Bitcoin subreddit is not about general financial news. Trades should usually not be advertised here. Last updated on March 18th, at Questions Tags Users Badges Unanswered. Hi confirmations have one question. Now miners can move on to build the next block on top of that one. The number will continue increasing for eternity.
You can also use Bitcoin Core as a very secure Bitcoin wallet. There's some good info here about double spending, there are a few attacks directly aimed at 1 confirmation. You can spend without even one confirmation: That's because the fork was caused by a bug in the upgrade and not a malicious attack. Transaction View information about a bitcoin transaction Please ask it in a different way… What do you mean by good share?
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Is it possible to prioritize my own unconfirmed transaction through my mining machines without being in a pool? And if its possible how can I do that? Aside from new merchant announcements, those interested in advertising to our audience should consider Reddit's self-serve advertising system. Bitcoin could make a replace-by-fee attack invisible, but at confirmations cost of only giving it a chance of success. I mean, confirmations miner goes offline for a bit, he bitcoin need to refresh his ledger, how would he do that and how would he confirm integrity of the new blocks? The number will continue confirmations for eternity. The risks for the attack bitcoin that this attack is probabilistic - he can't know that his chain will be longer after n confirms, he just has to get lucky.
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Each half would accept that transaction and until the two halves reconnected, you wouldn't know which transaction would be honored tomorrow. Confirmations are simply blocks that have been generated after the block that contains your transaction. Because there is no central authority that can be consulted to be sure a transaction will be committed, recipients use the number of confirmations as a way of protecting against double-spend attacks.
The network is always trying to extend the longest chain, and eventually, some chain will win. The deeper the transaction is in the chain, the higher the chance it will win because the network tries very hard not to duplicate efforts. Because miners want their coinbase transactions to win, they all try very hard to extend the chain most likely to win, which makes sure it does in fact win.
Effectively, the more confirmations, the higher the likelihood that a transaction will remain forever in the public hash chain rather than a conflicting transaction if there was one. At 6 confirmations, it is perhaps one in a billion that a transaction won't be permanent -- and that's if the sender is attempting a double spend attack.
By posting your answer, you agree to the privacy policy and terms of service. Questions Tags Users Badges Unanswered. Bitcoin Stack Exchange is a question and answer site for Bitcoin crypto-currency enthusiasts. Join them; it only takes a minute: Here's how it works: Anybody can ask a question Anybody can answer The best answers are voted up and rise to the top. David Ammouial 2 9 Joshua Kolden 3, 17 It would be great if that could be improved.
It is not "downright false", just unclear. JoshuaKolden Sorry, "downright false" was indeed the wrong way to put it. What I meant was: The problem with this attack, apart from the vast computational resources involved, is that while he's building up his private blockchain, he's not earning income from mining. So this attack is expensive and only worth it for large huge! I don't believe one has ever been performed in practice, even for small n.
For that matter I'm not aware of any deliberate Finney attacks either. Clients can occasionally see it, but they don't do anything about it. Bitcoin-Qt won't tell you if it sees a double-spend of one of your transactions. On a bitcoin level they can't do anything about it. But if it's a face-to-face transaction they can call the police, or clock you one, or whatever is appropriate given the situation ;. You're right though, clients should be better at reporting double spends in progress - especially if it involves one of your addresses.
Satoshi did some estimation And it can be automatized on clients Say, each time you buy a cheeseburger from a zero-confirmation accepting merchant, send a replacement tx with higher fee to miners which accept them Sometimes you will succeed.
I'd classify a replace-by-fee attack as a regular double spend. A Finney attack is specifically when you have already mined the block before you perform the double spend. A Finney attack is invisible unlike a regular double spend , but can only be done by miners and requires precise timing.
There is no such thing as a regular double-spend. I guess you mean a race attack https: I believe this difference is non-essential, Finney simply mentioned a simplest case which came to his mind.
The essential difference between Finney and basic race attacks is that Finney attack is miner-assisted, that is miner knows that double-spend is going on.
You can make replace-by-fee attack invisible too: The Finney attack is guaranteed to work, whereas a race attack isn't unless most miners run that patch I guess. You could make a replace-by-fee attack invisible, but at the cost of only giving it a chance of success. I seem to remember that's why BBQCoin disappeared. BBQCoin was just for fun though, and had very little hashing power on their network. I believe that an earlier fork case did cause some coins to be double spent, but don't quote me on this, since I can't back it up except by my mind screaming right now that it did happen.
I have no evidence to back it up, and am not somewhere where I could look to see if I'm correct right now. So that 2 confirm attack would cost the attacker btc per successful execution so it better be a big double spend. Though it's interesting to note that as the reward goes down these attacks will be cheaper to perform. Single block forks the equivalent of 1 confirmation happen in the chain quite frequently due to multiple miners discovering valid blocks nearly simultaneously and propagating them to the network.
More than single block forks are far less likely but not impossible, especially if there are network or country-wide firewall issues disrupting broadcast of blocks. The most recent "big fork" due to the bug in bitcoind 0. In this case, even requiring 6 block confirmations would not have prevented a potential double spend but this would we hope be a highly unusual and unlikely occurrence under normal conditions. Pools often get multiple blocks in a several times per day.
These aren't forks, only because the pools choose not to make them forks. That's because the fork was caused by a bug in the upgrade and not a malicious attack. There's some good info here about double spending, there are a few attacks directly aimed at 1 confirmation. Obviously for only one confirmation the requirements are very reduced.
In the end, the number of confirmations can be weighed against your potential loss and the cost of reversing the transaction; exchanges can deal in fairly large amounts of coins and would be potentially a juicy target for a double spend if they took only a single confirmation. One confirmation is not enough.
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