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Topic: 51% attack - page 4. (Read 5157 times)

legendary
Activity: 1302
Merit: 1008
Core dev leaves me neg feedback #abuse #political
April 20, 2014, 10:15:52 PM
#49
A 51% attack would NOT necessarily mean everyone would switch to litecoin. 

Instead, miners would just leave those corrupted pools and
join new ones not under the control of the dark lord of the sith.

And bitcoin lives on.
newbie
Activity: 55
Merit: 0
April 20, 2014, 10:10:52 PM
#48
can you say in a short way what is in this video about?
newbie
Activity: 56
Merit: 0
April 20, 2014, 10:06:06 PM
#47
https://www.youtube.com/watch?v=bi2thGzzNSs

seems like it's alot easier then some people claimed...

Oh no, hope it doesn't happen
sr. member
Activity: 365
Merit: 251
April 17, 2014, 03:52:14 PM
#46
[quoting Satoshi] An attacker can only try to change one of his own transactions to take back
money he recently spent"
The problem is that we won't know which transactions are theirs, so every transaction becomes suspect even if only a small number of transactions are directly affected.
full member
Activity: 224
Merit: 101
April 17, 2014, 03:15:52 PM
#45
According to Sotoshi's white paper, it seems that a 51% attack would only disrupt current transactions but not affect the previous blocks.
Where can one find this?

I think he means the original paper by Satoshi https://bitcoin.org/bitcoin.pdf
However I can't find any explicit mentioning of the 51% attack in it.
Hm me neither, that's what I thought he referred to as well.

Under "Calculations" section of bitcoin.pdf

quote:
-"We consider the scenario of an attacker trying to generate an alternate chain faster than the honest
chain. Even if this is accomplished, it does not throw the system open to arbitrary changes, such
as creating value out of thin air or taking money that never belonged to the attacker. Nodes are
not going to accept an invalid transaction as payment, and honest nodes will never accept a block
containing them. An attacker can only try to change one of his own transactions to take back
money he recently spent"
end quote.

To generate an alternate chain faster than the honest chain would mean that the attacker would have 51% or greater control of network.  How else would someone generate a chain faster than the main chain?
No that seems to make sense. Doesn't seem to be that big of a deal if this is true, however we can't know if he missed something until someone actually tries and succeeds.
legendary
Activity: 1512
Merit: 1012
April 17, 2014, 09:51:21 AM
#44
Quote
We consider the scenario of an attacker trying to generate an alternate chain faster than the honest
chain.

P2Pool create already this system ... but have "only" 160TH/s.
and the overhead, CPU, stale and Dead-On-Arrival ... is high, too.
full member
Activity: 210
Merit: 100
April 17, 2014, 09:48:14 AM
#43
According to Sotoshi's white paper, it seems that a 51% attack would only disrupt current transactions but not affect the previous blocks.
Where can one find this?

I think he means the original paper by Satoshi https://bitcoin.org/bitcoin.pdf
However I can't find any explicit mentioning of the 51% attack in it.
Hm me neither, that's what I thought he referred to as well.

Under "Calculations" section of bitcoin.pdf

quote:
-"We consider the scenario of an attacker trying to generate an alternate chain faster than the honest
chain. Even if this is accomplished, it does not throw the system open to arbitrary changes, such
as creating value out of thin air or taking money that never belonged to the attacker. Nodes are
not going to accept an invalid transaction as payment, and honest nodes will never accept a block
containing them. An attacker can only try to change one of his own transactions to take back
money he recently spent"
end quote.

To generate an alternate chain faster than the honest chain would mean that the attacker would have 51% or greater control of network.  How else would someone generate a chain faster than the main chain?
full member
Activity: 224
Merit: 101
April 17, 2014, 08:18:18 AM
#42
According to Sotoshi's white paper, it seems that a 51% attack would only disrupt current transactions but not affect the previous blocks.
Where can one find this?

