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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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134
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10answers
304k 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 ...
109
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5answers
19k 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
38k 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?
44
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8answers
16k views

Can bitcoin exist without miners?

In the past year only, the bitcoin mining difficulty has increased fivefold. If in the coming years the difficulty increases so much that mining is no longer profitable (i.e. consumes more power than ...
38
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2answers
9k 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?
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 ...
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 ...
19
votes
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? ...
18
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3answers
85k 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 ...
18
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4answers
48k 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?
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.
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 ...
11
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1answer
852 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 ...
11
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3answers
675 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 ...
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 ...
10
votes
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?
10
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3answers
6k views

Why does blockchain.info report “Estimated Confirmation time” not as 10 minutes?

Currently, it is a timer which counts down from 10 minutes starting when the transaction is first seen. When the timer reaches 0 minutes, it switches to "Unknown / Never." It is my understanding ...
9
votes
1answer
2k views

How does BitCoin prevent fraud during confirmation period?

I'm trying my best to understand how bitcoin works and while I've grasped the basics, there's a lingering question: What's to stop me from spending my bitcoin multiple times during a confirmation ...
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....
9
votes
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 ...
8
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4answers
6k views

Will transaction confirmation time be reduced as the network size increases?

Right now it takes 6 confirmations, which takes about an hour to verify a transaction. Will the rate at which transactions confirm become faster over time?
8
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1answer
2k views

When to worry about 1-confirmation payments

A customer sends me a payment for some digital good at my service, where delayed delivery is a deal-breaker, so I only wait for 1 confirmation by the network before releasing the links for the ...
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 ...
7
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2answers
2k views

Can I spend a coin sent to myself before it confirms?

If I spend the entire balance in my wallet to another address in my own wallet, do I need to wait until it gets one confirmation in order to spend it, or does the client know it is my own funds and ...
7
votes
3answers
3k views

How does SatoshiDice operate with 0 confirmations?

I understand they use your bet as an input, but what does that mean and how do they do it? Can they use the standard bitcoind as a server against which to run the API from?
7
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2answers
4k views

How can I determine the number of confirmations of a transaction and its fee using the Blockchain.info DATA API?

How can I know if any given transaction has confirmations and has paid the miner's fee, using the BlockChain.info DATA API?
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 ...
7
votes
1answer
6k views

Checking pending (not yet in the blockchain) transactions

Is there a service (like Blockexplorer) that shows pending transactions that have not (yet?) been included in the block chain?
7
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1answer
3k views

Fastest cryptocurrency

What cryptocurrency is the fastest in terms of reaching 100% transaction confirmation? I've found sites like this that show that Fastcoin is the fastest at 48 seconds. I think David Schwartz said ...
6
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2answers
2k 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 ...
6
votes
2answers
161 views

What precautions to take when working with only one or two confirmations?

I am providing a service that accepts Bitcoin. In order to speed things up a bit, I am planning to reduce the number of confirmations I require before I consider the money to have arrived. I have ...
6
votes
3answers
2k 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 ...
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" (...
6
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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
12k views

How long does it take for a transaction with 0 fees to be confirmed or rejected?

I have a problem with a transaction that has 0 btc fees: https://blockchain.info/tx/256301465d77affb6bc7087432a9130db48dd64efa28b0460fb674eda704f382 From what I understand, eventually this ...
6
votes
1answer
2k views

Why do some transactions take months to get into a block?

This page at bitcoincharts shows a list of transactions that didn't get included in a block yet. Many of them are from 2 or 3 months ago, even though they include a fee. What's going on? Why haven'...
6
votes
1answer
758 views

-walletnotify on 6 confirmations instead of 1?

Pretty straight forward. Right now im using -walletnotify to run some node.js code when i get an incoming transaction and when theres 1 confirmation. However, after reading around, i found out that 1 ...
6
votes
1answer
647 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
441 views

Spending own generated unconfirmed change in the v.0.9.0 era

Reading about spending own generated unconfirmed change some time ago I stumbled upon this reddit thread that convinced me that doing so is a really bad idea and could prove catastrophic for any ...
5
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2answers
6k views

Bitcoin successfully deducted on sender wallet but did not reach receiver wallet

Here is the wallet address for receiver: 1Gouzjo9Jav1k4AmRoUJJMzidVfnMoSieS. I had used the Blockchair site to see and track status. Based on the details, account had seen receiving last 21 hours. ...
5
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2answers
603 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 ...
5
votes
1answer
1k views

Bitcoind -walletnotify more than 6 confirmations?

I've configured bitcoind -walletnotify to run php script when callback is triggered. It works fine, but only notify until 3 confirmations are received. My goal is to notify when 6 confirmations are ...
5
votes
1answer
419 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 ...
5
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2answers
20k views

Why did my Coinbase transaction take 4.5 hours to get in a block?

Why did this transaction take so long to be put in a block? I initiated a 7 BTC transfer at 6:13 PM Eastern Time from Coinbase to an external address in an over the counter transaction today. It was ...
5
votes
2answers
62 views

Is there any discrepency on Confirmations?

Is there ever a situation where some bitcoin client thinks a transaction has 3 confirmations and another bitcoin client (or website) thinks a transaction has 4 confirmations, for example?
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 ...
5
votes
4answers
243 views

What technical properties does a confirmed Tx have that an unconfirmed Tx does not?

From a user perspective, each block confirmation reduces the probability that a transaction payment will be reversed. However from the perspective of the software, what happens when a transaction is ...
5
votes
1answer
1k views

Why does the Bitcoin client require at least one confirmation before I can spend?

If I accept bitcoin for payment, provide a new address for each payment and make it clear to payers that I consider payment complete only after waiting the ~10 minutes for a confirmation, is there a ...
5
votes
1answer
136 views

Bitcoind doesn't add miner fee

How do I make sure bitcoind's RPC call sendtoaddress adds miner fees to transactions? Tried adding to our bitcoin.conf file: mintxfee=0.0001 But some of the transactions still won't get any miner ...