Quote from: Rassah on November 19, 2012, 01:53:41 PM

Quote from: fergalish on November 19, 2012, 01:01:33 PM

But ASICs [would be] illegal...

Illegal where?

One answer: in your country! Alternative answer: in any country. The attack I outline could be carried out by any country and its citizens could therefore be subjected to perfect financial regulation. Other countries might seek to join that blockchain, or they might have one of their own.

Quote from: bitCooper on November 19, 2012, 03:14:18 PM

I think this hypothetical scenario is unrealistic. The cost of obtaining 51% control is so high that such an investment would be highly risky,

I disagree. Current network hash rate is ~ 25TH/s. BFL says they'll give you 1.5TH/s for $30k in a single box. You'd need only about 20 of them to gain > 50% of the hash rate, that's $600k. Six hundred thousand dollars! So let's suppose someone tries to set up this attack in the future when there are already, let's say, 10000 such boxes already running and connected. You'd still only need about $300 million (ignoring price reductions due to efficiencies of scale, and improved technology) - that'd still be small change to a central bank that's printing, what, $40 billion per month? Suppose there were 1 million such boxes running - that'd cost $30 billion, 8 months of QE3. Let me emphasize, the attack would have to be surreptitious so as not to raise suspicion. ASICs coming online would be the *perfect* moment to implement the attack because nobody will be worried at sudden massive increases in hashes-per-sec.

ASICs will be great for bitcoin if they become truly distributed, but it should be obvious to all that they'll never be as uniformly distributed as CPUs. Any argument on that point?

Quote from: Rassah on November 18, 2012, 04:30:18 AM

You are wrong, because you assume anyone would use a currency with a 51% weakness already in progress, and because your formula doesn't account for the initial investment in hardware required to achieve that 51%. You are only accounting for operating expense with that $212 million.

If civil servants get paid in a particular blockchain, then they'll use it. And if the police understand that their bitcoins become more valuable by beating on 'blackchain' exponents, then you can be sure they'll do just that.