself. However like Amph said for expensive products you can always wait for 2-3 confirmations which usually happens in half hour.

The transaction is broadcasted to the other nodes within seconds, but one confirmation time is minumum if  it inclues the required amount of fees. Probably you mean you use off chain wallet! 

I think they should rename the 'confirmation' time to something else to prevent these kind of misconceptions in terminology. Making a 1 on 1 anology with the confirmation a seller has when receiving a payment with credit or bank card or even cash is something else then the confirmation of a transaction. The chances of you making a double spend after making a purchase is a very small one, or a 0 transaction fee that will eventually bounce your payment, the same as when you can cancel a payment via creditcard or leave shop before paying with cash. Bitpay (https://bitpay.com/)does provide a payment service, it seems to work for them, they confirm the payment is made without the transaction being confirmed yet. So Bitcoin is more than suitable for payment. It is partly about trust, does the merchant trust its customer not to scam him, and vice versa.

credit cards do confirm in seconds, but they have a charge back option... charge back is an interesting topic discussion in itself.

Transaction time != confirmation time.

Transactions take seconds. Paying for a hamburger does not require someone to worry about you doing a double spend which requires waiting 10 minutes.

I have even done localbitcoins transactions of a few hundred euros and as soon as the person saw the unconfirmed transaction on the network (within seconds) we shake hands and go on our way.

Credit cards do the transaction in seconds. The confirmation time is at least 180 days.

The only reason to wait for confirmation with Bitcoin is to ensure there is no double spend. Almost mathematically impossible after 6 confirmations, reasonably unlikely after 3, fairly safe after just 1.

Credit cards can be "double spent" up to 180 days from the transaction for very little reason at all (just claim you didn't make that purchase, it's on the merchant to prove you did).

This is exactly the situation I see as ripe for scammers.  3 people in different shops using the same bitcoin wallet.  they coordinate via whatsapp to make the payment at approximately the same time.  3 transactions appear on the network but 2 are rejected as a double-spend. That is 3 €50 dresses for just €50.

What is the solution?  Wait ~10 minutes for 1 confirmation?

I see a business model here for multisig wallet providers that focus on shopping hot wallets for smartphones.  With a trusted counter-party to guarantee no double-spend the merchant lets you walk out the door immediately.  Yes we don't like centralization and counter-parties, but this just a niche, you put spending btc into your shopping wallet for the convenience of instant payments.

3 people coordinating to steal €50...or, one person just steals €50 worth of stuff and runs out.

Especially in bars, and restaurants you are usually there for a few minutes anyway. And just about every place I have paid in person has used a third party service like BitPay or another local processor.

So more than likely the three shops in your scenario will use the same processor. They see 3 payments coming through from the same address and drop the second 2.

If you want to get elaborate with stealing €50 with 3 people, one guy pays with his credit card, another guy climbs on the roof to block the satellite connection of the payment and the third guy for lookout.

Most people who complain about the long transaction times for in person payment have never paid in person. Try it. You'll see how simple it is.

Bitcoin transactions complete nearly instantly, but transactions do not fully settle (and become protected against double spends) until a minimum number of confirmations complete.
It is like Elwar said. Confirmations times are not the same as transaction times. But double spending is not as problematic as it seems.
While purchasing normal everyday groceries something like double spending exploit is hard to imagine. Bitcoin is suitable for retail purchases and will work fine on par with any credit card.

Confirmations are not really required I guess most payments.. What is the chance someone would try to double spend a 3 dollar coffee?

In the example of the vehicle,  you can probably pay for the car and then do the paperwork. During that time you should have easily 3 confirmations.

A lot of the gambling sites accept just the 1 confirmation and it usually takes under a minute so it is not as bad as you think in reality.

When depositing to a gambling site you expect to have to wait a little. When you are buying a coffee, you want to get going right away. Besides, what shop in their right mind would tell you to wait till your payment confirms?

this is kind of an issue but it is not something big that can not be resolved.

because of the bitcoin transaction being so fast (in matter of seconds) the shop owner can see the bitcoin in hos address (wallet) so he knows that the buyer have paid but he has to wait 5-10 minutes for confirmation which is ok by them and the customer don't have to stay in the shop.

This used to be all theoretical and we would discuss it over and over much like we are in this thread.


But you can already use bitcoins in stores and restaurants. It happens all the time. No need to theorize.

http://media0.giphy.com/media/rl0FOxdz7CcxO/giphy.gif

This could be a great method to help the current transaction limit of 7tsp as well.  The company would just square up all they owed at the end of the day.

It is technical question, with time everything with BTC transfer times will be ok  ;D

I am only theorizing attack vectors.  For the general use case I am happy to analyze the empirical evidence from actual scenarios.

Your scenario is based on using a bitcoin payment processor, this is very common currently because most merchants want to convert instantly to fiat.  even the bitcoin price is dynamically adjusted by the payment processor because the merchant has based his prices in fiat.  Under this scenario sure the payment processor would likely pick up on a double-spend attack.

However the scenario I am painting is based in the future when the merchant denominates prices and pays suppliers in btc.  In this scenario he just needs a wallet.  He sees the unconfirmed transaction show up in his wallet and lets the customer go.  but the customer has colluded with customers in other stores to spend the full amount of the wallet balance at the same time... only one merchant will have his transaction confirmed.

people accept credit cards for regular payments and you can cancel any transaction made with it, 6 months after!!

Nodes don't accept double spend transactions. If they were in close proximity it would be known within seconds.

Satoshi said that after 6 minutes it is reasonable for all the nodes in the network to have your transaction.

About the only way to successfully do a double spend is to spend at the same time as someone on the other side of the world. The transaction would populate all of the nodes in close proximity within seconds, moving on to other countries with more delay until finally reaching the other side of the world closer to a minute or so.

I still believe most merchants will use a payment processor, even when keeping it in Bitcoin. They enjoy the services of having their wallet up to date, accounting software included, the option of converting to fiat, etc.

You would probably have to run out of the building and hope there are no cameras in order to execute a double spend for your small purchase. Same as just grabbing everything and running out the door.

This Coindesk article describes how bitnet allows for instant approvals for merchants based on probability of the transaction later confirming... based on transaction propagation times etc.  This is in line with my thinking and counters the double spend attack mentioned above where two people on other sides of the planet spend simultaneously.  If the transaction is propagating at the normal rate, and not being rejected by any nodes (possible double spend detected) then notify merchant of approval.  I like this solution, fast and effective.

http://www.coindesk.com/bitnet-launches-instant-approval-tool-for-bitcoin-merchants/ (http://www.coindesk.com/bitnet-launches-instant-approval-tool-for-bitcoin-merchants/)

Cm'on man, Why don't you get it? Bitcoin is not a magic button, it's not like you just click it and whooossshhh....the money is transfered, that's not the case?

It still faster than any other fiat system. So be happy about it and deal with it.