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Cryptocurrency Blockchains Don’t Need to Be Energy Intensive

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Re: Cryptocurrency Blockchains Don’t Need to Be Energy Intensive

#151

Post by DennisP »

fogof wrote: post #142
hypertele-Xii wrote: post #135

Earlier quoted context omitted.

I don't get it. Suppose a bad actor tries to double spend. They have to cryptographically sign both transactions, so the whole network will eventually receive knowledge of both transactions. Why can't the network simply wait for some duration of time before accepting a transaction, to verify that no double-spends propagate from elsewhere? If double spending is ever detected from a party, that party is dis-trusted by…

Well let's say we do things this way, and I double spend a transaction, sending one to Alice and one to Bob. Suppose Alice waits t seconds after receiving the transaction, and if she doesn't see any double spends in that time, she accepts that the coin is hers and she then sends me something in return. One second before Alice "confirms" my transaction, I can send out my transaction to Bob. Since my message takes time…

The same thing happens in PoW networks. You have to wait several blocks to gain confidence that a transaction won't be reverted.

In Ethereum's PoS, by waiting a similar amount of time you actually get finality; at that point your transaction cannot be reverted without a third of total stake being destroyed.

Re: Cryptocurrency Blockchains Don’t Need to Be Energy Intensive

#152

Post by CryptoPunk »

tromp wrote: post #145
CryptoPunk wrote: post #104

Earlier quoted context omitted.

They absolutely could not grab an arbitrary part for free. What an absurd claim. The BTC paid during the Ethereum crowdsale went to the Ethereum Foundation bitcoin address, and that address can be audited. Misappropriating those funds would leave a massive chain trail, and require a massive conspiracy to plant the Ethereum Foundation with co-conspirators. It would be unthinkable. On top of all of that, the operators…

> Misappropriating those funds Where are the transparency reports detailing how the 31529 BTC raised in the crowdsale were spent? It would seem straightforward to spend a large fraction of that on software development which would mean that the creators can take part in the crowdsale (which is largely anonymous) and have the spent BTC flow back to themselves.

The point is how the prospects of scamming would look to the operators in 2014:

They would know that audits could always be demanded, and that an on-chain trail would exist. If said audits reveal massive grants being given to themselves, they would immediately fall under intense scrutiny, and it would only take one of their co-conspirators to spill the beans for them to all be burned.

For them to actually consider this subterfuge, with the risks involved, would be unthinkable.

Re: Cryptocurrency Blockchains Don’t Need to Be Energy Intensive

#153

Post by acjohnson55 »

Technically, the consensus mechanism is the mining lottery, which is how transaction order is finalized, preventing double spends.

The scheme for commitment of a scarce resource (e.g. PoW, PoS) is the Sybil resistance scheme, which is what makes lottery participation conform to some notion of fairness. You have to buy your lottery tickets.

Re: Cryptocurrency Blockchains Don’t Need to Be Energy Intensive

#154

Post by rep_movsd »

I cant believe that people still think anything other than PoW can provide the cryptographic guarantees required for a real cryptocurrency.

People need to think it through.

In PoS - you stake the coin itself, which is initially worthless when a coin is made

In PoB - how can you prove that you actually burned coins?

In PoC - everyone anyway computes millions of "answers" to store. So you use energy AND and waste valuable disk space too. The guy with the biggest HDD (or maybe 24/7 powered RAM disk) will be the winner always.

Re: Cryptocurrency Blockchains Don’t Need to Be Energy Intensive

#155

Post by rmtech »

fogof wrote: post #142
hypertele-Xii wrote: post #135

Earlier quoted context omitted.

I don't get it. Suppose a bad actor tries to double spend. They have to cryptographically sign both transactions, so the whole network will eventually receive knowledge of both transactions. Why can't the network simply wait for some duration of time before accepting a transaction, to verify that no double-spends propagate from elsewhere? If double spending is ever detected from a party, that party is dis-trusted by…

Well let's say we do things this way, and I double spend a transaction, sending one to Alice and one to Bob. Suppose Alice waits t seconds after receiving the transaction, and if she doesn't see any double spends in that time, she accepts that the coin is hers and she then sends me something in return. One second before Alice "confirms" my transaction, I can send out my transaction to Bob. Since my message takes time…

Yeah, good point. If the attacker knows how long each person will wait, then they can exploit that.

