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I'd be happy respond to this comment if it was a bit more fleshed out and didn't sound like an attempt at trolling, for instance why you don't consider existing

by drcode 9y ago

I'd be happy respond to this comment if it was a bit more fleshed out and didn't sound like an attempt at trolling, for instance why you don't consider existing POS currencies like NXT to be "evidence".

meebs 9y ago
For those of us still ignorant -- can you point to a resource where I can learn about these differences and evidence?
xorcist 9y ago
Because those all require a trusted third party to make regular checkpoints of the blockchain. The argument is not that it is impossible but that no one has been able to design it trustless. It is a reasonable argument and while you may not agree with the desire to avoid trusted third parties but there's no reason to dismiss it as trolling.
- drcode 9y ago
  Well, the precise criticism you're making is a bit unclear to me but I'll try to respond: Modern proof of stake systems have a concept of "finality" which I think is what you're referring to when you say "checkpoint" (older POS systems also had a more traditional checkpoint concept, but I assuming you're arguing against modern implementations) In order to determine whether a block has "finality" in a POS system you need to either (A) have a computer running regularly on the network to determine finality on your own or (B) trust a third party to give you a valid finality designator. So it is true that you have to trust a third party with these systems if (1) you haven't connected to the network for a year or so or (2) you are launching a brand new node. Of course, with bitcoin #2 is also an issue since there's no way you can install bitcoin software on a new node without getting it from a trusted party.
  - xorcist 9y ago
    I have never heard of "finality" being used outside Ethereum, but maybe you can point me at which existing PoS systems use the term? Or is it Ethereum specifically which is the modern PoS system? The Ethereum PoS system, which is still a prototype and may change before the final version, uses checkpoints to guard against chain re-orgs. It is not trustless in the same sense as the Ethash system is. It's not exactly a secret but a calculated tradeoff. The question here however was about how "currencies like NXT" work, which can hardly be described as modern seeing it was one of the first together with PPC. I believe they never fixed the fact that the optimum mining strategy is not the altruistic one the reference client uses. As long as all participants use the reference client they're safe, but it's not something you would want to base a trillion dollar economy on. In general the challenges with proof-of-stake systems are how to avoid collusion, how to avoid exploratory mining on every possible chain, and variants thereof. (There's also the related problem how to bootstrap a node from scratch in face of equally probable views of history.) Different blockchains have tried different ways to mitigate this, including hard coded re-org limits and coin weights, but the only ones that have proven at scale are the ones that regularly checkpoint the chain. But please correct me if you know of any exceptions.
    - drcode 9y ago
