30

The checkpoints are hard coded into the standard client. The concept is, that the standard client will accept all transactions up to the checkpoint as valid and irreversible. If anyone tries to fork the blockchain starting from a block before the checkpoint, the client will not accept the fork. This makes those blocks "set in stone".


20

I'm sorry to be the bearer of bad news: It looks like your funds are gone and the security of your computer is compromised. A quick google suggests that is one of the electrum phishing destination addresses. You can find more information on the attacks against electrum here: http://electrum-malware.surge.sh/


15

If a merchant accepts 0-confirmation transactions, he has to accept that the transaction can be reversed. So he only should do that if he trusts you for more than the amount you transferred to him. You won't get any bragging rights for doing that, since Bitcoin never promised to be secure without sufficient confirmations. That trust may come from different ...


13

A Bitcoin transaction, by design, will get one confirmation after an average of 10 minutes. Even before a confirmation has been received, a transaction is generally irreversible. If you were to send a second (double-spend) transaction, using the same inputs as a transaction you've previously sent, I suppose there might be some custom-developed nodes that ...


12

Bitcoin-Qt doesn't support anything like that. Theoretically: A transaction is canceled by publishing a second transaction which double-spends some of the coins used in the first transaction (this can be a send-to-self). If the second transaction is included in a block before the first one, the first one becomes invalid and can be considered fully ...


7

Bitcoin's security rests on the assumption that the majority of the hashing power follows the protocol. If instead miners/pools break protocol for a quick buck by switching to a conflicting transaction which is clearly a double-spend attempt, this assumption no longer fully holds. One can only hope that the mining pool (or any block issuing agent) will ...


6

Bitcoin is like cash: You don't use an intermediary. If you send money to someone, they got it. The only way you can get is back is to make them hand it to you. If there is no intermediary, you can't complain to that intermediary to take money from the person you sent money to and give it to you. The reason Bitcoin is like cash is that it's designed that ...


6

Bitcoin transactions cannot be reversed unless some kind of escrow is implemented. Take this as a hard learned lesson. Sorry for your loss.


4

From the help of the console : abandontransaction "txid" That will tag the transaction as abandonned "abandoned": true After that, you can reselect the input(s) to send it with higher fees Tested in bitcoin core 0.12.1


4

Update on this as of time of writing, just to clarify more specifically upon the other answer: dependence on checkpoints in the security model has been significantly reduced, they are only used in one very specific case now. That case is just to ignore forks from the chain early on, before the most recently seen checkpoint. When a node has seen a block it ...


4

You cant do basically nothing from your end, as you have lost the control of those bitcoins. One thing that you can do is to ask the recipient of the transaction to refund. If he refunds you will get back the bitcoins.


3

There is no estimated time, and in fact this transaction can potentially get confirmed at any moment, though the less likely the lower the transaction fee was. To fully revoke it, create another transaction that overrides it, and put a higher transaction fee to make it more likely that it will get confirmed before the other one.


3

You appear to have caught some malware that replaces Bitcoin your addresses with their own when copy-pasting one. You'll probably want to look into removing the malware from your computer. Meanwhile, it is unlikely that you'll be able to recover your bitcoins. The Bitcoin network doesn't have a way of reverting payments. Basically, you're in a similar ...


3

Each node in the network accepts any transactions with a higher sequence field (in TxIn) as long as the transaction isn't locked (lock time hasn't expired). This can't be used as an attack because the client is aware the transaction is unlocked and thus could be modified. The client (and thus any merchant) will/should treat the transaction as even less ...


2

The only way to "reverse" the transaction is to immediately double-spend from the same set of UXTOs to a different address that you control (within a few seconds after your original transmission) and pray that the doublespend reaches enough nodes and wins. But if your tx is already confirmed in a block, then no way.


2

You can do two things Wait until the transaction gets relayed. Transactions without fees usually get relayed as well, but often a later than those with a fee. Send a new transaction spending the same outputs, with a fee. It's possible that some miner will accept it eventually. This can be tricky when you use blockchain.info's wallet. It's called double ...


2

simply looking at this chart tells you that average transaction confirmation time is not 10 minutes (block confirmation is 10min) https://blockchain.info/charts/avg-confirmation-time https://www.quandl.com/data/BCHAIN/ATRCT-Bitcoin-Average-Transaction-Confirmation-Time


2

As of right now, there is not a standard way to return other than to ask the returnee for an address to which the returner can send. You could ask for them to verify the address by signing some text with its private key, however, users of web wallets are at a disadvantage because not all wallets provide this functionality. It is too onerous to ask for a ...


2

Bitcoin is designed to put you in control of your own money. While this allows you to "be your own bank", it unfortunately also leaves you without the safety net present in payment services provided by the banking network. Bitcoin payments are pushed out by the paying party instead of requested by the payment receiver. By design, there is no central referee ...


2

Firstly, Bitcoin Cash is not Bitcoin. Secondly, neither Bitcoin nor Bitcoin Cash have any sort of central authority or way to reverse/refund transactions. This is completely intentional - all confirmed transactions are final. The only way you can get a "refund" is to ask the person that you sent the Bitcoin Cash to to send it back to you. If you don't know ...


2

No, a confirmed transaction can not be reversed.


2

Your wallet software will handle all of this for you. Your wallet software generated the change address and stored its private key. When you want to spend more Bitcoin, it will still know about the change and can spend from it. Your balance in your wallet should still include the change. There is nothing you have to do in order to spend the change, and there ...


1

My interpretation is more that, since sellers are the ones receiving money, they are the ones who stand to be protected by an improved and non-reversible payment system. I don't think Satoshi particularly thought that protecting buyers (who are receiving goods) was less important or that they were less vulnerable, but that it simply wasn't within the scope ...


1

If the transaction has been confirmed there is nothing to do and that is probably your situation. If not (due a small fee) then you can pay yourself with a higher fee to "block" the previous one.


1

You've signed over the bitcoins to your trading partner. If you have any contact details, you can try to explain the situation to them and request that they return the unintended payment. As there are no chargebacks or other ways to cancel a payment in Bitcoin, you're at the mercy of their goodwill or would need to pursue legal action. Basically, the ...


1

How many btc have been transferred in orphan blocks, but then never included in any later block? This is not a statistic that's normally published by anybody, as far as I can tell. How many btc have been transferred in zero-confirmation transactions that have never been included in the blockchain? How could one find this info? The data necessary to do ...


1

I'm pretty knowledgeable about arbitration and mediation (collectively known as "alternative dispute resolution" or "ADR"). I'm not an arbiter, mediator, or attorney, but I am someone who uses contracts with arbitration clauses in them, has been advised about arbitration by attorneys, and has actually had a dispute resolved via arbitration. I became ...


1

There are two solutions here: Dispute Resolution Organizations (DROs) or multiple signature transactions. When you pay with a credit card or via paypal, part of your service fees go towards the provision of dispute resolution services. However if you were to mail a bundle of cash to someone, because there is no intermediary (just delivery), there is no ...


1

I'm a mediator and this is an interesting subject. In the conventional world it's seller beware, as the customer can either not pay at all, or charge back a credit card. In the case of Bitcoin, the situation is reversed, and payment once made is gone. I don't think that the issue is with the bias of the mediator, most are neutral, but I do think that a ...


1

To be honest all has been already said about this topic and all the competent previous posters are right in that Bitcoin is by design not reversible. But to have all the facts at hand, one needs to mention also the event of March 2013 where Bitcoin underwent a 24 block reorganisation. Before people start screaming this was a network issue/program issue and ...


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