8 ms·

Why would China not like bitcoin? They can - track all financial transactions by all people to find dissidents and find NGO funding sources - throw 10% of a

Why would China not like bitcoin? They can - track all financial transactions by all people to find dissidents and find NGO funding sources - throw 10% of a datacenter at it whenever they feel like it and pull off a 51% attack - lock up a huge number of bitcoins via the above point

blake8086 13y ago
That would be one powerful data center if it has 5.1 times the hashing power of the bitcoin network.
- jedunnigan 13y ago
  It wouldn't take but a few thousand wafers of 65nm ASICs to overpower the rest of the network. With direct access to chip manufacturing facilities this can be pulled off fairly easily.
smaili 13y ago
I think this is what makes me nervous about electronic currencies. A country, even just a person, could easily abuse it by throwing these huge machines at it. The only thing analogous to this with real currencies are printing presses that people somehow get a hold of and are able to print themselves. The nice thing about real currency though is we have some ways of knowing whether they're real or not (like looking under a light), but you can't really determine whether someone's bitcoins came from abuse because technically it's legit. Only solution I could think of would be if there's a way for the networks to have throttling so miners could only make so many per day or per hour or some other metric.
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 ago
  China spends $40MM/yr on Post-Its.
  - mrb 13y ago
    It 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 ago
      Bitcoin. It might work, as long as no large government in the world decides to make it stop working.
      - mrb 13y ago
        Governments 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.
mrb 13y ago
In addition to Tuna-Fish's excellent reply, bpodgursky, you need to ask yourself: what would be China's motive to destroy Bitcoin via a majority ("51%") attack? They have no particular reason to do so. On the contrary, they can instead economically benefit from being a participant in the Bitcoin ASIC design and manufacturing industry. (And they already are: Avalon, Blackarrow, ASICMINER/BlockErupter, etc, all these companies are operating primarily out of China). Also: China "locking up" coins would do nothing to stop or destroy it. It would just drive the value of the remaining coins higher and as we are seeing right now, an appreciation drive the interest in Bitcoin up, not down.
- mrb 13y ago
  Why the negative rating? I ask a question, state (multiple, verifiable) facts, and make a reasonable argument. Ah, the mystery of HN ratings...

blake8086 13y ago

That would be one powerful data center if it has 5.1 times the hashing power of the bitcoin network.

jedunnigan 13y ago
It wouldn't take but a few thousand wafers of 65nm ASICs to overpower the rest of the network. With direct access to chip manufacturing facilities this can be pulled off fairly easily.

smaili 13y ago

I think this is what makes me nervous about electronic currencies. A country, even just a person, could easily abuse it by throwing these huge machines at it. The only thing analogous to this with real currencies are printing presses that people somehow get a hold of and are able to print themselves. The nice thing about real currency though is we have some ways of knowing whether they're real or not (like looking under a light), but you can't really determine whether someone's bitcoins came from abuse because technically it's legit. Only solution I could think of would be if there's a way for the networks to have throttling so miners could only make so many per day or per hour or some other metric.

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 ago
China spends $40MM/yr on Post-Its.
- mrb 13y ago
  It 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 ago
    Bitcoin. It might work, as long as no large government in the world decides to make it stop working.
    - mrb 13y ago
      Governments 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.

mrb 13y ago

In addition to Tuna-Fish's excellent reply, bpodgursky, you need to ask yourself: what would be China's motive to destroy Bitcoin via a majority ("51%") attack? They have no particular reason to do so. On the contrary, they can instead economically benefit from being a participant in the Bitcoin ASIC design and manufacturing industry. (And they already are: Avalon, Blackarrow, ASICMINER/BlockErupter, etc, all these companies are operating primarily out of China). Also: China "locking up" coins would do nothing to stop or destroy it. It would just drive the value of the remaining coins higher and as we are seeing right now, an appreciation drive the interest in Bitcoin up, not down.

mrb 13y ago
Why the negative rating? I ask a question, state (multiple, verifiable) facts, and make a reasonable argument. Ah, the mystery of HN ratings...