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Ghash.io very close to 51% of bitcoin pool
- VMG 13y agoIt might already be considering that there is a substantial proportion that is "unknown" mining power: https://blockchain.info/pools https://blockchain.info/pools On the other hand, the heuristics of blockchain.info do determine block ownership are not perfect either: https://bitcointalk.org/index.php?topic=123726.0;all https://bitcointalk.org/index.php?topic=123726.0;all
- drcongo 13y agoCan you explain what the threat is please?
- smtddr 13y agohttp://www.cryptocoinsnews.com/2014/01/09/warning-ghash-io-nearing-51-leave-pool/ http://www.cryptocoinsnews.com/2014/01/09/warning-ghash-io-n... ---The attacker can----: Reverse transactions that he sends while he’s in control Prevent some or all transactions from gaining any confirmations Prevent some or all other generators from getting any generations Double spend Bitcoins ---The attacker cannot---: Reverse other people’s transactions Prevent transactions from being sent at all (they’ll show as 0/unconfirmed) Change the number of coins generated per block Create coins out of thin air Send coins that never belonged to him
- drcongo 13y agoThanks.
- michaelmior 13y agoIs there really a practical difference between double spending and generating coins out of thin air? I can just duplicate coins by sending to two wallets I control. Or is there something that would prevent me from later spending some of those coins?
- lostsock 13y agoYou can spend the same coins twice, but you do not end up with 2x as many if you don't spend them at all. So you can end up with 1x worth of goods and 1x in your wallet like you never spent them but you can't end up with 2x in your wallet.
- tyilo 13y agoGiven 1 BTC sent to two different addresses, there is maximum only one of them that is valid at one point in time. However after some time, the other coin could be valid and the first coin could be invalid. The timing attack gets harder the longer time has gone since the coin was sent.
- nano_o 13y agoI think that they would not be able to do that: only one of the two transactions could be in the longest correct block-chain. That's because it is easy for the clients to detect and reject a block-chain that contains double spending. What they can do is pay for goods or services and revert the transaction after the goods or services have been delivered.
- chaosmatic 13y agoIf you check https://blockchain.info/pools https://blockchain.info/pools Ghash.io is back down to 39% of blocks created, which is still big, but not as scary. A good explanation is due to the random variation in the who the block is a awarded to.
- andyjohnson0 13y agoCould 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.
- lmb 13y agoEssentially, Ghash.io would be in control of the Bitcoin blockchain, allowing double spending of BTC and other nefarious deeds. See https://en.bitcoin.it/wiki/Weaknesses#Attacker_has_a_lot_of_computing_power https://en.bitcoin.it/wiki/Weaknesses#Attacker_has_a_lot_of_... Edit: According to the Wiki linked, these attacks are also possible with <50% mining rate, although with lower probability of success. So this is a problem even if Ghash.io does not crack the 51%.
- krig 13y agoMy understanding is that if one entity controls 51% of the network, they can push arbitrary modifications into the block chain. In effect, they can do whatever they want.
- rlpb 13y ago> ...they can push arbitrary modifications into the block chain. In effect, they can do whatever they want. No, since who holds what coin is defined by consensus, which has to stretch out of the mining pool. If they arbitrarily gave themselves coin, for example, then no other client would accept that they hold that. See smtddr's reply for details of what they can and cannot do.
- andyjohnson0 13y ago"If they arbitrarily gave themselves coin, for example, then no other client would accept that they hold that." Would this be detectable in practice?
- VMG 13y agoyes, ever other Bitcoin client would refuse the blocks because they don't follow the transaction spec The purpose of Bitcoin mining is to establish an ordered sequence of transactions
- Kiro 13y agoI don't understand anything. What's going on?
- Nux 13y agoWish I could filter out the bitcoin news.
- lmb 13y agoYou can: http://hn-filter.appspot.com/#preset=bitcoin http://hn-filter.appspot.com/#preset=bitcoin
- mseebach 13y agoGhash.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 is a very strong incentive for each individual miner to refuse to participate.
