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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29 views

How to create a double spend to prioritize a new transaction over a previous unconfirmed transaction?

I'd like to generate a double spend transaction and increase the gas fees over the previous, unconfirmed transaction that has been stuck for a week. I know there's other answers regarding double spend ...
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322 views

Double spending on testnet or regtest?

I'm currently doing a research on bitcoin and I would like to know if there is anyway to replicate double spending in the testnet or regtest? If isn't possible is there any other type of "attacks" ...
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Why don't bitcoin nodes invalidate new blockchains that don't contain all the data of the old blockchain?

If nodes only accepted new valid blockchains that contained all the data of the old blockchain, then miners will still be able to add blocks to the current blockchain because their blockchain will ...
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44 views

Duplicate Transaction Prevention

I'm trying to understand Bitcoin a bit more and I'm struggling to find an answer for this scenario. Say for example I have access to a wallet and I have give a person on the other side of the world ...
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2answers
93 views

Mitigating a Double Spend Attack by Punishing the Attacker?

One of the main reasons it's not safe to accept Bitcoin with 0 confirmations is due to the possibility of a double spend (where Mr. Scammer first sends 1 BTC to Alice and then creates an identical ...
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terminology and conceptual question about progress of PoW

what is wrong about thinking prbobability of attacker increases with time t that goes into PoW since they have more time to secretly mine their alternate blockchain ? This refer to double ...
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339 views

Is there any software available for testing of Bitcoin security?

I'm currently in the process of working on my thesis about Bitcoin security and I'm wondering if there's any software available for testing of Bitcoin security? For example, are there any programs ...
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1answer
38 views

What were some discussed and current potential issues with pre-forked Bitcoin coins from August 2017 that have never moved since then?

I was speaking to a friend that mentioned that there were issues with pre-forked Bitcoin coins from Aug 2017 that never moved. He wouldn't tell me exactly what the potential issue was, but what were ...
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1answer
155 views

Would first-seen prevent a double spend attack?

It takes approx. 8 seconds for a transaction to propagate through the entire Bitcoin network. If we got rid of the concept of replace-by-fee and replaced it (no pun intended) with a first-seen ...
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1answer
53 views

Exchange Confirmation Requirements

What does the minimum confirmations required for a deposit mean for the security of exchanges? For example, Coinbase requires 3 confirmations for Bitcoin deposits. Suppose an adversary deposits 10 ...
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1answer
56 views

Does difficulty adjustment apply when you mine in secret?

Imagine you have an enormous amount of hashpower (say a nation state level attack) and you mine in secret. Does the difficulty adjustment apply specifically to your secret chain? Because that would ...
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1answer
33 views

Do you have to keep broadcasting transactions until mined?

From what I know, you can broadcast a transaction including input addresses, output addresses, and amounts, which is signed by your private key. I often hear that your transaction might not be mined ...
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1answer
64 views

Safely Accept Bitcoin Payments with 0 Confirmations [duplicate]

GAP600 is a service (that has processed $5 billion in cryptocurrency) which allows exchanges and payment service providers to process Bitcoin payments instantly (0 confirmation trx). It guarantees a ...
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29 views

Why can the race between the honest chain and an attacker chain be characterized as a Binomial Random Walk?

I am not familiar with Bitcoin, hope someone can tell me why. Thank you! Let's consider the following scenario. The probability of the attacker finds the next block is q and the probability of the ...
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1answer
31 views

Is PoW and consensus unnecessary without double spending?

Satoshi's whitepaper claims that the reason there must be a consensus on all transactions is to solve the problem of double spend. I'm curious then, how would a non-consensus based system work if ...
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61 views

Notable examples of double-spends

Do you know any real-world examples of double-spends, where the second transaction was accepted to the block? There's https://doublespend.cash/ for BCH but for BTC I would like some examples where the ...
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Which transaction would get confirmed in an uncongested network?

Scenario: Mallory sends some bitcoin with a $1 fee Later, Mallory double spends her transaction with a $5 fee A new block is found In an uncongested network with an average transaction fee of ~20 ...
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1answer
69 views

why is transaction history from genesis to date necessary to store on the blockchain to prevent double spending?

I am beginning to understand the mechanism of bitcoin blockchain, and I was wondering something. The transactions history represents the 'state' of the bitcoin at any point (or EVM according to the ...
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3k views

Negative Bitcoin Balance

I was playing around with bitcoin and I discovered an address that appears to have a negative balance on the blockchain. The details of this address are below. At the time of writing the blockchain ...
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1answer
52 views

How the bitcoin network solves the double-spending problem by adding all the transactions that happened at the same time into one block

According to my research, I understand if person A sends 2 BTC to person B and at the same time person A sends the same input to himself before the input is considered as spent. So, now there will be ...
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3answers
304 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 ...
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1answer
44 views

double spend the mempool to outbid an attacker

if I spend some input in a tx and a few seconds later spends the same input with other inputs in another tx with higher fees. If the first tx is still in the mempool would the 2nd tx replace the first ...
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1answer
91 views

how does bitcoin solve the same chain replay attack?

Let's say I send 10BTC to Bob. I have 30 BTC. So after transferring, I should have 20. Now, after I transfered 10, transaction can be copied and broadcasted to the network again by Bob(he might have ...
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33 views

How does longest chain propagation take place in bitcoin?

Let's say the valid blockchain that Node A has is: B1->B2->B3 Now, I am gonna cheat since I have lots of computing power. What I do is I download the above blockchain that Node A has and start ...
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3answers
190 views

Does double spending happen at all?

