Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Ghash.io very close to 51% of bitcoin pool

bitcointalk.org

Post reply on HN
Print view View original

51–60 of 130 posts

Re: Ghash.io very close to 51% of bitcoin pool

#51

Post by X4 »

TomGullen wrote: post #42
X4 wrote: post #33

Can someone please explain what Ghash.io and BTCGuild are? I have checked both homepages and subpages, but still don't understand what it is. Ghash.io wants me to download a binary, the other one talks about a "mining pool". Can't figure what that even means.. Disclaimer: Bitcoin noob here

You can mine Bitcoin on your computer. The chance of discovering a 'block' and receiving the 25 BTC reward are however very low as it's very competitive. Mining solo, you're playing an 'all or nothing' game and you could run for months, even years without earning any reward. Pools are collections of people who mine Bitcoin. When a block is discovered by someone in the pool, the reward is shared amongst everyone who i…

Oh that's completely new to me. I thought that mining means that I need to let the PC run for hours to get some BTC someone send to me. Is the mining you're mentioning unrelated to another one sending your BTC?

Can anyone "lucky" enough receive 25 BTC from nowhere, is that what you mean by `25 BTC reward`?

How can people share a "computer cluster"/minin pool (that is what you mean right?). Do you mean that one person or company owns such a huge cluster and let's all members share 'virtually' a single 'Bitcoin wallet'?

I'm not really that familiar with it, sorry for the nooby questions.

Re: Ghash.io very close to 51% of bitcoin pool

#52

Post by masklinn »

pron wrote: post #41

I don't know much about the particulars of BitCoin mechanics, but the general spirit of this story seems like a natural evolvement of any unregulated organization. People who favor unregulated markets/societies dislike the concentration of power in the hands of a central authority, but the reality is that in any social system there will always be concentration of power in the hands of the few. I've read a hypothesis[…

> in any social system there will always be concentration of power in the hands of the few

By default, subsystems can be put in place to diffuse power back into the realm (or at least attempt to)

Re: Ghash.io very close to 51% of bitcoin pool

#53

Post by aestra »

jpalomaki wrote: post #45

Why ghash.io is so popular? Is their some specific reason for mining in GHash pool instead of some other?

EDIT: I'm talking in general. I mine litecoins (and sometimes other alt coins), not bitcoins, so that's what I'm most familiar with.

Big pools are popular for a number of reasons:

1) Lots of hashing power means lots of blocks found means more payment more often, even if it is less coins. People get impatient and leave smaller pools if they aren't getting paid right away.

2) Network effect. It's the first Google search result. This might be the biggest factor.

3) Probably more reputable, so I'll probably get paid too, most pools have honest operators but some can shut down shop and take coins people haven't cashed out yet and run or do other shady things.

4) Probably less downtime, beefier hardware.

I don't know the specifics of GHash in particular if there's anything that makes it more appealing.

Re: Ghash.io very close to 51% of bitcoin pool

#54

Post by flatline »

darkFunction wrote: post #12
andyjohnson0 wrote: post #5

Could someone with knowledge of Bitcoin explain what happens when a share of the pool hits 51%? Is this dangerous in some way? Edit: Thanks to those who took the time to explain. Very interesting.

The pool operators could launch 'double spend' attacks. Essentially with > 50% of the hashing power, a bad operator is able to generate a chain faster than the rest of the network. They can hold back this longer chain in secret, execute some transactions on the honest chain, then broadcast their chain (which doesn't have those transactions included) to the network. The network will use the evil chain since it is the…

There is even some evidence that double-spending attacks have already happened. You don't strictly speaking need 51%, that majority just ensures that your chain will win out over time. The original bitcoin paper[1] details the probabilities involved for nodes controlling It could be even worse than that however. Another post on BCT[2] talks about a "time warp attack", where at 51% node could effectively mine all remaining bitcoins in one fell swoop.

[1] http://bitcoin.org/bitcoin.pdf

[2] https://bitcointalk.org/index.php?topic=114751.0

Re: Ghash.io very close to 51% of bitcoin pool

#55

Post by myvii »

jpalomaki wrote: post #45

Why ghash.io is so popular? Is their some specific reason for mining in GHash pool instead of some other?

They are backed by cex.io which is an exchange that trades GH/s for BTC.

They are able to run a pool for 0% fee, along with mining a couple of other altcoins makes them a more profitable pool than others.

Re: Ghash.io very close to 51% of bitcoin pool

#56

Post by X4 »

patio11 wrote: post #49
TomGullen wrote: post #42

Earlier quoted context omitted.

You can mine Bitcoin on your computer. The chance of discovering a 'block' and receiving the 25 BTC reward are however very low as it's very competitive. Mining solo, you're playing an 'all or nothing' game and you could run for months, even years without earning any reward. Pools are collections of people who mine Bitcoin. When a block is discovered by someone in the pool, the reward is shared amongst everyone who i…

To be more explicit: if you have > 50% of the hashing power for a sustained period of time, you can with 100% probability dictate which transactions are accepted, which allows you to perform double-spend attacks essentially at will. [+] If you control a significant percentage which is less than 50%, you can attempt to do this but it is both uncertain to work (on any given attempt) and costly if it fails. Note that yo…

So even gambling sites use Bitcoin! That double-spend attack sounds so weird, I wonder why it's even possible. Why does Bitcoin trust the owner of larger amount of BTC (51%) more than those with less? I thought that trusting every client equally (less) would be a greater advantage, than trusting the largest group of clients. That part is hard to understand.