      Tendermint and Ethereum are the ones I'm most familiar with- Both use the term "finality" frequently. In Ethereum POS, an arbitrary PC can use a deterministic algorithm to exactly calculate the checkpointed/finalized block- There is no magical signature used by the ethereum foundation that "blesses" blocks as being checkpoints. > how to avoid exploratory mining on every possible chainges with proof-of-stake systems are how to avoid collusion In both Ethereum POS and tendermint this is a solved problem, anyone can earn a reward by providing proof that a user is mining multiple histories. > There's also the related problem how to bootstrap a node from scratch in face of equally probable views of history Yes, this is still an existing theoretical limitation of POS that is not shared by POW and is a valid criticism of POS- But even on a POW chain you still have to trust software from a third party to some degree in order bootstrap your node.
      - xorcist 9y ago
- EthanHeilman 9y ago
  What about Algorand[0] or Proof-of-Delay[1] or Proof-of-Activity[2]? [0]: https://people.csail.mit.edu/nickolai/papers/gilad-algorand-eprint.pdf https://people.csail.mit.edu/nickolai/papers/gilad-algorand-... [1]: http://stevengoldfeder.com/papers/BGB17-IEEESB-proof_of_delay_ethereum.pdf http://stevengoldfeder.com/papers/BGB17-IEEESB-proof_of_dela... [2]: https://www.decred.org/research/bentov2014.pdf https://www.decred.org/research/bentov2014.pdf
  - xorcist 9y ago
    Thank you, while I haven't read but certainly will, it would be very interesting to see these papers implemented and peer reviewed!
    - EthanHeilman 9y ago
      I believe all of those papers were accepted to top peer-reviewed academic conferences.
- zodiac 9y ago
  There is an alternative if you (a staking validator, or even a full node) does need want to trust any third party: just stay online all the time. This has its own set if downsides but it's inaccurate to say that a third party is required for Pos.
DINKDINK 9y ago
www.truthcoin.info/blog/pow-cheapest/ Example: You come back online after your node had been off. You receive updates to the blockchain in a PoS world. This is literally no cost to someone trying to commit fraud against you by staking their coins and creating fraudulent blocks. You receive updates to the blockchain in a PoW world. You start receiving blocks with roughly the same amount of PoW included in previous blocks. You know that an attacker would have had to completely duplicate the entire PoW hashrate to create this clone of the blockchain. Since this would be extraordinarily costly, you can assume that after 6 blocks (or whatever is the expedience to transaction value trade of you're willing to make) it would be economically infeasible to commit. Creating the implementation of PoS doesn't take an inordinate amount of time. The reason it hasn't been released is because it's a vaporware of a consensus system. The Ethereum foundation won't publicize this because they can continue to convince new ethereum buyers that Ethereum will solve that pesky Byzantine General's problem. https://en.wikipedia.org/wiki/Byzantine_fault_tolerance https://en.wikipedia.org/wiki/Byzantine_fault_tolerance
- tyrust 9y ago
  >You receive updates to the blockchain in a PoS world. This is literally no cost to someone trying to commit fraud against you by staking their coins and creating fraudulent blocks. Ethereum proposes to prevent this by including "slashing conditions" that inflict large penalties on the type of fraudster you're talking about [0]. [0] - https://github.com/ethereum/wiki/wiki/Proof-of-Stake-FAQ#that-shows-how-chain-based-algorithms-solve-nothing-at-stake-now-how-do-bft-style-proof-of-stake-algorithms-work https://github.com/ethereum/wiki/wiki/Proof-of-Stake-FAQ#tha...
- rspeer 9y ago
  Bitcoin is not the first solution to Byzantine fault tolerance. It's not the best solution either.
  - ric2b 9y ago
    But it's the first one that's resistant to Sybil attacks without requiring centralization, is it not?

