51% w/o 51% ??

[AliceWonder]

If say pool X has 40% of hashing power, then 51% of the remaining 60% is (rounded) 31%

So could 31% of hashing power combined with a successful DoS on pool X pull off a 51% attack?

Granted the block time would be increased during the attack but this seems like a danger of the ASIC pools that have taken over bitcoin mining.

[slaveforanunnak1]

so, then another pool can take down the 31% pool with 34.5 % hashing power of the 31% of the original 100% hashrate.

huh

[AliceWonder]

I'm thinking PoW really needs decentralized mining to truly be safe.

[abacus]

I'm thinking PoW really needs decentralized mining to truly be safe.

Decentralization is the key, but I think I'm stating the obvious here.

Some time ago, when I read about it, I liked the idea of P2Pool and I thought that soon it would have become the norm.
That never happened and looking at the stats on blockchain.info it's currently just the 1% of total hash rate.

Why a so huge fail? 

[ljudotina]

I'm thinking PoW really needs decentralized mining to truly be safe.

You know, that's like saying: "We need to stop all the wars in the world and cure all diseases". Easier said than done.

[Relnarien]

I'm thinking PoW really needs decentralized mining to truly be safe.

You're not stating anything new or unknown. That's the whole point of Bitcoin -- decentralization. The fact that mining is now gradually converging into a centralized state is not a flaw in the mining process, but rather a direct consequence of miners becoming greedy. This trend will continue until all pool operators decide to limit their hashing capacity. Ghash and everyone who insists on mining there with only profit in their minds are the problem, not Bitcoin or mining.

[abacus]

You're not stating anything new or unknown. That's the whole point of Bitcoin -- decentralization. The fact that mining is now gradually converging into a centralized state is not a flaw in the mining process, but rather a direct consequence of miners becoming greedy. This trend will continue until all pool operators decide to limit their hashing capacity. Ghash and everyone who insists on mining there with only profit in their minds are the problem, not Bitcoin or mining.

Sorry but I think I disagree.
Quite on the contrary, I think that the problem with mining centralization can be effectively considered a flaw of the protocol and it has to be resolved somehow.

The greed is something inherent the human being, the man, the miner, the pool operator. Bitcoin must be superior to that.
We cannot just hope that these actors will change their minds and won't be greedy anymore, because it will not happen.
Sometime there is someone with good intentions, like the recent GHash.IO statement, but at all times it could appear a player greedier than the previous one. Also, we should consider that even if greed was totally absent, the problem would still be here because anyone with enought resources could be able to destroy bitcoin for whatever reason.

No, I really think that it should be the protocol itself able to auto-defends and to defeat any threat.

[colinistheman]

Some time ago, when I read about it, I liked the idea of P2Pool and I thought that soon it would have become the norm.
That never happened and looking at the stats on blockchain.info it's currently just the 1% of total hash rate.

Why a so huge fail?  

Same question here.

Why did P2Pool never become widely used?

It seems like the solution to all these pool hashrate centralization problems. So why is it barely being used?

[QuestionAuthority]

Some time ago, when I read about it, I liked the idea of P2Pool and I thought that soon it would have become the norm.
That never happened and looking at the stats on blockchain.info it's currently just the 1% of total hash rate.

Why a so huge fail?  

Same question here.

Why did P2Pool never become widely used?

It seems like the solution to all these pool hashrate centralization problems. So why is it barely being used?

Because humans are lazy.

[Lauda]

Nope, if it was this easy, everyone would do it. Do you think that the miners with large hashrates only mine on a certain pool?
This is why there are options for pool switching, mostly automatic.

[BTCfan668]

This is always a possibility. You could say the same thing if 5 pools with 11% each were to work together to attack the network. This is a non-issue.

[AliceWonder]

This is always a possibility. You could say the same thing if 5 pools with 11% each were to work together to attack the network. This is a non-issue.

Is it a non-issue or is it an issue that people ignore, thus it won't be addressed until it happens, causing a loss of confidence and thus crash of value first?

It would likely be a government that does it, and as bitcoin increases in value and governments lose their control over the flow of money, I think it becomes more likely that it will happen. Especially with the trend towards centralized mining.

[Este Nuno]

This is always a possibility. You could say the same thing if 5 pools with 11% each were to work together to attack the network. This is a non-issue.

Is it a non-issue or is it an issue that people ignore, thus it won't be addressed until it happens, causing a loss of confidence and thus crash of value first?

It would likely be a government that does it, and as bitcoin increases in value and governments lose their control over the flow of money, I think it becomes more likely that it will happen. Especially with the trend towards centralized mining.

It's a huge issue but the community has accepted the fact that we rely on trusting the miners. I've posted about this issue before, about how Bitcoin is not a 'trustless' currency at all. And I'm not saying that it won't function perfectly fine for the foreseeable future, but it's more convenient for people to ignore the issue in general. There is no easy answer really unless the devs could implement a forced p2pool mining system into the the protocol. Which I assume is not possible since it's such an easy answer, is it not?

[DannyHamilton]

If say pool X has 40% of hashing power, then 51% of the remaining 60% is (rounded) 31%

So could 31% of hashing power combined with a successful DoS on pool X pull off a 51% attack?

Depends on how the attack against the 40% pool works.

Are you blocking miners from connecting to the pool to get work?  Ar you blocking the pool from the network so it can't broadcast solved blocks?

If the miners can get work, but the pool can't get transactions or broadcast blocks, the pool will just create empty blocks.  It will build up it's own chain of empty blocks, and since it has 29% more hashing power it will create a longer chain than the attacker.  Once the attack is done and the attacker stops, the pool's chain will get broadcast and will replace the attacker's chain.

If the miners can't get work, then they will switch to some other pool that provides work.  Therefore, the 31% won't be a majority.

[Relnarien]

You're not stating anything new or unknown. That's the whole point of Bitcoin -- decentralization. The fact that mining is now gradually converging into a centralized state is not a flaw in the mining process, but rather a direct consequence of miners becoming greedy. This trend will continue until all pool operators decide to limit their hashing capacity. Ghash and everyone who insists on mining there with only profit in their minds are the problem, not Bitcoin or mining.

Sorry but I think I disagree.
Quite on the contrary, I think that the problem with mining centralization can be effectively considered a flaw of the protocol and it has to be resolved somehow.

The greed is something inherent the human being, the man, the miner, the pool operator. Bitcoin must be superior to that.
We cannot just hope that these actors will change their minds and won't be greedy anymore, because it will not happen.
Sometime there is someone with good intentions, like the recent GHash.IO statement, but at all times it could appear a player greedier than the previous one. Also, we should consider that even if greed was totally absent, the problem would still be here because anyone with enought resources could be able to destroy bitcoin for whatever reason.

No, I really think that it should be the protocol itself able to auto-defends and to defeat any threat.

The protocol is open source though, which makes any attempt to completely thwart the effects of human greed simply a delaying deterrent at best. Also, any theoretical principle will always play out differently when applied in the real world, which means that even a perfect protocol will eventually find itself abused and exploited. So the mining process is adequately functional as it is now, in my opinion.

If you want to keep the blockchain as decentralized as possible independent of people's behaviours, then you would need to rewrite a large part of, if not the whole, protocol and make it closed source. That's obviously out of the question. Ergo, it's the miners themselves who have to change.