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There's no free lunch. These gains come with a tradeoff in security. Bitcoin's proof of work which uses an algorithm and processing power to secure it. Vault/Al

There's no free lunch. These gains come with a tradeoff in security. Bitcoin's proof of work which uses an algorithm and processing power to secure it. Vault/Algorand throws out PoW and replaces it that with a pure "proof of stake" system that requires 2/3rds of the currency's value is held by honest actors. In addition, if the network were ever to go offline, there isn't a deterministic way to get it back online.

EthanHeilman 8y ago
>In addition, if the network were ever to go offline, there isn't a deterministic way to get it back online. I haven't heard anyone say this about Algorand. Can you provide more details? Lets say a bug causes all the Algorand nodes to crash. After a patch is released 90% of the network comes back online. What prevents the selected users from arriving at consensus over the next block?
- thesausageking 8y ago
  If the network goes down completely, as it's coming back up, groups of nodes will start adding blocks before all of the other nodes are back online. When connectivity is completely restored, you end up with different parallel chains, each of which thinks it's the main chain. With Bitcoin, there's a simple, deterministic way to decide which chain to trust: the one which has had the most work done it. With Algorand, it's not clear what would happen.
  - justicz 8y ago
    (I work for Algorand) This is false. The BFT protocol that Algorand uses guarantees that each round may have exactly one block (up to our security assumptions with regard to honest stake); this is one of the protocol’s “safety” guarantees. In the case that a large number of participating nodes crash, the network will refuse to produce a block until a sufficient amount of stake begins participating again. Nodes that fall behind can use the standard catchup protocol — the one that nodes new to the network make use of — to pick up where they left off.
    - thesausageking 8y ago
      Calling the case of the network halting "safety" doesn't help things. To walk through a plausible example: let's say 3 Chinese services control 35% of the stake of Algorand. Without warning or any public announcement, the Chinese government steps in and forces them to turn off their servers. The Algorand network will now stop functioning as it can't reach 2/3rds. Hours go by and no one is able to transact. At this point, the network needs to decide how to proceed. Does everyone just agree to take a complete loss? Most likely, a group of other stakers would work on a proposal to deal with it, maybe by removing the offline tokens. How do they get consensus for this proposal? And, if they do it, what do they do if the Chinese stakers come back online?
      - justicz 8y ago
        In this case the Chinese government can kill the liveness of the network (preventing it from producing new blocks), but not the safety of the network (they can't fork the chain). Your question has changed into: "doesn't the system break when a malicious party controls 35% of the stake?" To which the answer is yes. If a malicious party can control 35% of the stake, that is very bad. I should add, though, that if you know your machine is going to be taken down, you can mark your account as "offline" via a special transaction, which will allow the network to proceed without you by increasing the probability that others will be chosen to be on a committee.
        thesausageking 8y ago
        "If a malicious party can control 35% of the stake, that is very bad." That didn't happen in this case. The Chinese government never took anyone's keys or controlled any stake, which is the point of the example. The malicious parties don't need control. They don't need to take anyone's keys or access their servers. They just need to be able to bring it offline, which is much easier to do. Which raises the question I asked and you didn't answer: if 35% of the stake goes offline with no signs of coming back, how do participants reach consensus?
        8y ago
  - throwaway415415 8y ago
    False. Algorand has safety, unless you get confirmation from 2/3 of the "money", you don't go forward. The best you can get here is a denial of service.
    - EthanHeilman 8y ago
      The CAP theorem [0] states that during a network partition a consensus system must either lose availability or consistency. * Bitcoin loses consistency * Algorand loses availability I'm glad Algorand exists so that systems which value consistency over availability can be built. [0]: https://en.wikipedia.org/wiki/CAP_theorem https://en.wikipedia.org/wiki/CAP_theorem
      - throwaway415415 8y ago
        Usually, for distributed systems in adversarial settings we talk about safety and liveness. Bitcoin doesn't have safety, and both bitcoin and algorand seems to fail the liveness test as well. In your terms, both bitcoin and algorand have weak availability.
throwaway415415 8y ago
One could argue that it prevents hashing power attacks, where an attacker can duck with the network with no money at stake. Check the 51% attack websites, it shows how easy it is to duck with altcoins who use pow.

