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Not rolling your own consensus algorithm is approx. rules zero through ten of distributed systems programming. Nothing on this page provides any positive signal

Not rolling your own consensus algorithm is approx. rules zero through ten of distributed systems programming. Nothing on this page provides any positive signal indicating unique (or even average) competence to the task. To wit, > We are borrowing all the best parts of existing technology and combining them in a unique and innovative way. To the best of my knowledge, none of the listed existing technologies have been formally verified.

davidgerard 8y ago
Existing blockchain technologies. Historical knowledge is a mere speedbump on the path to number go up.
eloff 8y ago
This seems like a really, really bad idea. However, if everyone had that attitude we'd never improve on the existing art. So I'm glad some people are willing to risk it. But just to reiterate, if you're thinking of rolling your own consensus - or even implementing an existing consensus algorithm yourself (although that's much worse for Paxos than for Raft) - you're almost certainly making a big mistake.
- cremp 8y ago
  Just to drive it home. Those who actually make their own encryption libraries know their stuff, and have been in the space for years. You should never, ever, roll your own encryption. If it's a requirement, then change your damn requirements, because just like consensus; it is not easy to get right, and the pros make mistakes.
  - zzzcpan 8y ago
    Consensus is not crypto, it's ridiculously trivial in comparison and usually so useless, that nobody even bothers doing it correctly all the way to the end user.
    - bradhe 8y ago
      bingo.
    - sagichmal 8y ago
      Consensus is at least as hard as crypto.
  - dlubarov 8y ago
    I think it's worth distinguishing a few cases here: 1. Reimplementing an existing cryptographic primitive, such as SHA-256. 2. Inventing a new cryptographic primitive, with a reduction to existing cryptographic assumptions, and implementing it. A recent example is SPHINCS-256, which was proven secure in the random oracle model. 3. Postulating a new cryptographic hardness assumption, inventing a new cryptographic primitive based on it, and implementing it. Recent examples are IOTA's Curl hash function and StarkWare's Jarvis cipher. #1 is risky, but at least the risk can be mitigated by having qualified peers review the implementation. #2 is riskier, but still, it can be mitigated by having qualified peers review the proof. #3 seems far more dangerous, since it involves conjecture. What the Tupelo team is doing is like #2 -- risky, yes, but not comparable to #3.
- zzzcpan 8y ago
  If you have enough background in distributed systems to choose a consensus algorithm you are definitely capable of implementing one yourself and even invent your own. It's not a bad idea either, most existing consensus-based systems are absolute garbage. People just hugely overestimate how much those algorithms matter for production systems. EDIT: Note, I'm not talking about blockchains and byzantine fault tolerance, but in context of Paxos/Raft.
  - eloff 8y ago
    That's like saying if you have some crypto background you can implement your own crypto library. It's TERRIBLE advice. Read the Google paper on their chubby distributed locking system using paxos. They had a hard time getting it right - unless you think you're so much better than them. IIRC Leslie Lamport works (worked?) for them. Use an existing, well used, well scrutinized implementation of a known algorithm.
    - kjeetgill 8y ago
      Are you sure? I thought Lamport has been at Microsoft Research since forever.
      - eloff 8y ago
        Ah the vagaries of the human memory.
      - therein 8y ago
        You're correct. Lamport has joined MSR in 2001 right after publishing "Time, Clocks, and the Ordering of Events in a Distributed System" and has been there ever since. I am not sure if he is still at the MV office but he was one of the reasons why MSR kept a presence in MV for a while.
        lou1306 8y ago
        Actually "Time, Clocks..." is a paper from the late 70s. Maybe you were thinking of the Paxos paper, "The Part-Time Parliament" (1998)?
cdiddy2 8y ago
I believe bitcoins proof of work has been formally verified, however I can't find a source for that. There is also this https://iohk.io/research/papers/#9BKRHCSI https://iohk.io/research/papers/#9BKRHCSI that claims to be formally verified Proof of Stake.
- davidgerard 8y ago
  Unless you're actually a computer scientist following the area ... all claims of solving the "blockchain trilemma" - decentralisation, security and efficiency - should be ignored unless and until they have an implementation to show you, and it survives the hostile Internet. Promises are cheap. e.g. IOHK is behind Cardano/ADA, which has a marvellous white paper making all sorts of mathematical promises ... and still runs off a central node. In this case, it appears to be a system for private blockchains, i.e. a system with central administration. All "consensus" algorithms in this case are variants on taking turns - further elaboration is security theatre, given that attacking the system to that extent would go well beyond the legal agreements to be allowed to participate in the first place.
  - cdiddy2 8y ago
    Luckily I am a computer scientist however it is extremely hard to keep up with everything going on in the blockchain space. There must be some validity behind the idea of weighted random turn-taking though since it is similar to how the next version(serenity) of ethereum will work based
    - AgentME 8y ago
      I think the difference is how they choose whose turn it will be next. There's a big difference between a central authority picking people to take turns, and what Ethereum is working on.
zonotope 8y ago
We completely agree with you that, in general, you don't want to attempt to create an entirely new consensus mechanism. As you know, there are generally only 2 (perhaps 3) broad categories of byzantine tolerant consensus that boil down to PBFT and Nakamoto consensus. Ours is a flavor of PBFT designed to reduce message complexity. We also draw from Casper in order to get the incentives and game theory right which would not be considered part of the consensus algorithm traditionally, but must be considered in the DLT space. We're not really reinventing the wheel but rather adapting some interesting research to new problem set (which is consensus, without total ordering). We also plan on fully vetting and formally verifying our implementation before we move into production.
- davidgerard 8y ago
  So what's your system's threat model? What will this achieve that a centralised database and existing legal structures and agreements won't? (Assume I know the area and you can go into depth. However, remarkable claims will need a production system - anyone can and does claim anything's coming in "six months, for sure" - and an explanation of how you've achieved something that your many, many competitors haven't.)
- lifty 8y ago
  There is a new consensus algorithm called Avalanche, which apparently starts a new, 3rd category. You can read the white paper here: https://ipfs.io/ipfs/QmUy4jh5mGNZvLkjies1RWM4YuvJh5o2FYopNPVYwrRVGV https://ipfs.io/ipfs/QmUy4jh5mGNZvLkjies1RWM4YuvJh5o2FYopNPV...
  - tobowers 8y ago
    Absolutely. That’s the “perhaps 3” part of the above. Avalanche is really interesting. Can’t wait to see Ava.
  - Geee 8y ago
    From a quick glance, isn't this somewhat similar to what Nano is doing? Nano does balance-weighed voting on conflicting blocks via gossip until the network arrives at consensus. https://nano.org/en/whitepaper https://nano.org/en/whitepaper
kenhwang 8y ago
Hell, people even have a hard time correctly implementing the handful of provably correct consensus algorithms that already exist. Just look through the issues section of every raft implementation.

davidgerard 8y ago

Existing blockchain technologies. Historical knowledge is a mere speedbump on the path to number go up.

eloff 8y ago

This seems like a really, really bad idea. However, if everyone had that attitude we'd never improve on the existing art. So I'm glad some people are willing to risk it. But just to reiterate, if you're thinking of rolling your own consensus - or even implementing an existing consensus algorithm yourself (although that's much worse for Paxos than for Raft) - you're almost certainly making a big mistake.

cremp 8y ago
Just to drive it home. Those who actually make their own encryption libraries know their stuff, and have been in the space for years. You should never, ever, roll your own encryption. If it's a requirement, then change your damn requirements, because just like consensus; it is not easy to get right, and the pros make mistakes.
- zzzcpan 8y ago
  Consensus is not crypto, it's ridiculously trivial in comparison and usually so useless, that nobody even bothers doing it correctly all the way to the end user.
  - bradhe 8y ago
    bingo.
  - sagichmal 8y ago
    Consensus is at least as hard as crypto.
- dlubarov 8y ago
  I think it's worth distinguishing a few cases here: 1. Reimplementing an existing cryptographic primitive, such as SHA-256. 2. Inventing a new cryptographic primitive, with a reduction to existing cryptographic assumptions, and implementing it. A recent example is SPHINCS-256, which was proven secure in the random oracle model. 3. Postulating a new cryptographic hardness assumption, inventing a new cryptographic primitive based on it, and implementing it. Recent examples are IOTA's Curl hash function and StarkWare's Jarvis cipher. #1 is risky, but at least the risk can be mitigated by having qualified peers review the implementation. #2 is riskier, but still, it can be mitigated by having qualified peers review the proof. #3 seems far more dangerous, since it involves conjecture. What the Tupelo team is doing is like #2 -- risky, yes, but not comparable to #3.
zzzcpan 8y ago
If you have enough background in distributed systems to choose a consensus algorithm you are definitely capable of implementing one yourself and even invent your own. It's not a bad idea either, most existing consensus-based systems are absolute garbage. People just hugely overestimate how much those algorithms matter for production systems. EDIT: Note, I'm not talking about blockchains and byzantine fault tolerance, but in context of Paxos/Raft.
- eloff 8y ago
  That's like saying if you have some crypto background you can implement your own crypto library. It's TERRIBLE advice. Read the Google paper on their chubby distributed locking system using paxos. They had a hard time getting it right - unless you think you're so much better than them. IIRC Leslie Lamport works (worked?) for them. Use an existing, well used, well scrutinized implementation of a known algorithm.
  - kjeetgill 8y ago
    Are you sure? I thought Lamport has been at Microsoft Research since forever.
    - eloff 8y ago
      Ah the vagaries of the human memory.
    - therein 8y ago
      You're correct. Lamport has joined MSR in 2001 right after publishing "Time, Clocks, and the Ordering of Events in a Distributed System" and has been there ever since. I am not sure if he is still at the MV office but he was one of the reasons why MSR kept a presence in MV for a while.
      - lou1306 8y ago
        Actually "Time, Clocks..." is a paper from the late 70s. Maybe you were thinking of the Paxos paper, "The Part-Time Parliament" (1998)?

cdiddy2 8y ago

I believe bitcoins proof of work has been formally verified, however I can't find a source for that. There is also this https://iohk.io/research/papers/#9BKRHCSI https://iohk.io/research/papers/#9BKRHCSI that claims to be formally verified Proof of Stake.

davidgerard 8y ago
Unless you're actually a computer scientist following the area ... all claims of solving the "blockchain trilemma" - decentralisation, security and efficiency - should be ignored unless and until they have an implementation to show you, and it survives the hostile Internet. Promises are cheap. e.g. IOHK is behind Cardano/ADA, which has a marvellous white paper making all sorts of mathematical promises ... and still runs off a central node. In this case, it appears to be a system for private blockchains, i.e. a system with central administration. All "consensus" algorithms in this case are variants on taking turns - further elaboration is security theatre, given that attacking the system to that extent would go well beyond the legal agreements to be allowed to participate in the first place.
- cdiddy2 8y ago
  Luckily I am a computer scientist however it is extremely hard to keep up with everything going on in the blockchain space. There must be some validity behind the idea of weighted random turn-taking though since it is similar to how the next version(serenity) of ethereum will work based
  - AgentME 8y ago
    I think the difference is how they choose whose turn it will be next. There's a big difference between a central authority picking people to take turns, and what Ethereum is working on.

zonotope 8y ago

We completely agree with you that, in general, you don't want to attempt to create an entirely new consensus mechanism. As you know, there are generally only 2 (perhaps 3) broad categories of byzantine tolerant consensus that boil down to PBFT and Nakamoto consensus. Ours is a flavor of PBFT designed to reduce message complexity. We also draw from Casper in order to get the incentives and game theory right which would not be considered part of the consensus algorithm traditionally, but must be considered in the DLT space. We're not really reinventing the wheel but rather adapting some interesting research to new problem set (which is consensus, without total ordering). We also plan on fully vetting and formally verifying our implementation before we move into production.

davidgerard 8y ago
So what's your system's threat model? What will this achieve that a centralised database and existing legal structures and agreements won't? (Assume I know the area and you can go into depth. However, remarkable claims will need a production system - anyone can and does claim anything's coming in "six months, for sure" - and an explanation of how you've achieved something that your many, many competitors haven't.)
lifty 8y ago
There is a new consensus algorithm called Avalanche, which apparently starts a new, 3rd category. You can read the white paper here: https://ipfs.io/ipfs/QmUy4jh5mGNZvLkjies1RWM4YuvJh5o2FYopNPVYwrRVGV https://ipfs.io/ipfs/QmUy4jh5mGNZvLkjies1RWM4YuvJh5o2FYopNPV...
- tobowers 8y ago
  Absolutely. That’s the “perhaps 3” part of the above. Avalanche is really interesting. Can’t wait to see Ava.
- Geee 8y ago
  From a quick glance, isn't this somewhat similar to what Nano is doing? Nano does balance-weighed voting on conflicting blocks via gossip until the network arrives at consensus. https://nano.org/en/whitepaper https://nano.org/en/whitepaper

kenhwang 8y ago

Hell, people even have a hard time correctly implementing the handful of provably correct consensus algorithms that already exist. Just look through the issues section of every raft implementation.