I think he means the original paper by Satoshi https://bitcoin.org/bitcoin.pdf
However I can't find any explicit mentioning of the 51% attack in it.
Hm me neither, that's what I thought he referred to as well.
member
Activity: 73
Merit: 10
April 17, 2014, 08:17:10 AM
#41
Would this just only fork the chain which would leave the rest of us happy bitcoiners bitcoining as usual after the temporary disruption?
donator
Activity: 1617
Merit: 1012
April 17, 2014, 06:05:49 AM
#40
According to Sotoshi's white paper, it seems that a 51% attack would only disrupt current transactions but not affect the previous blocks.
Yes, and people seem to forget that these attack blocks still have to be accepted and propagated by regular Bitcoin nodes throughout the network. There are 2 possibilities:

1) The attack blocks violate the Bitcoin protocol. In this case they will not be relayed by regular nodes and they will immediately orphan out

2) The attack blocks do not violate the Bitcoin protocol. In this case they will be relayed by regular nodes and make  their way through the network. However, because the protocol is obeyed the scope of the attack would be restricted. E.g. the exclusion of certain transactions from the block.

In any case, although transactions would likely be lost the disruption would be temporary. Miners will eventually leave the compromised pool and things will go back to normal.
sr. member
Activity: 364
Merit: 250
April 17, 2014, 05:20:51 AM
#39
Not doable in my opinion
full member
Activity: 140
Merit: 100
April 17, 2014, 04:13:13 AM
#38
According to Sotoshi's white paper, it seems that a 51% attack would only disrupt current transactions but not affect the previous blocks.
Where can one find this?

I think he means the original paper by Satoshi https://bitcoin.org/bitcoin.pdf
However I can't find any explicit mentioning of the 51% attack in it.
sr. member
Activity: 420
Merit: 250
April 17, 2014, 03:26:33 AM
#37
Hope it dosent happen. Angry
full member
Activity: 224
Merit: 101
April 16, 2014, 08:53:38 PM
#36
According to Sotoshi's white paper, it seems that a 51% attack would only disrupt current transactions but not affect the previous blocks.
Where can one find this?
full member
Activity: 210
Merit: 100
April 16, 2014, 08:47:55 PM
#35
According to Sotoshi's white paper, it seems that a 51% attack would only disrupt current transactions but not affect the previous blocks.
member
Activity: 100
Merit: 10
April 16, 2014, 05:13:41 PM
#34
To prevent 51% attack, someone has to mass produce low power asic at low cost.
So when every bitcoin user are solomining, we can easily achieve a crazy hashrate deterring 51% attacks.

But the current problem is most people's mindset. They always think mining = profiting.
We have to remind them the fact that mining is to secure the network instead.

But we need low power asics just because using computer hardware to mine consumes too much power and slowing the pc so people definitely don't want that.
Each asic don't need to have the hashrate that is comparable with those profit-based farms, I believe we will have more users than the farms have asics.
full member
Activity: 224
Merit: 101
April 16, 2014, 03:20:19 PM
#33
It a lot harder than u think. Plus anyone spending that amount on mining hardware would make some btc  rather than attack it
I think the video was very clear on exactly how hard/easy it would be. The point was not to use the 51% of the hashing power to make money - but to gain an advantage over other people and destroy bitcoins.
full member
Activity: 140
Merit: 100
April 16, 2014, 03:19:55 PM
#32
What about the previously discussed argument of just threatening/bribing the largest pool owners?
And what if the goal is not to make money but just kill the system? I could think of many reasons for (some) governments to do this.
sr. member
Activity: 266
Merit: 250
April 16, 2014, 03:18:30 PM
#31
It a lot harder than u think. Plus anyone spending that amount on mining hardware would make some btc  rather than attack it
full member
Activity: 140
Merit: 100
April 16, 2014, 03:07:54 PM
#30
If you're replying at the last message, there's no need to quote the previous message.

I could think of many reasons, one being money and greed because people could benefit greatly from a 51% attack.
Also don't forget governments.
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