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Who gets to choose who is an attacker? Are there limits in place that ensure only once someone owns 51% the can steal their funds? Who gets to decide what a s

by toolz 9y ago

Who gets to choose who is an attacker? Are there limits in place that ensure only once someone owns 51% the can steal their funds? Who gets to decide what a single entity is? Sounds like a pretty huge centralized point of failure in my mind, but I'm admittedly pretty ignorant on the subject.

RoboTeddy 9y ago
You're hitting on a critical point about cryptocurrencies that isn't widely understood yet. Ultimately, the community of users and businesses at large decides. Cryptocurrencies are social contracts that are encoded in software. If everyone agrees that a rule should change, and updates their software in concert, then the rule de-facto changes. In the absence of total agreement, the decision is made by whoever wins the political fight for user/business mindshare. It's also possible for the question to be answered two different ways (a longstanding fork occurs).
- konschubert 9y ago
  > Ultimately, the community of users and businesses at large decides. Cryptocurrencies are social contracts that are encoded in software. If everyone agrees that a rule should change, and updates their software in concert, then the rule de-facto changes. That's called a chain split, isn't it? Usually there are people who follow the new protocol and people who follow the old protocol, so the currency splits into two. Bitcoin Cash is an example.
  - RoboTeddy 9y ago
    If everyone updates, then there isn't a longstanding chain split (e.g. https://en.bitcoin.it/wiki/Value_overflow_incident https://en.bitcoin.it/wiki/Value_overflow_incident). But yeah if there's longstanding disagreement, there are two ways for it to go: * Peaceable fork with replay protection, like Bitcoin Cash * Fork that seriously fights for the same brand/userbase --- we haven't seen one of these in Bitcoin. Segwit2x would've worked that way, but was canceled
    - masterjack 9y ago
      Actually that’s an example of a soft fork. When you change the rules to make them more restrictive (add limits, decrease block size, block addresses, etc) those running the old version will find the new blocks valid so will try to build on them and find their blocks to be rejected, but can keep running no problem and are incentivized to upgrade. When you change the rules to be less restrictive (add operations, increase block size, etc) then any old version will reject the new blocks, so will keep running their own chain until they are upgraded, potentially forever if there’s demand.
    - Shorel 9y ago
      I don't think BCC has replay protection. I bought something with BTC after the fork, and all my BCC was emptied within minutes.
      - hndamien 9y ago
        It does. You must have screwed up somewhere else. Segwit 2x had no replay protection, and hence was contentious.
- deleted 9y ago
  [deleted]
rictic 9y ago
In brief, an attacker is an agent or group of agents that execute a double-spend attack. In Ethereum's proposed PoS system, all stakeholders that collude in the double-spend attack would have their stake destroyed. These properties are automatically detectable, and once detected enforcement is automatic.
- amluto 9y ago
  I must be missing a few things, though: 1. What if there simply isn't a quorum of the selected signers for a given block, due to people being on vacation, DoS, network failure, etc? Does the whole chain grind to a halt? 2. PoS relies on punishing anyone who signs a block that's not on the main chain. But who defines what the main chain is? If I'm a selected blockmaker or, worse, I control a quorum once, can't I forfeit my deposit to fake someone else out so they sign a block on my bad chain? Then I report both them and myself, bankrupting them and recovering some of my own losses? 3. This whole scheme penalizes cold wallet users. If you don't use your cold wallet funds as mining collateral, you lose the reward. If you do, then anyone who compromises your deposit signing key (which needs to be hot) can wipe you out and steal 1/3 of your deposit.
  - jzoch 9y ago
    You are a bit off. As a preface, I really recommend reading https://github.com/ethereum/wiki/wiki/Proof-of-Stake-FAQ https://github.com/ethereum/wiki/wiki/Proof-of-Stake-FAQ. For your first question, if people are on vacation and there are no validators then Ethereum would be dead. It wouldnt make sense that the global pool of validators would disappear, but even so, it would wait I assume. IF half the validators left, it would choose from the other half. 2. THe main chain is currently defined as the longest defined chain fully validated. To fake someone out, you would need to tell them your vote for a block, and they would need to blindly vote the same without doing any due diligence on the block (which would defeat the purpose) and they would be rightfully burned. That is the same as a miner who just copies the work of other miners, they do nothing. 3. I dont understand this at all. You do not need to stake. You are rewarded but lose liquidity. It is your choice, just as lending compute was your choice with PoW. Hopefully this is good, the link goes into a lot of detail that should clear things up!
maksimum 9y ago
I think one thing to consider is that there is economic disincentive against acquiring >50% of the network, and even more disincentive against attacking it once you have 51%+. You have to pay full value to get >50%, but Ethereum could lose absolutely all value if anyone gets to >50%, so whatever the investment to get that stake would go to zero. The issue is whether can malevolant entities or coalitions can reliably be detected.

