Concern? over 50% of miners controlled by two pools

[thesouljourner]

Should we be concerned that over 50% of the mining power is controlled by two pools? https://blockchain.info/pools

This seems like a really bad concentration of power for a network that is supposed to be decentralized.  Sure, it's handy when you need to fix a bug in the system, but it's also a weak point that can be exploited.  Thoughts?

[BurtW]

No, it is not a concern.  Why?  Are you concerned?  If so, can you explain exactly why you are?

[t1000]

Because it makes it easier to pull off a 51% attack?

[WiFiPunk]

Any of the major pools with cap themselves if they even got close. BTCGuild has had to do that a few times. Nothing to worry about unless they suddenly announce a merger.

[CoinCidental]

Any of the major pools with cap themselves if they even got close. BTCGuild has had to do that a few times. Nothing to worry about unless they suddenly announce a merger.

what if the same guy already owns them both ?

[Blazed]

It is not a good thing that is for sure.

[BurtW]

Do you even know what a 51% attack is?  Do you know what can be done using it?  Do you know what would happen if a pool tried to do it?

Let's do a mind experiment.  Assume BTC guild, right now, has 60% of all the hashing power.  Now explain to me exactly what they would do in order to pull off a "51% attack", exactly what they would accomplish by doing it and most importantly exactly why they would do it.

[zimmah]

Should we be concerned that over 50% of the mining power is controlled by two pools? https://blockchain.info/pools

This seems like a really bad concentration of power for a network that is supposed to be decentralized.  Sure, it's handy when you need to fix a bug in the system, but it's also a weak point that can be exploited.  Thoughts?

Well if you are that concerned start your own pool that offers paying transaction fees, mines Altcoins and has low pool fees.

No one will mine in a pool that pays less....

[mindfulmojo]

Do you even know what a 51% attack is?  Do you know what can be done using it?  Do you know what would happen if a pool tried to do it?

Let's do a mind experiment.  Assume BTC guild, right now, has 60% of all the hashing power.  Now explain to me exactly what they would do in order to pull off a "51% attack", exactly what they would accomplish by doing it and most importantly exactly why they would do it.

This ^^^^

My biggest fear is that the Star Trek Enterprise will come back through time to our century and pull off a 51% attack.

I think they are only ones with their super advanced technology that could pull it off.

Hell, Commander Data could probably do it with his positronic brain. 



 

[pera]

Do you even know what a 51% attack is?  Do you know what can be done using it?  Do you know what would happen if a pool tried to do it?

Let's do a mind experiment.  Assume BTC guild, right now, has 60% of all the hashing power.  Now explain to me exactly what they would do in order to pull off a "51% attack", exactly what they would accomplish by doing it and most importantly exactly why they would do it.

the whole point of bitcoin is being a decentralized currency... yeah, I don't think any mining pool will want to have control over the blockchain, that would probably destroy bitcoin and obviously miners don't want that.. but I'm still concerned 

what happen with p2pool?

[thesouljourner]

Do you even know what a 51% attack is?  Do you know what can be done using it?  Do you know what would happen if a pool tried to do it?

Let's do a mind experiment.  Assume BTC guild, right now, has 60% of all the hashing power.  Now explain to me exactly what they would do in order to pull off a "51% attack", exactly what they would accomplish by doing it and most importantly exactly why they would do it.

Please don't talk down to people like that, it's not constructive, and given the nature of a lot of the conversations on this board, I don't think this was an invalid question.

Answers:

Yes. Yes.  : https://en.bitcoin.it/wiki/Weaknesses#Attacker_has_a_lot_of_computing_power

No.  I'm not sure what would happen.  If you have a good idea, and think that the consequences make it not something to worry about, I think many people would like to know that information.  That's pretty much why I asked.  Should we be concerned?  It sounds like no, but you haven't really explained why.

Here are my conjectures:

It seems like the double spend is probably not practically useful, since it's less of a double spend and more of a "spend and then unspend", which only helps if you're getting something from someone else for spending the bitcoin.  And in that case, the other party would start squawking up a storm about it, so it  wouldn't go unnoticed.

Forcing transactions not to be confirmed seems like it might be something to be concerned about.  It could be hard to determine why its happening, and could be used as a weapon against people that piss off the pool.  Of course, that requires the pool to know which transactions belong to that person, which is sorta the whole point of anonymity in the blockchain.... but I'm not sure how hard it would be in practice.

Preventing other miners from getting blocks seems like the most likely attack vector, since it could be the hardest to recognize.  The top two pools could just give themselves 10% more block awards by rejecting 10% of blocks submitted from outside their pools, and waiting until one of them finds the block.  I'm not sure how obvious that would be to people watching transactions on the block chain.  The benefits are obvious - they get 10% more block awards than they're entitled to.

I'm relatively new to bitcoin, so some or all of this may be off, feel free to tell me where I've gone wrong, after all, I am trying to learn.

[Gabi]

exactly what they would accomplish by doing it

They would be able to do everything.

why they would do it.

Maybe modify just some transactions... because someone pay them for that... you know, corruption... something wich will pass unnoticed but important...who know... no proof that "they" did it...

[smooth]

Support p2pool

[Lucky Cris]

Do you even know what a 51% attack is?  Do you know what can be done using it?  Do you know what would happen if a pool tried to do it?

Let's do a mind experiment.  Assume BTC guild, right now, has 60% of all the hashing power.  Now explain to me exactly what they would do in order to pull off a "51% attack", exactly what they would accomplish by doing it and most importantly exactly why they would do it.

