Questions tagged [doublespend]

This tag should be used for questions related to double spending. Double spends are when a money is spent more than one time. This is considered a form of fraud.

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3k views

Broadcast a signed transaction

I sent money from 4 inputs to 2 outputs, one of which I don't control. The transaction's fee is too small (didn't change my settings and the transaction fees got a lot higher, recently) and will not ...
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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 ...
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1answer
118 views

Bitcoin Wallet: Will 2 payments within 10 minutes cause double spending

I'm using a bitcoin wallet for managing all my transactions. For example, If I have bitcoin 2, 3 and 5. Firstly, I buy a product with price 5. Bitcoin wallet will create a transaction from 2 and 3. ...
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3answers
2k views

If a double spend is executed, what happens to the original transaction?

So I think i have read enough about double spending so as to be able to execute one. But I have found nowhere what happens to the original transaction.
3
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1answer
235 views

What if a pair of double-spent transactions are collected into a new block?

Let's say, Alice sent a bitcoin to Bob, and then immediately sent the same coin to another address controlled by her. A honest node collected these two transactions into a new block. Would the node ...
5
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1answer
3k views

Understanding a Bitcoin Double Spending Transaction by Performing one on yourself

Everyone talks about preventing a double spend transaction, but how does one do one to yourself in order to better understand the steps involved by the attacker? What is required to do a double spend?...
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2answers
240 views

NBitcoin - how to set RBF to true in order to give higher fee for transaction

I have a few transactions staying unconfirmed - been a few days now. I suspect the minimum mining fee was upped - 15 minutes prior I was still doing hundreds of transactions a day at that fee - but ...
2
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0answers
40 views

Globally distributed accomplices for improved outcome in race attack

Would it help you to win a race attack if you had accomplices from all over the world, say Berlin, Beijing, Boston, and Buenos Aires all propagate your transaction to the nodes that they're connected ...
2
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1answer
63 views

What information about a transaction can be assumed accurate before confirmation?

When sending a Bitcoin transaction, what information in that transaction can be assumed to be accurate before receiving a confirmation? Can you verify the from address? Can you verify that the ...
4
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1answer
96 views

Is Bitcoin the first e-cash scheme which solved the double-spend problem?

Is Bitcoin the first trustless e-cash scheme which solved the double-spend problem? I'm under the impression it is and that was one if its greatest contributions, but I couldn't really find a source ...
0
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1answer
122 views

Detection of double spend in Bitcoin for aged transactions

This is just to verify my understanding of Bitcoin double spend detection. 1) Use of UTXO indexes : This ensures that there as been no spend from that output (transferred to recipient in Block of ...
2
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1answer
269 views

why is double-spend not an issue for payment channels?

Micropayment Channels (MPC) cannot be used currently because of transaction malleability, I hear. AFAIK, people saying that have in mind that the refund & payment tx, which have as input the ...
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1answer
105 views

How long should I wait to consider that the transation is “definitely” confirmed?

When one transaction is broadcasted, what is the probability that it won't be confirmed? (By probability, I mean the observed probability on the blockchain. If a person intentionally spend twice 1 ...
3
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3answers
89 views

What incentive is there for a miner to not cancel his own 'real' txs

It is said that a Bitcoin miner attacker with enough CPU power to outrun the entire network is better off mining honest bitcoins - which is not correct since by creating a false block chain the ...
8
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1answer
66 views

Merchant tool that will dynamically adjust the # of required confirmations based on network hashrate data

Satoshi built Bitcoin to be a decentralized network. Some of the original recommendations (such as waiting for 6 confirmations) relied on statistics that related to level of decentralization. https://...
5
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2answers
744 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 ...
0
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1answer
83 views

How to pratically doublespend bitcoins?

I tried to put bitcoins into an p2p exchange with bitcoin-qt. I added a to small transaction fee, so the coins are now stuck as "Unconfirmed". The offer from the exchange is overdue, so all that will ...
2
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1answer
77 views

What makes an unconfirmed tx 'suspicious'? (likely to be replaced or never confirm)

When looking at Bitcoin unconfirmed transactions, I'm trying to distinguish between txs that are likely to confirm (whether that be in the first next block or in 2 hours) versus txs that are likely to ...
0
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1answer
116 views

Restrict the Bitcoin usage only during a particular period

I would like to know if its possible to use a Bitcoin at present in the following scenario. When I send a Bitcoin to an another user,I set certain parameters on the Bitcoin, like it can only be used ...
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1answer
230 views

How many confirmations do bitcoin escrow websites wait on average?

To me it seems very dangerous not to wait for 6 confirmations when running an escrow. The scenario I'm thinking of: a miner deposits a large sum of bitcoins the escrow waits for one or two ...
8
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3answers
4k views

How do miners detect double-spending?

Assuming I spent 1BTC, then waited a few months and then spent it again. How is this detected? Do the miners go through the entire blockchain to assure the coin was never spent before?
8
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3answers
759 views

Why is Poisson instead of Negative Binomial used for computing attacker's potential progress?

In chapter 11 of the Satoshi's paper it is claimed that: The recipient waits until the transaction has been added to a block and z blocks have been linked after it. He doesn't know the exact ...
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1answer
142 views

How to track and handle double-spend attacks?

If a double-spend attack is pulled off, how to manually verify transactions via the bitcoin daemon and how to know how much amount lost? Will the saved transaction hash be re-usable to obtain info ...
0
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2answers
142 views

Paranoid Merchants on double spending [closed]

How can merchants be alerted of Double-spending attacks? Let us take a hypothetical case where a merchant offer a BTC deposit wallet to his users, User deposits Bitcoins and it's credited to his ...
0
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1answer
153 views

Details in double spend detection [duplicate]

I'm confused with the details in double spend detection. my question is if Alice first sends her 10 BTC to Bob, and then sends the same 10 BTC to an address that belongs to herself. How do Bitcoin ...
2
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3answers
463 views

Will an attacker's forked branch of block chain be used in bitcoin confirmation?

