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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35
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2answers
16k 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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2answers
448 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?
2
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1answer
51 views

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? ...
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3answers
156 views

What happen when 2 transactions with one doublespending the other reachs the same block?

Let’s have 2 transactions. The second one is duplicating Input of the first one. Both have very high fees so they are selected by miner to be included in the same block but before passing validation (...
2
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1answer
676 views

Proof of Stake - double spending

I'm unsure how Proof of Stake prevents double spending. In PoW it's evident that I need 51% of the hashing power of the network, to "overtake" the real chain with my fraudulent fork. But what stops ...
5
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1answer
3k views

Can someone explain this double spend on blockchain.info?

I'm confused by double-spend linked below, in which both transactions ended up in blocks mined by different miners. Specifically, I'm wondering if there's any way to tell what exactly happened based ...
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2answers
2k views

How to minimize risk when accepting zero confirmation payments?

I'm trying to setup a way of accepting Bitcoin payments in real life situations, where waiting for confirmations is typically not an option. I understand this is never 100% risk free (especially with ...
5
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2answers
674 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 ...
2
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2answers
217 views

How confirm my own doublespend transaction got confirmed

Transactions in the testnet are right now almost always double spent with a new txid (possible due to tx malleability). This is actually quite nice for testing purposes. So I'm wondering - when I ...
3
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1answer
1k views

My blockchain.info wallet was hacked. How can I create a double send to foil the attacker?

This is the transaction. https://blockchain.info/address/1F8EP97jgQx8QD6XMRg2bCHHrJrZEMUTRt Which is still unconfirmed. I am trying to use https://coinb.in to create a double spend transaction with ...
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1answer
499 views

Ripple's validation of transactions / Ripple white paper?

Is there a ripple white paper or some safe source to understand how the transactions are validated and made in the ripple network? VS Bitcoin, XRP is not mined, so how is the agreement reached? (I ...
4
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1answer
85 views

Why isn't the block hash used to calculate accumulated work?

Why is this idea flawed? It doesn't seem to be a bad idea at first, because the miners should be incentivized to extend existing chain, instead of to "remine existing blocks", since such "remining" ...
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2answers
2k views

What is the Ripple equivalent of the “51% attack?”

In Bitcoin, if a participant gains control of more than 50% of the hash power, they can execute a double-spending attack. The "attack" could come from within, say if the existing powerful miners ...
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2answers
209 views

Can two or more transactions sent from the same address be mined in the same block in Bitcoin's blockchain?

Imagine a person Bob has 10 bitcoins in his wallet. He wants to send 5 bitcoins to Alice and another 5 bitcoins to Uncle Tom simultaneously (in separate transactions). Will both Bob's transactions be ...
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1answer
72 views

double spend attack: Is this actually true for the more time progress the higher the probability of success for attacker

I'm new here. I have a question here. Some experts keep saying that this assumption isn't formally correct and I don't really understand why or why they might be wrong. In the double spend attack; ...
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2answers
46 views

can attacker and honest node in double spend ever tie?

in bitcoin white paper there are only attacker and honest nodes. you have p, and q for probabilities. in double spend attack, in bitcoin whitepaper, can we talk about possible tie of attacker and ...
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1answer
41 views

Why “double spent” can only happen if attacker controls 51% (or more) of the network compute power?

As per many descriptions block hash is calculated based on it's headers and nonce field. The latter gives a chance to get the value that is less then a target by incrementing it. If it's a lottery why ...
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0answers
152 views

Sybil attack with IOTA? [closed]

IOTA is one of the DLTs uses DAG (Directed Acyclic Graph) as data structure. The solutions to attacks proposed by IOTA white paper seems unconvincing, in particular, in case of double-spending, it ...
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1answer
55 views

in the white paper you have 2 sides : attacker and honest node

What does it mean that there is either the attacker or honest node. This means that within 10 minutes either attacker or honest node mines a block but what about neither OR another side ? How could ...
1
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1answer
114 views

What does a double spend (CVE-2018-17144) look like if I gettransaction it?

Just wondering what the output from gettransaction (or should I be using getblock?) would look like if I passed it a txid(or blockhash) that contained a set of transactions that exploited the double ...
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1answer
62 views

Is a 51% attack on bitcoin likely?

Given that the majority of bitcoin processing is done in China (source: https://bitcoinmagazine.com/articles/report-links-74-bitcoin-mining-china-sees-threat-network/), is it possible for a single ...
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1answer
109 views

Regarding CVE-2018-17144 and test cases

Regarding the serious bug found (CVE-2018-17144) I am note sure if I understand the full scope of it correctly. As far as I understand, any block containing a double-spend of a transaction output ...
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3answers
88 views

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 ...
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1answer
52 views

double spending problem

Why is double spending a problem. Suppose I have 1 bitcoin and I intend to send 1 btc to Alice and 1 btc to Bob. Once I send 1 btc to Alice, UTXO of 1btc will be unlocked,transferred to Alice.No ...
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1answer
107 views

In Litecoin every single block is mined every 2.5 minutes, double spending?

In Bitcoin it takes roughly 10 minutes for every block to be mined. In Litecoin it takes 2,5 minutes. 2.5 minutes in Litecoin mean that transactions can be confirmed faster. In Bitcoin these 10 ...
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1answer
3k views

How do I double spend using electrum?

