Does difficulty adjustment exploiting selfish mining assume pool loyalty?

The 2018 paper "On profitability of selfish mining" by Cyril Grunspan and Ricardo Pérez-Marco [0] introduces a selfish-mining attack that relies on the difficulty adjustment algorithm. Their followup paper (same year) "On profitability of stubborn mining" [2] extrapolates this to attack variants.

It first explains how, when difficulty is constant, selfish-mining is less profitable than honest mining (see also [1]). But then it claims that the difficulty adjustment algorithm introduces a way to make profit. Before I even attempt to understand the math, I'm having a hard time making sense of this intuitively.

By temporarily withholding blocks in period N the attacker is increasing the stale block rate, both for themselves and for honest miners. This causes a drop in difficulty which makes mining in the next period more profitable. So far I follow.

But why would a lower difficulty in period N + 1 benefit the selfish pool more than its competitors? It seems to me all pools profit equally in period N + 1. But the selfish pool had to make an investment in period N, since we've already established that at constant difficulty this strategy is less profitable.

So as a neutral miner choosing between pools, you don't want to be in the attacker pool in period N when it's losing money. You also don't want to join it in period N + 1 because you can reap the same reward in any other pool.

So are they making an assumption about pool loyalty?

[0] https://arxiv.org/abs/1805.08281

[1] https://bitcoin.stackexchange.com/a/125844/4948

[2] https://arxiv.org/abs/1808.01041



from Recent Questions - Bitcoin Stack Exchange https://ift.tt/3W4SYAJ
via IFTTT

Popular posts from this blog

Bitcoin Mining Could Be Strengthening The Ruble, Russian Central Bank Says

Crypto Exec Warns Tokenization Is Moving Faster Than Expected

Bitwise Clients Pour $69M Into Solana as Bulls Fight to Reclaim $200 Resistance Zone