Questions tagged [zero-confirmation]

Collects questions concerned with the practice of accepting transactions before they reach their first confirmation, i.e. "zero-confirmation".

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133
votes
10answers
303k 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 ...
21
votes
3answers
5k views

How does Satoshi Dice's 'zero confirmations' transaction system work technically?

The popular bitcoin betting game Satoshi Dice sends back payments very fast, they don't wait for confirmations. The user sends money to Satoshi Dice and gets back winnings a couple of seconds later. ...
15
votes
4answers
1k views

How secure is zero confirmations?

I sent a small amount of BTC to someone and she was notified within seconds. But the first confirmation did not happen for ten minutes or so. What is the chance that this transaction could fail ...
12
votes
4answers
3k views

How do I safely accept bitcoins without waiting for confirmations?

Are there any arbitrators that would guarantee the bitcoin transaction such that no one has to wait ten minutes to confirm the transfer of the said bitcoins?
11
votes
2answers
1k views

Double spend attack by sending higher fee transaction directly to the pools possible?

The standard client prioritizes TXs by the time of receipt, e.g. a conflicting transaction will not be relayed. This is not enforced by the network, though. Is there anything that would prevent this ...
9
votes
2answers
2k views

Could any standard fee transaction be double spent by using a higher fee?

I realize that if somebody makes a transaction without any fees and there have not yet been any confirmations, then the transaction could be double spent by just spending the same inputs to a ...
8
votes
3answers
2k views

If Bitcoin transactions require ~10 min to clear, how can payments get recognized within seconds?

Bitcoin Monitor offers to issue a notification moments after a payment is sent to a Bitcoin address. Yet if Bitcoin transactions require ~10 min to get written into the blockchain and confirmed as ...
8
votes
1answer
468 views

What is the Lightning Network proposal? What problem is it trying to solve?

We already have a few questions about technical details of Lightning network, however, … What is the Lightning network proposal in the first place? What problem is it aiming to solve?
7
votes
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
400 views

What nodes are best for lessening the risk of loss from a race attack

A successful race attack is one where the payment recipient's node receives a spend transaction yet the next block that is mined has a different transaction that spends the same coin. Thus the ...
5
votes
2answers
862 views

0/confirmation race attack double spend transactions

I am developing a point of sale bitcoin app, which should accept "fast" transactions (~30 sec for merchant to accept). I researched double spending questions here already, but it is still unclear to ...
5
votes
2answers
714 views

Double Spending before confirmation [duplicate]

What's to prevent someone from using bitcoin at a store like subway and double spending to buy the sandwich before a confirmation is made? Since subway obviously isn't going to wait for a ...
4
votes
2answers
2k views

It's possible to spend a BTC without fee to forge a payment?

I would like to know if it is possible to make a transaction without fee (probably this transaction will never be confirmed) and some time later to take this money back and spend in another ...
4
votes
3answers
361 views

Could Bitcoins (or any other blockchain based cryptocurrency) feasibly ever be used for purchases that need to go through fast?

Today, one of the problems with cryptocurrencies like Bitcoin is that it takes quite some time for a transfer to go through and enough confirmations to take place. This really isn't a problem when it ...
4
votes
1answer
2k views

Get notified of incoming Bitcoin transaction, as soon as it broadcasted

After a few weeks of searching for an answer, I decided to ask here. I want to accept a Bitcoin payment, to a specific wallet, and immediately, when the user approved the payment, to receive an ...
3
votes
1answer
205 views

What does a merchant need to do to reject RBF transactions

I understand replace-by-fee transactions are no threat to merchants who require multiple confirmations. However many businesses still accept 0 confirmation transactions as a means of improving ...
3
votes
1answer
1k views

How can Blockchain.info wallet send unconfirmed bitcoins?

So i just opened a Blockchain.info wallet after years of using Bitcoin-qt. My Blockchain.info wallet had an empty wallet, i sent some bitcoins to it and right after that without waiting for ...
3
votes
1answer
100 views

Is there a way for merchants to insist on a tx fee to increase likelihood of the tx (eventually) being accepted into the blockchain?

I understand that some transactions may never get into a block, esp those with zero fee or with a fee below the current suggested minimum (which makes me wonder about tx fee inflation, but that's ...
2
votes
1answer
164 views

What restrictions are there to the application of opt-in RBF?

It is a common meme in some parts of the Bitcoin sphere that RBF erodes the option of accepting zero confirmation transactions. It would be beneficial if the following questions were answered: What ...
2
votes
2answers
1k views

0 fee transactions - possible that they never confirm?

I've made a Bitcoin tipping service for reddit: https://news.bitcoin.com/bitcoin-tipping-reddit-minitip/ Currently users pay a flat 0.1 mBTC miner's fee to tip others since it's done entirely on-...
2
votes
1answer
615 views

can someone explain what i did wrong here? (btc transaction with fee not confirming) [duplicate]

https://blockchain.info/tx/c782b48bba09dea21896b7c58292abaec81d7ce2db2975f30b77176dddad492c was the fee not high enough? i have never had an issue with fees using the recommended amount that bitcoin ...
2
votes
2answers
1k views

Why has this blockchain transaction not confirmed?

ea5ee0a3734356a71b2b39deafb656715bad42fb297497f7f694d4a7a0f6335c Is due to the fee being low 0.0001? or something else?
2
votes
0answers
157 views

bcoin how to get zero confirmation

I`m using a bcoin (version=v1.0.0-beta.14) and I´m trying to get information about zero confirmations of a address imported into my wallet. All I get are informations about transaction with at least 1 ...
1
vote
1answer
42 views

Could decentralised proof of time in BCHSV solve for high PoW power consumption?