by drcode 9y ago

meebs 9y ago

For those of us still ignorant -- can you point to a resource where I can learn about these differences and evidence?

xorcist 9y ago

Because those all require a trusted third party to make regular checkpoints of the blockchain. The argument is not that it is impossible but that no one has been able to design it trustless. It is a reasonable argument and while you may not agree with the desire to avoid trusted third parties but there's no reason to dismiss it as trolling.

drcode 9y ago
Well, the precise criticism you're making is a bit unclear to me but I'll try to respond: Modern proof of stake systems have a concept of "finality" which I think is what you're referring to when you say "checkpoint" (older POS systems also had a more traditional checkpoint concept, but I assuming you're arguing against modern implementations) In order to determine whether a block has "finality" in a POS system you need to either (A) have a computer running regularly on the network to determine finality on your own or (B) trust a third party to give you a valid finality designator. So it is true that you have to trust a third party with these systems if (1) you haven't connected to the network for a year or so or (2) you are launching a brand new node. Of course, with bitcoin #2 is also an issue since there's no way you can install bitcoin software on a new node without getting it from a trusted party.
- xorcist 9y ago
  I have never heard of "finality" being used outside Ethereum, but maybe you can point me at which existing PoS systems use the term? Or is it Ethereum specifically which is the modern PoS system? The Ethereum PoS system, which is still a prototype and may change before the final version, uses checkpoints to guard against chain re-orgs. It is not trustless in the same sense as the Ethash system is. It's not exactly a secret but a calculated tradeoff. The question here however was about how "currencies like NXT" work, which can hardly be described as modern seeing it was one of the first together with PPC. I believe they never fixed the fact that the optimum mining strategy is not the altruistic one the reference client uses. As long as all participants use the reference client they're safe, but it's not something you would want to base a trillion dollar economy on. In general the challenges with proof-of-stake systems are how to avoid collusion, how to avoid exploratory mining on every possible chain, and variants thereof. (There's also the related problem how to bootstrap a node from scratch in face of equally probable views of history.) Different blockchains have tried different ways to mitigate this, including hard coded re-org limits and coin weights, but the only ones that have proven at scale are the ones that regularly checkpoint the chain. But please correct me if you know of any exceptions.
  - drcode 9y ago
    Tendermint and Ethereum are the ones I'm most familiar with- Both use the term "finality" frequently. In Ethereum POS, an arbitrary PC can use a deterministic algorithm to exactly calculate the checkpointed/finalized block- There is no magical signature used by the ethereum foundation that "blesses" blocks as being checkpoints. > how to avoid exploratory mining on every possible chainges with proof-of-stake systems are how to avoid collusion In both Ethereum POS and tendermint this is a solved problem, anyone can earn a reward by providing proof that a user is mining multiple histories. > There's also the related problem how to bootstrap a node from scratch in face of equally probable views of history Yes, this is still an existing theoretical limitation of POS that is not shared by POW and is a valid criticism of POS- But even on a POW chain you still have to trust software from a third party to some degree in order bootstrap your node.
    - xorcist 9y ago
EthanHeilman 9y ago
What about Algorand[0] or Proof-of-Delay[1] or Proof-of-Activity[2]? [0]: https://people.csail.mit.edu/nickolai/papers/gilad-algorand-eprint.pdf https://people.csail.mit.edu/nickolai/papers/gilad-algorand-... [1]: http://stevengoldfeder.com/papers/BGB17-IEEESB-proof_of_delay_ethereum.pdf http://stevengoldfeder.com/papers/BGB17-IEEESB-proof_of_dela... [2]: https://www.decred.org/research/bentov2014.pdf https://www.decred.org/research/bentov2014.pdf
- xorcist 9y ago
  Thank you, while I haven't read but certainly will, it would be very interesting to see these papers implemented and peer reviewed!
  - EthanHeilman 9y ago
    I believe all of those papers were accepted to top peer-reviewed academic conferences.
zodiac 9y ago
There is an alternative if you (a staking validator, or even a full node) does need want to trust any third party: just stay online all the time. This has its own set if downsides but it's inaccurate to say that a third party is required for Pos.

DINKDINK 9y ago

www.truthcoin.info/blog/pow-cheapest/ Example: You come back online after your node had been off. You receive updates to the blockchain in a PoS world. This is literally no cost to someone trying to commit fraud against you by staking their coins and creating fraudulent blocks. You receive updates to the blockchain in a PoW world. You start receiving blocks with roughly the same amount of PoW included in previous blocks. You know that an attacker would have had to completely duplicate the entire PoW hashrate to create this clone of the blockchain. Since this would be extraordinarily costly, you can assume that after 6 blocks (or whatever is the expedience to transaction value trade of you're willing to make) it would be economically infeasible to commit. Creating the implementation of PoS doesn't take an inordinate amount of time. The reason it hasn't been released is because it's a vaporware of a consensus system. The Ethereum foundation won't publicize this because they can continue to convince new ethereum buyers that Ethereum will solve that pesky Byzantine General's problem. https://en.wikipedia.org/wiki/Byzantine_fault_tolerance https://en.wikipedia.org/wiki/Byzantine_fault_tolerance

tyrust 9y ago
>You receive updates to the blockchain in a PoS world. This is literally no cost to someone trying to commit fraud against you by staking their coins and creating fraudulent blocks. Ethereum proposes to prevent this by including "slashing conditions" that inflict large penalties on the type of fraudster you're talking about [0]. [0] - https://github.com/ethereum/wiki/wiki/Proof-of-Stake-FAQ#that-shows-how-chain-based-algorithms-solve-nothing-at-stake-now-how-do-bft-style-proof-of-stake-algorithms-work https://github.com/ethereum/wiki/wiki/Proof-of-Stake-FAQ#tha...
rspeer 9y ago
Bitcoin is not the first solution to Byzantine fault tolerance. It's not the best solution either.
- ric2b 9y ago
  But it's the first one that's resistant to Sybil attacks without requiring centralization, is it not?