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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Strange double-spending attack possibility
In Bitcoin you can have different UTXO with different public keys in a single transaction.
So suppose someone broadcasts a transaction with sending 10000 BTC. Theoretically I can copy this transaction,...
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is consensus needed when double spend attacks cannot happen(assume ideal case)
Suppose double spend attacks cannot happen(assume senders, miners etc are all ideal actors) in a network like BTC for cryptocurrency transactions. I am assuming still fork can happen if two miners ...
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Why is not good having forks in a blockchain?
To be more specific, if I imagine to work with isolated transactions chained to each other according to money flow, then I understand that we wish to have a single chain because forks would mean the ...
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What happens if I `sendrawtransaction` but tx is invalid?
I manually select from my UTXOs, sign the tx (offline programmatical signing, not with wallet) and only interact with bitcoind when I call sendrawtransaction. But in the meantime another process might ...
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Transaction with txin, which ran out of money
How does transaction validation verify that I am not trying to send transactions with the same txin? Does transaction validation go through all the blocks and make sure I'm not trying to write off ...
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Be notified when node rejects TX from mempool
I need to be notified on my C# backend implementing NBitcoin when my node detects a double spend and rejects a TX from its Mempool.
Is there a RPC call or some kind of events that I can register to to ...
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How is the double-spend problem related to the Byzantine generals problem?
I’ve read that Bitcoin’s key innovation is solving the double-spend problem. I’ve also read that Bitcoin solves the Byzantine generals problem.
Are the double-spend and the Byzantine generals problem ...
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Modelling random walks for double spending based on hashrate
I'm reading Analysis of hashrate-based double-spending where the following assumptions are made (on page 5):
The total hashrate of the honest network and the attacker is constant, say H. Let the ...
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How 2 chains co-exist together?
I am not able to understand, how 2 chains co-exist together, like these were the observations which are ambiguity for me:
In one reading I have read, Only longest chain is valid and and rest chains ...
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How does Bitcoin prevent double-spending without penalizing miners?
In the network nodes below as shown in picture:
Let's say A is trying to double spend by sending bitcoins to B,C (A->B) and (A->C) and let's say A tried to relay (A->B) transaction to honest ...
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Can miners double-spend with two transactions in one block?
Let's say Alice sends 5 BTC to Bob and Alice tries to make double spending by again sending those same 5 BTC inputs to carl and lets say that Alice is also a one of the miner node.
Here Alice tries ...
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What is an inflationary bug in the context of bitcoin?
I often hear that the worst bug that could impact bitcoin is an inflationary bug.
But what exactly is meant by 'inflationary bug'?
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Why does the network allow a fraudster (double spender) to broadcast a transaction to a single node (the victim)?
Let's assume for the sake of argument that a fraudster is able to create blocks faster than the rest of the network. Given that, they would be able to achieve double spending by making a fraudulent ...
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What stage of the bitcoin protocol deals (or 'solves') the double-spend problem?
I understand that a key innovation in bitcoin is that it solves a key problem faced by previous attempts at a digital currency: the double-spend problem.
In addition, I also understand that the ...
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Double Spend for small value transactions
maybe a naive q, but I read in a book that for small value items you don't really need to wait for confirmation of a BTC transaction (i.e. dont need to wait for it to be added to a block):
I ...
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Why does the longest chain rule make the most sense to deter double spending?
If there is double spending occuring, I don't understand why the longest chain rule would decrease the likelihood for only one transaction to be confirmed.
Can someone explain step by step why this ...
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what kind of a double spend attack is a career attack?
there is an article that name different type of double spent attach like "Several variations of attacks could allow miners with bad intentions to double spend. Included are the Finney attack, ...
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Can Finney attacks only be made by miners?
I read this article about double spending attacks. The article has a sentence that goes like this:
"Finney attacks can only be executed by miners, and are therefore fairly technical and obscure.&...
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What is the downside of having a default setting in which nodes will invalidate blocks that comprise a surprise reorg?
Suppose that suddenly, out of nowhere, a longest-chain appears that reorgs the last 15 blocks. Such an attack could be accomplished from time-to-time even by a minority attacker who is either lucky ...
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What verb best describes "causing another block to become stale"?
For example, suppose I'm selfish mining; you publish a block and then I immediately publish two, what did I do to your block?
Similarly, if I'm executing a double-spend attack, my goal is to ?___? the ...
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Why is PoW even necessary?
So I understand the concept behind PoW (that if someone wants to overturn the current chain, they'd have to do all that work again).
But why is it even necessary since transactions are confirmed only ...
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Why won't the second transaction pass the confirmation process
I'm reading How does a block chain prevent double-spending of Bitcoins?
, and it says
The first transaction would be approved via the confirmation mechanism and then verified into the subsequent ...
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What happens if a transaction is duplicated across different blocks?
I'm sure I am missing something trivial here but I have a question.
Let's say there are Node A and Node B. We send a transaction to both nodes. Both nodes now contain an unconfirmed transaction in ...
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How can double-spending occur?
I'm new to Bitcoin and trying to understand how the double-spending problem can occur and implicitly, the need for "mining".
Let's say Bitcoin worked the following way:
In the network, one ...
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Where is there a graph of total miner revenue (BTC) per unit time (e.g. day)?
Basically I'm looking for this graph, but denominated in BTC https://www.blockchain.com/charts/miners-revenue or this graph plus the block reward https://www.blockchain.com/charts/transaction-fees
I'...
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Noob question: Why is there not a limit of the number of blocks in a chain revision?
I have a noob idea and I want to understand where I'm going wrong :)
Say nodes agreed on a block revision limit, say, 6. This would mean that if they see an incoming chain that is longer than the ...
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If there was an easy way to check for double spends, will consensus algorithms be needed?
Currently, checking for double spends is very computationally expensive, so consensus algorithms, like POW, were put in place to more easily prevent double spends among other things.
Ignoring the fact ...
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What happens if a miner deliberately ignores a transaction, and "wins"?
Suppose a miner decides to solve the nonce for a particular block, where the miner deliberately excluded a particular transaction from this block. The miner "wins", i.e. they found the nonce ...
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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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How Bitcoin avoids double spending?
If someone is sending bitcoin with low transaction fees and then sends the same bitcoin with higher transaction fees before the previous one is confirmed, so it is obvious that miners will pick the ...
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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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