- haakon 13y agoNone of their miners have to collude in any way; scary stuff is entirely up to the pool operator to execute and the miners won't even know that they're helping until it has happened. At this point it's tempting to consider just mining for this pool as collusion, however. GHash.io have been known to abuse their mining power to double-spend already. Miners are not showing much will to leave for other pools, however. It's a dire situation.
- belluchan 13y ago> It's a dire situation. Hoards of people dump insane amounts of money into a new, unproven and unstable currency technology. What could go wrong?
- deleted 13y ago[deleted]
- VMG 13y agoMining power can centralize -- there are some solutions to this. One of them is https://en.bitcoin.it/wiki/P2Pool https://en.bitcoin.it/wiki/P2Pool
- aestra 13y agoWhen 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.
- joosters 13y agoThere's no safety even if GHash.io is below 50%. How can we tell that GHash.io and BTCGuild aren't already colluding? They have 61% between them.
- legutierr 13y agoEven without that collusion, if you control 40% you still have a high probability of pulling off a double-spend attack. My recollection (sorry, I don't have a link, so I might be wrong) is that someone somehow associated with GHash.io already pulled something like this off when they were still below 30%
- patio11 13y agoc.f. https://bitcointalk.org/index.php?topic=327767.0 https://bitcointalk.org/index.php?topic=327767.0
- philrapo 13y agoIn 2011, Jed McCaleb pointed out that bitcoin mining pools can collude. So in fact, Bitcoin is based on trust... it is based on trust that mining pools are not colluding against you. His idea was to make this trust explicit. And that's the birth of Ripple. Ripple's consensus process is predicated on trust that other entities are not colluding against you. The Ripple protocol is not subject to the 51% attack that Bitcoin is subject to. Making entries in the ledger has nothing to do with computational power. ----- Link to the 2011 discussion that spawned Ripple: https://bitcointalk.org/index.php?topic=10193.msg146250#msg146250 https://bitcointalk.org/index.php?topic=10193.msg146250#msg1... EDIT: Adding a link explaining Ripple's consensus process for making changes to a shared ledger: https://ripple.com/wiki/Consensus https://ripple.com/wiki/Consensus
- deleted 13y ago[deleted]
- goldenkey 13y agoNice try Phil. Please get your Ripple propaganda off of HN. Ripple currency, XRP, is magicked up by Ripple Corp which owns nearly all of it and is the purest form of a pyramid scheme.
- knowaveragejoe 13y agoJust to play devil's advocate here, is there any proof to that claim?
- jplewicke 13y agoI don't have a dog in this fight, but Ripple Labs did set things up so they would start off with all the network currency, and still own the majority of it: http://en.wikipedia.org/wiki/Ripple_(payment_protocol)#XRP http://en.wikipedia.org/wiki/Ripple_(payment_protocol)#XRP .
- philrapo 13y agoThat's correct. From Ripplelabs.com: "Because Ripple’s new architecture does not require mining [to reach consensus], the creators of Ripple faced a choice: exclusively distribute XRP via mining or diversify distribution methods to include useful mining, business development, funding third-party developers, and hiring talent at Ripple Labs, the company responsible for improving upon and promoting the Ripple protocol." XRP is currently distributed via the "Computing for Good" program: "We’re giving away XRP in exchange for donating computing power to scientific research via World Community Grid. Anyone with an Internet-connected computer or Android device can participate." link: https://www.computingforgood.org/ https://www.computingforgood.org/
- casca 13y agoFor a very good (if long) explanation about Bitcoin in general and why this information is potentially relevant to the progress of Bitcoin - http://www.michaelnielsen.org/ddi/how-the-bitcoin-protocol-actually-works/ http://www.michaelnielsen.org/ddi/how-the-bitcoin-protocol-a...
- TomGullen 13y agoIf a pool has control of >50% of the hashing power, it means that they could do damaging things to the Bitcoin network as far as I understand. People will explain that it's not in the pools interest to do this, but it's missing the point. The pool is now a potential weapon, with a very small number of people in control. This means they are now a potential weapon against Bitcoin, and if someone external wanted to hurt Bitcoin GHash.io might be a good starting point to do this of which there are many ways to potentially realise this goal (blackmail, hacking, bribery, covert seizing of control etc) The more pools there are, and the more evenly the hashing power is ditributed amongst these pools the safer it is for everyone who has interests in Bitcoin. Peer-to-peer decentralised pools to me sound like an excellent way to mitigate this sort of risk, and I think it's important. Consolodation of pool hashing power I beleive is a natural inevitable market force. One pool has to be objectively the best and will attract the most miners. From what I gather, p2p pools are a fairly large technical challenge and the question still remains as if they can still compete with centralised pools with regards to efficiency and reliability (profitability).
