5 ms·
Malice isn't enough. The only special power of a 50% miner is to consistently resolve double-spend attempts in its favor. If this happened, it would surely lowe
by sowbug 11y ago
Malice isn't enough. The only special power of a 50% miner is to consistently resolve double-spend attempts in its favor. If this happened, it would surely lower the value of Bitcoin. This, an attacker must be not just malicious but also irrational enough to forfeit the $800,000 in Bitcoin that it creates daily by virtue of its 50% control of the network. (6 blocks/hour x 24 hours/day x 25 bitcoin/block x $450/bitcoin x 50%)
- sanswork 11y agoShort first hope the exchanges don't fold and run it into the ground with double spends. Alternatively just attack it because you feel scared about it but I do t believe anyone in power is since it is not going anywhere
- crm416 11y agoIt's not necessarily 'irrational'. A 51% miner could profit from Bitcoin's downfall, or by threatening others, or even by bluffing an attack. See, e.g., the Goldfinger Attack in https://www.cs.princeton.edu/~kroll/papers/weis13_bitcoin.pdf https://www.cs.princeton.edu/~kroll/papers/weis13_bitcoin.pd....
- geofft 11y agoStupid question: if control of 50% of the hash power is so unimportant, why does Bitcoin rely on hash power anyway? Why not simply have a consensus system without proof-of-anything?
- circlecrimson 11y agoI think the reason is because then there would be no way for new coins to be mined and given to those who are rewarded for ensuring the security of the network.
- wizeman 11y agoWell, consensus between whom? How would you do distributed, anyone can participate at any time, byzantine consensus but still prevent Sybil attacks?
- ozmbie 11y agoIf you remove proof-of-work, then the question then becomes: what else do you measure consensus by? A few other crypto currencies have tried other metrics but they all aim to for the same thing: removing the need for human trust.
- iofj 11y agoNot true. A malicious 50% miner can cancel any transaction it wants, not just fix doublespend. Assuming the transaction was sufficiently recent (the more hash power they have the more such a transaction can be in the past). So they can "unspend" their own bitcoins, as follows : use 51% of your hash power to create a parallel blockchain, which is not published. Include all transactions, except the one you used to buy a TV. Put something else in it's place. Keep doing this until the TV is shipped/arrived. Then publish the parallel blockchain. Boom. Unspent.
- gavazzy 11y agoParent's point is that if BitFury did that, then nobody would trust Bitcoin anymore, thus crashing the price.
- mootothemax 11y ago>Parent's point is that if BitFury did that, then nobody would trust Bitcoin anymore, thus crashing the price. If they make good money from it, why would BitFury care about bitcoin's long-term outlook?
- celticninja 11y agothey make money by mining bitcoin, if the value drops then their return, even if they sell all BTC immediately, would be affected. They just spent $100m on a new mining facility so to trash bitcoin would be to write off that investment. They cannot make good money by screwing over bitcoin without screwing themselves over. Best case scenario is that at the end of the effective life of this DC BitFury decide to doublespend their coins to allow them to spend all bitcoins once, however by that time their relative % of the network will be less than 50%.
- mootothemax 11y ago>They cannot make good money by screwing over bitcoin without screwing themselves over. Why not? Surely this is more a lack of imagination on your part, rather than a hard fact?
- emin-gun-sirer 11y ago>The only special power of a 50% miner is to consistently resolve double-spend attempts in its favor. No, this post, and the handy table inside, explains the various attacks possible at different percentages of the hash rate: http://hackingdistributed.com/2014/06/16/how-a-mining-monopoly-can-attack-bitcoin/ http://hackingdistributed.com/2014/06/16/how-a-mining-monopo...