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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1answer
101 views

how to double spend Bitcoin transaction?

How it's possible to double spend a transaction if the transaction outputs are already spent? and why these types of attacks are not preventable? is it about blockchain sync time between nodes?
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1answer
294 views

Not sure if I accidentally double spent my LTC LITECOIN

LEDGER NANO S - CHROME APP LTC LITECOIN I just sent two transactions (with different amounts) from one address to the same receiver one after another. While sending the second the first was still ...
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1answer
72 views

What are the mechanics of verifying that an output transaction is not spent?

I am trying to understand the mechanics of how a bitcoin transaction works. When the output gets consumed by a later transaction, who and how prevents this output from being consumed a second time? Do ...
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1answer
1k views

From multibit to electrum : low fee and unconfirmed parent

I made 3 btc transfer from my old Multibit classic wallet a few weeks ago (dec. 11), then I discovered that the fee was far too low for the transfers to be confirmed. I then restored my original ...
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2answers
204 views

Detecting unconfirmed double spends using bitcoind

I want to get statistics on how many percentage of unconfirmed tx in the mempool are having attempted double spends and having what value. For this I want to get notification when an unconfirmed tx ...
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1answer
258 views

Why is CPFP (Child pay for parent) immune to double spend?

Assuming I have 10 Bitcoins in my wallet and I send 4 BTC with a tiny fee and it gets stuck in the mempool due to a low transaction fee. If I understand CPFP correctly I would then send a second ...
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1answer
98 views

Can I double spend this transaction?

b9d6d458f312b6ce2ef27bbb4a4a88f95e4a5db7aa04c9ab1f6225ecde47a77e Can I move it ? Thanks for your help
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1answer
64 views

Complete Tech Spec

Where can I find a comprehensive description of exactly how Bitcoin works. I'm not interested in an analogy, I want to know everything, including the maths.
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2answers
108 views

Does the entire blockchain have to be recomputed to validate a transaction?

Are transactions validated by recomputing the entire blockchain? If not, how else can it be confirmed that a bitcoin I'm attempting to transact is one that I actually had come into acquisition of ...
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7answers
3k views

Is performing a 51% attack / double spend on Bitcoin illegal?

Suppose I had an ultra large ASIC from the future, and could perform a double spend on the core Bitcoin network. At this point in Bitcoin's development, it is no longer a game - there's real money ...
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1answer
793 views

Unconfirmed transaction / double spend warning [duplicate]

I transferred some coins from my Electrum Wallet to my Coinbase Wallet, however the transaction got stuck as unconfirmed (possibly because of low fees). It has been already 19 days since the ...
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1answer
977 views

How does SPV prevent double spending of UTXO?

I am new to Bitcoins. I have read about how double spending is prevented in Bitcoins. Suppose A, a peer, receives 'B' BTCs from various transactions: B1,B2,B3, etc. Also, A had spent 'S' BTCs in ...
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1answer
207 views

Is this considered double spend?

I had a Receive transaction worth 0.185btc I was confident that it was ok since I saw 5 confirmation before I close the wallet. The next day when I checked I saw a sent transaction with 0.185 btc ...
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1answer
268 views

After being officially canceled, SegWit2x is live. Will transaction replaying be massive ? If yes what does this means?

As you know, segwit2x was officially canceled last week, but some miners decided to still go forward today, and some exchanges like coinbase plan to support the hard fork. So things will happen like ...
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1answer
2k views

Low fee Electrum wallet transaction disappeared, now when I increase the fee it seems to be rejected as a double spend

Can anyone tell me what is happening with my transactions ... First I move some small amount and didn't see that fee was set up to low so it was "low fee" after that I've made another one and It get ...
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1answer
129 views

double spend problem and trust

I am very new to bitcoin and sorry if the following is too simple. As far as I understood, if there is a double spend problem, the longest chain - collecting most work - will take over. However, ...
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2answers
127 views

How does the network know the legitimate chain in a double-spend attempt?

Apologies if this has been covered, but there's one area of the Bitcoin network that is not clear in my head, and it's intimately linked to the double-spend problem. Suppose Person A is purchasing an ...
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1answer
41 views

Can one node receive two transactions from the same user (doublespend)?

I'm learning how the blockchain works. I've read that when someone (say Alice) send twice a transaction to two different peoples (Bob and Charlie) such that Alice has only enough to pay Bob or Charlie,...
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2answers
57 views

Is in-person double-spending attacks negligible on bitcoin payments?

If I'm planning to accept in-person payments in a store, is it negligible a double-spending attack or isn't it too hard to do?
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1answer
399 views

What happens if I spend a bitcoin that has 1 confirmation?

Take these two transactions that happen one after the other: Transactions: 1) Exchange A -> (1 confirmation) My Wallet 2) My Wallet (With a high fee) -> Exchange B (needs 20 confirmations) ...
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0answers
81 views

Bitcoin Paper: Why do we need the probability of catching up in double spend attack?

In the Bitcoin original paper, we have two probabilities: 1- Probability of generating k number of blocks in the period T in which z confirmations are generated. 2- Probability that the attacker ...
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1answer
164 views

do isolated blocks create forks in block chain? (with forks I mean branches that are no longer valid) If yes then how does the node redeem itself? [duplicate]

I'm a newbie to cryto and wanted understand this. what happens to the chain when the isolated block is formed (in case of a double spend) ? Since chains only add blocks that come from the longest ...
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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.
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7answers
51k views

Can bitcoins be counterfeited?

