Bitcoin Stack Exchange
Bitcoin Stack Exchange

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.

In Bitcoin, double spends are impossible. A transaction that spends money already spent in another transaction will never be valid and confirmed. However unconfirmed transactions can conflict by spending money spent by another unconfirmed transaction. Double spends are often used to defraud merchants by allowing a customer to not pay the merchant. The risk of double spends is the primary reason that merchants wait for one or more confirmations before accepting a Bitcoin transaction.

282 questions
9
votes
3 answers

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?
frmsaul
  • 191
  • 1
  • 2
8
votes
2 answers

How does blockchain.info detect double spends?

http://blockchain.info/tx-index/242749/36080ed09eeb0fd66ad5dc8a909a49e364f55ff860c12327c2ff9fbe4a9dde77 Warning! this transaction is a double spend. You should be extremely careful when trusting any transactions to/from this sender.
ripper234
  • 26,550
  • 30
  • 111
  • 246
8
votes
4 answers

How do people actually try double-spends?

I've occasionally seen people online claiming they were victims of a double-spend because they handed over something of value in exchange for a bitcoin payment with no confirmations. Although I understand this is theoretically possible, how would…
RentFree
  • 2,539
  • 2
  • 20
  • 36
5
votes
1 answer

What can happen if/when a node is surrounded by rogue nodes?

If a node (V) accepts incoming connections, is he vulnerable to becoming completely surrounded by corrupted nodes? Would an attacker be able to control which transactions are relayed to V and which transactions V is able to broadcast to the…
Ploo
  • 101
  • 2
5
votes
1 answer

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?
Felipe
  • 1,738
  • 3
  • 19
  • 33
4
votes
2 answers

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 have doubled my coins? I know that they are not…
shredding
  • 143
  • 3
3
votes
1 answer

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. Steps to reproduce: I have 2 regtest nodes;…
zono
  • 1,935
  • 1
  • 20
  • 35
2
votes
1 answer

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 bitcoin? P.S. Given two transactions are conflicting,…
Ali Shakiba
  • 123
  • 4
2
votes
1 answer

Who first defined/coined The Double-Spending Problem?

The Double-Spending problem is a variant of the Byzantine Generals Problem which has a nice write up by Lamport, Shostak and Pease. But who first coined/defined the specific Double-Spending problem? Or linked the BGP to the digital currency domain?…
Johnstedt
  • 23
  • 4
2
votes
3 answers

Are bitcoins (or fractions of bitcoins) labeled with IDs?

Many sources describe the double spending problem by saying something like "people cannot be able to spend the same bitcoin twice." [1][2][3] So are bitcoins, or the smallest allowable bitcoin fractions, distinctly labeled entities? My understanding…
WillG
  • 123
  • 4
2
votes
2 answers

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?
user3785008
  • 23
  • 3
2
votes
2 answers

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/60821723b93e2ae5ed729e93c22ca824e7e91fe5a16cba3468139657dc953abc
zono
  • 1,935
  • 1
  • 20
  • 35
2
votes
1 answer

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't understand why do we need a proof of work if…
blockFrance
  • 41
  • 2
2
votes
3 answers

What's the easiest way to someone to double-spend 0-confirmation transactions?

I heard there is a desktop app today that 'easily double spends 0-conf tx'. Which is it? Is anyone working on a mobile version of this app?
ripper234
  • 26,550
  • 30
  • 111
  • 246
2
votes
1 answer

Double spending race attack first transaction

In tackling double spending, does the protocol enforces that only the first transaction (and by first i mean the first transaction to be send to the network) is considered as valid ?
perencia
  • 178
  • 6
1
2 3