EthanHeilman 8y ago

>In addition, if the network were ever to go offline, there isn't a deterministic way to get it back online. I haven't heard anyone say this about Algorand. Can you provide more details? Lets say a bug causes all the Algorand nodes to crash. After a patch is released 90% of the network comes back online. What prevents the selected users from arriving at consensus over the next block?

thesausageking 8y ago
If the network goes down completely, as it's coming back up, groups of nodes will start adding blocks before all of the other nodes are back online. When connectivity is completely restored, you end up with different parallel chains, each of which thinks it's the main chain. With Bitcoin, there's a simple, deterministic way to decide which chain to trust: the one which has had the most work done it. With Algorand, it's not clear what would happen.
- justicz 8y ago
  (I work for Algorand) This is false. The BFT protocol that Algorand uses guarantees that each round may have exactly one block (up to our security assumptions with regard to honest stake); this is one of the protocol’s “safety” guarantees. In the case that a large number of participating nodes crash, the network will refuse to produce a block until a sufficient amount of stake begins participating again. Nodes that fall behind can use the standard catchup protocol — the one that nodes new to the network make use of — to pick up where they left off.
  - thesausageking 8y ago
    Calling the case of the network halting "safety" doesn't help things. To walk through a plausible example: let's say 3 Chinese services control 35% of the stake of Algorand. Without warning or any public announcement, the Chinese government steps in and forces them to turn off their servers. The Algorand network will now stop functioning as it can't reach 2/3rds. Hours go by and no one is able to transact. At this point, the network needs to decide how to proceed. Does everyone just agree to take a complete loss? Most likely, a group of other stakers would work on a proposal to deal with it, maybe by removing the offline tokens. How do they get consensus for this proposal? And, if they do it, what do they do if the Chinese stakers come back online?
    - justicz 8y ago
      In this case the Chinese government can kill the liveness of the network (preventing it from producing new blocks), but not the safety of the network (they can't fork the chain). Your question has changed into: "doesn't the system break when a malicious party controls 35% of the stake?" To which the answer is yes. If a malicious party can control 35% of the stake, that is very bad. I should add, though, that if you know your machine is going to be taken down, you can mark your account as "offline" via a special transaction, which will allow the network to proceed without you by increasing the probability that others will be chosen to be on a committee.
      - thesausageking 8y ago
        "If a malicious party can control 35% of the stake, that is very bad." That didn't happen in this case. The Chinese government never took anyone's keys or controlled any stake, which is the point of the example. The malicious parties don't need control. They don't need to take anyone's keys or access their servers. They just need to be able to bring it offline, which is much easier to do. Which raises the question I asked and you didn't answer: if 35% of the stake goes offline with no signs of coming back, how do participants reach consensus?
        8y ago
- throwaway415415 8y ago
  False. Algorand has safety, unless you get confirmation from 2/3 of the "money", you don't go forward. The best you can get here is a denial of service.
  - EthanHeilman 8y ago
    The CAP theorem [0] states that during a network partition a consensus system must either lose availability or consistency. * Bitcoin loses consistency * Algorand loses availability I'm glad Algorand exists so that systems which value consistency over availability can be built. [0]: https://en.wikipedia.org/wiki/CAP_theorem https://en.wikipedia.org/wiki/CAP_theorem
    - throwaway415415 8y ago
      Usually, for distributed systems in adversarial settings we talk about safety and liveness. Bitcoin doesn't have safety, and both bitcoin and algorand seems to fail the liveness test as well. In your terms, both bitcoin and algorand have weak availability.

throwaway415415 8y ago

One could argue that it prevents hashing power attacks, where an attacker can duck with the network with no money at stake. Check the 51% attack websites, it shows how easy it is to duck with altcoins who use pow.