Proof of stake is incapable of producing a consensus • Hacker News Board

Re: Proof of stake is incapable of producing a consensus

#661

Post by cblconfederate » Sun, Nov 28, 2021, 8:17 PM UTC

cs702 wrote: post #655

brianolson wrote: post #133

(my day job is developer on Proof-of-Stake Algorand block chain, I'm a developer, this may not be polished official PR) Article's theory about malicious old blocks doesn't hold up. Let's say I start a new node and verify history since the beginning. Somewhere along the line I'm connected to a malicious node which hands me a fictionalized block. It would need to have been signed by not just one but about 30-45 account…

I would add that the silly argument that a super-wealthy individual or a government could in theory degrade or destroy a transaction platform is applicable, not just to Algorand and other block chains, but also, more generally, to ANY transaction platform . I mean, if Doctor Evil suddenly decided to spend tens of billions of dollars to destroy the three main credit card networks, he could probably do it. In fact, it…

he would in case of war

Re: Proof of stake is incapable of producing a consensus

#662

Post by dathinab » Sun, Nov 28, 2021, 8:19 PM UTC

SilasX wrote: post #642

dathinab wrote: post #625

Earlier quoted context omitted.

Which can (likely will) make you lose all the stacked money.

The article addresses that in the section starting: >>Therefore, once they have withdrawn their deposits, they are untouchable. This is the “nothing at stake” problem. There will inevitably come a point when a node is free to liquidate their entire stake and cash out. And later concludes that, In order to know which is the valid staking, you have to already have a decentralized mechanism for ordering transactions, wh…

But that's also true for PoW as you can use hardware which after an attack you can use for other things.

Re: Proof of stake is incapable of producing a consensus

#663

Post by sidiropo » Sun, Nov 28, 2021, 8:19 PM UTC

brianolson wrote: post #133

(my day job is developer on Proof-of-Stake Algorand block chain, I'm a developer, this may not be polished official PR) Article's theory about malicious old blocks doesn't hold up. Let's say I start a new node and verify history since the beginning. Somewhere along the line I'm connected to a malicious node which hands me a fictionalized block. It would need to have been signed by not just one but about 30-45 account…

The Algorand PoS consensus protocol assumes that honest nodes use so-called "ephemeral keys" (see Section 5.2 of the white paper). This implies they are supposed to "forget" part of their past state. A malicious node could choose not to forget their past state, thus making double-spend a possibility (assuming an adversary with majority of stake).

Therefore, the formal proof of security provided in the Algorand white paper does not resolve the nothing-at-stake problem, which is inherent to all PoS systems.

Re: Proof of stake is incapable of producing a consensus

#664

Post by PretzelPirate » Sun, Nov 28, 2021, 8:20 PM UTC

wizzwizz4 wrote: post #641

PretzelPirate wrote: post #637

Earlier quoted context omitted.

> Ethereum for instance had enormous amounts of money stolen or destroyed via weaknesses in the blockchain. These weaknesses weren’t due to consensus failures or protocol failures, but bugs in applications running on Ethereum. If Ethereum’s protocol allowed arbitrary funds to be stolen, that could certainly cause a loss of trust.

You overestimate the amount that people “investing” in crypto actually care about what it is. If my friends are anything to go by, anyway.

Most investors don’t care at all and blow off things like “the blockchain you’re using requires this fully centralized component”, but many players in the ecosystem that enable the speculation we see now, do care about protocol safety. If the Ethereum protocol was shown to be unsafe, they’d publicly promote safer alternatives and push their users to move.

Re: Proof of stake is incapable of producing a consensus

#665

Post by cblconfederate » Sun, Nov 28, 2021, 8:22 PM UTC

I think what rubs a lot of people wrong about PoS is that it puts a name behind the validator and people don't trust people. One may claim that all validations require some level of trust, but it s the same reason why people trust google and not 's link directory. And people have reasons to be suspicious because they know that when humans become actively malicious they find devilish ways to coopt others, while algoritms can just fail.

Re: Proof of stake is incapable of producing a consensus

#666

Post by akrymski » Sun, Nov 28, 2021, 8:26 PM UTC

brianolson wrote: post #133

(my day job is developer on Proof-of-Stake Algorand block chain, I'm a developer, this may not be polished official PR) Article's theory about malicious old blocks doesn't hold up. Let's say I start a new node and verify history since the beginning. Somewhere along the line I'm connected to a malicious node which hands me a fictionalized block. It would need to have been signed by not just one but about 30-45 account…

By this argument the only real consensus mechanism we need is FAITH. In PoS we trust.

