Double Spending for BTC businesses - Best practice Solutions ?

[RockHound]

for double-spending invalidate method, use 3 criterias to valid the real payment :
- bitcoin-QT server with instant verification
- blockchain.info instant verification (with blockr.io in backup or on main verification)
- bitcoinj verification (bitcoin android wallet)[/color]

when customer send bitcoin ... the cashier must see the 3 criterias at GREEN statut after max 10 seconds.

Brilliant! ty Sir,

Suggestions on here are great 

Will forward to our engineer for assessment/integration.

[ShakyhandsBTCer]

- Wonder how Coinbase instantly validates?
 

Because you would be paying with your coinbase account, so they are really controlling
the funds.  They are the trusted third party.   This is another LAYER.  Essentially, you are telling
coinbase to pay them, and the merchant is assuming coinbase won't double spend.  Hope that
makes sense.   

Both coinbase and greenaddress would be good to be sure that payment will be received with dealing with high value items.

If you are only selling low value items (a few dollars) you should not worry about double spending attacks as they are generally expensive to execute.

[edd]

- Wonder how Coinbase instantly validates?
 

Because you would be paying with your coinbase account, so they are really controlling
the funds.  They are the trusted third party.   This is another LAYER.  Essentially, you are telling
coinbase to pay them, and the merchant is assuming coinbase won't double spend.  Hope that
makes sense.   

Both coinbase and greenaddress would be good to be sure that payment will be received with dealing with high value items.

If you are only selling low value items (a few dollars) you should not worry about double spending attacks as they are generally expensive to execute.

But that would require both consumer and merchant to have accounts with the same service.

In any case, if it was a high value item, why would you mind waiting for one confirmation?

[ShakyhandsBTCer]

- Wonder how Coinbase instantly validates?
 

Because you would be paying with your coinbase account, so they are really controlling
the funds.  They are the trusted third party.   This is another LAYER.  Essentially, you are telling
coinbase to pay them, and the merchant is assuming coinbase won't double spend.  Hope that
makes sense.   

Both coinbase and greenaddress would be good to be sure that payment will be received with dealing with high value items.

If you are only selling low value items (a few dollars) you should not worry about double spending attacks as they are generally expensive to execute.

But that would require both consumer and merchant to have accounts with the same service.

In any case, if it was a high value item, why would you mind waiting for one confirmation?

You should not mind, in general.

The issue would come into play when you are selling high volume items in masse. Say for example someone is buying  a computer at Best Buy, the buyer would not mind waiting 10 minutes for the TX to confirm, but the seller (Best Buy) likely would. Now a transaction that could take 30 seconds to a minute will take, on average 10 minutes (if it gets confirmed in the next block), meanwhile everyone in line will need to wait, making their employees less efficient.

[edd]

- Wonder how Coinbase instantly validates?
 

Because you would be paying with your coinbase account, so they are really controlling
the funds.  They are the trusted third party.   This is another LAYER.  Essentially, you are telling
coinbase to pay them, and the merchant is assuming coinbase won't double spend.  Hope that
makes sense.   

Both coinbase and greenaddress would be good to be sure that payment will be received with dealing with high value items.

If you are only selling low value items (a few dollars) you should not worry about double spending attacks as they are generally expensive to execute.

But that would require both consumer and merchant to have accounts with the same service.

In any case, if it was a high value item, why would you mind waiting for one confirmation?

You should not mind, in general.

The issue would come into play when you are selling high volume items in masse. Say for example someone is buying  a computer at Best Buy, the buyer would not mind waiting 10 minutes for the TX to confirm, but the seller (Best Buy) likely would. Now a transaction that could take 30 seconds to a minute will take, on average 10 minutes (if it gets confirmed in the next block), meanwhile everyone in line will need to wait, making their employees less efficient.

For a transaction like that, I imagine the clerk would put your purchased items to the side, issue a claim ticket and move on to the next customer. Once the first confirmation goes through, the items are released.

Alternatively, the cashier can verify an adequate transaction fee was included (to minimize the risk) and obtain ID so that, in the event of a (still very unlikely) successful double spend at least the perpetrator can be prosecuted.

Brick and mortar businesses already accept a certain amount of risk with current payment methods. IMO, bitcoins are still less likely to be spent fraudulently and a few precautions practically eliminates the possibility of falling victim to a double spend without inconveniencing customers more than they already are.


