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     5 years ago  

    Ok, but the honest consensus is not made by >1/2 majority. Consensus in permissioned systems is made by at least 2/3! In Steems dPOS-BFT it is the longest chain rule, where the last irreversible block (LIP) is the block where >2/3< of the Witnesses have jumped on. With up to 1/3 byzantine Nodes you can "only" create a minority fork. In a round-robin scheduling like Steem where a block is added every 3 seconds (which is dertermined by network delay/speed of light) a malicious 1/3 minority can only add blocks every 9 seconds to their "wrong" chain, while the 2/3 honest majority adds blocks still every 6 seconds. When you get more than 1/3 it becomes undecidable. This is why the security assumption of permitted chains is [(n-1)/3] or in other terms for f faulty nodes you need 3 f + 1 aka >2/3+1< honest nodes.

    So there is no 51% attack vector when you can violate the correctness with only >33%. When 51% of the stake can vote more than 1/3, then this is a dumb design decision and not a 51%-attack. The 51%-attack vector in open=asynchronous systems like Bitcoin is due to the laws of physics (Fisher-Lynch-Peterson Impossibility Theorem). When you want a synchronized system which is not subject to the FLP-problem you need a fixed direct or indirect quorum like Steem or Eos but then you have no >1/2 anonymous majority election.

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     5 years ago (edited) 

    Thanks for the explanations. That was quite enlightening and I learned something new. 👍

    However, I'm more worried about the ability to make hard and soft forks and therefore change the rules. Including the rules you just explained.

    The very real attack which we just had — twice. First the old witnesses locking @justinsunsteemit's funds. That was a bit hasty.

    And then Justin by retaliating by taking over the whole chain with sock puppet witnesses. Which is even worse. And makes me wonder if I should retract me delegations and prepare for power down. Because if Justin gets his way and becomes “benevolent blockchain dictator for 6 weeks” I don't think I don't want to stay.

    We all know how those “benevolent dictatorships” end each and every time.

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     5 years ago  

    We all know how those “benevolent dictatorships” end each and every time.

    yeah true the community has to react anyways. We are not here for centralisation. 👍