What would happen, if due to a war many of the datacenters on earth were destroyed and we would only have 1/4 of the computing capacity left. Would sending BTC become impossible, or is mining not possible then?

Re: Ghash.io very close to 51% of bitcoin pool

#57

Post by aestra »

mseebach wrote: post #14

Ghash.io is "just" a pool. For them to do anything scary, all the members would need to collude, right? Or can the pool "direct" the mining in such a way that eg. double-spending can happen without the consent of individual miners? Obviously, the second there's evidence of double spending or similar, any value of Bitcoin will disappear as dew on a summer morning and the value of all the ASIC gear with it - so there i…

When you mine on a pool you are giving that pool complete control over your hashing power. For example there's pools that completely switch which coins you are mining every once in a while (every few minutes to hours) up to the pool operator.

Re: Ghash.io very close to 51% of bitcoin pool

#58

Post by unlimited_power »

darkFunction wrote: post #47
pron wrote: post #41

I don't know much about the particulars of BitCoin mechanics, but the general spirit of this story seems like a natural evolvement of any unregulated organization. People who favor unregulated markets/societies dislike the concentration of power in the hands of a central authority, but the reality is that in any social system there will always be concentration of power in the hands of the few. I've read a hypothesis[…

Proof-of-stake attempts better enforcement of decentralisation, but I think the various implementations are pretty immature.

I encourage people to look at the paper Transactions as Proof-of-Stake & The End of Mining[0] defining a form of the idea. BitShares[1] (due out in Q2 2014) will implement this.

[0] https://bitsharestalk.org/index.php?topic=1138.0

[1] https://www.youtube.com/watch?v=5BV55IrZi7g

Re: Ghash.io very close to 51% of bitcoin pool

#59

Post by aestra »

X4 wrote: post #56
patio11 wrote: post #49

Earlier quoted context omitted.

To be more explicit: if you have > 50% of the hashing power for a sustained period of time, you can with 100% probability dictate which transactions are accepted, which allows you to perform double-spend attacks essentially at will. [+] If you control a significant percentage which is less than 50%, you can attempt to do this but it is both uncertain to work (on any given attempt) and costly if it fails. Note that yo…

So even gambling sites use Bitcoin! That double-spend attack sounds so weird, I wonder why it's even possible. Why does Bitcoin trust the owner of larger amount of BTC (51%) more than those with less? I thought that trusting every client equally (less) would be a greater advantage, than trusting the largest group of clients. That part is hard to understand. What would happen, if due to a war many of the datacenters o…

See the other posts in this thread for more technical details, it isn't the owner of the largest amount of bitcoins, it is the miners with the most amount of hashing power. See, miners are supposed to be decentralized to prevent double spending. When you mine in a pool, you are giving up your hashing power to a pool operator in exchange for a payout that is more regular. When that operator controls over half the bitcoin network, they become bitcoin God.

In theory everyone mines alone to prevent this, in practice, this isn't very feasible.

Re: Ghash.io very close to 51% of bitcoin pool

#60

Post by patio11 »

X4 wrote: post #56
patio11 wrote: post #49

Earlier quoted context omitted.

To be more explicit: if you have > 50% of the hashing power for a sustained period of time, you can with 100% probability dictate which transactions are accepted, which allows you to perform double-spend attacks essentially at will. [+] If you control a significant percentage which is less than 50%, you can attempt to do this but it is both uncertain to work (on any given attempt) and costly if it fails. Note that yo…

So even gambling sites use Bitcoin! That double-spend attack sounds so weird, I wonder why it's even possible. Why does Bitcoin trust the owner of larger amount of BTC (51%) more than those with less? I thought that trusting every client equally (less) would be a greater advantage, than trusting the largest group of clients. That part is hard to understand. What would happen, if due to a war many of the datacenters o…

You should know that you don't understand enough about Bitcoin to reason about it [+], and before trusting my representations about it, you should know that I am approximately the most skeptical person about it in the entire tech community.

+ This phrasing is rather more robust than I'd prefer, but you're dangerously mistaken about something which many people will attempt to get you to equate with money.

The Bitcoin protocol does not trust owners of large amounts of bitcoins. An emergent behavior of the protocol is that it trusts people with large amounts of hash power over given periods of time. Why not trust every client equally? Because Satoshi believed that IP addresses were really easy to conjure up, and compute farms were really hard to conjure up, so a malicious actor could easily get a majority of the network if you were counting via IP addresses but it would be hard if you required computational proof of work.

This is one of the core engineering decisions in Bitcoin. One of the other ones is, to incentivize people to spend computational power on computations which have no utility the overwhelming majority of the time, periodically they're allowed by the protocol to claim bitcoins which are created from nothing. Every bitcoin in circulation first came into possession by someone who won a lottery with tickets basically bought by the expenditure of hash power.

Response to edit: In a war during which 75% of the world's datacenters are destroyed, the Internet collapses, Bitcoin dies along with many hundreds of millions of people, and cryptocurrency enthusiasts join Beanie Baby collectors in the long line of people who will not find their favorite hobbies treated well in a nuclear winter.

If you're answering purely as a math abstraction, though, the protocol will eventually self-correct by picking a new, lower block difficulty, with the goal being creating a new block approximately every ten minutes. The approximate upper bound on how long it would take to recalibrate if you lost 3/4th of the hashing power is plus or minus eight weeks. (I originally said "an hour", which is clearly in error.) During the interim, Bitcoin would be possible to transact in and mine but it would be slower than previously -- instead of it requiring about an hour to know that a given transaction was safe to rely on, it would require about four hours.

But again: Bitcoin is very much not robust against "the end of the world."

Post reply on HN