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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

#181

Post by ywei3410 »

danbruc wrote: post #180
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…

Yes and no. Yes, proof of works prevents double spending or more generally establishes consensus on which transaction become accepted. But no, this could be achieved with many different consensus protocol and does in general not require any irrecoverable loss. Just issue a key pair to each human and make them send signed votes to establish consensus by simple majority. The true reason something like proof of work is…

For context, this is usually known as a 'Sybil attack'.

[1] https://en.wikipedia.org/wiki/Sybil_attack

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

#182

Post by sparkie »

DennisP wrote: post #151
fogof wrote: post #142

Earlier quoted context omitted.

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.

Unless Vitalik proposes a rollback.

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

#183

Post by dagss »

kerkeslager wrote: post #173
Slartie wrote: post #70

Earlier quoted context omitted.

> nobody can just become richer because they started rich Right. In PoW, they need access to limited semiconductor supplies and cheap electricity. Which are two things that can be bought with...what was that stuff called...? Ah, yes: money! So PoW does just the same - the rich tend to get richer - but it adds the necessity to cause unnecessary environmental pollution on the scale of an entire country to it. Oh, and a…

1. Including sarcasm in your post didn't achieve anything except to increase the reader's blood pressure and make people like you less. Let's keep this polite, please. 2. You're right that the rich get richer with PoW as well, but I think we can agree that the connection between existing wealth and increasing wealth is stronger with PoS--PoS is almost literally just a statement of "the rich get richer". 3. The "it ad…

Re 3), there is not anywhere near enough renewable energy to go around to phase out fossils is there? So make Bitcoin harmless you would have to postulate:

- The energy could not have been transferred to reduce use of fossils

- The energy could not have been stored to reduce use of fossils

- Production of other, more necessary goods (batteries, aluminum, datacenters serving humanity in better ways) could not have been moved to the source of clean energy

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

#184

Post by jasode »

KallDrexx wrote: post #168
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…

> The problem proof-of-work solves is double spending, That doesn't seem to be my understanding. In my mind the problem proof of work solves is how quickly new blocks can be generated, thus limiting the supply of new blocks and giving an incentive to move the head pointer to an agreed upon next value (by granting coins to the miner who was able to compute the value). Double spend is solved due to the single branch tr…

>Proof of work has nothing to do with that, any system that can encourage everyone to agree on the next block does the same prevention of double spend.

What foundational frame of reference are you using to write that sentence above?

Because for Bitcoin's specific implementation, the purpose of POW is to prevent double spend without centralized trust. Consider the following "if()" statement in bitcoin source code:

Excerpt from validation.cpp [1]:

  bool CBlockIndexWorkComparator::operator()(const CBlockIndex *pa, const CBlockIndex *pb) const {
      // First sort by most total work, ...
      if (pa->nChainWork > pb->nChainWork) return false;
      if (pa->nChainWork nChainWork) return true;
In older versions of source code, excerpt from main.cpp [2]:

  if (pindexNew->bnChainWork > bnBestChainWork)
    { ...
The motivation for the C++ code above to compare the chain work is in the original 2009 Bitcoin whitepaper. Excerpt:

>12. Conclusion : We have proposed a system for electronic transactions without relying on trust. We started with the usual framework of coins made from digital signatures, which provides strong control of ownership, but is incomplete without a way to prevent double-spending. To solve this, we proposed a peer-to-peer network using proof-of-work to record a public history of transactions that quickly becomes computationally impractical for an attacker to change if honest nodes control a majority of CPU power.

[1] https://github.com/bitcoin/bitcoin/blob/271155984574a5bba961...

[2] https://github.com/bitcoin/bitcoin/blob/40cd0369419323f8d738...

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

#185

Post by skybrian »

kerkeslager wrote: post #166
bouncycastle wrote: post #140

Earlier quoted context omitted.

PoW is not the only way to solve double spending (and make sure that the blocks are ordered in a particular timeline), in PoS it is solved by randomly choosing which validator will create the next block according to an algorithm that all the nodes follow. So there's no race to find the next block, the block producer is known in advance. What's more, in PoS, you have guaranteed finality, meaning that after a certain a…

There are a bunch of ways in which you're not exactly correct here. First, you're describing a very particular implementation of PoS. Not all PoS implementations include slashing. This isn't a mere technicality: the most popular implementation of PoS (as measured by market cap) is Cardano's and it doesn't include slashing. And not all PoS implementations involve randomly choosing a validator. The bigger problem here…

How do you know you have the longest chain without having all the blocks? You need to reach consensus on which blocks exist, and you can't get that without talking to enough other nodes to be pretty sure you have enough blocks that a longer chain is unlikely.

When there is a network split, nodes on one side of the split might think they have the longest chain and be wrong about it. Unless you know you have most of the computing power on your side of the network split, you can't really know which side has the longest chain until the network split is over.

So no, Bitcoin doesn't avoid the need to achieve consensus.

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

#186

Post by SheinhardtWigCo »

danbruc wrote: post #45

The fundamental problem that needs to be solved is voting power allocation. You have a group of people that wants to use a cryptocurrency and you want to allow everyone to voice his opinion about what transaction are valid and should be recorded and which are not so that you can determine the consensus. Your first problem is to decide who gets to vote. Does everyone get to vote or do you have to participate in the sy…

Algorand solves this by using a verifiable random function, with the output weighted according to the user's stake. It's quite elegant. Paper: https://eprint.iacr.org/2018/377

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

#187

Post by billytetrud »

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…

> any scheme to replace proof-of-work needs to maintain that element of irrecoverable loss of value for a failed double spending attack.

As others have said, this is not true. All that is required is that it is expensive to successfully double spend.

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

#188

Post by sparkie »

admax88q wrote: post #158
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.

Which one was the first spend and which one was the double-spend?

You are talking about a distributed network where there is no universal time by which this can be measured.

The blockchain is the solution to this problem. It provides an ordering which is to be universally agreed upon, because the only way to disagree with the ordering is to use >51% of the amount of electricity securing the network to state your disagreement.

A spend is invalid if the consensus in the network is that the TXO being used as an input for a transaction has already been spent in a transaction which has been mined into a valid block. Until that happens, any valid transaction which spends a TXO may be the correct one.

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

#189

Post by [deleted] »

dandanua wrote: post #46
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

You don't need PoW mining or any sophisticated consensus at all if you use tamper-proof hardware. Here is my proposal of using FIDO keys https://news.ycombinator.com/item?id=26214175

[deleted]

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

#190

Post by SheinhardtWigCo »

dandanua wrote: post #46
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

You don't need PoW mining or any sophisticated consensus at all if you use tamper-proof hardware. Here is my proposal of using FIDO keys https://news.ycombinator.com/item?id=26214175

> tamper-proof hardware

Does not exist. FIDO keys are merely tamper resistant.

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