A 51% Attack doesn't have to be intentional, does it? If any pool had 60% of the hashing power, an attack would be forthcoming. The pool doesn't have to try to do it, it will, which is why the pools cap themselves. Blocks other miners solve would be orphaned left and right... The longest chain always win the conflict, right? That isn't to say it was done intentionally or with malice. But whoever has the upper hand would benefit from the block rewards and transactions fees of those resolved 'conflicts.'  On the other hand, if a pool wanted to orchestrate an attack... well, I guess that's another topic.

[Lucky Cris]

Do you even know what a 51% attack is?  Do you know what can be done using it?  Do you know what would happen if a pool tried to do it?

Let's do a mind experiment.  Assume BTC guild, right now, has 60% of all the hashing power.  Now explain to me exactly what they would do in order to pull off a "51% attack", exactly what they would accomplish by doing it and most importantly exactly why they would do it.

Please don't talk down to people like that, it's not constructive, and given the nature of a lot of the conversations on this board, I don't think this was an invalid question.

I'm relatively new to bitcoin, so some or all of this may be off, feel free to tell me where I've gone wrong, after all, I am trying to learn.

You did good, hehe.

[mgio]

Do you even know what a 51% attack is?  Do you know what can be done using it?  Do you know what would happen if a pool tried to do it?

Let's do a mind experiment.  Assume BTC guild, right now, has 60% of all the hashing power.  Now explain to me exactly what they would do in order to pull off a "51% attack", exactly what they would accomplish by doing it and most importantly exactly why they would do it.

A 51% Attack doesn't have to be intentional, does it? If any pool had 60% of the hashing power, an attack would be forthcoming. The pool doesn't have to try to do it, it will, which is why the pools cap themselves. Blocks other miners solve would be orphaned left and right... The longest chain always win the conflict, right? That isn't to say it was done intentionally or with malice. But whoever has the upper hand would benefit from the block rewards and transactions fees of those resolved 'conflicts.'  On the other hand, if a pool wanted to orchestrate an attack... well, I guess that's another topic.

No, that's not how it works. There is no problem with a pool having more than 50% of the hash power as long as they don't abuse that power.

[Lucky Cris]

Do you even know what a 51% attack is?  Do you know what can be done using it?  Do you know what would happen if a pool tried to do it?

Let's do a mind experiment.  Assume BTC guild, right now, has 60% of all the hashing power.  Now explain to me exactly what they would do in order to pull off a "51% attack", exactly what they would accomplish by doing it and most importantly exactly why they would do it.

A 51% Attack doesn't have to be intentional, does it? If any pool had 60% of the hashing power, an attack would be forthcoming. The pool doesn't have to try to do it, it will, which is why the pools cap themselves. Blocks other miners solve would be orphaned left and right... The longest chain always win the conflict, right? That isn't to say it was done intentionally or with malice. But whoever has the upper hand would benefit from the block rewards and transactions fees of those resolved 'conflicts.'  On the other hand, if a pool wanted to orchestrate an attack... well, I guess that's another topic.

No, that's not how it works. There is no problem with a pool having more than 50% of the hash power as long as they don't abuse that power.

Can you explain how it works, or how the pool can prevent from abusing that power? Can that power be abused - oh, hell yes! I'm not talking about the many things that a pool powerhouse has the ability to do.... But how can said pool prevent from NOT taking other miners' block rewards and transaction fees? This isn't intentional - As the authority on the network (so to speak), clients will believe the pool's hashed transaction block over any other. That means the pool will win all transaction conflicts, and get the rewards.

I'll accept what you said that there's no problem with having more than 50% of the hashing power, but you've got to explain just a lil... after all, I'm still an infant in this world too.

[smooth]

No, that's not how it works. There is no problem with a pool having more than 50% of the hash power as long as they don't abuse that power.

Arguably it is still a marketplace problem in that there may be lack of confidence that the pool is honest, will stay honest, and won't be compromised by (internal or external) dishonest actors.

The pool model is highly problematic and isn't solved by starting a new low-fee pool as someone else suggested because a new (presumably smaller) pool will have payout variance that is too high. There are some very nice smaller pools right now that don't even reliably solve one block per week. The incentive for the individual miner is always to sign up with the bigger pools to get consistent payouts, and that's bad for the system as a whole.

The way out of this trap is with p2pool (or build a new system like it if you don't like p2pool).

[Lucky Cris]

Look at you OP... got me challenging veteran members and I don't know what the hell I'm talking about 

[Gabi]

Do you even know what a 51% attack is?  Do you know what can be done using it?  Do you know what would happen if a pool tried to do it?

Let's do a mind experiment.  Assume BTC guild, right now, has 60% of all the hashing power.  Now explain to me exactly what they would do in order to pull off a "51% attack", exactly what they would accomplish by doing it and most importantly exactly why they would do it.

A 51% Attack doesn't have to be intentional, does it? If any pool had 60% of the hashing power, an attack would be forthcoming. The pool doesn't have to try to do it, it will, which is why the pools cap themselves. Blocks other miners solve would be orphaned left and right... The longest chain always win the conflict, right? That isn't to say it was done intentionally or with malice. But whoever has the upper hand would benefit from the block rewards and transactions fees of those resolved 'conflicts.'  On the other hand, if a pool wanted to orchestrate an attack... well, I guess that's another topic.

No.

This isn't intentional - As the authority on the network (so to speak), clients will believe the pool's hashed transaction block over any other. That means the pool will win all transaction conflicts, and get the rewards.

Epic confusion.

A 51% attack is then the attacker blockchain voluntarily ignore every other blocks. An honest 51% holder would accept the blocks found by other people.