I have created a transaction several days ago, with a very low fee. The transaction was meant to remove dust from my wallet, so increasing the fee won't help as the transaction is very big (1.6KB), ...
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1answer
54 views

double spending , you can create money out of thinner air [duplicate]

I am a little confused about how doublespending is done. The basic case is basically creating transactions to the seller and yourself and simultaneously broadcasting those. This is the very classic ...
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1answer
44 views

what does it mean to have >51% hashing power for mining a block? [duplicate]

Can someone please shine some light on this and how it links to the analogy between honest node and attacker ? also can attacker start mining 2 blocks ahead ? or 3 or 4 blocks ahead ? In the white ...
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1answer
46 views

Security via Proof - of - Work

I am reading Satoshi's original paper, merely for the sake of understanding the concept. I have minimal computer science background (some), mostly just mathematics. In Section 4. Proof of Work of ...
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2answers
197 views

What happens if full nodes don't check for double spends or deliberately lets a double spend TX pass and then this full node relays the transaction?

I am studying about Bitcoin and Blockchain tech via the Princeton crypto course, and it mentions that Full nodes do the following checks : i)transaction is valid with the current blockchain, ii)...
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2answers
222 views

Why we need mining?

I know is related to these: What is the rationale behind Bitcoin mining? Why do we need Proof of Work in bitcoin? But I don't fully understand those answers, and I think usually is much easier to ...
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1answer
105 views

What happens to rejected transactions ( i.e double spend or invalid transactions)?

Do they get put in an orphaned block or not get put into any block at all?
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2answers
230 views

Possible error in the white paper Calculations section?

Section 11 presents calculations of the probability of double spending, P(z, q), given an attacker relative hash rate q and a block count z. P(z, q) can only be understood by knowing exactly what z ...
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1answer
2k views

Race Attack vs. Double-Spending Attack: are they same?

Race Attack vs. Double-Spending Attack: are they same? I know definition of both attack both some times it is called as "race attack" and most of the time called as "double-spending". I guess (maybe) ...
2
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4answers
208 views

What can make an unconfirmed transaction (0-conf) an invalid one other than Double-spend?

It's obvious that inputs that already been spent will make the transaction invalid (pure double-spend scenario), but is there's anything else that could make a tx invalid? Invalid inputs? Invalid ...
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2answers
82 views

What is the average time for an honest network to find a block when its hash rate is p?

let p be the hash rate that belongs to honest network and T be the time a block is found. In the Bitcoin paper it's said "assuming the honest blocks took the average expected time per block...". In ...
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1answer
49 views

Can there be double spend between propagation of block chains between 2 set of peers?

It shouldn't be as simple to do a double spend. I think I am missing something here. I understand Consensus rules and P2P networking. But since a node is connected only to some limited number of other ...
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2answers
123 views

How two transactions with the same hash can cause double-spending

Let's consider following situation: Vendor owns address X. Adversary sends transaction T1 to X with hash Y and receives product from vendor. Adversary sends transaction T2 to address which he owns ...
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2answers
242 views

Why are blocks in a permissioned blockchain linked together?

My question: Do the blocks in a blockchain without proof-of-work (i.e. a permissioned blockchain) have to be linked together via a cryptographic hash? Longer version of my question: (Please correct ...
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0answers
27 views

Can low-cost purchases be accepted safely with no confirmations? [duplicate]

From reading online, the general sentiment to this seems to be "no". You need at least 1 confirmation to prevent a double spend attack. But in Mastering Bitcoin, there's this note: A common ...
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1answer
154 views

Is “fee higher than block reward” attack possible?

Imagine the following scenario: I send you 1000 BTC. After 6 confirmations, you give me what I bought. I create another transaction with 900 BTC to my own wallet and 100 BTC as transaction fee, using ...
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1answer
102 views

Mining & The Double Spending Dilemma

My understanding of the double spending problem is as follows: Suppose account A has 1 Bitcoin and sends it to account B and then creates another transaction which sends the same Bitcoin to account ...
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2answers
7k 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 ...
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1answer
137 views

Transactions in a shorter blockchain branch

As I understand it, in a situation where two miners solve a block at the same time, a branch is created on the blockchain which is resolved when one branch is built upon, and thus becomes longer than ...
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1answer
219 views

Double spending UTXOs

I know that the inputs for a transaction(which is not coinbase) are UTXOs. Are UTXOs kept track of by some servers and also the owner's wallet? If there are servers which keep track of UTXOs, is it ...
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2answers
120 views

Can I save stuck bitcoins by creating a completely new transaction? [duplicate]

I tried to make a bitcoin payment but accidently set a too low transaction fee so it got stuck. By now the payment is cancelled so I don't want to do this transaction anymore. Can I now instruct my ...
0
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1answer
886 views

How does the bitcoin exactly prevent Double spending attacks?

I recently started reading about Bitcoin, the idea seems hard to get, and I'm trying to understand the basics now. I read the white paper by Satoshi Nakamoto but I still have some confusions First, ...
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1answer
44 views

In case of a double spend (after double spend and prior getting resolved) what is actual account balance?

For eg. if Ta and Tb are a double spend of the same transaction with different outputs. These two transactions can flow through different path in the network, and assume flow in exactly opposite path. ...
0
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1answer
491 views

why is the double spending problem is a problem in cryptocurrency?

The bitcoin original has the "double spending problem." But in a transaction using standard currency (dollar), the double spending problem is not a problem. Why is this a problem in crypocurrency?
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2answers
625 views

100% double spending attack probability

When we plot the attacker's computational power against the probability of double spending with a number of blocks equal to zero, we always get a chance of 100%. This plot is based on the original ...