Bitcoin security scenario

[poyke]

When trading bitcoin for cash or food most people dont wait for confirmations.
When I do that I want for the btc to appear at my unconfirmed balance, shake hands and leave.
What would it take for a scammer to send fake funds that will appear at unconfirmed but will never confirm?

[softron]

U should really wait for 1 confirmation.

[railzand]

It's worth re-reading this famous thread: https://bitcointalk.org/index.php?topic=423.0

[Rannasha]

When trading bitcoin for cash or food most people dont wait for confirmations.
When I do that I want for the btc to appear at my unconfirmed balance, shake hands and leave.
What would it take for a scammer to send fake funds that will appear at unconfirmed but will never confirm?

Provided the sender added a sufficient fee, it is very difficult to successfully double-spend the payment in such a way that the merchant loses the funds. It is just not worth the effort for small purchases like the ones made in stores. Simply receiving the payment and checking that the fee is correct is sufficient.

I recently wrote an article about this subject, why it is safe enough to accept transactions without any confirmations and what potential measures you could take to further reduce the risk. See http://bitcoin.rannasha.net/?p=34 for more on that.

[poyke]

When trading bitcoin for cash or food most people dont wait for confirmations.
When I do that I want for the btc to appear at my unconfirmed balance, shake hands and leave.
What would it take for a scammer to send fake funds that will appear at unconfirmed but will never confirm?

Provided the sender added a sufficient fee, it is very difficult to successfully double-spend the payment in such a way that the merchant loses the funds. It is just not worth the effort for small purchases like the ones made in stores. Simply receiving the payment and checking that the fee is correct is sufficient.

I recently wrote an article about this subject, why it is safe enough to accept transactions without any confirmations and what potential measures you could take to further reduce the risk. See http://bitcoin.rannasha.net/?p=34 for more on that.

The only way to send you "fake" money that would never confirm is to double spend all one's balance once to one's-self and again to the recepient before the next block is found?