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    Author Topic: Security analysis of PoW/PoS hybrids with low PoW reward  (Read 13313 times)

    • mgburks77
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    April 02, 2014, 03:40:08 PM
     #121
    Quote from: tacotime on April 02, 2014, 02:38:04 PM
    Quote from: mgburks77 on April 02, 2014, 02:35:57 PM
    Quote from: tacotime on April 02, 2014, 02:29:10 PM
    Quote from: mgburks77 on April 02, 2014, 02:14:50 PM
    What if everyone else IS NOT mining both?

    As soon as someone doublespends successfully on the network using the current PoS protocol, any node that is even modestly intelligent is going to switch to a more belligerent protocol that better defends the value of their coins.  Then you run into this problem.

    OK, but can they doublespend if some miners are already only doing PoW mining for a hybrid PoS coin?

    No, so long as the PoW difficulty is high enough to actually secure the network.  This requires subsidy (block reward) to be high enough to justify lots of people mining the chain.  Hence why PeerCoin works.

    Hi Tacotime, thanks for the information! I notice you have an ad in your signature that describes a PoS/PoW hybrid.

    Have you been able to resolve the issue with that coin?

  • tacotime
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    April 02, 2014, 03:42:41 PM
     #122
    Quote from: mgburks77 on April 02, 2014, 03:40:08 PM
    Hi Tacotime, thanks for the information! I notice you have an ad in your signature that describes a PoS/PoW hybrid.

    Have you been able to resolve the issue with that coin?

    It's a very different system; basically PoS miners vote on every PoW block to verify the contents, and PoW blocks are validated one block at a time.  PoS miners are given complete control over the contents of PoW blocks and whether or not the PoW miner gets rewards.

    This is a *really* experimental incentives system and it might do crazy things yet.  The Bitcoin core devs I've talked to are wary of it doing things I haven't predicted.  Additionally, it relies heavily on PoW (which I think is a good and reasonably fair distribution system).  But it does not have the "nothing at stake" forking issue.

    It's more comparable to a blockchain with "two factor authentication" for every PoW block, to ensure that miners aren't putting weird transactions into the network or are simply not including transactions.
    Code:
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  • omahapoker
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    April 02, 2014, 03:56:21 PM
     #123
    I've been a MINT investor from the start. go most on my MINT at 8

    today i told them I sold half my stake and keeping it BTC. first thing i thought was just stick it in blackcoin.

    but from what ive seen fromthe exchanges market has become the last 2 months i'm just sticking with BTC.


    i wished they was a bigger response from MINT people.



    people know i never bash MINT, but we have to address issues like this.

  • mgburks77
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    April 02, 2014, 03:58:55 PM
     #124
    Quote from: tacotime on April 02, 2014, 03:42:41 PM
    Quote from: mgburks77 on April 02, 2014, 03:40:08 PM
    Hi Tacotime, thanks for the information! I notice you have an ad in your signature that describes a PoS/PoW hybrid.

    Have you been able to resolve the issue with that coin?

    It's a very different system; basically PoS miners vote on every PoW block to verify the contents, and PoW blocks are validated one block at a time.  PoS miners are given complete control over the contents of PoW blocks and whether or not the PoW miner gets rewards.

    This is a *really* experimental incentives system and it might do crazy things yet.  The Bitcoin core devs I've talked to are wary of it doing things I haven't predicted.  Additionally, it relies heavily on PoW (which I think is a good and reasonably fair distribution system).  But it does not have the "nothing at stake" forking issue.

    It's more comparable to a blockchain with "two factor authentication" for every PoW block, to ensure that miners aren't putting weird transactions into the network or are simply not including transactions.
    Is there a projected release date or is it totally experimental? 

  • tacotime
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    April 02, 2014, 04:01:39 PM
     #125
    Quote from: mgburks77 on April 02, 2014, 03:58:55 PM
    Is there a projected release date or is it totally experimental? 

    Hopefully testnet within 2-5 months or so, then mainchain launch after the testnet seems stable.
    Code:
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  • mgburks77
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    April 02, 2014, 04:10:02 PM
     #126
    Quote from: tacotime on April 02, 2014, 04:01:39 PM
    Quote from: mgburks77 on April 02, 2014, 03:58:55 PM
    Is there a projected release date or is it totally experimental? 

    Hopefully testnet within 2-5 months or so, then mainchain launch after the testnet seems stable.

    Interesting. Thanks for the info!!! Cool

  • virtualfaqs
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    April 02, 2014, 07:53:33 PM
     #127
    Sheesh. Wish I saw this thread when it was first posted. For someone running around MINT & BC thread, I'm still missing info.  Undecided
    https://twitter.com/virtualfaqs
    Looking for altcoin pump advice? Then follow me.

  • stormia
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    April 02, 2014, 09:20:23 PM
     #128
    Thank you for your help Blackcoin community, you know which people you are (rat4, Soepkip, etc). Perhaps now we can put our differences aside and work together or at the very least coexists as pure PoS coins.

    Quote from: mintcointeam on April 02, 2014, 09:15:15 PM
    Update on the potential security issues mentioned earlier.

    As a cautionary measure and since MINT does not really need PoW, we have decided to get rid of the PoW. We don't want to take any security risk.
    And since our ego is less important than your hard earned money, we won't have any problem to be thankful to another coin dev if it appears he has helped to increase MintCoin's security.

