There is no such thing as a double spending with confirmation. At any point in time, each chain should not have a scenario whereby the same inputs are being spent twice because that would violate protocol rules. The so-called one confirmation double spending that you might encounter would be when a longer chain supersedes another, where a transaction would belong to a stale chain and thereby abandoned. Take the following two scenario:
Propagation of blocks across the network is not instantaneous. Take for example, a miner mines a block (Block A) and propagates it throughout the network. When the block is being propagated, another miner mines a block (Block B) at the same height and relays his. If another miner sees block A first, the miner would build their block ontop of Block A and the same goes for block B. If a miner happens to mine another block (Block A*) ontop of Block A, the block is relayed and chain containing Block A and A* would be the longest chain and thereby accepted by the network.
In this case, if your transaction is included in Block B but not included in Block A, your transaction would become unconfirmed and returned to the mempool. However, if there is another competing transaction that is spending the same input as that transaction which is included in Block A or A*, your transaction would become invalid and thereby abandoned. The latter is commonly considered double spending.
Topic: Trying to understand double spending after 1 confirmation. - page 2. (Read 305 times)
The double spending thing is not new to me, I have a certain idea but one thing I read has made me think and look for information about it:
With this thread I would like to raise doubts as well as expose what I think I understand because explaining also helps to learn.
The first type of double spending I believe has little to do with what the quote raises, as it does not involve any miners. It is simply someone who sends a transaction with RBF enabled as payment for a product or service but receives such product or service before the transaction is confirmed and what they do is send that amount of Bitcoin to another address with a higher fee.
Now let's move on to the hypothetical double spending that already involves some miner, in my opinion. I have searched a bit to see if there have been any cases of double spending after a confirmation and I haven't found anything either.
I don't quite understand how this could happen. In theory a miner should somehow mine an invalid block in which there would be a transaction or transactions that we could not consider valid as such?
It is clear to me that as more blocks are mined and in turn the previous blocks are reconfirmed, the probability of invalidation of the previous blocks increases, up to 6 confirmations, which are considered safe, leaving only the hypothetical case of the 51% attack as a threat, quite unlikely with Bitcoin.
Can you help me understand what a double spend transaction that has already been confirmed once would look like?
Is there anyone who has ever lost Bitcoins to a double spend attack after 1 confirmation? Personally, I have never come across such a case.
With this thread I would like to raise doubts as well as expose what I think I understand because explaining also helps to learn.
The first type of double spending I believe has little to do with what the quote raises, as it does not involve any miners. It is simply someone who sends a transaction with RBF enabled as payment for a product or service but receives such product or service before the transaction is confirmed and what they do is send that amount of Bitcoin to another address with a higher fee.
Now let's move on to the hypothetical double spending that already involves some miner, in my opinion. I have searched a bit to see if there have been any cases of double spending after a confirmation and I haven't found anything either.
I don't quite understand how this could happen. In theory a miner should somehow mine an invalid block in which there would be a transaction or transactions that we could not consider valid as such?
It is clear to me that as more blocks are mined and in turn the previous blocks are reconfirmed, the probability of invalidation of the previous blocks increases, up to 6 confirmations, which are considered safe, leaving only the hypothetical case of the 51% attack as a threat, quite unlikely with Bitcoin.
Can you help me understand what a double spend transaction that has already been confirmed once would look like?
Jump to: