6 ms·

Neat paper, but: "Gnomes know each other, to start with, so the problem itself is non-existant, not to mention the price of the solution. Similarly, the Byzanti

by api 5y ago

Neat paper, but: "Gnomes know each other, to start with, so the problem itself is non-existant, not to mention the price of the solution. Similarly, the Byzantine generals problem was found to be irrelevant at first. Gnomes know who their friends are." That makes it useless for real world coordination outside of systems run by closed vertically integrated organizations like companies, governments, etc. In the real world you don't know who your friends are. That's the point of Nakamoto consensus, which is AFAIK the only known partial real world solution to this problem. Unfortunately it's grotesquely inefficient and still has failure modes when you assume "irrational" actors willing to burn resources just to destroy the system. That's why I called it a partial solution. I still wonder if an efficient general solution with no subjectivity and no assumption of a sentient or AI operator who can intervene is possible. This could potentially be better than Raft and friends for geographically distributed consensus or extreme scalability. Raft based systems ultimately end up being limited by the ability of the leader to lead a sufficiently large cluster. In practice with modern server-grade hardware this limit is quite high but it still exists.

noxer 5y ago
FBA does not require to know who your friends are you just need to know enough nodes. If some of the nodes are not your friend aka they lie to you, you would know as soon as they lie and you can simply stop listen to them. This however requires identities. You cant just listen to anyone because someone could simply fire up 1000 lying nodes and if you pick 100 at random you'd have mostly lying nodes. You would figure out if they lie but then you have to stop listen to them all and you are offline. In practice this is not a real problem because obvious you would pick old nodes and not the 1000 freshly generated "identities". The assumption that you know nothing about any other node is a more or less made up thing for theoretical analysis that has no relevance in the real world. You dont start a network form zero you just want to join an existing one and you know its there so you might as well know who is there.
- api 5y ago
  Ahh, okay, but requiring identities means you must have a central authority to issue them or they must be extremely costly (proof of work or similar). Of course this doesn't make this useless. If identities are all you need then you've devolved the role of the central authority to nothing more than something that says who you are. If there is no provision for centralized identity revocation then you don't have a censorship problem because once you have an identity you have it forever. Identities could also be anonymized keys where only the central authority knows the true identity, minimizing privacy exposure surface area. Decentralization isn't boolean. This is more decentralized than Raft. Edit: I suppose proof of work for identities could be less costly than continuous PoW. The work required just has to be high enough to make sybil attacks expensive enough to meet your threat model threshold.
  - noxer 5y ago
    >identities means you must have a central authority to issue them These are cryptographic identities. You create one by publishing the public key of your node. There is no authority needed. You decide if you believable a given identities to be who they calm to be. Lets say HN would run a node they would simply publish the public key on their website and if it has been there for weeks you can reasonably assume the page wasn't hacked and the key actually belong to the operators of HN. (The key can also be signed with the domain cert) It doesn't really matter that 100 other nodes could claim to be operated by NH too. There is no need for a central authority because every user can easily figure out which one is the real key. People can curate lists of nodes they "trust" and publish thous to make it easier for new people. Since everyone can publish such a list the curator of such a list is also no authority. The obvious downside of this is ofc that only existing "names" will be recognized. If you just say here is my key and I have a cool website then most people would not add you for a long time. (You can still participate in the network.) But this is also wanted because everyone should only add nodes that are reliable, have the proper hardware and maintenance and all that. Basically being part of the community helps to exclude someone who just make a bunch of identities that look like they belong to different people. Even if no one adds your node to the list you can still participate by relaying info form other nodes since the data is signed by the origin node someone who gets the data from you can still use that data even if it does not use your nodes data. There are a few ledgers running on these principles today most notably the XRPL[1] since 8+ years. [1]https://xrpl.org/intro-to-consensus.html https://xrpl.org/intro-to-consensus.html

by api 5y ago

noxer 5y ago

FBA does not require to know who your friends are you just need to know enough nodes. If some of the nodes are not your friend aka they lie to you, you would know as soon as they lie and you can simply stop listen to them. This however requires identities. You cant just listen to anyone because someone could simply fire up 1000 lying nodes and if you pick 100 at random you'd have mostly lying nodes. You would figure out if they lie but then you have to stop listen to them all and you are offline. In practice this is not a real problem because obvious you would pick old nodes and not the 1000 freshly generated "identities". The assumption that you know nothing about any other node is a more or less made up thing for theoretical analysis that has no relevance in the real world. You dont start a network form zero you just want to join an existing one and you know its there so you might as well know who is there.

api 5y ago
Ahh, okay, but requiring identities means you must have a central authority to issue them or they must be extremely costly (proof of work or similar). Of course this doesn't make this useless. If identities are all you need then you've devolved the role of the central authority to nothing more than something that says who you are. If there is no provision for centralized identity revocation then you don't have a censorship problem because once you have an identity you have it forever. Identities could also be anonymized keys where only the central authority knows the true identity, minimizing privacy exposure surface area. Decentralization isn't boolean. This is more decentralized than Raft. Edit: I suppose proof of work for identities could be less costly than continuous PoW. The work required just has to be high enough to make sybil attacks expensive enough to meet your threat model threshold.
- noxer 5y ago
  >identities means you must have a central authority to issue them These are cryptographic identities. You create one by publishing the public key of your node. There is no authority needed. You decide if you believable a given identities to be who they calm to be. Lets say HN would run a node they would simply publish the public key on their website and if it has been there for weeks you can reasonably assume the page wasn't hacked and the key actually belong to the operators of HN. (The key can also be signed with the domain cert) It doesn't really matter that 100 other nodes could claim to be operated by NH too. There is no need for a central authority because every user can easily figure out which one is the real key. People can curate lists of nodes they "trust" and publish thous to make it easier for new people. Since everyone can publish such a list the curator of such a list is also no authority. The obvious downside of this is ofc that only existing "names" will be recognized. If you just say here is my key and I have a cool website then most people would not add you for a long time. (You can still participate in the network.) But this is also wanted because everyone should only add nodes that are reliable, have the proper hardware and maintenance and all that. Basically being part of the community helps to exclude someone who just make a bunch of identities that look like they belong to different people. Even if no one adds your node to the list you can still participate by relaying info form other nodes since the data is signed by the origin node someone who gets the data from you can still use that data even if it does not use your nodes data. There are a few ledgers running on these principles today most notably the XRPL[1] since 8+ years. [1]https://xrpl.org/intro-to-consensus.html https://xrpl.org/intro-to-consensus.html