    For now, a new wallet is available and this is a mandatory update!
    https://mega.co.nz/#!YI4DETrC!0Cy_PFqWkLF52Ic_Hoo-5v_oyUGWa2R4dcIvlX1S2H0

  • brokedummy
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    April 02, 2014, 09:51:01 PM
     #129
    Quote from: brokedummy on March 31, 2014, 07:55:47 PM
    Not really a big deal, if it is an issue just fork it to not accept any more POW blocks.

    Looks like I called it on the first page. Thanks rat4 for exposing the flaw and not leaving anybody with a bag of unconfirmed mints. Good guy dev makes competing coin more secure.

  • stormia
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    April 02, 2014, 10:19:35 PM
     #130
    Quote from: brokedummy on April 02, 2014, 09:51:01 PM
    Quote from: brokedummy on March 31, 2014, 07:55:47 PM
    Not really a big deal, if it is an issue just fork it to not accept any more POW blocks.

    Looks like I called it on the first page. Thanks rat4 for exposing the flaw and not leaving anybody with a bag of unconfirmed mints. Good guy dev makes competing coin more secure.

    +1. And sorry for being rude and assumptious with my initial post of this thread, it was uncalled for.

  • damiano
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    April 03, 2014, 04:54:57 AM
     #131
    Hmm I know what I'm trying out tomorrow morning

     Roll Eyes

  • mchrist152
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    April 03, 2014, 03:16:18 PM
     #132
    Were not there other ways to fix this issue?

    For example, if the problem is PoW difficulty gets too low, why not set a minimum difficulty for PoW mining?

    Or, do not allow two PoW blocks in a row.  Enforce that a least one PoS block is between each PoW block?

    I think those fixes might be better than to just eliminating PoW altogether.  Just trying to understand this better.

  • noerc
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    April 03, 2014, 04:40:16 PM
     #133
    Quote from: mchrist152 on April 03, 2014, 03:16:18 PM
    Were not there other ways to fix this issue?

    For example, if the problem is PoW difficulty gets too low, why not set a minimum difficulty for PoW mining?

    Or, do not allow two PoW blocks in a row.  Enforce that a least one PoS block is between each PoW block?

    I think those fixes might be better than to just eliminating PoW altogether.  Just trying to understand this better.

    If you set a lower bound to the difficulty that is much larger than the actual difficulty level then it is absolutely not profitable for any miner to generate PoW blocks anymore which basically leads to the same problem.

  • mgburks77
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    April 03, 2014, 04:47:44 PM
     #134
    Quote
    Or, do not allow two PoW blocks in a row.

    What about this idea? Can it be implemented? And is it worth doing?

  • sidhujag
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    April 03, 2014, 04:52:58 PM
     #135
    Quote from: noerc on April 03, 2014, 04:40:16 PM
    Quote from: mchrist152 on April 03, 2014, 03:16:18 PM
    Were not there other ways to fix this issue?

    For example, if the problem is PoW difficulty gets too low, why not set a minimum difficulty for PoW mining?

    Or, do not allow two PoW blocks in a row.  Enforce that a least one PoS block is between each PoW block?

    I think those fixes might be better than to just eliminating PoW altogether.  Just trying to understand this better.

    If you set a lower bound to the difficulty that is much larger than the actual difficulty level then it is absolutely not profitable for any miner to generate PoW blocks anymore which basically leads to the same problem.
    Most of the premined pos coins are not profitable to mine pow anyway.. 1 coin per block at 20 sats.

    I figure the devs were either lazy or dont understand the code enough to fully remove pow thus they just set the reward to the minimum so its quick and dirty. In reality if the pow is not helping with block authentication it
    should be removed... surely devs knew if a hybrid approach was beneficial or not to the security against attacks that are common sense with both pow and pos?

  • noerc
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    April 03, 2014, 05:32:33 PM
     #136
    Quote from: mgburks77 on April 03, 2014, 04:47:44 PM
    Quote
    Or, do not allow two PoW blocks in a row.

    What about this idea? Can it be implemented? And is it worth doing?

    Wouldn't this be the same as raising the PoW difficulty to the level that only one PoW would be generated in the time one PoS block gets generated? I don't really see the difference.

  • mgburks77
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    April 03, 2014, 05:36:08 PM
     #137
    Quote from: noerc on April 03, 2014, 05:32:33 PM
    Quote from: mgburks77 on April 03, 2014, 04:47:44 PM
    Quote
    Or, do not allow two PoW blocks in a row.

    What about this idea? Can it be implemented? And is it worth doing?

    Wouldn't this be the same as raising the PoW difficulty to the level that only one PoW would be generated in the time one PoS block gets generated? I don't really see the difference.

    it wouldn't require that minors participate for a low block reward, yet you receive the same result

  • omahapoker
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    April 03, 2014, 08:04:11 PM
     #138
    I'm a MINT investor and want to thank you guys for exposing the issue. and no destroying the coin


     i never bash people and dont know why MINT people did.


    thanks again.

  • danbi
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    May 24, 2014, 08:23:55 AM
     #139
    I am trying to qualify the claim made by the OP, that MintCoin had no PoS block in a hour.

    What is the proof that this was because of the "attack", or there was just nothing to stake during that hour?

    Also, how would an PoS block in a hybrid coin "invalidate many PoW blocks"? The PoW and PoS chains are pretty much independent, no?
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  • TotalPanda
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    March 04, 2015, 04:32:59 PM
     #140
    Hi

    Is a classic standart non-POS sCrypt (end of POW) easily attackable ?
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