Hacker News Reader

Comment by sprash | Hacker News Reader

> It sounds as if Nano is still vulnerable to a 51% attack.

Every cryptocurrency is vulnerable to a 51% attack including Bitcoin.

As much as people like to complain about Bitcoin's energy usage, it makes a 51% attack prohibitively expensive and if you were to invest all that money, you'd want to make money with it rather than cause a short term disruption to the network.

If you are a central bank that can print money out of thin air you can use that money to buy the majority of the mining capacity and make bitcoin useless with a 51% attack. People that want to destroy bitcoin have no interest in making money "with it". They invest that money to destroy it.

Except central banks don't live in a vacuum. If they print tons of money to buy it, that would push the price even higher, incentivizing even more miners.

And I don't think central banks would want to destroy it. In many ways, many useful transactions in crypto occur in stablecoins pegged to the dollar. If anything, central bank might want to participate and innovate with everyone rather than try to destroy Bitcoin.

Central banks print Trillions of dollars to buy bonds right at this moment and get away with it. They live in a vacuum and can do what they want without much democratic oversight. Since all the relevant mining is happening in China nowadays the fate of bitcoin lies in the hands of the autocratic Chinese regime. If they instruct all miners to use their Chinese version of Bitcoin that e.g. dismisses all transactions and only produces empty blocks, Bitcoin is over.

And considering your argument of absolute power of CBs, you still prefer central banks over bitcoin?

1. Get an international coalition behind a ban on PoW mining. Would make sense as part of a climate agreement.

2. Once enforcement crashes the hash rate, fire up government controlled miners to perform a 51% attack on BTC. Repeat as many times as it takes to make the point.

The question is, which states need to be convinced to join the coalition, and how hard is that? I can see pariah states like e.g. Russia seeing an opportunity in encouraging mining instead of banning it.

~65% of BTC mining capacity in operation today is operated within China, so there's no coalition needed. A single nation's governance needs to decide (or be persuaded) that it's in their interests to do so.

One relatively cheap way to attack Bitcoin without ever owning any mining equipment at all is to create a pool (or several) and advertise no or even negative pool fees. Over time it would be possible to undercut legitimate pools and amass 51%.

Well, all current data-centric global consensus cryptocurrencies are vulnerable.

In the Holochain model (https://holo.host/) of distributed agent-centric consensus, a single non-fraudulent DHT node can detect any fraudulent transaction, and all other non-fraudulent nodes are informed of the self-incriminated fraudulent agent and transaction, confirm the fraud, and no longer respond to the fraudulent node.

So, only a 100% attack will succeed. And, the ill-gotten gains are permanently useless.

Well, in that sense Nano is immune too: every honest node agrees that only the owner of the private key can change the wallet balance. Only thing 51% can do is stall the network, it doesn't allow double spends or creating new money or reverting history.

And Holochain is not a cryptocurrency as far as I understand: while they say something about mutual-credit cryptos they definitely not the main scope of the project.

There are different degrees of system compromise. Avalanche is resilient to a 51% attack. Check out https://tedyin.com/archive/snow-bft-demo/#/snow and the paper

For some cryptocurrencies, a 51% attack would only be able to halt the network (prevent new transactions) but wouldn't be able to cause a double spend or other safety failures.

Reply on news.ycombinator.com