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Author Topic: Is everything in this article on 51% attacks correct?  (Read 809 times)
virtfund
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March 18, 2015, 03:06:32 AM
 #1

I wrote this article a few months ago, and I want to make sure it's facually correct.

Here it is: http://www.virtfund.com/51-attack.html

Thanks for the help  Grin!

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odolvlobo
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March 18, 2015, 07:21:33 AM
 #2

It is pretty accurate, but I would make some minor corrections:

1. A 51% attack doesn't "damage" the blockchain.
2. Mining with the majority of hashing power does not guarantee "that you will be the first to successfully hash every block more quickly than the rest of the network." It means that your chain will generally be longer. You can prevent certain transactions from being confirmed by excluding them from your blocks, which are the only blocks if you lock out all other miners.
3. The ability of a 51+% miner to lock out other miners is not temporary. It can last as long as the attacker maintains 51+%.

Note also that the ability to lock out other miners means that if mining overall is profitable before an attack, then the attacker will make a profit from a 51% attack as long it doesn't affect the value of a bitcoin.

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LiteCoinGuy
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March 18, 2015, 05:08:52 PM
 #3

also watch:

https://www.youtube.com/watch?v=bi2thGzzNSs

franky1
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March 18, 2015, 05:37:03 PM
 #4

I wrote this article a few months ago, and I want to make sure it's facually correct.

Here it is: http://www.virtfund.com/51-attack.html

Thanks for the help  Grin!

first paragraph instills FEAR, which is unwarranted.

so make
Quote
"ever obtains more than 50% of all hashing power for a proof-of-work coin they can cause significant damage to the blockchain."

which sounds like simply getting >50% causes the damage
to
Quote
ever obtains more than 50% of all hashing power for a proof-of-work coin they could cause significant damage to the blockchain, if their lack of ethics deemed so.

next..
Quote
Preventing Confirmations
  
    Mining with the majority of hashing power virtually guarantees that you will be the first to successfully hash every block more quickly than the rest of the network. If a 50+% miner wants to prevent certain transactions from being added to a block and confirmed on the blockchain, all they need to do is complete blocks, without the unwanted transaction in them, faster than the rest of the network. You really don't need to worry about these transactions, though. They will simply sit with no confirmations until the miners hash rate drops to below 50% and they lose control of the network.

even without 50%, denying transactions IS happening right now. as miners are greedy and only let a few hundred out of the 4k transaction limit, and mainly only the ones with fee's attached.. so that whole paragraph has no below 50% barrier as a prevention method

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virtfund
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March 20, 2015, 01:32:39 AM
 #5

I wrote this article a few months ago, and I want to make sure it's facually correct.

Here it is: http://www.virtfund.com/51-attack.html

Thanks for the help  Grin!

first paragraph instills FEAR, which is unwarranted.

so make
Quote
"ever obtains more than 50% of all hashing power for a proof-of-work coin they can cause significant damage to the blockchain."

which sounds like simply getting >50% causes the damage
to
Quote
ever obtains more than 50% of all hashing power for a proof-of-work coin they could cause significant damage to the blockchain, if their lack of ethics deemed so.

next..
Quote
Preventing Confirmations
  
    Mining with the majority of hashing power virtually guarantees that you will be the first to successfully hash every block more quickly than the rest of the network. If a 50+% miner wants to prevent certain transactions from being added to a block and confirmed on the blockchain, all they need to do is complete blocks, without the unwanted transaction in them, faster than the rest of the network. You really don't need to worry about these transactions, though. They will simply sit with no confirmations until the miners hash rate drops to below 50% and they lose control of the network.

even without 50%, denying transactions IS happening right now. as miners are greedy and only let a few hundred out of the 4k transaction limit, and mainly only the ones with fee's attached.. so that whole paragraph has no below 50% barrier as a prevention method

Why do you think that the first paragraph instills fear that is unwarranted? I've changed the paragraph to explain that a miner with 50+% of hash power cannot damage the blockchain, but otherwise I don't understand what is unwarranted in the first paragraph. As far as I know, it is all true.
What do other people think?

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OROBTC
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March 20, 2015, 01:42:32 AM
 #6

...

There was a real fuss when GHash.IO briefly went to 51% not too long ago (maybe a year?).  To my knowledge, nothing bad happened.

Right now there are four mining pools out of China with some 52% of the hashing power.  But, I see no reason for worry as a country as big as CHINA would likely not have those four collude enough to damage the Bitcoin Ecosystem.  They might even be located far from each other and be owned by different people.

Also re Chinese mining pools, the apparent fact that many in China want to get money OUT might suggest that most would want Bitcoin to be operating very smoothly...
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March 20, 2015, 01:57:13 AM
 #7

we must experience once 51% attack, that can know it right or wrong/

otherwise, all is theory
juju
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March 20, 2015, 02:51:14 AM
 #8

I wrote this article a few months ago, and I want to make sure it's facually correct.

Here it is: http://www.virtfund.com/51-attack.html

Thanks for the help  Grin!

Could you post a pastebin of the text?

Regardless, I would just make sure you just read Section 11 a few extra times as well, certainly can't hurt. https://bitcoin.org/bitcoin.pdf

we must experience once 51% attack, that can know it right or wrong/

otherwise, all is theory

Look at some of the Altcoins that have been attacked like this, its a small scale example of what would happen.

https://bitcointalk.org/index.php?topic=332584.0

That was back in 2013, so I am sure many altcoins have met similar fates.

Edit: Feathercoin was focused several times, here an infographic on the attack http://imgur.com/a/fTye4#0
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March 20, 2015, 07:00:45 AM
 #9

This is a non-issue according to Andreas... He gets this question regularly in his Q&A section in his seminars and it's always the same answer..." There are counter measures in place to stop or minimize it's impact"

This topic has come to the front again, with the Chinese having several seperate mining operations and the fear that they could dominate the mining scene and cause a 51% attack.

When this happened with GHash.IO .....miners just left that pool and things balanced out again. You would have to maintain a 51% attack for a long time to be a real threat. {Double spending}

Also.... Why kill the cow that produce the milk?  

Let's not blow oxygen into the conspiracy flame.  Grin

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