Traditional currencies have anti-counterfeiting features designed to make them hard to copy, but despite this attempt counterfeit money is a real threat. Since bitcoins are digital, it's trivial to ...
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1answer
49 views

Misledgering possibility for double spending attack

Imagine a malminer with two important abilities: having enough hashrate for producing blocks in a single-miner mode in reasonable amount of time and having a malconfigured miner software which doing ...
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1answer
356 views

How spending same coins both at BCC and BTC blockchains prevented? [duplicate]

------X--.---------- BTC Blockchain \ .--------- BCC Blockchain Let's say that we have some BTC coins from a transaction at block X. And, there are two blockchains now. ...
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5answers
186 views

Application of proof of work in bitcoin

Proof of work in spam I understand very well how proof of work is used to prevent email spam for example. Reasoning is since computing the right hash (e.g. with predefined number of zeros for example)...
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1answer
780 views

Mining two block at the same time

Reading the question and the answer What happens if two miners mine the next block at the same time?, I completely agree with the answer, but there are still 3 very interesting open question: How ...
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1answer
238 views

How does Bitcoin protect against doublespends?

I am trying to understand the blockchain and I have read a bunch of these explanations, but they all don't address some of the questions I am still wondering about. So first I'll explain what I know, ...
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3answers
1k 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
127 views

How do nodes behave in light of a doublespend?

Recently I have been studying on the bitcoin. while going through the double spend process, I found this link as How do I detect a double-spend? and an answer there describes different scenarios: ...
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2answers
319 views

Is something gained by double spending myself on a 51% attack?

I try to understand what consequences double spending may have. Let's assume I own 51% of the network and own three bitcoins wallets. If I double spend the coins from Wallet A to B and C - would I ...
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2answers
8k views

How do I detect a double-spend?

As a vendor, how do you detect a double-spend? I'm happy to tell end-users that I'm proceeding with a transaction on 0 confirms, simply assuming everything is fine. I'm selling physical goods and so I ...
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1answer
169 views

Is there a visualisation tool for discarded block chains in Bitcoin?

A lot of papers about cryptocurrencies explain the concept of the "longest chain", which goes along with these kind of figures: I was wondering if there exist any kind of visualisation tool for these ...
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2answers
711 views

Why most bitcoin wallet apps don't have Replace-by-fee feature?

As a bitcoin user, it seems that Replace-by-fee feature is useful to solve the problem of transactions not confirming because of an insufficient fee. However, as far as in know, most bitcoin wallet ...
4
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1answer
765 views

How does CryptoNote prevent a 51% attack and double-spending?

How does CryptoNote prevent a 51% attack and double-spending? I’m interested to know what is the mechanism that protects CryptoNote coins from 51% and double-spending attacks.
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2answers
716 views

Why does only the earliest transaction matter for double spending?

On page 2 of Bitcoin paper, it says: The problem of course is the payee can't verify that one of the owners did not double-spend the coin. A common solution is to introduce a trusted central ...
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2answers
982 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 ...
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3answers
959 views

How would a centralized block chain work?

If I'm a company who pays my employees and my supply chain with my own currency created on a block chain and they can spend it wherever it is accepted, would I need a POW or POS scheme to maintain the ...
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0answers
679 views

Is double spending with electrum still possible?

I tried to follow this tutorial, but I kept on getting an error message saying that there was a mempool conflict and that it was rejected by the network.I even used a script so that the mouse clicked ...
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2answers
764 views

blockchain.info says my tx is double spend. Which tx use the same utxo?

My transaction is marked as double spend. I don't remember when I spent it twice. How can I see what transaction used the same utxo? https://blockchain.info/ja/tx/...
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2answers
842 views

How does the Bitcoin client check for double spend?

When the Bitcoin client looks at the input of a transaction, it know the hash of the previous transaction from which the funds are coming, however then, how does it know that this output has not been ...
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1answer
266 views

Which clients offer a way to replace unconfirmed transactions?

On this site, we see a lot of questions from people who have sent a transaction which isn't being confirmed, often because they have neglected to include an adequate fee. The Satoshi client doesn't ...
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2answers
358 views

Is there a service that alerts about attempted double spends for merchants accepting 0-confirmation transactions?

I often come across merchants accepting payment in bitcoin, who require several confirmations on transactions, but where the probability of a successful double spend doesn't justify the waiting time ...
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3answers
2k views

How does Open Transactions solve the double spend problem?

OT is based on digital cash. From the article: To tackle the double spending problem, the payee has to verify the coin with the bank at the point of sale in each of the transactions. This ...
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0answers
1k views

Unconfirmed bitcoins 258: txn-mempool-conflict

I made a transaction a few days ago, but the fee was to low so it doesn't get confirmed. So I want to give the transaction a higher fee. But when I resend the transaction I get this error: 258: txn-...
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0answers
1k views

Bitcoins unconfirmed even after double spend

I'm very new to bitcoin and recently bought 0.066 bitcoins and transferred them to my electrum wallet. I then transferred them to another wallet but I set the fee too low (40Sat/b) and it was stuck in ...
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1answer
468 views

Double spend question during fork

What happens to a double spend during a fork where one of the transactions are in a orphaned block and the other in the main chain? 2 transactions get broadcasted in the network and 2 conflicting ...
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2answers
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 ...