All Questions
Tagged with majority-attack blockchain
17 questions
2
votes
2
answers
215
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How can an external party be sure that node's response is valid?
Assume that 51% of nodes are honest and 49% malicious. Fur sure, longest chain would make the chains consistent/same all over the world as 51% can outweigh the 49%, but my question is slightly ...
1
vote
1
answer
80
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Noob question: Why is there not a limit of the number of blocks in a chain revision?
I have a noob idea and I want to understand where I'm going wrong :)
Say nodes agreed on a block revision limit, say, 6. This would mean that if they see an incoming chain that is longer than the ...
- 15
2
votes
1
answer
516
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51% attack, miners, nodes or both
If 51% of the hashrate was controlled by bad actors mining invalid blocks, this would become the longest chain. Where do nodes come into the 51% attack? The canonical chain is the longest chain. Is ...
- 193
1
vote
2
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261
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What are the benefit of mining an empty block
Something peculiar just happened on the newly mined block number 655534, it contain only the coinbase transaction, nothing else.
I have searched for a similar question but only found this one Why ...
- 2,820
1
vote
1
answer
236
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How can Forks and Orphan Blocks be used to attack a Blockchain?
So I'm trying to learn about the security aspects of Blockchains and one of the papers I'm reading (https://arxiv.org/pdf/1904.03487.pdf) states that Forks and Orphaned Blocks can be used to attack a ...
- 79
1
vote
1
answer
64
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Why one miner can dig out many blocks continually in one moment?
I am new to bitcoin and blockchain, I browed the website just now. There is a question confusing me, I find that one miner dig out blocks many times even in one hour. For example, this miner dig out ...
- 13
0
votes
1
answer
47
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51% attack + ignore blocks not mined by yourself [duplicate]
If you own 51% of the mining power and decide to ignore all blocks not mined by yourself.
You would eventually end up having the longest chain, and would eat up the 49% of block-reward you werent ...
0
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2
answers
2k
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What do we mean by honest nodes?
In his recent paper, Vitalik often mentions the term "honest nodes". What do we mean by that exactly?
- 115
0
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1
answer
28
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Are smalltime block chains susceptible to brute force liars?
My understanding is that the integrity of the bitcoin block chain is dependent on the consensus of the masses - that no single actor can write entries at will unless they. controlled over 50% of the ...
- 175
2
votes
1
answer
99
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On a low level, how are long chains kept secret and later broadcast during 51% attacks?
I've been reading about the vulnerabilities of PoW crypto, and there's a part of it that I don't understand.
Suppose I wanted to stage a 51% attack on Bitcoin (not really feasible, but bear with me). ...
- 123
0
votes
1
answer
87
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What prevents a majority attack from undoing transactions of others?
From the Wiki:
If the attacker has the majority of computer power, "the attacker can't reverse other people's transactions without their cooperation."
I don't quite understand why this must be the ...
- 289
1
vote
1
answer
276
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What is the worst an attacker could do with full control over the blockchain?
Let's assume somebody gains control over 100% of the hashing power and is now free to mine and control as many new blocks as he wants. What would happen?
The attacker still could not include any fake ...
4
votes
1
answer
375
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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 ...
- 143
1
vote
1
answer
135
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Was the 51% attack a real threat in the early days of bitcoin existence?
The hypothesis of 51% attack is based on a malicious entity is able to control more than 50% hashrate of all mining nodes. It's understandable that there's huge amount of mining power existing ...
- 193
2
votes
2
answers
365
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Why wouldn't miners change the protocol? (e.g. change difficulty)
How about a scenario where a few miners change their protocols by setting difficulty to something easy. Let's take it to the extreme and say they are able to accept any block.
They would keep ...
- 123
1
vote
2
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265
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What's to stop someone from making a ton of mining nodes as an attack method?
My understanding is that if two miners make a block by completing a hash at the same time, it is then up to the miners to decide which is going to be 'accepted' by vote of which block reaches 51% of ...
- 13
6
votes
3
answers
723
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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 ...
- 337