From what I understand, transactions are agglomerated into a block, proof of work is done by computing a hash value for the block, then added to the block chain. When a block is added to the block ...
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1answer
144 views

Why can't a transaction be redirected after it is signed? [duplicate]

Scenario: Step 1: User-1 initiates the TXN-1 to pay to User-2 and the TXN is not yet confirmed with the ongoing block POW. Step 2: What prevents fraudster (anyone a miner or someone listening/...
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1answer
904 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, ...
2
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1answer
247 views

double spending

I do understand the necessity for a proof of work to avoid malicious miners mining a fork on the current blockchain. This is difficult as this proof of work takes lots of power (and time). Yet I don'...
5
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2answers
877 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 ...
2
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1answer
312 views

Can a malicious majority miner rewrite history?

Is it the case that a malicious miner with the majority of hash power (say, 99%) can perform a double-spending attack by rewriting history? If so, I can't understand how. If not, under what ...
0
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1answer
196 views

Bitcoins stuck - No double spend possible

I have a problem with my address 1Dss5sKJDZ1Kkhh3KRyoekeZpC4S1WehD. As you can see, I transferred money to the same address by mistake - without any fee. The transaction ...
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2answers
2k views

When are multiple transactions spending the same output in the same block considered a double spend?

Here is an example of multiple transactions in the same block, all spending from the same output. I created these using the Electrum wallet, telling Electrum to spend a little bit of the BTC from the ...
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1answer
113 views

What are the chances of someone coming up with a new and simple/out-of-the-box solution for the double-spending problem?

The proof-of-work solution is simple but has many drawbacks (waste of time, energy and uncertainties about its security in the future). The consensus solutions proposed by Ripple/Stellar are too ...
3
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1answer
211 views

Why it is not possible for a payee to verify double-spends of the coin?

I'm reading Bitcoin paper of Satoshi Nakamoto (https://bitcoin.org/bitcoin.pdf). It says: Each owner transfers the coin to the next by digitally signing a hash of the previous transaction and ...
1
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1answer
138 views

How do I detect a double-spend in real-time, like Bitpay?

By Bitpay to pay only take 10 seconds to complete. How do they do it?
2
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1answer
211 views

What would you do while a hard fork lasts?

It is conceivable (though generally buried with cognitive dissonance, I imagine) that a hard fork might not get resolved. This almost happened once before, and the miners picked the fork that solved ...
1
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2answers
598 views

Where is coinbase transaction after a hacker successfully performs >50% attack?

Here is the scenario: Honest nodes build one block from Block_1. Hacker nodes privately build four blocks from Block_1 and broadcast these malicious blocks. Now, where is the honest node's ...
2
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3answers
12k views

How many confirmation do i have to wait before i can spend the inputs I already received?

Can I spend Inputs with 0 confirmations?? If I could, are there some restrictions?
3
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2answers
510 views

What can a dishonest node do (or try to do)?

Except this kind of attacks: https://en.bitcoin.it/wiki/Double-spending For example can he simply create a new block that includes some invented transactions that steal money from real address? ...
7
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1answer
618 views

Speeding up confirmation by double-spending a transaction stuck in mempool

In the context of no-fee transactions that can take a long time to get their first confirmation, is it possible to use raw transactions and double-spend the original transaction by broadcasting ...
1
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1answer
105 views

How would this double spend attack be prevented?

I know, that a user cannot create a fork in the chain. Also, it is said, that since every transaction is publicly announced, any attempt of double-spend on the same chain would be rejected as the ...
2
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1answer
334 views

Is it possible to use Selfish Mining to steal bitcoins?

Is it possible to use the Selfish Mining algorithm to steal bitcoins?
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2answers
311 views

Using Transaction with multiple outputs

Since the output can be spend only once, I am confused by transactions containing multiple recipients. For example, if Alice transfers 5 BTC to Bob and 5 BTC to David in the same transactions. In the ...
6
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3answers
677 views

Why doesn't bitcoin place additional constraints on competing block chain forks, other than length of chain? (e.g., time and confirmation count)

In Bitcoin's proof-of-work system, consensus on which chain of blocks should be considered the "true" block chain is based only(?) on which chain is longer. Accordingly, to quote a nicely written ...
5
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1answer
359 views

What exactly happens when a node detects a double spend?

Does the node drop both transactions? Does the node choose which one to keep? What exactly happens? Will both transactions be rejected by the network or will one of them be eventually accepted?
3
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2answers
4k views

How does ShapeShift operate on 0-1 confirmations

ShapeShift can exchange user's crypto currency almost instantly. They state that most transactions don't require any confirmations: Small deposits are processed with zero confirmations. Larger ...
3
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2answers
378 views

Blockchain for internet-of-things or is there any mining algorithm that can be utilized in low-computational power devices preserving security?

Recently IBM and Microsoft showed their interest (IBM post, Microsoft post) in utilization of blockchain for internet of things development. Let's assume that in close future the blockchain technique ...
3
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1answer
216 views

What happens if a miner confirms their own double spend?

Suppose an attacker makes a double-spend and controls the mining pool that happens to find the good which confirms the transactions. What happens? I suppose the network hopes that a vigilante sees ...
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3answers
500 views

What happens if a TX was a double spend?

What happens if the 'High' risk option (one confirmation) was chosen and then the TX turns out to be a double spend in the end? Would the value deposited be revoked? Would the user be notified somehow?...