Re: Cryptocurrency Blockchains Don’t Need to Be Energy Intensive

#157

Post by janmo »

pornel wrote: post #49
janmo wrote: post #37

The article assumes that PoW cannot be done in an energy efficient way. Last year I wrote an article on how to do PoW in an energy efficient way by using the digital signing capability from the NFC chip of modern passports. The proposal was discussed here: https://news.ycombinator.com/item?id=23066477

That's trusting private keys of passport-issuing governments and makers of the NFC chips. If you can trust an authority like that, then you don't even need a blockchain. The whole scheme will fall apart as soon as value of cheating will be higher than the cost of equipment needed to extract keys from a passport.

That's of concern but solutions to these problems have been discussed in the original post. This includes:

- Have a custom difficulty for every single passport so that it wont be profitable to extract the private key. Let's say a passport has already mined a block, then it will be twice as difficult for that same passport to mine a second one.

- Make it so that 51% of the countries have to collude in order to run a double spend.

Now think about the advantages:

- No Botnets mining it.

- Potentially many more "small" miners (individuals). Not huge mining farms somewhere in China or Island.

Re: Cryptocurrency Blockchains Don’t Need to Be Energy Intensive

#158

Post by admax88q »

aazaa wrote: post #107

> The granddaddy of all consensus mechanisms—behind Bitcoin, Litecoin, Monero, and (for the time being at least) Ethereum—is called proof of work. Essentially, PoW makes adding transactions to the blockchain computationally—and therefore financially—very expensive, so as to discourage fraudulent activity. ... This passage reflects a deep-seated, widespread misunderstanding of how/why Bitcoin works. I suspect the auth…

I would consider a double spend transaction to be invalid.

Re: Cryptocurrency Blockchains Don’t Need to Be Energy Intensive

#159

Post by nootropicat »

rawtxapp wrote: post #67
Negitivefrags wrote: post #8

I'm not really convinced. Proof of Stake has a startup issue that Proof of Work doesn't have. If you want to have your coin begin as proof of stake you have to have some mechanism for how the initial coins are distributed and that method is usually going to involve the creators giving themselves a lot of coins. A lot of crypto projects have all sorts of ways of obfuscating this or claiming that the intial coins will…

PoS is a pretty broken system imo, it essentially codefies "rich gets richer" into the protocol. The biggest holders now control both the supply on the exchanges and the protocol itself. It creates all kinds of weird issues (for example, what happens if an attacker gets a hold of a significant percentage of the coins, now they also have a great control over the network). Stakers don't have the same pressure to sell t…

PoW empirically isn't secure. Attacks already happened, most notably on ethereum classic. If it was possible to rent enough hashpower all PoW blockchains would already be attacked because daily mining rewards are trivial compared to potential gains.

The actual security relies on obfuscated proof of stake - how hard it is to attain enough mining hardware. Even so, attacking bitcoin is relatively cheap - even starting from zero, few billions are enough to order mining chips from a fab and organize mining warehouses with enough power to 51% the network. The reason it didn't happen is because there's not enough genuine economic activity on btc to profit from it - the worst you could do is try to steal other crypto from several exchanges, but given that they all require kyc today and the impossibility of hiding such a big operation, it's extremely unlikely to turn out profitable. If btc ever becomes widely used - for example, by Iran to sell their oil, to the point that freezing their btc bankrupts the country - attacking btc may become a military objective, and given the cost involved it would be trivial for the US military. They could leverage all Western owned mining facilities trivially, by telling them to enforce OFAC sanctions - chances are they wouldn't even have to build any mining facilities themselves.

Another way to summarize this is: PoW only works for bitcoin as long as it remains a speculative toy.

Such an attack is impossible in PoS, because unlike mining chips, acquiring enough staking tokens is simply impossible for sufficiently distributed coins - there isn't enough for sale and most owners are anonymous, making sanctions unenforceable. For this reason PoS is the only existing consensus system that can actually support something widely used for real world commerce.

Re: Cryptocurrency Blockchains Don’t Need to Be Energy Intensive

#160

Post by brighton36 »

aazaa wrote: post #107

> The granddaddy of all consensus mechanisms—behind Bitcoin, Litecoin, Monero, and (for the time being at least) Ethereum—is called proof of work. Essentially, PoW makes adding transactions to the blockchain computationally—and therefore financially—very expensive, so as to discourage fraudulent activity. ... This passage reflects a deep-seated, widespread misunderstanding of how/why Bitcoin works. I suspect the auth…

Proof of work also enables users to buy Bitcoin from their power company. Which, is a necessary feature for many applications.
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