"Double-Spending" is an attack or failure which results in the same digital moneys being spent twice or more.

learn more… | top users | synonyms

4
votes
1answer
79 views

Bitcoin without mining - what needs to be implemented

I have read this related question - Bitcoin without mining and I am trying to understand the very basics of Bitcoin network and the blockchain. I wonder, if we take the mining out of Bitcoin, what ...
8
votes
1answer
45 views

Merchant tool that will dynamically adjust the # of required confirmations based on network hashrate data

Satoshi built Bitcoin to be a decentralized network. Some of the original recommendations (such as waiting for 6 confirmations) relied on statistics that related to level of decentralization. ...
5
votes
2answers
69 views

Double Spending before confirmation

What's to prevent someone from using bitcoin at a store like subway and double spending to buy the sandwich before a confirmation is made? Since subway obviously isn't going to wait for a ...
0
votes
1answer
56 views

How to pratically doublespend bitcoins?

I tried to put bitcoins into an p2p exchange with bitcoin-qt. I added a to small transaction fee, so the coins are now stuck as "Unconfirmed". The offer from the exchange is overdue, so all that will ...
1
vote
1answer
29 views

What makes an unconfirmed tx 'suspicious'? (likely to be replaced or never confirm)

When looking at Bitcoin unconfirmed transactions, I'm trying to distinguish between txs that are likely to confirm (whether that be in the first next block or in 2 hours) versus txs that are likely to ...
0
votes
1answer
75 views

Restrict the Bitcoin usage only during a particular period

I would like to know if its possible to use a Bitcoin at present in the following scenario. When I send a Bitcoin to an another user,I set certain parameters on the Bitcoin, like it can only be used ...
-1
votes
1answer
50 views

How many confirmations do bitcoin escrow websites wait on average?

To me it seems very dangerous not to wait for 6 confirmations when running an escrow. The scenario I'm thinking of: a miner deposits a large sum of bitcoins the escrow waits for one or two ...
4
votes
3answers
87 views

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?
6
votes
2answers
71 views

Why is Poisson instead of Negative Binomial used for computing attacker's potential progress?

In the chapter 11 of the Satoshi's paper found at http://bitcoin.org/bitcoin.pdf, it is claimed that: The recipient waits until the transaction has been added to a block and z blocks have been linked ...
1
vote
1answer
54 views

How to track and handle double-spend attacks?

If a double-spend attack is pulled off, how to manually verify transactions via the bitcoin daemon and how to know how much amount lost? Will the saved transaction hash be re-usable to obtain info ...
0
votes
2answers
67 views

Paranoid Merchants on double spending [closed]

How can merchants be alerted of Double-spending attacks? Let us take a hypothetical case where a merchant offer a BTC deposit wallet to his users, User deposits Bitcoins and it's credited to his ...
0
votes
1answer
52 views

Details in double spend detection [duplicate]

I'm confused with the details in double spend detection. my question is if Alice first sends her 10 BTC to Bob, and then sends the same 10 BTC to an address that belongs to herself. How do Bitcoin ...
0
votes
2answers
94 views

Will an attacker's forked branch of block chain be used in bitcoin confirmation?

From what I understand, transactions are agglomerated into a block, proof of work is done by computing a hash value for the block, then added to the block chain. When a block is added to the block ...
1
vote
1answer
50 views

Why can't a transaction be redirected after it is signed? [duplicate]

Scenario: Step 1: User-1 initiates the TXN-1 to pay to User-2 and the TXN is not yet confirmed with the ongoing block POW. Step 2: What prevents fraudster (anyone a miner or someone ...
1
vote
1answer
86 views

What is the risk of waiting for just one confirmation to validate a transaction, assuming the counterparty is not a miner?

I am trying to determine how many confirmations would be reasonably safe to wait before accepting a Bitcoin transaction from an attacker that is not a miner and hence cannot rely on Finney attacks, ...
2
votes
1answer
98 views

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 ...
3
votes
2answers
139 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 ...
1
vote
1answer
77 views

Can a malicious majority miner rewrite history?

Is it the case that a malicious miner with the majority of hash power (say, 99%) can perform a double-spending attack by rewriting history? If so, I can't understand how. If not, under what ...
0
votes
1answer
72 views

Bitcoins stuck - No double spend possible

I have a problem with my address 1Dss5sKJDZ1Kkhh3KRyoekeZpC4S1WehD. As you can see, I transferred money to the same address by mistake - without any fee. The transaction ...
2
votes
2answers
184 views

When are multiple transactions spending the same output in the same block considered a double spend?

Here is an example of multiple transactions in the same block, all spending from the same output. I created these using the Electrum wallet, telling Electrum to spend a little bit of the BTC from the ...
1
vote
1answer
83 views

What are the chances of someone coming up with a new and simple/out-of-the-box solution for the double-spending problem?

The proof-of-work solution is simple but has many drawbacks (waste of time, energy and uncertainties about its security in the future). The consensus solutions proposed by Ripple/Stellar are too ...
3
votes
1answer
60 views

Why it is not possible for a payee to verify double-spends of the coin?

I'm reading Bitcoin paper of Satoshi Nakamoto (https://bitcoin.org/bitcoin.pdf). It says: Each owner transfers the coin to the next by digitally signing a hash of the previous transaction and ...
1
vote
1answer
91 views

How do I detect a double-spend in real-time, like Bitpay?

By Bitpay to pay only take 10 seconds to complete. How do they do it?
2
votes
1answer
98 views

What would you do while a hard fork lasts?

