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Comment by KirinDave | Hacker News Reader

The PoW blockchain is slow to propagate updates but design. If you don't know how proof of work blockchains work, I advice you to Google around for a nice technical breakdown. Suffice to say, it is fundamental and a property people specifically code in to make blocks take a specific amount of time to complete.

As for the 1/3 citation, I guess that's slightly less known: "Selfish Mining". Citation: https://arxiv.org/pdf/1311.0243

Of course "1/3" is a joke. It's actually closer to 1/4.

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Great paper!

TL;DR for those of us on small viewports?

People can collude to get a disrporotionate amount of the profit from a blockchain. The more people collude, the more profit they get, the more rational it is to join them.

This then bridges into traditional 51% attacks.

> The more people collude, the more profit they get, the more rational it is to join them.

This is not true. Colluders diminish the value of their PoW reward by reducing the trust of all other participants in the system and honest actors have an even strong incentive not to join them. Just a few years ago a mining pool that gained a very large share of the Bitcoin hashrate had members choose to leave -- https://www.coindesk.com/bitcoin-miners-ditch-ghash-io-pool-...

Please see the referenced paper. They address this.

Because Selfish Mining attacks are not inherently detectable, you cannot expect the average user to detect them.

Too many refutations of selfish mining appeal to an oracle. This is an example of such an argument.

If the big miners need to self regulate like that, then why bother with proof of work in the first place?

You say, "traditional," but has one ever actually taken place?

Bitcoins are mined by a uniformly random process, which means even groups with a small amount of power can mine blocks, and even can occasionally mine more than one in a row. But instead of publishing that mined block immediately, there is a better strategy. Waiting on publishing makes a fork, and the colluders can keep mining on the fork until the strategy defines that they should publish - which is basically when the "honest" branch catches up to the colluding branch. Since the colluders don't have a majority, this will always happen, but that's ok.

Due to the way that the Bitcoin protocol works, honest miners will sometimes "help out" the colluding group by mining on that published fork. This basically amplifies the power of the colluding group, which is the goal. Worse, the paper proposes that the percentage of honest miners switching to the fork can be influenced cheaply, by choosing which blocks to forward along in the p2p network.

Interesting. Wouldn't this be riskier than non-collusion, since it diverts hashpower from the main chain and the merging of the side chain depends on help from non-colluding miners?

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