by toolz 9y ago

RoboTeddy 9y ago

You're hitting on a critical point about cryptocurrencies that isn't widely understood yet. Ultimately, the community of users and businesses at large decides. Cryptocurrencies are social contracts that are encoded in software. If everyone agrees that a rule should change, and updates their software in concert, then the rule de-facto changes. In the absence of total agreement, the decision is made by whoever wins the political fight for user/business mindshare. It's also possible for the question to be answered two different ways (a longstanding fork occurs).

konschubert 9y ago
> Ultimately, the community of users and businesses at large decides. Cryptocurrencies are social contracts that are encoded in software. If everyone agrees that a rule should change, and updates their software in concert, then the rule de-facto changes. That's called a chain split, isn't it? Usually there are people who follow the new protocol and people who follow the old protocol, so the currency splits into two. Bitcoin Cash is an example.
- RoboTeddy 9y ago
  If everyone updates, then there isn't a longstanding chain split (e.g. https://en.bitcoin.it/wiki/Value_overflow_incident https://en.bitcoin.it/wiki/Value_overflow_incident). But yeah if there's longstanding disagreement, there are two ways for it to go: * Peaceable fork with replay protection, like Bitcoin Cash * Fork that seriously fights for the same brand/userbase --- we haven't seen one of these in Bitcoin. Segwit2x would've worked that way, but was canceled
  - masterjack 9y ago
    Actually that’s an example of a soft fork. When you change the rules to make them more restrictive (add limits, decrease block size, block addresses, etc) those running the old version will find the new blocks valid so will try to build on them and find their blocks to be rejected, but can keep running no problem and are incentivized to upgrade. When you change the rules to be less restrictive (add operations, increase block size, etc) then any old version will reject the new blocks, so will keep running their own chain until they are upgraded, potentially forever if there’s demand.
  - Shorel 9y ago
    I don't think BCC has replay protection. I bought something with BTC after the fork, and all my BCC was emptied within minutes.
    - hndamien 9y ago
      It does. You must have screwed up somewhere else. Segwit 2x had no replay protection, and hence was contentious.
deleted 9y ago
[deleted]

rictic 9y ago

In brief, an attacker is an agent or group of agents that execute a double-spend attack. In Ethereum's proposed PoS system, all stakeholders that collude in the double-spend attack would have their stake destroyed. These properties are automatically detectable, and once detected enforcement is automatic.

amluto 9y ago
I must be missing a few things, though: 1. What if there simply isn't a quorum of the selected signers for a given block, due to people being on vacation, DoS, network failure, etc? Does the whole chain grind to a halt? 2. PoS relies on punishing anyone who signs a block that's not on the main chain. But who defines what the main chain is? If I'm a selected blockmaker or, worse, I control a quorum once, can't I forfeit my deposit to fake someone else out so they sign a block on my bad chain? Then I report both them and myself, bankrupting them and recovering some of my own losses? 3. This whole scheme penalizes cold wallet users. If you don't use your cold wallet funds as mining collateral, you lose the reward. If you do, then anyone who compromises your deposit signing key (which needs to be hot) can wipe you out and steal 1/3 of your deposit.
- jzoch 9y ago
  You are a bit off. As a preface, I really recommend reading https://github.com/ethereum/wiki/wiki/Proof-of-Stake-FAQ https://github.com/ethereum/wiki/wiki/Proof-of-Stake-FAQ. For your first question, if people are on vacation and there are no validators then Ethereum would be dead. It wouldnt make sense that the global pool of validators would disappear, but even so, it would wait I assume. IF half the validators left, it would choose from the other half. 2. THe main chain is currently defined as the longest defined chain fully validated. To fake someone out, you would need to tell them your vote for a block, and they would need to blindly vote the same without doing any due diligence on the block (which would defeat the purpose) and they would be rightfully burned. That is the same as a miner who just copies the work of other miners, they do nothing. 3. I dont understand this at all. You do not need to stake. You are rewarded but lose liquidity. It is your choice, just as lending compute was your choice with PoW. Hopefully this is good, the link goes into a lot of detail that should clear things up!

maksimum 9y ago

I think one thing to consider is that there is economic disincentive against acquiring >50% of the network, and even more disincentive against attacking it once you have 51%+. You have to pay full value to get >50%, but Ethereum could lose absolutely all value if anyone gets to >50%, so whatever the investment to get that stake would go to zero. The issue is whether can malevolant entities or coalitions can reliably be detected.