Questions tagged [confirmations]

Confirmations correspond to the number of blocks that are dependent on a given transaction. This includes the block containing that transaction and all blocks after it in the blockchain. The more confirmations a transaction has, the more likely is it that it will remain in the blockchain permanently.

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130
votes
10answers
301k views

Why is my transaction not getting confirmed and what can I do about it?

I sent a transaction without (or with an exceptionally small) transaction fee using extremely small or unconfirmed inputs while the stars were not standing right. For whatever reason, I have been ...
108
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5answers
18k views

Why is 6 the number of confirms that is considered secure?

Why is 6 is the number of confirmations that is considered secure? I haven't found any mathematical explanation or otherwise that explains why it is 6 and not 5 or 7. Is there a historical reason for ...
49
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2answers
37k views

What are bitcoin “confirmations”?

When I receive bitcoins I see a certain number of "confirmations" in the client. What do these mean? Why do most sites make me wait for 6 "confirmations" before a purchase will go through?
37
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5answers
2k views

How do I accept bitcoin payments at a real world store?

From what I understand, there are some requirements for using bitcoins at a physical store: Both the store owner and the client must have Internet access The client must have a cellphone or a laptop ...
11
votes
1answer
850 views

How has the problem of waiting for confirmations been eradicated?

On the bitcointalk forum, evoorhees wrote: For a long time people said the "waiting for six confirmations" was a significant drawback, but most people understand that problem has been almost ...
6
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2answers
1k views

Can you mine without transactions?

As far as I know, mining means verifying transactions and thus keeping the Bitcoin network alive. Today, at a local meetup, some people have informed me that mining doesn't need transactions. They ...
28
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5answers
4k views

Has there ever been a successful double spend attack on the Bitcoin network? If not, is it really necessary to wait for confirmations?

There is a lot of concern about waiting for confirmations to avoid a double spend attack, but has there ever actually been a double spend attack? It seems to be that there are two types of double ...
18
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3answers
83k views

How many confirmations do I need to ensure a transaction is successful? [duplicate]

As a regular user of Bitcoin, I often send bitcoins to other, or receive BTC from others, sometimes this might be a trade or deposit. Some traders require at least 6 confirmation, some require at ...
9
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1answer
14k views

How does confirmation exactly work?

When user A sends Bitcoins to user B, user A signs the transaction with his private key. This signed transaction is being sent to the Bitcoin network and all the nodes collect, confirm and pack these ...
38
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2answers
8k views

What are Green Addresses?

What are Green Addresses? Is it true that they can solve the "confirmation delay" problem, and how does that work? Are there any drawbacks?
18
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4answers
47k views

What happens if your transaction is never confirmed?

If I have a low amount and don't include a fee, the transaction takes forever to get confirmed. What happens if it never gets confirmed? Can the wallet that I sent it to still spend the money?
11
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3answers
669 views

What can be done to mitigate the risk of a Finney-attack?

Related Question: Would a reduced block generation time make the Finney attack more difficult? I understand that the Finney-attack is the main reason why accepting a zero-confirmation transaction ...
3
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2answers
355 views

Energy to confirm one block?

What is the minimum energy (or CPU operations) required for someone to confirm one block on their own, to launch a double-spend attack? How can I calculate this from the current difficulty or ...
10
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4answers
3k views

How important is the fee for speed of confirmation?

I am developing a Bitcoin application, so I am sending a lot of "toy" transactions for testing, with 0 fees. But it seems that those take forever to get confirmed. (Right now I am waiting 45 minutes ...
5
votes
1answer
407 views

Where can I learn more about BIP30; namely the exploit and the background discussion?

I'm having trouble understanding the bug that was fixed in BIP030, and how it would be exploited. Is the premise of this attack that there would have to be a netsplit and the chain was forked, then ...
11
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2answers
2k views

What's the longest chain of orphan blocks? (How many confirmations have been necessary?)

I believe my two title questions are the same (are they?): Heretofore, what is the longest chain of orphan blocks (of N blocks), such that if someone didn't wait for N+1 confirmations, they may have ...
19
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2answers
5k views

What happens if my transaction is not accepted because I did not pay fees?

I was reading this thread about a client fork that does not force transaction fees and I noticed the big red warning saying that some coins might get lost if I am not careful. What does this mean? ...
9
votes
2answers
7k views

How long does it take to receive bitcoins?

I bought 1.25 BTC but after 2 days I see nothing. What is wrong? This is the transaction. Also, I went to freebitcoins.appspot.com, since they claim thay they give for free 0.005 bitcoins per visitor....
13
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2answers
2k views

How to minimize risk when accepting zero confirmation payments?

