Bitcoin Stack Exchange
Bitcoin Stack Exchange

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.

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.

187 questions
40
votes
2 answers

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".
Dr.Haribo
  • 8,409
  • 10
  • 43
  • 62
27
votes
4 answers

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?
Dr.Haribo
  • 8,409
  • 10
  • 43
  • 62
22
votes
6 answers

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 are we all in a bubble, in some kind of utopia…
johnsmiththelird
  • 837
  • 1
  • 6
  • 12
21
votes
1 answer

Have any SPV users lost money because they accepted forged bitcoins?

I'm making a list of real-life examples of occasions where bitcoins were lost to various known attacks. One of these known attacks is that lightweight (SPV) wallets can't verify whether a transaction only spends UTXOs (a requirement full nodes…
David A. Harding
  • 11,626
  • 2
  • 44
  • 71
17
votes
2 answers

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 withholding blocks can form the basis for many different…
Dr.Haribo
  • 8,409
  • 10
  • 43
  • 62
17
votes
4 answers

What are the risks of using Strongcoin.com as an online wallet?

Strongcoin claims it is "The Safest way to store your Bitcoins. The only Bitcoin e-wallet service that's not vulnerable to security breaches. Your Bitcoin keys are encrypted in the browser." As I understand it, with their system your private keys…
Highly Irregular
  • 10,910
  • 6
  • 52
  • 102
16
votes
3 answers

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 ~30%. If the growth rate continues, in about two…
BinaryMage
  • 1,346
  • 10
  • 22
15
votes
2 answers

Why do we call it a 51% attack instead of a 50% attack?

From the Bitcoin paper: p = probability an honest node finds the next block q = probability the attacker finds the next block qz = probability the attacker will ever catch up from z blocks behind qz = 1 if p ≤ q In other words, when an attacker…
Nick
  • 185
  • 1
  • 8
15
votes
3 answers

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 attack can create some many bitcoin to complete the…
Nulik
  • 285
  • 2
  • 8
14
votes
1 answer

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? If one was writing a cryptocurrency would you…
Leah Cornelius
  • 362
  • 2
  • 7
14
votes
8 answers

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 release (unless the time between launch and release is…
Paul
  • 266
  • 1
  • 8
13
votes
2 answers

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 Stuxnet. This was also the answer of David…
David
  • 3,444
  • 2
  • 27
  • 37
12
votes
1 answer

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 is made every N blocks and (for example) 3/4 of…
Anon
  • 121
  • 3
11
votes
2 answers

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 operation. This means the entirety of its miners…
Massimo
  • 1,048
  • 6
  • 20
11
votes
2 answers

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?
user189
  • 303
  • 1
  • 6
1
2 3
…
12 13