Hacker News Reader

Comment by gus_massa | Hacker News Reader

> nobody believes that Proof of Work is here to stay

I do. I prefer to call it "Proof of Burn" instead of "Proof of Work". With Proof of Burn you can assure that it's difficult to create fake blocks because the attacker must burn even more petrol barrels that the good people.

Also, with Proof of Burn you get protection against an explosion of too many hard forks. If you have a hard fork in a Proof of Burn coin, the miners must select one chain to mine (or split the resources), so usually only one chain survives. In a Proof of Stake coin, after a hard fork the miners can continue mining in both chains.

View on HN

>Also, with Proof of Burn you get protection against an explosion of too many hard forks. If you have a hard fork in a Proof of Burn coin, the miners must select one chain to mine (or split the resources), so usually only one chain survives. In a Proof of Stake coin, after a hard fork the miners can continue mining in both chains.

That's not what happened with the Bitcoin Cash fork though -- it resulted in "sloshing" between the two networks as miners would congregate in the currently-most-profitable network. That makes it so at any given time, one of the networks is easy to attack.

Look at the block creation and hash rates for BTC vs BCH:

https://fork.lol/blocks/time https://fork.lol/pow/hashrate

That is a contentious hard fork with a rule change, completely different from a normal fork caused by an orphan race. With proof of stake there is no marginal cost to playing multiple forks, ultimately opening up the network to a flood of competitive same-rule forks that have to be resolved using "weak subjectivity."

Adding layers of complexity like Ethereum's Casper to solve the incentive incompatibilities caused by the nothing at stake and long range attacks do not address the fundamental issues, as consensus then require users to agree on a list of bonded validators (for which there is no switching cost). "Phone a friend" consensus is objectively weaker as a security model compared to POW which just requires users to validate the rules and calculate the chain with the most work.

POW is secure because it requires energy from outside the system to be provably burned. It's thermodynamically sound in that respect. /u/nullc recently described POS as a logical tautalogy which I think captures the issue well. If chains were a car, Bitcoin would be fueled by gas and a POS coin would be fueled by the leather on the seats. You're not going to get very far.

You seem to have a deeply intuitive knowledge of blockchain tech, and you've posted with a throwaway. I'm assuming you are a well known member of the community.

At risk of being petty, no, they don't and aren't. See sibling thread: they're not disputing the core point I raised (that PoW schemes are not immune to being weakened by forks), but changed the topic to different one and seem to have copy-pasted general arguments in favor PoW. (It's copypasta because they have a cryptic reference to a poster on a different forum, /u/nullc that doesn't help us find the argument here without searching their history on reddit [I guess.])

> It's thermodynamically sound

Due to the algorithms being inefficient

If that is resolved then the entire history will be suspect

And any thermodynamically similar future will have to compete on constants and exponents

Or you could regulate the hardware, 'this blockchain is only compatible with, and so calculated on, a gateway lt1700 with exactly 640k of ram' ;P

>> It's thermodynamically sound

> Due to the algorithms being inefficient

This is by design, when the hardware gets better Bitcoin network starts requiring even more work, so being "efficient" is actually what is not desired here. See: https://en.bitcoin.it/wiki/Difficulty

It doesn’t sound like you’re disagreeing with my claim that forks under PoW (at least of a specific kind) can make the branches vulnerable to attack as soon as the hash power sloshes away; your comment is only speaking to PoS and a different kind of Bitcoin fork that doesn’t match the BCH one.

No, I am disagreeing with you. You are claiming that the hashpower oscillations between BTC and BCH contradict the GP's comment, when in fact you have you missed exactly what I and the GP have said:

>the miners must select one chain to mine

I am pointing out that the "sloshing" is in fact perfect evidence that they are only mining one chain at a time, or splitting their hashpower to varying proportions. This is completely normal and healthy miner behavior, they are simply greedy actors looking for the most profit. They cannot however mine both chains with their full hashpower for free (as you can with PoS), and this is an essential understanding when analyzing the security model of a consensus algorithm.

Also, the oscillations are most commonly exploitable only when the difficulty adjustments happen very quickly (see: BCH's EDA), so if 70% of the hashpower left, even if 16% of the remaining hashpower was malicious, the efficacy of a 51% will be handicapped by the disproportionately high difficulty.

Sorry if I’m being dense here, but I don’t actually see how you’re disputing that the threshold for attacking a single fork has (in the example) fallen from 51% of all bitcoin-capable miners, to 16%.

I don’t care whether sloshing is “normal healthy behavior”. I care whether a fork has become easy to attack. You seem to focus on every topic but that one.

I guess you are missing the entire point of this conversation. It is about the marginal cost of participating on multiple chains with PoW. You can point out oscillations as much as you like, it doesn't change the marginal cost. You are pointing out something that is entirely orthogonal.

Your point was different from my point. I entered the thread to dispute that PoW schemes aren't weakened by forks. Here's the exchange where I came in[1]:

Original comment: "Also, with Proof of [Work] you get protection against an explosion of too many hard forks..."

My reply: "That's not what happened with the Bitcoin Cash fork though ... any given time, one of the networks is easy[er than 51%] to attack."

If you're not disputing that point, then you're not refuting my objection to that original comment.

[1] https://news.ycombinator.com/item?id=15606486

IMO PoW scarcity is only more important to the future of cryptocurrency than global speed and cost of exchange if: You are already heavily invested in PoW coins.

Proof of Work (PoW) is inherent inferior to Proof of Stake (PoS). PoW is just the most simple way to archive consensus through cryptoeconomic incentives and that is why first blockchains implemented it.

It is not true that on PoS you can mine multiple forked chains without being penalized. On the chain that "wins" you can be penalized for mining multiple chains which is clearly bad behavior.

The main problems of PoS that Casper, the Ethereum implementation, is trying to solve are "Nothing at Stake" and "Long Range Attacks". Both problems are being tackled right now and close to be solved.

> It is not true that on PoS you can mine multiple forked chains without being penalized.

You're confusing multiple branches competing for being the most-cumulative-difficulty branch, with multiple distinct cryptocurrencies resulting from a hardforking code change.

Penalization only applies to the first case, but the parent was talking about the latter case. E.g. a miner could mine both ETH and ETC once both adopt PoS.

True. OP said hard forks and I talked about natural forks.

I don't see any problem in hard forks and being able to stake on multiple chains. Let people hard fork as much as they want and decide, later on, which chains hold value.

>decide, later on, which chains hold value

How? Who decides?

This is really where every PoS algorithm seems to break down. The whole idea of blockchain is to build a decentralized consensus, and PoS just handwaves it away.

>Who decides?

Every user of the system.

>How?

Mostly by taking in consideration the differences of the software from both chains.

You don't give any support for your initial thesis, nor does the post you're responding to.

Make a technical or economic argument.

Meanwhile: http://www.truthcoin.info/blog/pow-cheapest/

Counterpoint, on the thermodynamics of PoW: https://download.wpsoftware.net/bitcoin/asic-faq.pdf

What does "close to being solved" mean? These types of problems are either solved or not.

Reply on news.ycombinator.com