- DrJokepu 13y agoMalicious attackers or disgruntled employees could also gain access to the pool and do nasty things.
- btown 13y agoWith Bitcoin as popular as it is, it would be an increasingly lucrative strategy to short BTC, damage the network, re-buy low, and undo the damage. Sure, this is sort of a one-time use weapon, but there's no reason to believe that GHash.io's operators are in this for the long haul - perhaps, in the words of that amazingly catchy television commercial, they "need cash now."
- josu 13y agoIt is currently pretty much impossible to short large quantities of bitcoins. Besides, such an attack would probably crash the whole system which could render the potential shorts useless. Too much uncertainty for anything that big. I really can't see the way for anybody to benefit from a 51 attack. However, a potential attack will probably be a black swan, which will make it "impossible" to foresee for 99% of us, so the fact that there isn't any clear way to benefit from it, doesn't actually mean that there isn't a way.
- X4 13y agoCan 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
- TomGullen 13y agoYou 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 is in the pool relative to their contributed hashing power (often minus a small fee for the pool operator). Ghash.io is the largest pool, and the member of the pool control a good 35-45% of total hashing power on the Bitcoin network. A pool with >50% the total hashing power is bad, because the operators in charge of the pool could carry out malicious acts on the Bitcoin network without any members of the pool being aware they are contributing to these acts.
- patio11 13y agoTo 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 you can take many bites at the apple if you're willing to suffer the opportunity cost, so if you have a sufficiently profitable transaction to cheat on, you'll come out ahead. The most vulnerable players in the Bitcoin system currently are gambling sites, but in principle with sufficient hash power you can do this to anybody using Bitcoin. Gambling sites are particularly at risk because their intended behavior is swapping bitcoins for bitcoins very quickly, and if you can doublespend, you can swap bitcoins for bitcoins but then say "You know those bitcoins I sent you? Psych, I didn't have them, even though you thought I did." after you've been told that you lost a bet. If you win the bet, you simply don't rewrite history to invalidate your bet. Repeat as desired. This is the planned and anticipated vulnerability in Bitcoin. Great news: it's rarely the planned and anticipated vulnerability that kills a system. + Double spend attacks are not the only attacks you can envision. For example, if you control 51% of hashing power for a month, you're capable of essentially invalidating all transactions globally in the past month, at a time of your choosing. Like, if an unrelated party Bob had been paid in bitcoin by his employer two weeks earlier, and Bob then attempted to transfer bitcoins to Mt. Gox to change into dollars, Bob's bitcoin client would suddenly tell him "Dude, you might remember that salary payment, but it never actually happened." and Mt. Gox would say "Umm, you don't have bitcoin to transfer in, what are you talking about?"
- pron 13y agoI 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[1] that it was this dynamics that propelled the neolithic revolution (the transformation of humans from nomadic hunters-gatherers to settled farmers): most people suffered as consequence (hunger, disease, less leisure), but a few benefitted greatly. The same thing happened in the American Gilded Age. In that period of unprecedented (and largely unregulated) growth, much of the US population became quickly enslaved by a few members of an elite group, later called the robber barons (Rockefeller, Frick, JP Morgan, Vanderbilt, Carnegie, Mellon et al.), and it took tremendous efforts by the American press and then by President Roosevelt (the first) to partially dismantle that semi-feudal structure and strengthen the central government, to free the populace from the stranglehold of the robber barons. While a central power can be abusive, it is almost always better than feudal oligarchy, at least if it is governed more-or-less democratically. So while BitCoin is an algorithm intended to avoid a single organizing entity, it is no replacement for a social pact, enforced politically by some fair means. Perhaps a better algorithm could somehow prevent any sort of concentrated power, but I doubt it. The desire for power (even with the best of intentions) is so essential to humans, that it probably cannot be circumvented by technology alone. [1]: http://www.newyorker.com/reporting/2011/12/19/111219fa_fact_batuman?currentPage=all http://www.newyorker.com/reporting/2011/12/19/111219fa_fact_...
