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> throw 10% of a datacenter at it whenever they feel like it and pull off a 51% attack The rise of ASIC miners have made the BTC network essentially invulnera
by Tuna-Fish 13y ago
> throw 10% of a datacenter at it whenever they feel like it and pull off a 51% attack
The rise of ASIC miners have made the BTC network essentially invulnerable to attacks from general-purpose devices. SHA is very amenable to being directly implemented in hardware, making general purpose computers useless for bitcoin.
Because of all the new hashing power coming from all the new asic miners, difficulty has risen to the point that you'd need more than four hundred million modern cpu cores to take over the network. Using top of the line GPUs, you'd need more than 5 million of them.
China could take over the BTC network, however, to do so they would have to attack it with ASIC miners. This would imply ~6 months of preparation, tens of millions in funding, and they'd have to make the decision to pull the trigger some 3-4 months in advance or the money would go to waste.
- deleted 13y ago[deleted]
- tptacek 13y agoChina spends $40MM/yr on Post-Its.
- mrb 13y agoIt would cost a lot more than $40 million to majority-attack Bitcoin. I estimate $3-4 billion or more. Mostly data center costs. Let's assume an attacker is very good and needs only 6 months to design his own ASICs and build data centers to host the farm. The network is at 4 Phash/s today, so 6 months from now we should be around 4 * 2^6 = ~250 Phash/s (the network has been doubling in size every month for the past 10 months). The best ASICs, 28nm KncMiner, are approximately 100 ~Ghash/s and 100 Watt each. So an attacker would have to build 250 Phash/s of these to clearly outperform the network: that is 2.5 million chips at 250 megawatt total. And to plan for a potential delay of 30 days in his plan, an attacker would have to build not 250 Phash/s but 500 Phash/s of ASICs to attack the network. 5 million chips. 500 megawatt data center. For comparison, Facebook spent $210 million on their 28 megawatt Prineville data center. So a 500 megawatt data center would probably cost $3-4 billion. Even the well-funded NSA couldn't get their comparatively punny Utah data center to run correctly and it has been delayed by more than 1 year: http://www.pcworld.com/article/2052960/nsa-data-center-suffers-meltdowns-is-delayed-by-a-year-report-says.html http://www.pcworld.com/article/2052960/nsa-data-center-suffe... Is China seeing Bitcoin as a threat? No. And even if it was, is it big enough for them to be willing to spend $3-4 billions to destroy it? I don't think so.
- tptacek 13y agoBitcoin. It might work, as long as no large government in the world decides to make it stop working.
- mrb 13y agoGovernments cannot stop Bitcoin on a global scale for the same reason they cannot stop Internet on a global scale. There is no cost-effective way to destroy a well-designed decentralized technology/protocol, plus it would require co-operation of most countries to destroy it.
- tptacek 13y agoYou mean, unless they buy enough asics.
- mrb 13y agoDid I not demonstrate in a back-of-the-napkin way that it is out of reach of the NSA ($3-4 billion & deploying 500 megawatt within 6-7 months)? If the NSA cannot do it, no government can.
- eli_gottlieb 13y agoNever call something impossible when there are political and financial points to be scored by doing it.
- bpicolo 13y ago$3-4 Billion is nothing for China. If they want to destroy it it's totally trivial. Besides, I bet they can cook up more efficient devices than commercially available asics.
- mrb 13y agoTrivial? Let's assume attacking the Bitcoin network would be a project falling in the hands of the most well-funded Chinese government agency: the military. (It would not, but let's assume it). This represents about 3-4% of their annual budget (~$100B), which is not quite insignificant.