As long as a sufficient number of people believe some currency has value - it has value. If they don't believe, it doesn't have value, and the stakes are worthless too.

Re: Proof of stake is incapable of producing a consensus

#667

Post by runeks » Sun, Nov 28, 2021, 8:27 PM UTC

xg15 wrote: post #93

josnyder wrote: post #8

PoW systems rely on the "phone a friend method" as well. When you download a Bitcoin client from a "friend", you are trusting them to honestly introduce you to the network. If you fall asleep for a period of years, you have to trust your friends to honestly inform you of all of the PoW forks and policy changes that have occurred over that interval. The only difference is that PoS blockchain clients must be bundled wi…

I think the difference is which kind of hash you needed. For PoW, you'd have to know the hash of the start of the chain (the "genesis block") in advance to verify you downloaded the correct chain. That's true, but this hash doesn't change during operation. You could get that hash from a history book if you will. For PoS, the hash is from the end of the chain and therefore constantly changing. This means the challenge…

> For PoW, you'd have to know the hash of the start of the chain (the "genesis block") in advance to verify you downloaded the correct chain.

No. For Bitcoin you can accept a chain with an arbitrary starting point and you would still arrive at the same chain everyone else uses.

Although you do need to have an idea of the earliest acceptable starting point-in-time — e.g. verifying a low-difficulty chain starting the year 200,000 BC (with one block every 10 minutes) would take quite a while

Re: Proof of stake is incapable of producing a consensus

#668

Post by javert » Sun, Nov 28, 2021, 8:29 PM UTC

rufusroflpunch wrote: post #658

meribold wrote: post #553

Earlier quoted context omitted.

I imagine the idea of a hard fork of Bitcoin may become more popular as the supply limit is approached and transaction fees go up. The current transaction fee is only a few dollars but the cost is over a hundred. Eventually the fee will have to cover the full cost and a hard fork may start to look more interesting. If this happens I can technically stay on the original protocol, but that would be rather pointless if…

I wouldn’t worry about it. Bitcoin incentivizes energy development. As the world moves to a Bitcoin standard, we will unlock new types of energy that were previously unproductive. It’s likely that energy will more cheap and plentiful under a Bitcoin standard, leading to downward pressure on transaction prices as mining is more economical. Also, more transactions are likely to move off chain to Lightning Network and s…

I agree with this. Just want to add, bitcoin mining can happen in remote locations with available power (hydro, geothermal) which are too far from cities to be transported by power wires. There is a limit to how far you can transmit electricity through wires. So, there are tons of untapped natural energy sources.

Re: Proof of stake is incapable of producing a consensus

#669

Post by Kranar » Sun, Nov 28, 2021, 8:32 PM UTC

tromp wrote: post #229

inter_netuser wrote: post #153

Earlier quoted context omitted.

> As for auditing the the integrity of the code or binary, it is signed by GPG keys > hosted on public key servers accessed using X509 certificates pinned by a a > couple of trust anchors preloaded in your OS. So much for distributed consensus... You can literally validate the entire chain with a simple python script. Millions of those on github. >Not to mention very few people actually bother to verify the full chai…

> You can literally validate the entire chain with a simple python script. I challenge you to present a "simple python script" that implements the exact bitcoin consensus rules (as codified in bitcoin core). Bitcoin is not all that simple and there's a nontrivial amount of complexity in bitcoin script alone [1]. > The chain is validated in its entirety upon first sync. 100% from genesis to tip. The default behavior i…

You're misunderstanding the default behavior which is fine becaue it's commonly misunderstood and discussed. At any rate signature verification is not skipped by default, what assumevalid skips is script verification. Everything else including UXTO, proof of work, the transactions themselves, are validated.

Re: Proof of stake is incapable of producing a consensus

#670

Post by runeks » Sun, Nov 28, 2021, 8:33 PM UTC

barbegal wrote: post #5

Proof of work has always had an economic flaw that you could theoretically temporarily rent enough mining power to perform double spends of more value than the cost of renting those devices. But this attack has never been performed because the reality of all these cryptocurrencies is that the security depends only relatively weakly on proof of work. Instead it relies on trust between the main stakeholders: miners, bi…

> Proof of work has always had an economic flaw that you could theoretically temporarily rent enough mining power to perform double spends of more value than the cost of renting those devices.

It’s not a flaw if it’s only theoretical. In practice, no miner with billions of dollars of capital bound in mining hardware would rent it out to someone who might do something that would significantly depreciate this capital (e.g. attack the Bitcoin network).