- darkFunction 13y agoProof-of-stake attempts better enforcement of decentralisation, but I think the various implementations are pretty immature.
- unlimited_power 13y agoI 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 https://bitsharestalk.org/index.php?topic=1138.0 [1] https://www.youtube.com/watch?v=5BV55IrZi7g https://www.youtube.com/watch?v=5BV55IrZi7g
- jpalomaki 13y agoWhy ghash.io is so popular? Is their some specific reason for mining in GHash pool instead of some other?
- aestra 13y agoEDIT: 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.
- myvii 13y agoThey 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.
- blazespin 13y ago1. Buy millions of alt crypto coins (e.g., PPC which is less vulnerable to 51 attack), 2. destroy BTC by getting 51% control of hash pool, 3. profit.
- darkFunction 13y agoWhat?
- bigdubs 13y agoi think what is implied there is a potential plan to make tons of money by destroying bitcoin in favor of an alternative coin you've heavily invested in.
- gcp 13y agoAltcoin value is very closely linked to BTC value. Most (all?) altcoins are vulnerable to 51% attacks, so killing bitcoin would leave little hope of leaving value left in the altcoins.
- jobeirne 13y agoFolks are missing an important point here about the incentives of a pool majority (that I recall Satoshi mentions in the original whitepaper[0]): even if a particular agent has a majority in the mining network, it isn't in their interest to upset trust in a system that they have such a large investment in. Where would the sense be in taking the risk to undermine public trust in BTC for a short-term gain like modifying a few transactions when you have such a large stake in the system? [0]: http://bitcoin.org/bitcoin.pdf http://bitcoin.org/bitcoin.pdf
- iterationx 13y agoWhat if somebody incentives the pool operator with a rubber hose?
- jre 13y agoHere is a thought experiment : Say the pool operator is also the owner of Bank A (which has nothing to do with BTC). Now, a competitor of Bank A, Bank B, just announced that they will support BTC. The pool operator can now decide to "destroy" bitcoin and therefore cause severe financial loss for Bank B, leading to bankruptcy. If putting Bank B out of business results in gains (in USD), for the pool operator, that are greater than what he just lost in bitcoins, then it might be worth it. Of course, this is very hypothetical, but it's not hard to come up with similar situations where Bank A is "State A" and Bank B is "State B".
- jobeirne 13y agoThanks for the concrete counterexample. I still find it dubious that the owner of Bank A would be willing to destroy a stream of income as considerable as a 51% stake in BTC just to preempt a competitor in another market. That seems too self-sacrificial to be practical. Also, you're missing the point that Bank B's successful adoption of BTC would also benefit Bank A's owner, since that adoption would be a boon for BTC, which Bank A owner has a very large stake in.
- msandford 13y agoIt's all a matter of the right price. Bank A doesn't own 51% of bitcoin, it has control over 51% of the mining pool. As a rational agent in the bitcoin-only world that's worth SOMETHING but not billions. As a rational agent in the total world it might be worth sacrificing $100mm on the pool if it can cost your competitor $10b.
- philliescurt 13y agohttps://bitcointalk.org/index.php?topic=26656.msg334463#msg334463 https://bitcointalk.org/index.php?topic=26656.msg334463#msg3...
- morphar 13y agoOMG it is NSA trying to eradicate Bitcoin!!! :-P
- mrfusion 13y agoWith all the concern over double spending, I'm wondering doesn't double spending happen frequently? It seems like all you'd have to do is make two transactions within a short time period like < 1 second. Doesn't this happen from time to time?
- oakwhiz 13y agoI'm doing my part by moving my altcoin mining capacity over to Bitcoin pools. Not much, but every little bit reduces ghash.io's share.
- alecsmart1 13y agoI don't understand the forum thread. Can someone please explain it in layman terms?