0-conf requires decentralised consensus of time in order to determine the order and time of each transaction. Bitcoin has a block time of 10 minutes achieved by brute forcing hashing algorithms of ...
1
vote
2answers
347 views

As a solo miner how can I prioritize my own unconfirmed transactions?

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?
1
vote
2answers
408 views

Can bitcoin be used for instant payment?

As transactions have to be confirmed, does it imply bitcoin cannot used for instant payment?
1
vote
1answer
893 views

What is the risk of waiting for just one confirmation to validate a transaction, assuming the counterparty is not a miner?

I am trying to determine how many confirmations would be reasonably safe to wait before accepting a Bitcoin transaction from an attacker that is not a miner and hence cannot rely on Finney attacks, ...
1
vote
1answer
276 views

Instantaneous exchange/conversion of bitcoin into cash

My question is : how can some exchanges instantaneously convert bitcoins into cash, in light of the fact that it takes 10 minutes to "validate" a bitcoin transaction? A bitcoin transaction takes 10 ...
1
vote
0answers
54 views

confirmations: 0 vs confirmations: -1?

I'm looking at a bitcoin clone, not sure what codebase it was cloned from, but I've noticed that the listSinceBlock output sometimes includes: a receive that has 0 confirmations a send that has 0 ...
1
vote
0answers
27 views

Can low-cost purchases be accepted safely with no confirmations? [duplicate]

From reading online, the general sentiment to this seems to be "no". You need at least 1 confirmation to prevent a double spend attack. But in Mastering Bitcoin, there's this note: A common ...
1
vote
1answer
491 views

bitcoin transaction is still unconfirmed after 30+ hours [duplicate]

Yesterday evening (6.45pm) i moved 1.4 bitcoin from my local bitcoin wallet to my blockchain wallet, the transaction was completed. But before the transaction was fully complete i submitted a request ...
1
vote
0answers
250 views

How big is the chance of double spending for 0, 1, 2, 3, 4, 5 and 6 confirmations?

I'm messing around with bitcoins a bit, and I'm now looking at the confirmations. In several places I read that 6 is the "normal" figure of confirmations needed to say a transactions has actually and ...
0
votes
1answer
237 views

Why is this unconfirmed?

Can someone tell me how to get a confirmation please or cancel this; e8c5489abcb60ecdb925ac880ec1e238c9a65ca4c5480065a6ca268bf00ea7ba-000
0
votes
2answers
154 views

Wasn't 0-conf more secure than Visa, before blocks got full and RBF was added?

RBF and full blocks make 0-conf useless, because it's easy to override. Wasn't it once useful? I've heard without those it's more secure than Visa in terms of double spending.
0
votes
2answers
69 views

How could a lightweight wallet determine the validity of 0-conf transaction?

I found that a lot of people are interested about security of 0-confirmation payments. But, it seems that most discussions focused on double-spending (like broadcasting two or more conflicting-but-...
0
votes
1answer
51 views

ways to improve bitcoin tx finalization time

On GDAX website, they claim that 3 confirmations is needed to finalize your tx in. I assume they've done thorough research on this and might've come up with some logic to protect themselves from ...
0
votes
2answers
337 views

How to integrate 0-conf BCH payments into a web app?

I am currently working on a Bitcoin Cash related project with the goal of helping contribute to the ecosystem. I am getting to the point where I will soon be ready to start integrating with the ...
0
votes
1answer
82 views

what will be the best approach to accept Bitcoin payment instantly? [closed]

How could I receive Bitcoin instant payment?
0
votes
0answers
29 views

Bitcoin Transaction never confirmed even with a significant fee? [duplicate]

I just had some questions in regards to relating fee/byte to confirmation. From an exchange the withdrawal fee for bitcoin is fixed to 0.0005 btc but the bytes vary very much, and thus you get very ...
0
votes
2answers
1k views

Transaction with 0.0002 BTC fee but not confirmed sice 2 days [duplicate]

I'm a Bitcoin noob. This is my second Bitcoin transaction and I'm getting very nervous. My wallet (KryptoKit on Chrome) doesn't have a possibility to change the fees or anything on transactions. ...
0
votes
1answer
405 views

0/unconfirmed and now no transactions anymore

So recently (2days ago) I made this transaction: Status: 0/unconfirmed, in memory pool Date: 20.12.2017 23:30 To: N**** 1LecRzTpKXh9kCgqXbUXtdXfQjE145BR87 Debit: -0.00447735 BTC Transaction fee: -0....
-1
votes
2answers
628 views

Why were BTC not accepted in the Humble Borderlands Bundle?

AFAIK, so far, BTC has been accepted in every Humble Bundle since they started accepting them… instead they weren't an available option with the Borderlands bundle. Is there an official, semi-...