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0 pointslittlestymaar2y ago0 comments

> with an (empirically battletested) consensus mechanism.

In fact there almost as many consensus mechanisms as there are blockchains. In the beginning it was PoW that defined what was a blockchain, but with its obsolescence in favor of Proof of stakes for many chains the situation got muddier. Facebook's Libra/Diem for instance was based on a strongly consistent algorithm (as opposed to the eventually consistent nature of PoS) that's not that different from PBFT and ByzPaxos.

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mattwilsonn8882y ago· 2 in thread

I'd argue that most PoS networks are not fundamentally different from the consensus algorithms before Bitcoin - the difference is they include a token as an entry point into authority, and that getting caught attacking will demerit tokens from you.

But the attack vectors are the same, and now there is an incentive to pull off an attack since the system is representing money people are willing to trade for goods. I think PoS is dangerous for this reason - same vulnerabilities and defenses but with higher stakes on both sides.

Not defending PoW wholesale, but it is fundamentally different as a network defense tool - though, it too has a reward for attacking it, so long as you can get 51% together - or less with selfish mining (network latency attacks).

nullc2y ago

> , and that getting caught attacking will demerit tokens from you.

even that's only true if you define dememerit attack and caught in particular ways.

E.g. I have a lot of tokens then sell them. (or go around and buy up worthless no longer used keys from people who had a lot of tokens at some point).

Now I can bifuricate the history at that point, create all the alternative histories I can't and you can't take anything from me.

To protect against these alternative histories one needs to use a separate consensus mechanism. In many systems this has been essentially "some trusted third party signs the real stuff" -- often with some obfuscation in between. If you're okay with that security model, why not eliminate the intermediate step theater and just use the ultimate centralized consensus?

mattwilsonn8882y ago

I ultimately agree - I'll play Devil's advocate a bit:

Such an attack is referred to as a "long range attack" and is 'solved' by 'finality' in Ethereum, the largest running PoS network. Finality basically means a hard checkpoint. I won't make you say it: finality can of course be changed on different forks, and that's the core issue in PoS.

There is probably some utility in adding friction to such corruption, but that the mechanism doesn't ultimately prevent it and really just adds incentives to controlling it.

Attacks on PoS are more convoluted, but there are more of them and more ways to approach them. I fully agree this fact is lost in obfuscation and jargon.

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