Every supercomputer in either the U.S. or China plus its cloud resources would be able to mount a 51% attack. And this isn’t counting e.g. the NSA or GCHQ’s supercomputers, which are optimised for code cracking.
Fair enough, supercomputers + cloud was optimistic. They can’t do 40 zettaflops.
Half of that, worst case, we could, though not triviallt. For bursts at a time. (Worst case because the math supercomputers designed to break encryption do is similar to that required to break Bitcoin.)
Practically speaking, were we to do this, we’d procure the ASICs. (And target in-jurisdiction mining, lowering the hurdle.) No private party is particularly incentivised to launch such an attack de novo. We may never need to actually attack: a law appropriating tens of billions to create a crypto deterrent would crash prices on its own.
Doubt that. All that would happen is driving the industry underground or overseas. It wouldn't be the first time a government overplayed its hand and failed to acknowledge that bitcoin is a global technology.
https://data.nasdaq.com/data/BCHAIN/HRATE-bitcoin-hash-rate
That isn't slowing down. I have exactly 0 faith that governments across the world could start from scratch and cooperate to outpace and then surpass the private sector in a chip fabrication project, no matter how many billions they throw at it.
You move to seize it. ASICS are manufactured in China and among American allies.
But sure, I guess they could try.
Specialized mining hardware is in the exahashes range whereas even the best general purpose are terahashes at best and even that is a stretch.
Plus the attack has to be sustained, you can't just do it for a few seconds or minutes and disrupt much.