I'm trying to setup a way of accepting Bitcoin payments in real life situations, where waiting for confirmations is typically not an option. I understand this is never 100% risk free (especially with ...
12
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1answer
1k views

How do Bitcoin clients determine the number of confirmations a transaction has?

The protocol specification doesn't seem to address this.
10
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1answer
3k views

With 100% segwit transactions, what would be the max number of transaction confirmation possible on a block?

With 100% segwit transactions, what would be the max number of transaction confirmation possible on a block? And, how many utxo can be updated by a block full of segwit transactions?
5
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2answers
601 views

How to perform a double spend attack in websites that accept transactions with 0 confirmations?

To perform a Finney attack or a 51% attack I need to have lots of computational power, but in this case (a website that accepts transactions with 0 confirmations) it seems to me that I only need to ...
7
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2answers
3k views

How would one monitor an address for a transaction and 1 confirmation in PHP?

I have a small PHP script with my static bitcoin address shown. When someone sends any btc to that address, how can I get the PHP script to check if the transaction has had 1 confirmation? Do I have ...
6
votes
3answers
1k views

Shortest and Longest block interval time ever recorded in Bitcoin

Bitcoin block interval time is on average 10 minutes, that is the difficulty is adjusted in such a way that every 10 minutes a miner will manage to find the right hash. This is just an average time ...
4
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3answers
4k views

If you confirm others' transactions, what do you do to earn 25 bitcoins per block?

I was a bit surprised to learn that you can earn 25 bitcoins, just by confirming a block worth of transactions. If I've done the math right, at $493 per bitcoin, that's $12,325. Does one do a lot of ...
3
votes
1answer
350 views

How to accept BTC payments

I'm developing a website that will be accepting BTC as a form of payment. I (technically) know how to accept payments, I'm currently experimenting with the daemon and the Python-BitcoinRPC library ...
3
votes
2answers
3k views

How do we check the time when a transaction hits x confirmations?

Consider the transaction 948a427.. which has 3341 confirmations as of now: We can see that the time the relay is received at 8:36:30 and it has one confirmation at 08:50:04 (after 14 minutes). How ...
3
votes
4answers
2k views

How does a wallet use unconfirmed outputs as inputs after unconfirmed transactions?

I have 10 btc on address A. Using raw transaction, I send 5btc from A to B and set the change address as A itself. Now because the transaction from A to B is not confirmed I can't spend the remaining ...
8
votes
2answers
191 views

Is the proposed “Miner Promise” method of accepting 0-confirmation transactions safe?

This thread proposes a method for miners to promise "that their next block/s will contain a specific transaction", and/or that "they won't mine a conflicting transaction". If adopted by a large ...
6
votes
1answer
645 views

Is it possible to recognize conflicting 0-confirmation transactions with the Bitcoin client or other available software?

Is there already a way to detect conflicting 0-confirmation transactions? I'm assuming at least one transaction goes to my wallet. I would expect the client to list the transaction as conflicting but ...
6
votes
1answer
4k views

How many confirmations does bitpay wait?

I've made one purchase with bitpay, it has been received by the merchant who is stating "Payment received. Waiting for more confirmations". While this is fine, I find it quite odd I didn't manage to ...
6
votes
1answer
2k views

listsinceblock parameter: target-confirmations

listsinceblock help returns: listsinceblock ( "blockhash" target-confirmations ) Get all transactions in blocks since block [blockhash], or all transactions if omitted Arguments: 1. "blockhash" (...
5
votes
1answer
281 views

Understanding speed vs. fees on various wallets, esp. Instawallet and original client

The Bitcoin Wiki don't say much about fees, more precisely if you have a choice between speed vs. fees (pay more, deliver faster). In fact, I don't yet even have a clue how fast are bitcoin ...
4
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2answers
3k views

how long do i have to keep Bitcoin-Qt open after sending coins

Can I close Bitcoin-QT client and power off my computer just after sending coins to someone or do I need to wait until 1, 2...6 confirmations?
2
votes
1answer
210 views

Is there a way of rewarding users who confirm others' transactions?

Users who confirm or validate others' transactions are performing a public service on the Bitcoin network. Is there any way to reward such users, perhaps by giving them priority for confirmation of ...
0
votes
2answers
32 views

Determinant of confirmation time

There seems to be a lots of variations in confirmation time. https://blockchain.info/charts/avg-confirmation-time I would like to understand factors that affects the confirmation time.