It is conceivable (though generally buried with cognitive dissonance, I imagine) that a hard fork might not get resolved. This almost happened once before, and the miners picked the fork that solved ...
1
vote
2answers
534 views

Where is coinbase transaction after a hacker successfully performs >50% attack?

Here is the scenario: Honest nodes build one block from Block_1. Hacker nodes privately build four blocks from Block_1 and broadcast these malicious blocks. Now, where is the honest node's ...
0
votes
3answers
754 views

How many confirmation do i have to wait before i can spend the inputs I already received?

Can I spend Inputs with 0 confirmations?? If I could, are there some restrictions?
2
votes
2answers
109 views

What can a dishonest node do (or try to do)?

Except this kind of attacks: https://en.bitcoin.it/wiki/Double-spending For example can he simply create a new block that includes some invented transactions that steal money from real address? ...
5
votes
1answer
164 views

Speeding up confirmation by double-spending a transaction stuck in mempool

In the context of no-fee transactions that can take a long time to get their first confirmation, is it possible to use raw transactions and double-spend the original transaction by broadcasting ...
0
votes
1answer
51 views

How would this double spend attack be prevented?

I know, that a user cannot create a fork in the chain. Also, it is said, that since every transaction is publicly announced, any attempt of double-spend on the same chain would be rejected as the ...
1
vote
1answer
189 views

Is it possible to use Selfish Mining to steal bitcoins?

Is it possible to use the Selfish Mining algorithm to steal bitcoins?
0
votes
2answers
63 views

Using Transaction with multiple outputs

Since the output can be spend only once, I am confused by transactions containing multiple recipients. For example, if Alice transfers 5 BTC to Bob and 5 BTC to David in the same transactions. In the ...
4
votes
3answers
476 views

Why doesn't bitcoin place additional constraints on competing block chain forks, other than length of chain? (e.g., time and confirmation count)

In Bitcoin's proof-of-work system, consensus on which chain of blocks should be considered the "true" block chain is based only(?) on which chain is longer. Accordingly, to quote a nicely written ...
4
votes
1answer
98 views

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?
2
votes
2answers
883 views

How does ShapeShift operate on 0-1 confirmations

ShapeShift can exchange user's crypto currency almost instantly. They state that most transactions don't require any confirmations: Small deposits are processed with zero confirmations. Larger ...
3
votes
2answers
232 views

Blockchain for internet-of-things or is there any mining algorithm that can be utilized in low-computational power devices preserving security?

Recently IBM and Microsoft showed their interest (IBM post, Microsoft post) in utilization of blockchain for internet of things development. Let's assume that in close future the blockchain technique ...
3
votes
1answer
149 views

What happens if a miner confirms their own double spend?

Suppose an attacker makes a double-spend and controls the mining pool that happens to find the good which confirms the transactions. What happens? I suppose the network hopes that a vigilante sees ...
0
votes
3answers
121 views

What happens if a TX was a double spend?

What happens if the 'High' risk option (one confirmation) was chosen and then the TX turns out to be a double spend in the end? Would the value deposited be revoked? Would the user be notified ...
0
votes
1answer
70 views

How do you inspect a transaction?

How do you inspect a bitcoin transaction to avoid getting scammed by a double spender? I'm buying bitcoins in cash and the seller said I could inspect a transaction instead of waiting 6 blocks. Is ...
0
votes
1answer
81 views

How to detect a race attack and re-spend the already-spent outputs?

My service automatically accepts, processes and sends payments to its users. It connects to bitcoind through its JSON-RPC API and makes use of the raw transactions interface. What is going to happen ...
5
votes
2answers
504 views

Double Spending - Does each node maintain a list of unspent transaction references?

My Understanding Of How Bitcoin Prevents Double Spending Each transaction contains references to the input transactions and ever node has to verify all transactions from time immemorial to ensure ...
-1
votes
2answers
148 views

How to recover from a double spending attack?

I found myself incapable of answering what would happen in this case, so here it is: A hacker (Mr Hacker) spends UTXO_1 and UTXO_2 in TX_1, depositing the monetary value of all TX_1's outputs into a ...
1
vote
1answer
113 views

JSON-RPC to detect double-spent TXs

How can I be positive that one of the incoming payments to my bitcoin-core was double-spent after it was confirmed once by the network, through the JSON-RPC interface? Related questions: How do I ...
2
votes
3answers
449 views

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?
1
vote
0answers
148 views

Why are double-spends bad? [duplicate]

In the answer to this question it is stated the bitcoind filters doublespends. What is the reasoning behind this?
1
vote
1answer
162 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.
1
vote
1answer
531 views

Warning about possible double spend at blockchain.info

What does this blockchain.info alert mean? Warning! this bitcoin address contains transactions which may be double spends. You should be extremely careful when trusting any transactions to or from ...
2
votes
2answers
668 views

How is a Transaction Output Marked as Spent?

The Bitcoin developer guide states that each output of a particular transaction can only be used as an input once in the block chain. Any subsequent reference is a forbidden double spend—an ...
5
votes
2answers
110 views

Double spend transactions flag the node as “bad”?

I'm playing with raw transactions. It's easy to send two signed valid transactions at the same time from the same output to different addresses (making a double-spend attack). My doubt is: if I make ...
6
votes
2answers
478 views

Could any standard fee transaction be double spent by using a higher fee?

I realize that if somebody makes a transaction without any fees and there have not yet been any confirmations, then the transaction could be double spent by just spending the same inputs to a ...
7
votes
3answers
167 views

Does using Ripple to accept Bitcoin reduce risk of Bitcoin fraud?

Does Ripple reduce the risk of double-spending, or other types of issues that may crop up when using Bitcoin natively?