Questions tagged [attack]

Relates to attempts to harm the Bitcoin network. In cryptography, an attack is a method/technique to break the code. Bitcoin also has to deal with other types of attack, such as double spends and denial of service.

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26
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4answers
38k 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?
36
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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".
3
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3answers
563 views

How exactly are Bitcoin's consensus rules enforced?

There are some rules called consensus rules, for example the block generation amount. And it is said that "a change to consensus rules is a hard-fork". But how exactly are the consensus ...
13
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1answer
2k views

What are the potential attacks against ECDSA that would be possible if we used raw public keys as addresses?

According to this answer about why addresses are hashes rather than public keys there are potential attacks that are possible if you have the public key rather than the address, what are these attacks?...
16
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3answers
4k views

What can be done about the no-transaction block relayer (currently 71.123.170.150)?

An unknown major solo miner (currently IP 71.123.170.150), most likely a botnet, is relaying blocks with zero transactions. Two weeks ago this miner constituted ~15% of the network, now it constitutes ...
13
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2answers
893 views

How much would it cost for a government to undermine Bitcoins?

Articles by for example the Economist stating that Bitcoins are being used for drug trading (Silk Road), I believe that the biggest risk to Bitcoins is that a government will pull a stunt similar to ...
10
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2answers
2k views

Which blocks get to be checkpoints?

Which blocks get to be checkpoints, and why is one block chosen to be a checkpoint, rather than another block? And where can I find a list of checkpoint blocks?
5
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1answer
4k views

Understanding a Bitcoin Double Spending Transaction by Performing one on yourself

Everyone talks about preventing a double spend transaction, but how does one do one to yourself in order to better understand the steps involved by the attacker? What is required to do a double spend?...
10
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4answers
603 views

Wouldn't the "malleable transaction" attack be foiled by common sense?

I'm trying to understand the malleable transaction attack, as it seems to me that only a rather careless operator would be vulnerable in the first place, as described below. Mainly to clarify my own ...
11
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3answers
824 views

Flaw in Bitcoin protocol regarding incentives to share transactions

Once the 50BTC per block rewards have halved many times and the transaction fees start to become the primary reward for miners, it sound like there is incentive for miners to not pass on transactions ...
9
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1answer
1k views

Why does Bitcoin no longer have checkpoints?

I've read that checkpoints in Bitcoin were removed because they were not preventing any meaningful attack. Why should a regular checkpoint not prevent majority attacks? For instance, if a checkpoint ...
8
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1answer
1k views

Could a mining pool attack Satoshi Dice?

Is it possibile for a mining pool to attack Satoshi Dice? A strategy might be: bet on Satoshi Dice and if the bet wins, do nothing, if it looses, don't put the transaction in the block (try to double ...
8
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2answers
2k views

What is the story behind the "Linode problem"?

What is the story behind the "Linode problem"? How did the service become compromised and what has exactly happened because of it?
5
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1answer
113 views

Isn't bribe smearing possible because no payee signature is required?

The Bitcoin protocol does not require the payee to sign for a payment; only the payer signs (the payer signs a hash of the payee and payer's public keys). In other words, a payee signature is not ...
4
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1answer
2k views

How does a time warp attack work?

I more or less understand how an attacker (with less than 50%+1 of the hashing power) can artificially lower the block difficulty by messing with timestamps. I also understand how such an attacker ...
3
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2answers
331 views

To what extent does asymmetric cryptography secure bitcoin transactions?

Is there a specific attack or bug which asymmetric cryptography prevents during bitcoin transactions?
3
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2answers
1k views

Developments to prevent 51% hack [duplicate]

How might Bitcoin be made impervious from attack by large monied interests that could atttack with a brute force majority hashrate hack?
15
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3answers
8k views

Attacking Bitcoin with a supercomputer

The difficulty in Bitcoin is recalculated every 14 days. What if immediately after this difficulty adjustment someone targets Bitcoin nodes with a supercomputer and start creating new blocks? Such ...
14
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8answers
1k views

bitcoins from the future

It is likely that the Galaxy Note 2 will be launched in August. As it has taken two weeks to mine my very first bitcoin, it seems unlikely that I will have mined enough to purchase a Note upon ...
3
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1answer
304 views

51% attack clarification

Im just reading a book on the basics of blockchain and I encountered a confusion regarding the 51% attack. If I'm right, it says that an attacker holding 51% or more of the network's computing power ...
0
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1answer
97 views

Possibility of a DDoS attack

Theoretically. This is not a mechanism of any kind of attack, but It's about the "lost" coins. May be. It is just for an educational experiment. What if someone has the ability to send transactions ...
21
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6answers
7k views

51% attack - apparently very easy? refering to CZ's "rollback btc chain" - How to make sure such corruptible scenario can never happen so easily?

