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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40
votes
2answers
5k views

How does Ripple solve the double-spend problem?

How does the Ripple system solve the double-spend problem? Does it also use some block-chain-like entity that officially dictates which transactions are confirmed and which are not, or does it use ...
4
votes
2answers
789 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 ...
5
votes
1answer
231 views

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 ...
3
votes
1answer
254 views

Double spending from “green addresses” & mitigation

Suppose a user pays for a service (service1) using a "green address" (0 confirmations required) and service1 needs to immediately respend it using it's own green address How many blocks should the ...
1
vote
1answer
226 views

In a given contract, should the “LockTime” timestamp include an extra hour for confirmations to prevent a double spend?

Anytime a transaction has a timestamp attached to it, and there are signed but not submitted transactions at play, shouldn't the holder of the non-submitted tx have to take into account the ...
25
votes
3answers
37k views

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?
32
votes
2answers
14k 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".
1
vote
2answers
204 views

Without being continuously connected to the network, how can I protect from Double Spend attacks?

I'm a vendor who is interested in protecting myself from double spend attacks. What software, configuration, connectivity, or timeout is required to mitigate this risk? Namely, how would I protect ...
4
votes
1answer
304 views

How to force bitcoind to include a specific transaction as an input of another transaction?

I would want to force bitcoind to include a specific transaction as an input of another transaction. This is so as to prevent people front wanting to launch a double-spend attack on the website. The ...
7
votes
7answers
2k 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 ...
2
votes
1answer
311 views

My wallet won't load because it says it contained a duplicate transaction. Are my coins lost forever or can i load it some other way?

Question pretty much says my dilemma. Wallet won't load due to a "duplicate transaction" which I thought could not happen. I use multibit btw, if that helps. Please tell me I can load my wallet ...
5
votes
1answer
2k views

What to do about a “stuck” transaction?

I started the standard client with --rescan instead of -rescan after switching wallets and before synchronizing with the latest blockchain, and made an going transaction. This transaction got "stuck",...
6
votes
1answer
1k views

What does a double spend look like?

What does a double spend look like? Can anyone link to an example on blockchain.info? Will invalid half of the double spend simply remain at 0-confirmations, or might it ever reach 1 or 2? Will the ...
5
votes
1answer
2k views

How to clear invalid transactions from one's wallet?

I've recently been testing double-spend attacks against myself using a couple wallets, and the standard client does not appear to clear conflicting transactions from its transaction list, even if the ...
8
votes
3answers
4k views

What is the best way to recover from an accidental double-spend?

Came across an issue where I was given the message: "Error: The transaction was rejected. This might happen if some of the coins in your wallet were already spent, such as if you used a copy of ...
14
votes
2answers
1k views

Does any pool accept higher-fee transactions of a double spend, instead of the earlier one?

Some pools use a modified bitcoind that uses different rules for choosing the transactions to include in a block. Are there any pools that knowing one transaction to be included in a block would ...
11
votes
2answers
1k views

Double spend attack by sending higher fee transaction directly to the pools possible?

The standard client prioritizes TXs by the time of receipt, e.g. a conflicting transaction will not be relayed. This is not enforced by the network, though. Is there anything that would prevent this ...
8
votes
2answers
840 views

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 ...
7
votes
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 ...
5
votes
2answers
607 views

How to perform a double spend attack in websites that accept transactions with 0 confirmations?

To perform a Finney attack or a 51% attack I need to have lots of computational power, but in this case (a website that accepts transactions with 0 confirmations) it seems to me that I only need to ...
7
votes
4answers
234 views

Do no-fee transaction represent a greater risk if the product is delivered instantly?

Let's say I want to accept payments instantly on a site for digital downloads. So I publish an address and wait for the unconfirmed transaction, I see the transaction and release the digital download....
15
votes
1answer
976 views

Would a reduced block generation time make the Finney attack more difficult?

Related Question: What can be done to mitigate the risk of a Finney attack? The Finney attack is a form of double-spending attack where the attacker pre-mines a block containing a conflicting ...
11
votes
2answers
587 views

In a double spend attempt, how is the valid transaction chosen?

Suppose I publish the private key of an address that contains 1 bitcoin. If two people try to transfer this bitcoin to another address before a new block is found, who gets it? How is this decision ...
21
votes
1answer
3k views

What does the Bitcoin client do when it receives conflicting transactions?

I've been assuming that the second transaction will simply be discarded as invalid, while the first waits at 0/unconfirmed until it actually gets into a block (requiring a "-rescan" or similar if the ...
28
votes
5answers
5k views

Has there ever been a successful double spend attack on the Bitcoin network? If not, is it really necessary to wait for confirmations?

There is a lot of concern about waiting for confirmations to avoid a double spend attack, but has there ever actually been a double spend attack? It seems to be that there are two types of double ...
54
votes
7answers
44k 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 ...