Part of this post addresses the economics of creating a 6 block re-org. This makes sense as 6-confimations is the standard for Bitcoin finality today.

However, as Bitcoin's security inevitably weakens over the coming years due to diminishing miner rewards (denominated in BTC), I believe this "6-confimation" acceptance policy will change to include not only the number of confirmations, but the timing of those confirmations as well. Consider a scenario where an exchange deciding whether a tx with 6-confirmations that took 4 hours to arrive (this happens occasionally) is safe to consider finalized/settled. Even though 6-confimations may be considered safe by today's acceptance policies, this tx would still have a high probability of double spend due to the assumed 4-hour long wait for the 6 confirmations (as the attacker would have 4 hours to produce 7 blocks instead of the normal/expected 1 hour). Instead of ignoring block interarrival timing, it may make sense to include block timing as part of an acceptance policy.

So, going forward Bitcoin acceptance policies may change from today's 6-confirmation standard to something more complicated that involves the amount of time those blocks took to arrive. This would significantly enhance Bitcoin's double spending resistance without adding/altering any code and may give the network a much needed security boost in the coming years to prevent the attack discussed in the post.

▲

copirate 2 hours ago | parent | next [-]

If the attacker is waiting for a lucky event to occur (finding more blocks than others while having less than 51% of the mining power) it means that they are constantly wasting mining time. That in itself is a huge cost (operational cost and block rewards thrown away), but it also means that they can't predict when it will happen. A double spend attack must be planned in advance because the first transaction must occur at the beginning of the attack. I'm not sure how they could constantly try double spends without risking losing the money each time the attack doesn't happen.

I don't see how it could be profitable. If it can't be profitable, then the risk of someone doing it is pretty low. If they already have the necessary hardware, they'd be much better off mining.

▲

mrb 3 hours ago | parent | prev | next [-]

"Bitcoin's security inevitably weakens over the coming years due to diminishing miner rewards (denominated in BTC)"

That's incorrect. Security scales with USD-denominated rewards, not BTC-denominated. And there are 16 years of real-world data showing they have been generally increasing, so a healthy sign that the Bitcoin experiment is working:

https://newhedge.io/bitcoin/block-reward-per-block

And not only that, but rewards are still expected to stabilize even when measured in BTC (thereby not relying on an increase of BTC's price) as they are progressively composed more and more of tx fees instead of newly mined BTC.

It's puzzling to me why some still don't understand the systemic incentives that make all this work as it has for 16 years and counting...

▲

officialchicken 2 hours ago | parent | next [-]

> It's puzzling to me why some still don't understand the systemic incentives...

Then I guess you're the type who will be really surprised to learn that with diminishing rewards comes increasing consolidation.

> ... that make all this work as it has for 16 years and counting...

That's convenient way to memory hole the market flash crashes, network forks, the blocks mined without consensus, and everything bad that happened over that timeframe.

▲

free_bip 2 hours ago | parent | prev [-]

How are you so confident that it will never weaken? Especially since there will come a time when the block reward is literally 0.

▲

mrb 2 hours ago | parent [-]

Tx fees make up a bigger and bigger fraction of miner rewards over time.

	▲	jcfrei 10 minutes ago \| parent \| next [-]
		transaction fees are not increasing though, so they can't offset miner rewards. they have been in the $100k-$200k per day range for a long time, with only occasional breakouts: https://www.blockchain.com/explorer/charts/transaction-fees-... and the trend is not to the upside. in fact with the arrival of ETFs in 2024 the trend is clearly downwards.
	▲	rcxdude 35 minutes ago \| parent \| prev \| next [-]
		Is a store of value that requires a significant fraction of it be eaten up by transaction fees to maintain security going to be actually useful in the long term?
	▲	officialchicken 2 hours ago \| parent \| prev [-]
		Rewards are also a permanent infinite money glitch that last in perpetuity? Or won't be changed in the future?

▲

ur-whale an hour ago | parent | prev | next [-]

> However, as Bitcoin's security inevitably weakens over the coming years due to diminishing miner rewards (denominated in BTC),

Says you, without a hint of a rationale backing your argument.

It seems to me that the historical hashing rate curve tells a different story.

And block rewards have been diminishing regularly (and very predictably) pretty much since day one.

	▲	tromp an hour ago \| parent [-]
		The hashing rate is not directly relevant. That's roughly proportional to the daily dollar value of the reward times the efficiency of the leading mining hardware. The latter has gone up many orders of magnitude over the years. > block rewards have been diminishing regularly That's exactly what the poster you're replying to argued; the BTC denominated block subsidy halves every 4 years, and so without a corresponding doubling in price, the bitcoin security budget keeps diminishing, at least until tx fees start to dominate the subsidy.

▲

nathias an hour ago | parent | prev [-]

you can accept bitcoin at any confirmation you want, it isn't a policy