I'm a complete beginner to anything and everything about crypto. I've been trying to research a lot about it, and I have recently just been trying to learn and understand some of the basics. I was ...
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2answers
206 views

How would one relay a raw tx double spend to a node that accepts it?

All of the pushtx sites reject the tx as a double spend. Would I have to run my own node through bitcoind? How would one do this?
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How to find if two transactions in mempool are conflicting?

There are lots of transactions over the mempool of the bitoin. However, there might be double spends. How can we verify whether two transactions are conflicting, i.e. they are double spends of a ...
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What is a double spend?

What is a double spend? As someone who uses Bitcoin, what do I need to know about how the Bitcoin system prevents double spends? Are there still circumstances where they can occur?
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Could it be possible to secure transactions against double-spending with other utxos?

I'm new to Bitcoin Script, and I was wondering if it is possible to use funds from one utxo to "insure" that other utxo will not be double-spent (until the Lightning Network will save us all). Suppose ...
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2answers
3k views

How does a double spend get resolved when two miners find conflicting blocks at the same time?

I was trying to learn about Bitcoin and its flow. Actually, I was stuck how the control flows in solving the double spend. For eg. if Ta and Tb are a double spend of the same transaction with ...
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4answers
191 views

If two parties submit a conflicting transaction between each other, how does the network decide which one is correct?

Let's say parties A and B both submit a transaction to the blockchain with a different version of what happened. Party A submits a transaction saying Party B gave him 3 BTC and Party B submits a ...
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1answer
658 views

Bitcoin Transaction Stuck, Attempt to double spend with higher fees [duplicate]

I made a BTC transaction a few days ago, where I set the fee amount way too low. It seemed that the transaction was lost in limbo. I did some research, and apparently you are able to double spend ...
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2answers
76 views

Cryptocurrency acceptance

I heard that the recommended waiting confirmation time for a bitcoin transaction is 6 blocks/ 1 hour. So a shop which lets its customer to pay in bitcoin without any waiting for confirmation would ...
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60 views

Wallet's role in a double spend attack

How does my wallet allow me to double spend? As soon as I make a payment, shouldn't my wallet delete those bitcoins or does it leave them until the transaction is added into the blockchain?
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1answer
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Handling “dead” (double-spent) transactions in my mempool

Say I receive transaction A and it is in my node's mempool and unconfirmed. Then a block gets mined directly, which spends one of transaction A's inputs, rendering transaction A invalid. What can I ...
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69 views

Double spending problem in Bitcoin

Suppose Alice sent 2 bitcoins to Bob, Bob ships the product to Alice, then Alice sends 2 bitcoins to herself. Why is this a problem ? If both the transactions are approved then also Bob gets his 2 ...
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1answer
41 views

If I were executing a 51% attack, would I be broadcasting my state of the network to nodes?

In the scenario where an entity has control of greater than 51% of the hash power and wishes to build a longer chain where they double-spend previously confirmed transactions, do they broadcast the ...
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1answer
115 views

How does the blockchain prevent spending money during a “short fork”?

I'm currently reading "Mastering Bitcoin" (i haven't finished it tho, but i don't see my answer and it bother me so I prefer asking it here) and there's something i don't understand. So from what I ...
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1answer
61 views

Understand double spending through an example

Let’s suppose you have 1 BTC which you try to spend twice. You made the 1 BTC transaction to a merchant (Transaction T1). Now, you again sign and send the same 1 BTC on another Bitcoin address to try ...
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1answer
71 views

What happens if I spend a double spend?

Given I can receive a double spend and potentially re-spend it after 1 confirmation, what happens to that transaction once the double spend is detected during a blockchain reorg?
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1answer
383 views

Which wallets support double spending?

Which wallets support double spending? i.e. cancelling a transaction with 0 confirmations by using higher fees
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1answer
28 views

Double Spend Behavior on First Network Propagation

Supposing there is a double spend, call the transactions T1 and T2. If someone propagated both transactions within a short space of time to the network, of course only one of them can make it into the ...
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241 views

Single tx included in two different blocks

https://www.blockchain.com/btc/tx/a7bacce00e5df85d3547a3f83ac10c65eec30f715c1d77d8d4a7bc17fd470965 How is it possible that a single tx is included in two different blocks? Isn't it considered double ...
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1answer
79 views

reproduce CVE-2018-17144 (inflation bug) on regtest for learning

I'm reviewing CVE-2018-17144 inflation vulnerability for learning. I think I reproduced the error on regtest. Is it a correct way to reproduce it? I want to know if I'm missing something about it. ...
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1answer
576 views

Does proof-of-work contribute directly to prevent double-spending?

I know similar questions have been asked before (e.g. How proof of work prevents double spend) but I'm struggling to visualise the solution to double-spending being directly reliant on proof of work. ...
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1answer
82 views

How to prevent double spending Bitcoins?

If I create a transaction, my node will check my UTXO's and if i have enough BTC to do this transaction it will be mined. So let's say I want to spend 12 BTC to Anna. The System will check if i ...
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4k 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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Bitcoin, BTC.com and monitoring double-spend attempts

I'm reading Analysis of hashrate-based double-spending article. On page 10 there's a table listing probability of successful double-spend attack in relation to required number of confirmation. ...
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15k views

What is a Finney attack?

What is a Finney attack? Extra points for explaining its purpose, the prerequisites for it to be possible, how the attack can be performed and the origin of the name "Finney attack".
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280 views

Can a malicious Internet Service provider launch a double spend attack?

If a malicious internet service provider completely controls a user's connection, can it launch a double-spend attack against the user? How much computational effort would this take?

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