I was shocked to see binance CZ comment to literally "roll back" the bitcoin chain by just "calling" in some favors from "friendly" Asian miners . This ONE person could effectively do it??? I mean ...
7
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3answers
418 views

What nodes are best for lessening the risk of loss from a race attack

A successful race attack is one where the payment recipient's node receives a spend transaction yet the next block that is mined has a different transaction that spends the same coin. Thus the ...
6
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2answers
2k views

What stops miners/nodes lying about what time a block was mined?

From what I understand, the difficulty required by the proof-of-work in bitcoin is a function of block history, specifically the average time between last ~2000 blocks, with the intention that its ...
5
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2answers
681 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 ...
4
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2answers
1k views

How does the Bitcoin network deal with bad actors?

Can someone explain at a high level how the network deals with bad actors (either intentionally (ie- attacker) or unintentional (ie- misconfigured node or a node running outdated code, forked code, ...
16
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2answers
8k views

What is a block withholding attack?

How can a block withholding attack be performed, what would be its purpose and who is it a danger to? Edit: when I posted this I was thinking about withholding a block you mined in a pool. But ...
11
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2answers
2k views

DDoS on big mining pools: a quick way to 51%?

Slush's Pool, the second biggest mining pool around, is currently down, allegedly due to a DDoS attack: News 16.04.2013 Pool is under DDoS attack. I'm working on recovering the service back to ...
8
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4answers
586 views

Would any of the current botnets be able to launch and sustain a 51% attack?

The "owners" of botnets probably runs them as businesses, meaning that they will always seek profit-optimization. Do you believe that it is a matter of time before they will seek to launch and sustain ...
8
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1answer
1k views

What prevents similar time-warp attacks in Bitcoin as happened to Verge?

Right now (may 2018), Verge (an altcoin with proof of work) was attacked by time-warp attack. More can be read here https://blog.theabacus.io/the-verge-hack-explained-7942f63a3017 What exactly ...
6
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6answers
4k views

Is it possible to spam the bitcoin network with 'dust'?

Someone could buy or mine bitcoins, and send them in small transactions all day to spam the blockchain. Is this possible? And could this mean the end of the trust people have in bitcoin? edit: And ...
4
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1answer
240 views

70% of nodes accept Bloom filters, despite DoS attack vector?

Could someone explain why so many Bitcoin nodes allow Bloom filtering given that DoS attacks exist [1], [2] for such nodes? According to bitnodes.21.co, right now 3879 nodes out of the total of 5515 ...
3
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1answer
198 views

How does headers-first prevent fill-disk attack?

Checkpoints prevented an attack where a node could mine many many low-difficulty blocks from an early point in the blockchain and serve those blocks to syncing nodes who would see their disks fill up. ...
3
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1answer
402 views

How do mining pool payout methods affect the cost of executing a block withholding attack?

I'm wondering how each payout method (PPS, DGM, PPLNS, Proportional, etc) influences the cost of executing a block withholding attack. Does it matter how the payout method places variance between ...
2
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1answer
183 views

How does the bitcoin core protect against initial DNS seed changes?

While the bitcoin network is essentially P2P, one still needs to identify an initial node to connect to. I understand that a method for such initial connections is connecting to known DNS seeds, e.g ...
2
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1answer
511 views

What is the story behind MyBitcoin?

The name of MyBitcoin eWallet comes up quite often here and there. What is the story behind it and the attack on it they claimed occurred?
2
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1answer
615 views

Specifics on "Race Double Spending Attacks"?

Hi guys I am doing some research on double spending in the bitcoin network several ideas have been confusing me: In prevention of Race attacks, merchants are advised to "connect to a large random ...
0
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2answers
1k views

What prevents an attacker from doing DDOS on bitcoin network by sending billions of transaction to himself?

I know that transacion fees on low-priority transactions adds additional cost, but what if an attacker uses a lot of 0.100001 BTC transactions, so he doesn't have to pay the fee, because transactions ...
0
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2answers
169 views

What happens if an ISP isolates a portion of nodes?

I came to believe that an ISP can easily detect full nodes, BTC connections and isolate them from reaching any other nodes. When and if an ISP decided to do so, could they easily perform a 51% attack ...
0
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1answer
111 views

Implicit/Tacit mechanisms in Bitcoin Core disclosing Selfish Mining

I'm referring to the selfish mine attack described by two researchers from Cornell University who describe a "possible" attack with lower than 51% hashing power. Now it's interesting to know what ...