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Comment by api | Hacker News Reader

One of the major things that has always bothered me about crypto: if an economically "irrational" large player wanted to 51% something like Bitcoin, they could.

I am thinking of, for example, a nation-state. Let's say the US, EU, or China decided for some reason that it was in their national interest to blow up Bitcoin. This could happen if an adversary like Russia or its allies were using Bitcoin for funding and there was a war or a major Cold War style struggle. Such players could afford to purchase and build, in secret, a huge mining farm, and then suddenly turn it on, not caring about the cost because the goals are strategic. It would be massively expensive but it doesn't matter for this case.

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A more economical version of the same thing is to engage in honest mining through several front companies that together have 51%. Until a strategic opportunity presents itself and they start colluding.

Sure, and this is well within the capabilities of any competent large intelligence agency.

It's only a secure system if adversaries are either small or economically rational.

For monero and other smaller chains maybe, but for BTC this is already at the point of being quite difficult (the intelligence agency really would have to be quite large).

The money is one thing, you also have to somehow acquire a huge % of the ASIC supply over years, and the not insignificant amount of energy to run them

While that's certainly possible with a large enough expenditure, they'd also have to have the miners be sufficiently indistinguishable that they couldn't easily be denylisted with an update to the official codebase.

State entities can also destroy real banks with all sorts of means if they really want. The vulnerability is real, but beyond the scope of discussion because then it's war we're talking about.

But states generally like having a financial system, and don't like (or are at least annoyed and worried by) cryptocurrencies, so the incentives aren't the same.

I'm also curious about an attack vector whereby if a coin has a single reasonably well-installed mining software stack, this effectively gives the developers of that stack control over any miner, which could easily add up to 51% if there's only a few mining software options. Sneaking in a backdoor is well within the capabilities of any developer; do the mining companies compile from source?

The moment anyone does this, people will notice, and the coin plummets.

Which is what they want.

at 75 million a day what is the motive?

> a nation-state. Let's say the US, EU, or China decided for some reason that it was in their national interest to blow up Bitcoin

Irrelevant and impossible to "know", given that it hasn't happened yet (if it ever does)

They could borrow 1 Billion in Monero and sell it. Then they would only have to pay back a fraction and keep the rest.

Imagine if you will that the Russian economy ran on Bitcoin or whatever.

75 million a day to destroy the Russian financial system is less than half of what Ukraine currently spends on their defence budget.

Yep. From the comment you replied to:

> Let's say the US, EU, or China decided for some reason that it was in their national interest to blow up Bitcoin.

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