Anyway, I believe the OP wishes to operate a site that somehow will allow users to conduct business with high values of BTC extremely quickly and possibly anonymously without any risk whatsoever. I think that's asking a little too much of Bitcoin this early in the game. We're still in beta, remember? 

[Harley997]

- Wonder how Coinbase instantly validates?
 

Because you would be paying with your coinbase account, so they are really controlling
the funds.  They are the trusted third party.   This is another LAYER.  Essentially, you are telling
coinbase to pay them, and the merchant is assuming coinbase won't double spend.  Hope that
makes sense.   

Both coinbase and greenaddress would be good to be sure that payment will be received with dealing with high value items.

If you are only selling low value items (a few dollars) you should not worry about double spending attacks as they are generally expensive to execute.

But that would require both consumer and merchant to have accounts with the same service.

In any case, if it was a high value item, why would you mind waiting for one confirmation?

You should not mind, in general.

The issue would come into play when you are selling high volume items in masse. Say for example someone is buying  a computer at Best Buy, the buyer would not mind waiting 10 minutes for the TX to confirm, but the seller (Best Buy) likely would. Now a transaction that could take 30 seconds to a minute will take, on average 10 minutes (if it gets confirmed in the next block), meanwhile everyone in line will need to wait, making their employees less efficient.

For a transaction like that, I imagine the clerk would put your purchased items to the side, issue a claim ticket and move on to the next customer. Once the first confirmation goes through, the items are released.

Alternatively, the cashier can verify an adequate transaction fee was included (to minimize the risk) and obtain ID so that, in the event of a (still very unlikely) successful double spend at least the perpetrator can be prosecuted.

Brick and mortar businesses already accept a certain amount of risk with current payment methods. IMO, bitcoins are still less likely to be spent fraudulently and a few precautions practically eliminates the possibility of falling victim to a double spend without inconveniencing customers more than they already are.


Anyway, I believe the OP wishes to operate a site that somehow will allow users to conduct business with high values of BTC extremely quickly and possibly anonymously without any risk whatsoever. I think that's asking a little too much of Bitcoin this early in the game. We're still in beta, remember? 

If bitcoin were to catch on enough then it would be possible for there to be 5 or 10 people in a row for example to be issued a claim ticket waiting for transactions to confirm.

A semi centralized service like greenaddress, circle or coinbase could solve the issue, as the store could advise customers to send their bitcoin to their account at one of the above services when they enter, then TX gets confirmed by the network while they shop, then the customer pays for their merchandise via their account at one of the above, then withdraws their coins back to their wallet that they did not spend.

[edd]

If bitcoin were to catch on enough then it would be possible for there to be 5 or 10 people in a row for example to be issued a claim ticket waiting for transactions to confirm.

A semi centralized service like greenaddress, circle or coinbase could solve the issue, as the store could advise customers to send their bitcoin to their account at one of the above services when they enter, then TX gets confirmed by the network while they shop, then the customer pays for their merchandise via their account at one of the above, then withdraws their coins back to their wallet that they did not spend.

It still wouldn't be necessary to involve a third party. Businesses could require their own pre-paid gift cards for  big ticket items. Simply load it with bitcoins before you leave the house and they're confirmed by the time you get to the store. Unspent funds can be refunded by the cashier.

[Harley997]

If bitcoin were to catch on enough then it would be possible for there to be 5 or 10 people in a row for example to be issued a claim ticket waiting for transactions to confirm.

A semi centralized service like greenaddress, circle or coinbase could solve the issue, as the store could advise customers to send their bitcoin to their account at one of the above services when they enter, then TX gets confirmed by the network while they shop, then the customer pays for their merchandise via their account at one of the above, then withdraws their coins back to their wallet that they did not spend.

It still wouldn't be necessary to involve a third party. Businesses could require their own pre-paid gift cards for  big ticket items. Simply load it with bitcoins before you leave the house and they're confirmed by the time you get to the store. Unspent funds can be refunded by the cashier.

This would be true for bigger companies/retailers that you can "trust" with your funds for a short time.

If you were buying from Best Buy or Target this would work perfectly.

Would you trust a "no name" retailer holding your money for you while you shopped (for much smaller businesses)?

[edd]

Would you trust a "no name" retailer holding your money for you while you shopped (for much smaller businesses)?

If a shop is processing many large ticket transactions per hour, they've probably already established themselves as reputable.