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I don't think there has been any empirical evidence regarding the idea that proof-of-stake method can reach consensus, so I'm not sure about the quality of this
by sktrdie 11y ago
I don't think there has been any empirical evidence regarding the idea that proof-of-stake method can reach consensus, so I'm not sure about the quality of this document. It is sort of implied, but in reality one can easily fake n chains and there would be no way for a peer to independently figure out which one is valid. In proof-of-work a peer can always rely on the idea that the chain with the most work is the valid chain.
Proof-of-stake is an interesting idea, but until I see empirical evidence showing that it actually works, I remain skeptical.
Here's a good read on the subject: https://download.wpsoftware.net/bitcoin/pos.pdf https://download.wpsoftware.net/bitcoin/pos.pdf
- kushti 11y agoAuthor is here! Here's my feedback and discussion with Poelstra https://www.reddit.com/r/Bitcoin/comments/2zpmlj/expanded_rewrite_of_distributed_consensus_from/cplj4ug https://www.reddit.com/r/Bitcoin/comments/2zpmlj/expanded_re... . There's no any formal proof of consensus (im)-possibility around. But we have some cryptocurrencies successfully working for years already(despite promises to hack them easily), also there're some simulations around, e.g. ours https://github.com/ConsensusResearch/ForgingSimulation https://github.com/ConsensusResearch/ForgingSimulation and https://github.com/ConsensusResearch/MultiBranch https://github.com/ConsensusResearch/MultiBranch (corresponding articles https://github.com/ConsensusResearch/articles-papers https://github.com/ConsensusResearch/articles-papers ). I hope more formal framework will be established someday, and would be happy to help with that(I can contribute with Coq code etc).
- sktrdie 11y agoThere's a proof in Bitcoin's paper that shows the probability of someone catching up with the main chain. That's actual real data that we can measure. Of course nothing's 100% true in the real-world, but with PoW you get very real numbers on the probability of someone catching up, which decreases drastically after each confirmation. On the other hand with PoS I still haven't seen any data whatsoever. I asked a simple question: since there's no cost for someone to simulate a chain, what's stopping peers from doing this? I know there are checkpoints and things like Nxt don't allow deep reorgs, but for new users joining the network it means you need to point them to trusted parties that can give them this information: they can't trust the chain independently.
- kushti 11y agoIn the first place, by using modern ASIC it's possible to draw a chain from the genesis having no difficulty changes(by setting proper timestamps), and it will be longer than network's probably as latter has delays more than 10 mins pretty often. So Bitcoin has checkpoint as well ( https://github.com/bitcoin/bitcoin/blob/86cfd23f68367af072500b1758a4c446cdd36e74/src/chainparams.cpp https://github.com/bitcoin/bitcoin/blob/86cfd23f68367af07250... ). In the second place a chance of drawing a long chain suffix with cumulative difficulty better than network's is negligible. Short-range attacks are possible, but they are not a huge problem. Please read the forum post with some results got with simulations https://bitcointalk.org/index.php?topic=897488 https://bitcointalk.org/index.php?topic=897488
- sktrdie 11y agoWhat do you mean? If I look at the latest block hash and difficulty I can actually measure how much hashing power went into finding such block (and it's a lot). How would you simulate that with timestamps?
- kushti 11y agoYou can generate blockchain since genesis setting timestamps every 10 mins so no any difficulty change. And that chain drawn to the moment will be longer than network's.
- sktrdie 11y ago@kushti I think you might have misunderstood how the consensus protocol works in Bitcoin. It's not the longest chain, but the one with the most work put into it that is accepted.